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LONG PAPER ON “CONSTRUCTION OF PEB HANGAR WITH ANNEXE AND SERVICES AS PART OF MODERNISATION OF AIRPORT INFRASTRUCTURE By ZUBER AHMED PGPPM MODULE:M-58 REGN. NO.211-07-31-9628-2131 NATIONAL INSTITUTE OF CONSTRUCTION MANAGEMENT AND RESEARCH SODE, PUNE 211-07-31-9628-2131
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DECLARATION
I declare that the long paper entitled “Construction of PEB hangar with annex and services as part of modernization of airport infrastructure” is the bonafied work carried out by me, under the guidance of Prof. P. Nagarjuna, further I declare that this paper has not been previously formed the basis of award of any degree, diploma, associate-ship or other similar degrees or diplomas, and has not been submitted anywhere else.
Date:
ZUBER AHMED PGPPM MODULE:M-58 REGN NO. 211-07-31-9628-2131 NICMAR SODE,Pune
211-07-31-9628-2131
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DECLARATION
I declare that the long paper entitled “Construction of PEB hangar with annex and services as part of modernization of airport infrastructure” is the bonafied work carried out by me, under the guidance of Prof. P. Nagarjuna, further I declare that this paper has not been previously formed the basis of award of any degree, diploma, associate-ship or other similar degrees or diplomas, and has not been submitted anywhere else.
Date:
ZUBER AHMED PGPPM MODULE:M-58 REGN NO. 211-07-31-9628-2131 NICMAR SODE,Pune
211-07-31-9628-2131
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CERTIFICATE This is to certify that the long Paper entitled “Construction of PEB hangar with annex and services as part of modernization of airport infrastructure” is the bonafied work carried out by Mr. Zuber Ahmed, in partial fulfillment of the academic requirements for the award of Post Graduate Program in Project M a n a g e m e n t ( P GP P M ) . T h i s w o r k h a s b e e n c a r r i e d o u t u n d e r m y guidance and supervision.
Date: Prof. P. Nagarguna NICMAR SODE, Pune
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ACKNOWLEDGEMENT I express my sincere and heartfelt thanks to Dr. J.C. Edison, Dean NICMAR SODE, Pune and Dr. Arun Kumar Co-Ordinator SODE, Pune, for giving me an opportunity to undertake this research subject for preparing long paper.I also express a deep sense of gratitude to Prof. P. Nagarjuna, faculty, NICMAR, Pune for his constructive support, constant encouragement, guidance and channelizing my efforts in the right direction without which this long paper would not have attained its present form.I also thank librarians of NICMAR, Pune, for giving us access to the facility whenever required.I would also like to thank my family and friends who encouraged us constantly throughout the research period.
(Zuber Ahmed)
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ABSTRACT: Hangars are always considered as prestigious projects d u e t o t h e i r operational use, constructional aspects and structural comp lexi ty . Due to rece nt advancement in concepts, materials and construction techniques a revolutionary change could be seen world over in conceiving industrial structures like Hangars, Garages, Workshops, etc not merely as covered shed for housing aircrafts, specialist vehicles, equipments, etc but as Architectural M a r v el s a s we l l . Th i s co nc e p t u al change could be seen in almost all ports, workshops and factory projects. Modern hangars are large sized with respect to span and height and require most modern facilities to suit the modern days aircrafts. A Hangar project constructed during modernization of ai rpo rt in fra st ruc tu re pro jec t was als o conceived with state-of-the-art concept of Pre Engineered Building using all modern materials and techniques which no doubt makes this an ideal project in the category of A Complex Architectural and Engineering Marvel. The project d e m a n d e d u s e o f m o d e r n t e c h n i q u e s a n d m a t e r i a l s w i t h h i g h d e g r e e of construction precision, excellent quality control, constant supervision through experienced executives and regular monitoring up to the highest level. The paper cov er the case study of this hangar constructed as a large span Pre - Engineered Rigid Frame Structure. The paper shall depict the evolution of Steel Hangar Structures through a Gallery of hangar constructed in India over last five decades. Due to revolutionary change in concept of design, construction techniques and materials i t is no w possible to provide large span hangars at considerably faster rate and lighter in wei ght . Req ui rem ent of Han gar use rs hav e als o cha nge d o ve r t he y ea rs f r om s i m p l e , s m a l l size d hang ar for hous ing s m a l l a i r c r a f t s u s u a l l y c o n c e i v e d a s industrial sheds to considerably large sized hangars with all modern facilities like repair shops, office accommodations for the technical staff, testing labs, etc in the form of side annex. The executives involved in the execution of the project had varied and unique experiences and challenges during execution of the work which shall be presented in this paper. The use of steel structures in various types of buildings/accommodation is not uncommon, e.g.aircraft hangars,covered garages,storage accommodation auditoriums, towers,etc. Most of these structures commonly consist of elements s u c h as beams, columns, trusses & portal frames which are basically two-dimensional from the point of view of analysis as well as design. Inter-connecting members in the third dimension (for example pur li ns) are usual ly of sec ondar y character, present merely for the purpose of transferring load and not contributing t o t h e r i g i d i t y o f t h e s t r u c t u r e . A structural arrangement in which there is integrated load 211-07-31-9628-2131
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sharing in all the three directions will obviously have more advantage, since every part of the structure makes an effective contribution. Such structures are known as Space Structures and are gaining importance in its use all ov er the world due to various advantages over traditional structures. The s tud y s h a l l p r e s e n t s o m e i n s i g h t i n t h e a d v a n t a g e s o f u s e o f P E B s y s t e m f o r h a n g a r construction as part of any major airport modernization project.
TABLE OF CONTENTS Title page
1
Certificate
2
Declaration
3
Acknowledgement
4
Abstract
5
Contents
6
List of Tables List of figures CHAPTER I. INTRODUCTION.
Page No. 7
II. NEED OF PEB WITH RESPECT TO CONVENTIONAL R.C.C. STRUCTURE.
11
III. COMPLETE HISTORY AND EVOLUTION OF PEB STRUCTURE. IV. CONCEPT AND METHODOLOGY OF PEB STRUCTURE SYSTEM.
13
V. IMPORTANCE OF PEB STRUCTURE SYSTEM VI. ADVANTAGES AND LIMITATIONS OF PEB STRUCTURE SYSTEM.
28 31
VII.CASE STUDY WITH APPLICATIONS OF THE PEB SYSTEM. VIII.SUMMARY FINDINGS, CONCLUSIONS AND RECOMMENDATIONS.
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76
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CHAPTER - I INTRODUCTION 1.1 GENERAL: Today, the Indian construction industry is in full bloom and so is the real estate sector. With the demand for both residential and commercial segments increasing, there is a need to get the projects completed on time so as to minimize extra costs. Also, with a major emphasis being laid on the infrastructure as well as the current boom in the commercial buildings, developers are now looking towards other options so as to meet the deadlines and curtail the expenditure. This is where the prefabricated or the prefab industry comes in. To name it as the 'fastfood' of construction industry would not be wrong as this has now come across as the most viable option for instant completion of projects for various endeavors. The pre-engineered building technology, which entered the Indian construction arena during the late nineties has over a period of time gained widespread acceptance among the end users and is steadily making inroads in the construction and infrastructure projects across the country. This is largely due to the fact that PEB-based construction technique is offering the most innovative, hi-tech, and quicker methods of construction ensuring efficient, cost effectiveness and speedy completion of projects, which is perhaps the pre-requisite for the construction sector to meet tight construction schedules and demanding deadlines. Drawing overwhelming response from construction and infrastructure builders, due to heightened construction activities currently going on across the country, the global players in the PEB industry have not just set up their shops but also launched multiprong brand building initiatives by holding technical seminars, exhibitions and events displaying their products to popularize the benefits of PEB brands. In the process, they have been able to create awareness informing people that under the PEB systems buildings are built keeping the, eco-friendly environs, aesthetic value, designing, durability, energy efficiency, cost effectiveness and speedy completion of the construction projects in mind. With increased emphasis on the on-going green buildings ensuring sustainable construction, the PEB structures are created with a high proportion of recycled content making them lighter by about 30% than the conventional steel buildings. They contain higher degree of fire and dust resistant and are maintenance free. As a result today the PEB system is the most preferred choice among the architects, builders, developers 211-07-31-9628-2131
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and industrialists. The experts in the field are unanimous in their view that the PEB industry in India is currently heading to achieve growth trajectory of about 35% per annum. Kirby Building Systems is one of the world's largest producers of quality steel buildings and has been operational since 1976. The company recognized the need of customers and the potential in the Indian market and was the first to set up a mega manufacturing facility in India near Hyderabad in 1999. Since then it aggressively promoted the use of PEB concept in India. Generally, steel structures and specifically PEBs market have, on the domestic front, surpassed the GDP from both the Indian steel industry and the Indian construction sector. Over the next 2-3 years, the industry is optimistic about a 15 to 20% annual growth, resulting in doubling of the market over five years.The sector is going international as companies move to tie up with multinationals for upgrading offerings to their customers. "Technical association and JV's with leading PEB companies in Europe, USA and Middle-east are quite useful in terms of engineering excellence, product quality and superior products range.
1.2 BACKGROUND: Construction is an activity, which cuts across almost all sectors of the economy. It is an activity, which transforms various resources into economical and social infrastructure and facilities. It includes all phases of the process of transformation viz. planning, designing, financing, procurement, construction, operations etc. The construction sector is an essential contributor to the process of development. It usually accounts for three percent to eight percent of a developing country’s Gross Domestic Product. In the context of liberalization of the Indian economy, domestic and foreign investment is likely to flow into various infrastructure projects in a big way. This is more so, taking into consideration the conferring of industry status to the construction sector by the Government of India. Fluctuations in construction demand affect the economy in many ways. They affect the demand for labour and materials as well as the lag time taken to supply the industry’s output. Backward and forward linkages affect the working of a wide range of operations. In fact, construction industry has been ranked among the top four out of twenty economic sectors in terms of inter sectoral linkages. These linkages together with a high ‘value added output’ ratio, indicates that construction provides a substantive growth stimulus throughout the economy. Its importance as an agent for development is enhanced by its ability to provide gainful employment for a large number of people. 211-07-31-9628-2131
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1.3 OBJECTIVES OF STUDY: The paper shall depicts the evolution of Steel Hangar Structures through a Gallery of hangar constructed in India over last five decades. Due to revolutionary change in concept of design, construction techniques and materials it is now possible to provide large span hangars at considerably faster rate and lighter in weight. Requir ement of Hangar user s have also chang ed ov er th e ye ar s fr om si mp le , sm al l si zed ha ng ar fo r housing small aircrafts usually conceived as industrial sheds to considerably large sized hangars with all m o d e r n f a c i l i t i e s l i k e r e p a i r s h o p s , o f f i c e a c c o m m o d a t i o n s f o r t h e tech nical staff, testing labs etc in the form of side annex. The executives involved in the execution of the project had varied and unique experiences and challenges during execution of the work which shall be presented in this paper. So the objectives of the study can be summarized as: To understand Evolution of technologi es in construction of l a r g e hangars over past 05 decades. To analyze Latest technology i.e. PEB system being used in Ha ng ar construction, and its advantages and importance over conventional system. To Prepare a case study of a Large span Hangar covering all relevant aspects of planning, material and construction management etc.
1.4 LITERATURE REVIEW: There is a lot of literature available on steel structure as the steel is the main construction material world over. However in India we have mostly concrete intensive construction instead of steel intensive construction due to cheap availability of labour. PEB system being new concept to India not many books are available on the subject, however a lot of material and data is available on internet and write-up available in structural journals and relevant IS codes like BIS-800 etc. has been used.
1.5 METHODOLOGY OF STUDY: The study requires detailed study of conventional system of Hangar Construction and the PEB system and their applicability. The following method of study has been adopted for conducting the study: Literature review regarding conventional and PEB system of Hangar construction from various published material. Interviews with experts in the field of PEB steel construction. Websites related to the PEB construction. Case study after discussion and collection of data for an already completed project. 211-07-31-9628-2131
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1.6 SCOPE AND LIMITATION OF STUDY: The study shall present some insight in evolution of technologies in construction of large hangars over past 05 decades and the advantages of use of PEB system for hangar construction as part of any major airport modernisation project. The project demanded use of modern techniques and materials with high degree of construction precision, excellent quality control, constant supervision through experienced executives and regular monitoring up to the highest level. The study shall cover the case study of this hangar constructed as a large span Pre-Engineered Rigid Frame Structure. Although, the scope of the subject is enormous, the study shall have following limitation: Application of the proposed study is mainly suitable to steel intensive construction Time and monetary constraints may limit the depth of penetration of the study. The data required for case studies are many times confidential which limits the study to certain extent.
1.7 SCHEME OF CHAPTERIZATION: The study shall consist of following 08 Chapters: In Chapter 1 will be an introduction chapter. This chapter highlights the importance of construction sector. It also deals with the importance of the concept and study of PEB structures. In Chapter 2 will be an introduction to PEB providing the need of PEB with respect to conventional R.C.C. Structure. In Chapter 3 will give the complete history and evolution of PEB structure. In Chapter 4 will give the detail description of concept and methodology of PEB structure system. In Chapter 5 will give the detail description of importance of PEB structure system. In Chapter 6 will give the detail description of advantages and limitations of PEB system. In Chapter 7 will be case study giving the detail description of Application of the PEB system. I have covered the case study of a 70 meter clear span hangar constructed at Airport under modernization of airport infrastructure project covering following issues: (a) Project definition concept and scope and cost. (b) Project institutional framework with role and responsibility matrix. (c) Project planning and phasing. (d) Project execution and related issues. In Chapter 8 will be summary findings, conclusions and recommendations. 211-07-31-9628-2131
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CHAPTER - II NEED OF PEB WITH RESPECT TO CONVENTIONAL R.C.C. STRUCTURE 2.1 WHY PEB SOLUTION: •
•
• • •
Such buildings are detailed and designed in advance and manufactured in a quality controlled environment. Every manufacturing operation is carried out through advanced technologies such as sophisticated welding techniques, standardization of components, etc. Pre engineered construction system also facilitates mass production. The construction is faster than the conventional method. Such buildings are detailed and designed in advance and manufactured in a quality controlled environment.
2.2 NEED OF PEB: India has the second fastest growing economy in the world and a lot of it, is attributed to its construction industry which figures just next to agriculture in its economic contribution to the nation. In its steadfast development, the construction industry has discovered, invented and developed a number of technologies, systems and products; one of them being the concept of Pre-engineered Buildings (PEBs). As opposed to being on-site fabricated, PEBs are delivered as a complete finished product to the site from a single supplier with a basic structural steel framework with attached factory finished cladding and roofing components. The structure is erected on the site by bolting the various building components together as per specifications. PEBs are developed using potential design software. The onset of technological advancement enabling 3D modeling and detailing of the proposed structure and coordination has revolutionized conventional building construction. PEBs have hit the construction market in a major way owing to the many benefits they possess. They exemplify the rising global construction, technology and while they oppose the practice of conventional building construction they simultaneously have taken it to a higher level too. Worldwide, they are a much used concept with studies revealing that 60% of the non-residential low-rise building in USA are pre-engineered; for India the concept has been gaining momentum and the scope of growth is guaranteed looking at India's huge infrastructural requirements. Studies already validate that India has the fastest growing market in the PEB construction segment. The scope of using PEBs ranges from showrooms, low height commercial complexes, industrial 211-07-31-9628-2131
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building and workshops, stadiums, schools, bridges, fuel stations to aircraft hangers, exhibition centers, railway stations and metro applications. While we are still to see PEBs being used in residences in India, one can see their optimal use in warehouses, industrial sheds, sports facilities, etc. The Delhi Airport and the metro projects of Delhi, Bengaluru and Mumbai are also examples of PEB applications. A PEB system in totality consists of a structural system, sandwich panels, roofing, exterior facade and accessories. The PEB concept based on a proper design usually involves a thorough project information data including complete details like building parameters, grade of steel, secondary member details, paint coat on steel members, welding, anchor bolts steel grade, roof & wall liner / panel, insulation, sky light, gutters, facia, mezzanine, ridge ventilation to name a few. Following this input, the drawings for General Arrangement, Anchor Bolt & Template Fabrication & Erection are prepared.
2.3 COMPARISON PEB V/S CONVENTIONAL: PEB Buildings
Conventional Building
Aesthetically appealing appearance.
Special aesthetic design required
Reduced time because of international
Increased design time due to scratch and
design standards & codes using standard
availability of less design aids.
sections and connections. Higher resistance to seismic forces due
Rigid heavy weight structures not suitable
to low weight flexible frames.
for seismic zones.
30% less PEB steel structures weight
High weight due to excessive safety factor
through efficient use of steel.
and heavy RCC work.
Factory controlled quality.
Every project to be fabricated at site.
Lower initial cost of PEB steel buildings
Special design and features developed for
(cost per square meter about 30% less
each project at higher costs.
than the conventional) and faster delivery Simple Foundation, easy to construct and
Extensive heavy foundation.
light weight of PEB structures. Span size may be designed up to 40m.
Span size with limitation of beam width may be limited to 10-15 m.
Average delivery time 6-8 weeks.
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Average delivery time 22-28 weeks.
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CHAPTER - III COMPLETE HISTORY AND EVOLUTION OF PEB STRUCTURE SYSTEM 3.1 HISTORY OF PEB STRUCTURE SYSTEM: In early 1900s - Concept of metal buildings originated in U.S. - Simple industrial structures using truss rafters, straight columns, sectional roofs & wall. - Wedge pins for connections.
In 1940s - Mass production of Nissen and Quonset housing and storage Modules for: - US army during world war II. - Metal building system recognized as a favourable method of construction over conventional methods.
-
-
Late 1950s & early 1960s Computerized design allowed buildings to be tailored to individual Customer requirements. Roll forming lines allowed continuous span cold rolled Z-purlins. Colour coated panels and factory insulated panels improved Architectural appearance. Major increase in design possibilities contributed to the boom in metal buildings. The term Pre-Engineered Buildings came into existence. In 1990s - Today Pre Engineering metal buildings dominate the low rise building market. Precision roll forming lines for the cladding and sectional members. Auto production lines for the structural sections. High quality paint system for steel and cladding. MBMA statistics show, About 60% of low rise industrial and commercial in the U.S.A. use the P.E.B. system.
3.2 HANGARS AS PEB STRUCTURE SYSTEM: Hangars are always considered as prestigious projects due to their operational use and constructional and structural complexity. Due to recent advancement in the concepts, materials and construction techniques a revolutionary change could be seen world over in conceiving industrial structures like Hangars, Garages, Workshops etc not merely as 211-07-31-9628-2131
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covered shed for housing aircrafts, specialist vehicles, equipments etc but as Architectural Marvels as well. This conceptual change could be seen in almost all the air ports, workshops and factory projects. Modern hangars are large sized with respect to span and height and require most modern facilities to suit the modern days aircrafts. Hangar project at Bangalore was also conceived with state-of-the-art concept of PreEngineered Building using all modern materials and techniques which no doubt makes this an idle project standing in the category of A Complex Architectural and Engineering Marvel. The project demanded use of modern techniques and materials with high degree of construction precision, excellent quality control, constant supervision through experienced executives and regular monitoring up to the highest level. In this project executives have had varied and unique experiences and challenges during execution of work which have been documented in this report. Pre-engineered buildings are the state-of-the-art steel solution to developing an efficient and cost-effective infrastructure. PEB’s offer ultimate design flexibility and an extremely short construction time (right from initial design to completion). They are supplied as a fully finished product along with steel structure, building accessories and roof cladding. They require no onsite fabrication or welding – they can simply be bolted together as per specifications. PEBs are best suited for warehouses, sports halls, factories, workshops, distribution centers, cold storages, supermarkets, aircraft hangars or any ground + two-storey construction.
3.3
EVOLUTION OF STEEL STRUCTURE AND HANGARS IN INDIA:
In India, the use of steel structures in various types of buildings/accommodation is not uncommon, e.g. aircraft hangars, covered garages, storage, auditoriums, towers, etc. Most of these structures commonly consist of elements such as beams, columns, trusses & portal frames which are basically two dimensional from the point of view of analysis as well as design. Interconnecting members in the third dimension ( for example purlins) are usually of secondary character, present merely for the purpose of transferring load and not contributing to the rigidity of the structure. A structural arrangement in which there is integrated load sharing in all the three directions will obviously have more advantage, since every part of the structure makes an effective contribution. Such structures are known as Space Structures and are gaining importance in its use all over the world due to various advantages over traditional structures. Among various structures developed by Civil Engineers in aircraft hangars are considered important from operational point of view. These hangars are of span varying from 30m to 70m and cover large spaces. Traditional arrangement for covering such structures with trusses and purlins was being adopted in MES till recent years. The 211-07-31-9628-2131
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requirement of steel in such structures was as high as 100 kg/m2 to 150 kg/m2 depending upon the span and spacing of trusses. The modern trends for covering large spaces with much reduced requirement of steel are Pre-Engineered Rigid Frame Structures, Space Structures and Tensile Structures. A Gallery of hangar structures constructed at Bengaluru since inception of the base can be seen in Photographs P1 to P8 for understanding the evolution of Steel Hangar Structures over last five decades. Due to revolutionary change in concept of design, construction techniques and materials it could be possible now to provide large span hangars at considerably faster rate and lighter in weight. Requirement of users have also changed during this period from simple, small sized hangar for housing small aircrafts usually conceived as industrial sheds to considerably large sized hangars with all modern facilities like repair shops, office accommodations for the technical staff, testing labs, etc in the form of side annex.
P-1 : SW TYPE HANGAR(1965) SPAN – 49.9m, HEIGHT – 9m 211-07-31-9628-2131
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P-2: LATTICE FRAME TYPE HANGAR (1965) SPAN – 28.25m, HEIGHT – 8.5m
P-3 : TRADITIONAL TRUSS TYPE HANGAR (1998) SPAN 70m, HEIGHT -11m
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P-4, P-5:BOWSTRING – GIRDER TYPE HANGAR (1993) SPAN – 60m HEIGHT- 11m 211-07-31-9628-2131
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P-6:LIGHT WEIGHT TWIN HANGAR-TUBE SECTIONS (1996) SPAN 35m HT.- 6m
P-7 : PRE ENGINEERED BUILDING HANGAR (2003) SPAN 40m x 3, HEIGHT – 8m 211-07-31-9628-2131
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P-8 : PRE ENGINEERED BLDG HANGAR (2003) SPAN 60m, HEIGHT - 10m
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CHAPTER-IV CONCEPT & METHODOLOGY OF PEB STRUCTURE SYSTEM 4.1 METHODOLOGY OF PEB SYSTEM: Pre-Engineered Steel Buildings use a combination of built-up sections, hot rolled sections, cold formed elements and profiled steel sheets which provide the basic steel frame work with a choice of single skin sheeting with added insulation or insulated sandwich panels for roofing and wall cladding or brick wall. The concept is designed to provide a complete building envelope system which is air tight, energy efficient, optimum in weight and cost, and above all, designed to fit user requirement like a well fitted glove. These Pre-Engineered Steel Buildings can be fitted with different structural accessories including mezzanine floors, canopies, fascias, interior partitions etc. The building is made water-tight by use of special mastic beads, filler strips and trims. This is a very versatile building system and can be finished internally to serve any required function and accessorized externally to achieve attractive and distinctive architectural styles. It is most suitable for any low-rise building and offers numerous benefits over conventional buildings. Pre-engineered buildings are generally low rise buildings, however the maximum eave heights can go up to 25 to 30 meters. Low rise buildings are ideal for offices, houses, showrooms, shop fronts etc. The application of pre-engineered concept to low rise buildings is very economical and speedy. Buildings can be constructed in less than half the normal time especially when complimented with other engineered sub-systems. The most common and economical type of low-rise building is a building with ground floor and two intermediate floors plus roof. The roof of a low rise building may be flat or sloped. Intermediate floors of low rise buildings are made of mezzanine systems. Single storied houses for living take minimum time for construction and can be built in any type of geographic location like extreme cold hilly areas, high rain prone areas, plain land, extreme hot climatic zones etc. There are basically eight major components in a pre-engineered residential building such as : Main framing or vertical columns. Purlins, girts and eave struts. Sheeting and insulation or prefab panels. Brick & Cement Board Walls. 211-07-31-9628-2131
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Flooring. Paints and finishes. False Ceiling. Miscellaneous services.
4.1.1 MAIN FRAMING: Main framing basically includes the rigid steel frames of the building. The PEB rigid frame comprises of tapered columns and tapered rafters (the fabricated tapered sections are referred to as built-up members). The tapered sections are fabricated using the state of art technology wherein the flanges are welded to the web. Splice plates are welded to the ends of the tapered sections. The frame is erected by bolting the splice plates of connecting sections together.
4.1.2 PURLINS, GIRTS AND EAVE STRUTS: Purlins, girts and eave struts are also known as secondary cold-formed members. There is no welding involved in their preparation. They are prepared by just bending the steel coil giving it the desired shape (Z-shape for purlins and girts, and C-shape for eave struts). Purlins: Purlins are the secondary members which are for supporting the roof panels & wall cladding.
4.1.3 PANELS AND INSULATION: Single skin profile or ribbed steel sheets are used as roof and wall sheeting, roof and wall liners, partition and soffit sheeting. The steel sheets are generally made from steel coils. Minimum thickness of steel coils used is 0.5 mm high tensile steel. The steel sheets are normally of zincalume or galvanized bare and permanently colour coated or plain which can be coated at site after installation. These buildings can be properly insulated by providing fibrous insulation slabs / rolls of non- combustible Rockwool, Aluminium foil laminated, placed over a metal mesh bed created between the purlins, and then the roofing steel sheet fixed over it. The siding walls can also be insulated by providing a double skin profile or ribbed steel sheet or cement board sheets on inner side wall cladding having Rockwool Insulation slab sandwiched in between and held in position with the help of ‘Z’ spacers in between the two steel sheets. In similar pattern a double skin insulated roofing system can also be erected. The cement boards will give a conventional white finish after painting.
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Another alternative is to provide pre-fabricated insulated panels, which comprises of two single skin panels (plain steel sheets galvanized / zincalume colour coated) with polyurethane foam insulation in between. These panels are intended for use as thermally efficient roof and wall claddings for buildings e.g. in high altitude areas and hilly terrains. Roof is of profile steel sheet with or without insulation fixed underneath. False Ceiling of particle / rigid board is fixed to a steel frame work hung from the trusses. Insulation can also placed over the false ceiling packed in polythene. Here a 2 ft. high brick wall is required to be given on the outside for protection. For walls a second alternative can be by way of normal brick work. The latest trend developed for construction of pre-fab single storeyed residential houses does not involve any steel structure (columns & purlins). The walls are constructed with profiled GI sheet of high crest height and faced with cement particle boards and the crest depths filled with either high density Rockwool or Rigid insulation material like Polyurethane Foam or Expanded Polystyrene. The roof is erected with trusses placed over the walls and profile sheet fixed to purlins and bolted to the trusses. The corners of the walls are provided with steel flashings fixed to the profiled GI sheet on both sides before fixing of the cement particle boards.
4.1.4 PAINTS AND FINISHES Normally the primary and secondary steel are coated with one coat (35 microns) of redoxide paint without any special treatment to steel. However, if some special paint has to be applied to steel in order to give better anti-corrosion properties etc. then the steel members have to be shot-blasted and then coated with the special paints. For houses inside & outside painting on walls & false ceiling is to be provided.
4.1.5 DOORS AND WINDOWS: Steel or aluminium framed doors and windows are fixed to the purlins or the supporting profiled steel either by welding or bolted to the flanges already fixed to the purlins. Proper flashings are applied wherever necessary .
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from the ceiling and false ceiling of rigid boards are either bolted or placed over the frame work.
4.1.7 PARTITION WALLS: This is usually required for residential building or offices. Partition wall comprises of two rigid boards having insulation sandwiched in between and fixed to the steel columns or supporting profiled steel and purlins. Alternatively prefab sandwich panels can also be fixed to the columns and purlins.
4.1.8 FLOORING Flooring is usually of conventional nature consisting of cement concrete. For intermediate floors metal decking sheet is fixed to purlins and concrete poured over it.
4.1.9 DESIGN CODES: Design codes that govern the design procedures and calculations are as follows :Frame members (hot rolled or built-up) are in accordance with AISC (American Institute of Steel Construction) Specifications for the design, fabrication and erection of structural steel. Light gauge cold-formed members are designed in accordance with AISI (American Iron and Steel Institute) Specification for the design of light gauge cold formed steel structural members. IS : 8750 - 1987 : Code of practice for design loads of buildings & structures. IS : 800 -1984 : Code of practice for general construction in steel. IS : 801- 1975 : Code of practice for use of Cold formed light gauge Steel Structural Members in general building Construction
4.2 ERECTION: Steel framing members are delivered at site in pre-cut sizes, which eliminates cutting and welding at site. Being lighter in weight, the small members can be very easily assembled, bolted and raised with the help of cranes. This system allows very fast construction and reduces wastage and labour requirement. These buildings can then be provided with roof decking and wall cladding with metal profile sheets and proper insulation. The framing are so designed that electrical and plumbing services are part of it and can be very easily concealed.
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For the latest developed technology on pre-fab residential house construction without steel columns & purlins, the construction method begins with grouting of ‘C’ channels to the floor on the periphery of the building. Thereafter placing 1.2mm GI profiled sheets (of high depth crest) over the ‘C’ channel and fixed with screws. Fixing of high density Rockwool or Polyurethane Foam or Expanded Polystyrene with adhesive on the crests on both sides. Then providing and fixing 8mm cement particle boards on inner side and 10mm cement particle boards on outer side of the profiled GI sheet, with screws, followed by fixing of a ‘C’ channel on top of the GI profiled sheet. Then trusses are placed over the top ‘C’ channel and purlins fixed to it at 1500mm distance. Colour coated profile steel sheets are fixed to the purlins. GI ‘T’ frame work making a grid of 600 x 600mm hung from the trusses with GI rods for false ceiling frame work and 68mm E boards are placed over it. Floors are constructed of cement concrete at a raised level for special requirements tiles can be fixed as the final finish. For kitchen and toilets, the floor and walls up to 2-3 feet is constructed or in tradition houses or normal cement finish or with tiles. For fixing of electrical accessories, grills, shelves and other miscellaneous services wooden supports are pre-fixed to the GI profiled sheet ceiling fan support is taken from the trusses. Doors & windows frames are made of steel and fixed to the profiled GI sheet with proper flashings. Rain guard covers over windows made of steel are fixed to the profiled GI sheet of walls. The gaps between the cement particle boards are filled with a putty and finally painting is done on both sides of the walls .
4.3 MAINTENANCE: In Pre-engineered Pre-fabricated steel houses the maintenance area is the roofing & cladding. Steel roofing & side wall cladding requires minimum maintenance. The roof should be inspected immediately after installation to check if cleaning of the roof has been carried out fully. It is very often seen that the drilled out metal and debris are not swept away. These can act as initiators of corrosion and lead to premature failures. In case of cement particle board walls painting required every 3-4 years. Installed roofing must be inspected atleast once a year. Any exposed metal that can rust or has rusted should be painted. Leaves, branches, and trash should be removed 211-07-31-9628-2131
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from gutters, at ridge caps and in corners. Also watch out for discharge from industrial stacks, and particulate matter and high sulphur exhaust from space heaters which could get piled up. Roof top ancillaries and air conditioning supports, drains and housing should be checked. Particular attention should be paid to add-on roof ancillaries that create new roof penetrations. Roof-top air conditioners should be installed on curbs designed to avoid pounding water. Condensate from air – conditioning and refrigeration equipment should never be allowed to drain directly on to the roof panels. The drainage contains ions from condenser coils that accelerate corrosion. In the event of a roof leak, do not indiscriminately plaster the suspected leak area with tar or asphalt or use repair tape. Water can collect under the repair material causing corrosion. Instead, have an experienced roofing foreman locate the leak, identify its cause and properly repair the roof.
4.4 CONCEPT OF PEB SYSTEM: The synergy between the various building components is as described below: Exterior cladding. Secondary framing. Main frame. Wind bracing
4.4.1 EXTERIOR CLADDING: Single Skin Panels are trapezoidal ribbed sheets roll formed from thin mill finish or prepainted aluzinc coated steel and aluminum coils and cut-to-length to meet the requirements of a specific building Sandwich Panels have a polyurethane foam core sandwiched between two single skin metal panels (or an exterior single skin metal panel and an interior aluminum faced laminate).
4.4.2 SECONDARY FRAMING: Secondary Members in the PEB industry refer mostly to longitudinal roof and wall members that are roll formed from galvanized coils. Secondary members used in a PEB include steel purlins, side runners, fascia channels, door posts, window posts, rafter stays, column stays base angles and other miscellaneous structural parts.
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”Z” sections acting as longitudinal roof purlins and longitudinal wall girts that connect to columns & rafters and support exterior roof and wall panels. "C” sections used primarily in framed openings and as a transition member between partial block walls and wall panels. Steel Deck used to support concrete slabs in second level flooring.
Figure Showing Steek Deck Base angles, gable angles, and mezzanine edge angles.
Figure Showing Base Angles
4.4.3 MAIN FRAME: H/I Beams in the PEB industry often refer to primary built-up members. Primary members consists of columns, rafters, beams etc. These are fabricated from high strength Gr. 50 HR plates. Plates are cut to size and shape. Built up sections a re-made form these plates in Automatic Beam Welding Line by submerged arc welding.
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4.4.4 WIND BRACING: MPIL PEBs offer you choice of 5 different types of roofing and cladding systems that enhance the aesthetic appeal of the building and are ideally suited for rapid and low cost construction.
Roofing and Cladding Systems
PEB Parts Classification
Varieties of Sheets
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PEB Main Frame
Structure of PEB Frame
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CHAPTER-V IMPORTANCE OF PEB STRUCTURE SYSTEM 5.1 IMPORTANCE OF THE STUDY:
Pre-Engineered Building system is computer assisted, and design to create a building for a specific use. The complete Building system is Pre-Engineered to facilitate easy production & assembly on site. In PEB system, a superior protection of a thin coating of resin applied on the top of the Aluminium Zinc coating make Galvalume sheet. A colour coating is given on the top surface for a bright appearance with a colour of the customer’s choice.
A clear organic acrylic resin coating is then applied & thermally cured. At the present time the use of pre-engineered buildings become a widespread trend. These buildings are constructed keeping in mind the aesthetic value cost, effectiveness, durability and fast construction.Pre-engineered buildings has been very successfully implemented all around the country; this is one of the most cost effective, speedy and inexpensive way to set up a strong building. Therefore this are best for use of residential homes, Industrial areas, offices, showrooms, etc since they offer speedy construction at the lowest cost. As per the requirements of the customers, pre-engineered steel buildings can be designed and manufactured speedily. The major reason for the spurt in construction events of these pre-engineered buildings is the low cost, comparatively lesser time of construction and environment friendly construction etc. The cost is low due to the reality that the labor charges have been minimized by manufacturing different parts in the factories. The key factor is the time because of simple construction techniques Involved. Good structural design of the building necessitates integration of the structure into a whole physical system. It is necessary to understand the influence of structural design on the architectural design and also vice versa for the development of the subsystems for power, lighting, thermal control, ventilation, water supply, waste handling, firefighting etc. The steel structural systems have come out more popular largely because of their ability to provide flexibility in accommodating these subsystems in the building while allowing architectural form .
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Apart from the state of the art technology used for fabrication of pre-engineered buildings, the other main difference is in the assembling of PEB. The varied components of the PEB are joined to each other based on the nut and bolt methodology as against the welding and riveting methodology used for conventional steel buildings. Metal building technologies permit almost complete freedom to the designer and the architect in incorporating whatever features may be needed in the building-structural, thermal, ventilation or acoustical, to name a few.
5.2
PEB Accessories:
Trims and Flashing include eave trim, eave gutters, downspouts, gable trim, curved eave panels, flashing around building accessories, etc. which are produced from prepainted aluzinc coated steel or aluminum sheets that are bent to the required shape. Building Accessories include sliding doors, rollup doors, personnel doors, fiberglass insulation, sandtrap louvers, windows, ridges ventilators.
Girt Joint
5.3
Purlin Butt Joint
Recent Innovations:
High performance steels (HPS) Fire-resistant steels: o
Steels with increased ductility
o
Corrosion resistant steels
o
Concrete filled steel tubes (CFT)
5.4 Future Trends: In this era of competition it is increasingly important to build more economical structures, which provide good integrated system performance. Steel is basically better suited for bigger, taller, and longer span and geometrically complex structures, as a result, steel is likely to be predominantly used for many years into the future. Increased economy in civil engineering construction is achievable through higher strength steel, composite form of construction and improved materials therefore engineering community is more akin to use steel structural systems in the future and it is felt that this 211-07-31-9628-2131
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trend will continue. Engineers will need to develop suitable Codes and specifications for the purpose to meet the requirements of future generations. There is increased invest more for research and development for innovative material and construction methodologies. One has to use the PEB products, with a word of caution, and frame the contract provisions accordingly. We are fairly close to a day when steel buildings should be the rule, rather than being the exception, if we work together to give the Client, best value for his money.
HIGH-RISE BUILDING IN PEB STRUCTURE SYSTEM
FACTORY/WAREHOUSE IN PEB STRUCTURE SYSTEM
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CHAPTER-VI ADVANTAGES AND LIMITATIONS OF PEB STRUCTURE SYSTEM 6.1 ADVANATGES: Pre-engineered building systems provide real value to clients without sacrificing durability, seismic and wind resistance, or aesthetic appearance. Cost savings begin right at the drawing preparation stage. Systems engineering and fabrication methods help reduce interim financing costs through faster construction and minimised field erection expense. An added benefit is earlier occupancy of the facility and a head start on day-to-day operations by the client. . Apart from costs, there is an assurance of factory-built quality and uniformity in design and fabrication. These systems are also energy efficient; incorporate watertight roofing systems; enable easy disassembly or future expansion and have the lowest life cycle maintenance costs. . Adding to these; there is no mess of sand and cement; power savings; walkable ceilings; progressive and non-progressive panel systems for walls. A poor man can be provided with a home created under strict quality control and having a longer life span, with greater safety against natural disasters like earthquakes and cyclones. Moreover, It is possible to create the building in required form and shape. And the 'system approach' renders a holistic way of thinking at one platform for consultants, designers, architects, and builders. Thus it tends to achieve a perfect harmony among various stringent specifications and aesthetic requirements in a most economic way. In nutshell, the benefits may be summarized as under:
Increased speed of construction, quicker return on investment. Ensured quality of material, Design and construction. Unlimited architectural possibilities. Enhanced Durability and seismic reliability. Easy construction, maintenance and refurbishing. Increased Life cycle performance and cost competitiveness. Environment–friendly structures.
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Better value for money. Cleaner and unencumbered sites. Sustainability in construction through reuse of most materials. Suitability for Hilly regions and other geographically difficult areas. Hassle Free. Optimized design of steel reducing weight. Better Earthquake & Wind pressure resistant. Energy efficient roof and wall system using insulations. Easy integration of all construction materials. The building can be dismantled and relocated easily. Future extensions, expansion modification can be easily accommodated without much hassle. Faster delivery and erection, saving around 30-40% of project time. Column-free large spans, up to 90 m. Virtually maintenance free. Single-source responsibility. 'Systems approach' ensures integrity and safety of all building components. Lighter weight; savings in foundation cost of 10-20 percent. Insulated from sound and heat, as per the requirement. Better rainwater harvesting through gutters and down-take arrangements. Overall economy.
In pre-engineered building concept the complete designing is done at the factory and the building components are brought to the site in knock down condition. These components are then fixed / jointed at the site and raised with the help of cranes. The pre-engineered building calls for very fast construction of buildings and with good aesthetic looks and quality construction. Pre-engineered Buildings can be used extensively for construction of industrial and residential buildings. The buildings can be multi storeyed (4-6 floors). These buildings are suitable to various environmental hazards. PEB concept has been very successful and well established in North America, Australia and is presently expanding in U.K and European countries. PEB construction is 30 to 40% faster than masonary construction. PEB buildings provides good insulation effect and would be highly suitable for a tropical country like India. PEB is ideal for construction in remote & hilly areas.
6.2 Strengths of PEBs:
Clear spans up to 100m without internal columns. Flexibility in building dimensions. ISO 9001 quality accreditation. Easy expansion.
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Fixed deadlines and costs. Weather-tight roof and wall coverings with accessories for long maintenance free exteriors.
TYPICAL PEB STRUCTURE SYSTEM
6.3 SOME ISSUES IN PEB DESIGN: While the Analysis of any Structure would be universal, designs need to be done as per the local/ regional codes. Otherwise why different countries have different codes of Practice? For example, if a PEB is built in India, The load calculations need to be as per the latest IS 875, the designs need to be as per IS800 for main frame members, as per IS 801 for thin rolled secondary members (Z and C purlins and Girts). If a country does not have a code, the building may follow the UBC or the code of a country near by IF suitable. To make the superstructure most economical and very competitive, most of the PEB vendors select the codes as per their requirement. For example, for a structure built in India, they might calculate the loads as per IS 875, but do the design as per AISC or 211-07-31-9628-2131
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AISI, MBMA and use welds as per AWS. If they feel that the Steel Section is lighter as per one code, they will adopt that clause of the code and select another clause of another code of another country for the design of some other part of the same building. Some PEB vendors select some clauses of previous versions of the Code and other clauses of the Latest Versions! This style is not the same every time. PEB Design teams are on constant research in the Selection of Codal provisions of various countries and are on trials with different clauses.
FLOWCHART EXPLAINING PARELLEL PROCESSES IN PEB The evolution of a Code of Practice is based on the Weather & other climatic conditions, Material, Local Practices, Skill levels at manufacturing, Transporting, Assembling, erecting, finishing and maintaining. Hence it is ridiculous to use Indian Steel plate of any yield stress, Cut and manufactured in India, Loaded & transported in Indian Style, Unloaded and stacked in Indian Style, Assembled & erected by Indian (skilled) Labour, Finished by Indian Painters using Indian paints, Maintained by Indian Client in an Indian Town or village BUT DESIGNED USING AMERICAN CODE..! Several clients, structural engineers, Architects and consultants in India have a myth that American Codes are Better than Indian! . This way of varied design is legally not valid. If the loads and Codes are not specified by the buyer, it should be on the PEB supplier to use the Local/ Regional Codes of practice. To conclude, Clients, Architects and Engineers in India, Beware! The Pre Engineered Buildings are not a New Concept. But the Jumping-Code-Practice is the NEW Concept and STYLE. If you are not sure of the Codes, DO NOT SIGN a Purchase order just 211-07-31-9628-2131
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copying the Specifications given by the PEB Vendor. Just mention somewhere that the Latest Revisions of Indian Standard Codes should be followed. Luckily, India has all the codes available for the design of all the Parts of a PEB structure.
6.4 High Engineering Production/Erection Process: The PEB production process primarily consists of FOUR major parallel processing lines, as under:
Built-up members for Primary frame
Cold forming for Secondary framing
Profiling for Roof and Wall sheeting Accessories & Bracings like Gutters, down take pipes, ridge Vents, Skylights, clips etc.
The flow chart in image explains the parallel processing and then after final inspection, ready for shipment in CKD conditions. The production & shipment of these components for a PEB structure uses following processes: 1. Plate cutting using Shear/Plasma/Multi-torch through nesting software for optimized use of plate area. 2. H-beam welding on automatic welding machines using SAW or MIG welding process. 3. Fabrication for fitments like end plates, stiffeners and connections cleats. 4. Cleaning the surface for painting. 5. Slitting HR coils for cold forming operations to make Z and C sections with punching. 6. Cutting and threading sag rods and bracing rods. 7. Fabrication of Diagonal bracing angles or pipes. 8. Profiling the Galvalume/Zincalume sheets for roofing and wall cladding. 9. Manufacturing Gutters, down take pipes in press bend. 10. Procuring and assigning required matching fasteners for connections. 11. Organizing some bought out accessories. 12. Quality control tests & inspection; and matching with project wise Bill of Quantities as given by the engineering department. 13. Dispatching to project sites as per sequence of erection.
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6.4 ERECTION: Steel framing members are delivered at site in pre-cut sizes, which eliminates cutting and welding at site. Being lighter in weight, the small members can be very easily assembled, bolted and raised with the help of cranes. This system allows very fast construction and reduces wastage and labour requirement. These buildings can then be provided with roof decking and wall cladding with metal profile sheets and proper insulation. The framing are so designed that electrical and plumbing services are part of it and can be very easily concealed . However, the erection process is highly technical and needs skilled and trained manpower to handle heavy construction equipments. Proper training of erection engineers for understanding of drawings and execution of work is necessary. A qualified and experienced work agency should be employed for erection work. Grey Areas: Points of Concern: What Glitters is not always GOLD…???? The evolution of the application of steel in civil engineering practice gives rise to many issues from the point of view of engineering design, research and development of steel structures.
6.5 ISSUES OF CONCERN:
Fire protection: Although great advances have been made in lighter and more economical fire protection systems but fire protection remains an issue of greater concern for steel structures than compared to concrete or other construction materials. The smaller members and thermal mass associated with steel structures makes it more vulnerable. The memories of collapse of world trade centre towers in USA due to fire caused by burning of aviation fuel and sudden rise of temperature leading to complete destruction of structure might not have faded away. Fire protection adds up to larger part of structural cost. It would be a challenge to engineers toward reducing these costs, while assuring adequate resistance to elevated temperatures expected during a fire.
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Buckling:
Buckling and stability become more critical in Steel structures due to smaller members and large stress levels.
Micro-Cracks:
The increasing yield stress, operating stress levels, emphasis on plastic and ultimate capacity, and use of welded construction have resulted in increased frequency of initiation of micro cracks and cause of fracture in bridges and industrial structures. Further development of Micro Cracks and crack growth become a major concern in areas of seismically vulnerable areas.
Corrosion:
Steel has great tendency to corrode when exposed to the environment, which leads to deterioration, increased maintenance costs, and increased reconstruction costs. Although Galvanization, paint, and coatings may provide protection against corrosion, yet they increase the overall fabrication costs of the steel structure appreciably. In hot and humid regions and industrially polluted severe environments problem is more pronounced. Therefore, engineers have to continually seek economically viable solutions to aim at reducing these costs.
Welding:
Presently welded constructions are more commonly used, for these provide stiffer, stronger structures with reduced building weight. Increased steel yield strength requires new innovative welding methods, because high strength steels pose more difficulty to weld without affecting adversely the ductility and performance of the structural system. Recently the use of fully automatic and semi-automatic submerged arc welding results in increase in welding speed apart from the good quality. The elimination of any fumes, smoke or any visible arc column gives an ease of operation and efficiency; better quality & thus encourages its application in welding industry.
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Ductility from seismic considerations:
Seismic design is today a must requirement for almost all civil engineering structures. Although steel is an ideally more suited material from point of view of seismic design because of its property inherent material strength, stiffness, and ductility. Weldability may affect the seismic performance and it follows that new methods to improve inelastic seismic performance of steel structures need to be investigated.
Meliorations: Critics point to poor aesthetics with a typical 'industrial' or 'warehouse' look; minimal flexibility regarding location, shape and size of structural members; the need to utilise off the shelf building shapes and sizes in order to realise cost savings; and a lighter structure which does not achieve the longevity of more conventional structural systems . "The most basic prerequisite of PEB is 'single sourcing' of the entire building. Any slight deviation from this can deprive the customers of the real advantages. Also, as steel is prone to corrosion, it would require various protective coatings which may sometimes make PEB unfeasible economically."
Maintenance: In PEB the maintenance area is the steel roofing & cladding. Installed roofing must be inspected at least once a year. Any exposed metal that can rust or has rusted should be painted. Leaves, branches, and trash should be removed from gutters, at ridge caps and in corners. Also watch out for discharge from industrial stacks, and particulate matter and high sulphur exhaust from space heaters which could get piled up.
6.6 THE FUTURE FUTURE BRIGHT TOWARDS THE ECONOMIC GROWTH: Steel is a preferred material for construction, due to its various advantages like quality, aesthetics, economy and environmental conditions. This concept can have lot of scope in India, which can actually fill up the critical shortage of housing, educational and health care institutions, airports, railway stations, industrial buildings & cold storages etc. Pre-engineered Metal building concept forms a unique position in the construction 211-07-31-9628-2131
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industry in view of their being ideally suited to the needs of modern Engineering Industry. It would be the only solution for large industrial enclosures having thermal and acoustical features. The major advantage of metal building is the high speed of design and construction for buildings of various categories . The present construction methodology for buildings calls for the best aesthetic look, high quality & fast construction, cost effective & innovative touch. One has to think for alternative construction system like pre-engineered steel buildings. India has an installed steel capacity of 35 to 40 million ton & apparent steel consumption is around 27 to 30 million ton. In pre-engineered building concept the complete designing is done at the factory and the building components are brought to the site in knock down condition. These components are then fixed / jointed at the site and raised with the help of cranes. PEB concept has been very successful and well established in North America, Australia and is presently expanding in U.K and European countries. PEB construction is 30 to 40% faster than masonry construction. PEB buildings provide good insulation effect and would be highly suitable for a tropical country like India. PEB is ideal for construction in remote & hilly areas . They are the only answer to the backlog of 33 million houses required in India alone, provided that the system offers quality, economy, and speed together. The building system is developed considering all aspects of building requirements and simultaneously offers technological advancement to all sections of society.
VARIOUS SHAPES OF PEB AS BUILDING STRUCTURE SYSTEM 211-07-31-9628-2131
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6.7 LIMITATIONS OF THE STUDY:
Marginal Design, Material and construction.
Higher lifetime lifetim e maintenance.
No secondary roof membrane.
Usually no internal finished walls.
6.8 APPLICATION OF THE SYSTEM:
Warehouses.
Factories.
Workshops.
Offices.
Gas stations.
Vehicle parking stations.
Showrooms.
Aircraft hangers.
Schools.
Sports and recreational facilities.
Hospitals.
Labour camps.
Low cost housing.
Metro Stations, Bus Terminals and Parking lots.
Indoor Stadiums
outdoor stadiums with with canopies.
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CHAPTER-VII CASE STUDY WITH APPLICATION OF PEB SYSTEM CASE STUDY OF A 70 METER CLEAR SPAN HANGAR CONSTRUCTED UNDER MODERNISATION OF AIRPORT INFRASTRUCTURE PROJECT 7.1 SUMMARY: A large number of technical accommodations including hangars of varying sizes have been constructed at different air ports and air force bases since the invention of Aircraft. The oldest of these hangars were constructed during 1955 to1965 for small sized aircrafts operating from this air strips at that time. Over a period of time the type and size of hangars have grown from simple steel trussed structure to complex 70m span bowstring girder type and light weight steel tubular section structure to the modern trend of PEB structure. Requirement of hangars as covered exhibition space for aviation companies in aero shows being held at different locations near airports has also increased many fold since 1996 when first Aero India Exposition was held in India. The participation level of national and international companies has also increased from 10 numbers to 24 numbers during this period. A work initiated by authorities “ Construction of Hangars with Annex” for parking of aircrafts and facilitating additional covered space for exhibition and other allied facilities. Approval to go ahead with the work was issued under fast track procedure wherein tender action was completed based on go-ahead sanction The work commenced on 30 Mar 13 and was successfully completed on 18 Jan 2014.
7.2 BRIEF SCOPE OF WORK: The scope of the work broadly consisted of construction of 60m x 70m x 10m clear size Hangar with no intermediate supports, flanked with Annexes on three sides and an electrically operated gate on the fourth side along with associated services. The annexes on two sides were to be in Double Storey and the third side to house two auditoriums of 200 and 50 seats capacity each with Air conditioning, complete furniture and PA system besides a VIP lounge, a large Dining Hall and acoustically treated Class 211-07-31-9628-2131
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Room etc. The plinth area of the Hangar and annexes put together was about 9000 Sq.m. State-of-the-art Hangar with Rigid Frame construction and maintenance free Galvalume colour coated steel profiled sheets along with FRP sheets having minimum light transmission of 60% for receiving the natural light was planned. The work being of specialized nature and keeping in view the availability of reputed manufacturers in the field, the design and fabrication was assigned to the tenders. The design check and certificate for structural stability with respect to the Indian Standards was specified to be obtained from any IIT or IISc Bangalore or SERC Chennai. Steel PEB structure for the Hangar and rear side annex has been designed by one of the leading manufacturers of pre-engineered, pre -fabricated Buildings in the country. The two side annexes, foundation for pre-engineered structure including steel gate are designed by private consultant (Structural Designers). Both the designs were checked at Indian Institute of Science, Bangalore and certified correct. Detailed scope of work for the Project was as given below:(A)Hangar: (i) A single span hangar was proposed to be constructed north of existing hangar. The dimensions of the proposed hangar were 60m x 70m with a clear height of 10m inside the hangar to cater for servicing and maintenance of aircrafts. The physical dimensions of an aircraft were taken into consideration while planning the clear height required. It was decided that the new hangar would be pre-engineered pre-fabricated structure. The floor of the hangar was planned for PCN 36 with Pavement Quality Concrete(PQC). (ii) The hangar was planned to be provided with sliding doors at the front. The hangar doors were proposed to be provided with motor mechanism for opening and closing of the doors. (B) Annexes to the Hangar: Two double storey annexes were proposed to be constructed on the Northern and southern sides of the hangar. (C) Media Centre: (i) It was proposed to provide PEB Media Centre in the Eastern side annexe catering for two air conditioned briefing halls with a seating capacity of 200 and 50 seats respectively along with communication centre, cafeteria, VIP Lounge, class room and sanitary annexe etc.
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(ii) The briefing halls was planned to be acoustically treated. PA system was catered in both the halls. Provision of control room out side the briefing rooms was catered for controlling the light and sound systems. (iii) Communication Centre being the nodal communication point during Air Show, it was proposed to house facilities for Computers, Internet facilities, Telephones, Fax, Photocopying machines, etc. (iv) The cafeteria was required to meet the catering requirement of ground crew during the intervening period between air shows. The cafeteria could also be used by the organisers and personnel during the preparatory and conduct phases of the air show. (v) Class room of 50 seating capacity was planned with sound proofing of noise level within 60 db. (vi) All toilets in Media Centre and Officers toilets were planned to be equipped with Hand Dryers, soap dispensers, wash hand basins with Granite top and designer tiles with borders and motifs. The urinals in Media Centre were to have sensors. All the toilets were to have stainless steel doors. These special requirements were worked out keeping in view the fact that these toilets would be used during the actual conduct of the air show. (vii) The roof of annex on the Northern side was proposed to be viewing area for the air show. The terrace was therefore planned with PCC tiles. (viii) The flooring in verandahs, Officers rooms, Tech Library, Computer room, Dining Hall, Communication Centre, Class room and toilets were proposed to be of granite slabs, vitrified tiles and rectified ceramic tiles. The flooring of entrance foyer, lobbies, stage and Media centre were proposed to be of granite slabs. (D) External Services: Roads, Hard Standings, Water Supply, Electric supply, Stand by Power Supply DG set with AMF panel of 250 KVA capacity etc were planned as external services. An architectural plan and four side elevations of the Hangar are shown in Fig(1) and Fig( 2) on next page:
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Fig(1) : Ground Floor Plan of the Hangar 211-07-31-9628-2131
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Fig(2):All Four Side Elevations of Hangar 211-07-31-9628-2131
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7.3 PROJECT PLANNING SCHEDULE: Based on the recommendations of board of officers a go ahead sanction was accorded by MOD on 28 Oct 2003. Total time available for detail planning, preparation of architectural drawings, structural design, tendering, processing of all documents for issue of A/A and execution of work till completion was only 16 months. Based on the available crashed time, a schedule drawn for above activities is shown in Table (1)
Table(1): Time Schedule for Engineering Activities S.NO. 01 02 03 04 05 06
STAGE
DATE
REMARKS
GO AHEAD DIT DRT
28 OCT,2012 11 DEC,2012 27 JAN.2013
PLANNING, DESIGNING 45 DAYS TENDER ACTION 47 DAYS
ISSUE OF A/A COMMENCEMENT COMPLETION
23 MAR, 2013 30 MAR, 2013 18 JAN, 2014
ADMIN APPROVAL 55 DAYS EXECUTION 294 DAYS
It was decided to provide “Pre-engineered Building” structure for main hangars similar to that provided during AI-03 for Hangar –D. Since the time available for all the above activities was not enough for in house preparation of drawings and carry out design, it was decided to outsource this activity through the tenderers to the manufacturers of PEB structure and other consultant with an explicit requirement of getting the design verified from premier institutions like IIT’s or IISc Bangalore. Apart from design and drawings of PEB structure, design and drawings of RCC structure, acoustics in Auditorium and Air-conditioning works were also outsourced though the tenderers. This approach could certainly reduce 2 – 3 months time in over all planning and Tender action. With an aim to reduce the execution time entire structure was sub divided into five independent buildings/structures so that execution of these five buildings could be undertaken concurrently. These five buildings are as under:(i) PEB Hangar. (ii) Double storey Northern Annexe in two parts with a crumple joint in between. (iii) Double storey Southern Annexe in two parts with a crumple joint in between. (iv) Rear annexe housing Media Centre, Communication Centre, Cafeteria. (v) Hangar Gate & Gate structure.
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In the above planning, it was important to design the interface of two buildings keeping in view the requirement of movement joints and over lapping of roof projections so that water ingress could be prevented. Details of such interface have been discussed subsequently. All specifications with respect to finishes were frozen to the micro level by specifying even catalogue numbers for avoiding delay in decision/changes during execution. Important items where such detailed specifications were given in the tender are:(a) Flooring tiles. (b) External finishes (c) Furniture items of Featherlite & Design. (d) Acoustic Boards & wall & ceiling. (e) PA Equipments. In order to materialize the above innovative ideas of planning, tender document was also framed suitably with relevant clauses to cater for out-sourcing of design of various structures /items and their verification. It was decided to conclude only one tender for all activities including PEB structure, RCC Buildings, Gate structure, Air conditioning, Acoustics, Furniture and PA equipment. This was considered necessary for avoiding non co-ordination among contractors, at the time of execution which usually causes delay in such type of multidiscipline projects. A typical execution schedule in the form of bar chart is shown in Figure (3) on next page. PEB PEB
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A TYPICAL BAR CHART OF PROJECT DESCRIPTION
Apr-13
May-13
Jun-13
Jul-13
Aug-13 Sep-13
Oct-13 Nov-13 Dec-13 Jan-14
OF ACTIVITIES LAYOUT, DEMOLITION OF BLDGS, EXCAVATION FOR FOUNDATION S DESIGN MIX FOR CONCRETE FOUNDATION PEB STRUCTURE RCC ANNEXE RCC ANNEXE RCC ANNEXE RCC ANNEXE GATE STRUCTURE FINISHES AIRCONDITIONIN G ACOUSTICS
FIG (3): Bar Chart of Project Showing Concurrent Activities of Five Parts 211-07-31-9628-2131
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7.4 DESIGN CONCEPTS OF PEB STRUCTURE: “Pre-engineered Building” Structure used in this project is comparatively a new concept in India. In this type of structure, all structural elements like Columns, Beams, Purlins, Bracings, Base plates etc. are prefabricated in modular forms at modern workshops equipped with fully computerised machineries required for precision fabrication. Advantages of such structure over traditional steel structure are:(a) Quality control is par-excellence since fabrication work is through computerised plants. All members are cut to shape and tailor made as per structural requirement thus works out to be lighter and economical. (b) Elements are in modular forms where each module is of length not exceeding 10 M which can be transported easily. (c) Construction in faster and erection is easier. (d) Structure is maintenance free and aesthetically elegant General Parameters: General design and architectural parameters like dimensions, type of structure, spacing of frames / portals roof slope etc. are given in Table (2). Table ( 2) : General Design and Architectural Parameters BUILDING TYPE
A RIGID FRAME(RF)
B LEAN-TO
WIDTH
60.00 m I/I OFSTEEL COLUMNS
164.00 m O/O
LENGTH
70.00m C/I OF STEEL COLUMNS
[email protected] +
[email protected] +
[email protected] C/I
71.70 m O/O
C LEAN-TO & UNSYM RF 8.6m LEAN-TO + 1.9m O/O UNSYM RF 35.0 m O/O
10.0 m CLEAR
[email protected] +
[email protected] +
[email protected] +
[email protected] 5.50 m CLEAR
[email protected] +
[email protected] +
[email protected] +
[email protected] 3.20 m CLEAR
2 WITH HALF BAY LOADING 1:10
2 WITH HALF BAY LOADING 1:10
2 WITH HALF BAY LOADING 1:20
Kr 26 Ga COLOUR (KIRBY GALVALUME ROOF SHEETS) Kw 26 Ga Coloured (KIRBY GALVALUME WALL SHEETS)
Kr 26 Ga COLOUR
Kr 26 Ga
Kw 26 Ga COLOUR
BRICK WORK INCL GABLES
BAY SPACING EAVE HEIGHT NO. OF MAIN ENDS ROOF SLOPE ROOF COVERING WALL COVERING
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Design Criteria: (a)
Code of Practice for General construction in steel
(IS:800-1984)
(b)
Code of Practice for design loads
(IS:875-1987)
(c)
Cold form light Gauge steel
(IS:801-1975)
(d)
Welding Design
(AWS-D1.1)
(e)
Criteria for Earthquake resistance
(IS:1893-2002)
Material Specifications: (a)
Built-up Sections
ASTM A 570/A572 Gr 50
(Fy = 50 Ksi)
(b)
Hot-Rolled Sections
ASTM A 36
(Fy = 36 Ksi)
(c)
Angle-Bracings
ASTM A 36
(Fy = 36 Ksi)
(d)
Tubes
ASTM A 500 Gr C
(Fy = 50 Ksi)
(e)
Cold-Formed Sections
ASTM A 570 Gr 50
(Fy = 50 Ksi)
(f)
High Strength Bolts
ASTM A 325
(Fy = 92 Ksi)
(g)
Anchor Bolts
ASTM A 36
(Fy = 36 Ksi)
Loading: Dead Load
:
0.10 KN/m2 + Self Weight of Structure for Frame. (Sheeting– 0.0427 KN/m2 & Purlins–0.0482 KN/m2).
Live Load
:
0.75 KN/m2 on Purlin & Sheeting.
Wind Speed :
120 KMPH Applied on Main Frame Rafters as per IS: 875 (Part 3) – 1987.
Seismic Load :
Zone II (IS:1893 Part -I : 2002).
The design was carried out for all possible combinations of Dead Load + Live Load, Dead Load + Wind Load and Dead Load + EQ Load.
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Design Assumptions: (a) The main frame rafters and columns are moment connected to each other. (b) The lateral stability of the building is provided through the frame action of the main frame. (c) The longitudinal stability of the building is provided through the braced action in the braced bays of the building. (d) The roof purlins are continuously supported beams supported at rafter location and span the bay spacing of the building. (e) The roof sheeting provides lateral support for purlins. (f) The Main frame column base is pinned for building A & C. For building B, base is assumed to be fixed. (g) The Main frame rafter of lean-to frames are pin connected to wind columns. Purlin Design: All purlins were designed as per IS:801 using Cold Form light weight Z Sections. Purlins of size 200 Z 2.0 with two 12 mm dia sag rods for buildings A & C and of size 200 Z 2.5 with two 12mm Dia sag rods for buildings B were used with a Lap of 706 mm. All purlins were considered continuous over rafters. It is worth mentioning here that with the use of cold form section purlins and Galvalume sheets dead load over frame got reduced considerably as compared to traditional angle or channel sections of mild steel. In the instance case a channel section ISMC 250 (weight 15KN/m2 ) would have been required for the span of 7.2m.
Eave Struts & End Wall Girts: Similar to purlins eave struts of Cold form section of size 200 Es 2.5 with two sag rods with Lap of 706 mm, Girt on side walls of size 200 Z 2.0 with two sag rod all for building ‘A’ and Girt of size 200 Z 2.0 for building ‘B’ on grid Q & 200 Z 2.5 on grid Z with two sag rods were found adequate as per design.Important structural details of PEB structure viz portal frames at different grid lines, purlins, girts, moment flange joints, gutter fixing with brackets, lean-to porch, etc are as shown in fig (P1) to Fig(P4). 211-07-31-9628-2131
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P-1 : PEB ELEMENTS: RAFTERS
P-2 : ERECTION OF RAFTERS
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P-3: PEB ELEMENTS: RAFTERS
P-4: ERECTION OF STANCHIONS 211-07-31-9628-2131
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7.5 SPECIAL ARCHITECTURAL FEATURES AND NEW MATERIALS INTRODUCED IN THE PROJECT: Specifications of large span steel structures have seen advancements from heavy weight mild steel two dimensional traditional truss type structures over pylons or RCC columns to third generation Rigid Frame Pre Engineered Buildings of profile Commensurate to bending moment diagram to fourth generation three dimensional space, transigrity and tensile structures. It has been possible to develop such structures due to advancement in construction materials and techniques like High Strength Steel (Fe-510), large length Galvalume sheets as roofing and cladding materials etc. State-ofthe-art building materials recently introduced in our country were effectively used in this work to their advantages. Description of some of the important materials is given as follows:
(a) High Strength Steel PEB Structure: As already brought out in preceding paragraphs, Pre Engineered Building Structure fabricated from high strength steel plates were used for the hangar. All the materials used in PEB structures viz steel plates , cold formed sections, High tension bolts etc. were tested in the quality control laboratory at the manufacturers end before fabrication. Quality assurance tests were also got carried out at IISc Bangalore as confirmatory tests for these materials.
(b) Galvalume Roofing System: A significant advancement in the field of metallic roofing system could be seen in the market from CGI sheets of maximum length 3.0m to GALVALUME and ZINCALUME Sheets of 10m to 12m length. In this project GALVALUME high tensile cold rolled steel sheets conforming to AS 1397, coated with min 150 gms/m2 of Zinc-aluminium alloy coating mass (class AZ150),and colour coating with oven baked paint applied to substrate manufactured by M/S Kirbi Building System India Ltd was used in this project. The profile of sheets used are shown in Figures on next page:
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KIRBY RIB SHEET FOR PEB ROOF SYSTEM
KIRBY WALL SHEET FOR PEB WALL SYSTEM 211-07-31-9628-2131
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Other new materials and important architectural features used in this work are: (a) Alu-K-Bond Lining for Wall and Columns for improving aesthetics of the structure. (b) Cold Formed Section for Purlins, Girts as light weight secondary members in lieu of traditional open structural steel sections. Weight of CFS purlins of size 200Z2.0 used in this work is 4.8 Kg/m2 as compared to ISMC 250 structural steel section of weight 15.6Kg/m2. (c) Vitrified and Rectified tiles have been provided in various rooms and corridors in lieu normal ceramic tiles as has been discussed subsequently. (d) Structural Glass Façade in staircase mumty has been provided in lieu of PCC block masonry panel wall with an aim to improve side elevations and increase lighting level in staircase hall. (e) Polycarbonate Double Walled Sheet Dome. 7.6 METHOD OF PHYSICAL EXECUTION:
Survey and Investigation:
Prior to commencement of work, proper and accurate survey and investigation of existing soil and area of the plot was of paramount importance. Soil investigation was carried out by Karnataka Test House Pvt Ltd, Bangalore. Five bore holes were explored for this purpose and SBC reported was 13 T/m2. North-eastern edge of the rectangular plot as shown in Fig(1) was appx 3.5m higher than the south-western corner. Total Station survey equipment was used to take the initial and final levels. The architectural drawings and specification were prepared by CE (AF) Bangalore and the design drawings were supplied by the contractor. The Pre Engineered Building was designed by M/S Kirby India, Hyderabad and other works by M/S Civil World, Bangalore.
Site Clearance and Foundation Work:
Before commencement of excavation of earth all the existing buildings were demolished. The ground was made level as hangar floor was required to be in level. Existing water pipes and cables passing in the area were diverted. Cutting of appx 20,000 Cum earth was involved. Foundation of the annexe was designed as raft foundation. The Main Hangar was designed as Pre-Engineered structure with stanchions erected over RCC pedestals and fixed with anchor bolts. The foundation for the pedestals was designed as strip footing. SBC of soil being low, the soil was stabilized with sand cement (10:1) cushion 500mm 211-07-31-9628-2131
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thick. M 25 concrete was used for all RCC works and Ready Mix Concrete(RMC) with cement content of 340 kg/cum, was supplied by M/S ACC Ltd.. Photographs P(13) to P(16) depict site clearance and foundation activities in the project.
PEB Structure:
Primary members called stanchions and rafters were fabricated in the factory of M/s Kirby India Ltd in Hyderabad and were transported to site by road. The stanchions were single piece and rafters were in six pieces assembled with nut and bolts at site. These members were erected within a short span of 30 days. The erection was done with the help of derricks & cranes. All stanchions were erected first on the top of pedestals. The gap in pedestals and stanchions was filled with non shrinkable grouts. Thereafter rafters were put on stanchions. The erection manual of manufacturer was followed for safe erection. After erection of all members the roofing and cladding was done with Galvalume sheet 0.5mm thick. The sheet was fixed to purlins etc with the help of self driven screws. The roof of rear bay of the hangar was provided with polycarbonate sheet dome of 10 m span and 12 m height for better elevation and natural lighting. The polycarbonate sheet used was 6mm thick Multi wall marketed by M/S GE Corpn. Various activities of PEB structures viz individual members, erection work, connection and junction details, completed frames, fixing of Galvalume roof and wall sheeting could be seen in Photograph P-(05) to P-(31).
Pavement Quality Concrete Floor:
Pavement Quality concrete designed for Flexural strength of 45 Kg/Cm2 with cement content 395 Kg/Cum and water cement ratio of 0.38 with slump 25 to 30 mm considering compaction factor 0.82 was designed by ACC (RMC). The concrete was manufactured under strict quality control from ACC Ready Mix Concrete plant brought in Transit Mixers to the site and discharged over WMM & Polythene sheet. The concrete was initially leveled manually and vibrated with the help of needle vibrators subsequently concrete was paved. Compacted and leveled with “Mechanical Paver” (MULTI EQUIP). The compacted and leveled concrete was allowed for its initial setting when concrete is still green (Approximately after 20 to 35 minutes) the non metallic monolithic surface hardening compound NITOFLOR Hard top of M/s FOSROC Chemicals was spread over the concrete surface at the rate of 3 Kg per SM. If the concrete is designed with higher water cement ratio for easy pouring of Ready Mix concrete from Transit Mixer it is recommended to go for “Vacuum-De-Watering”.
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Vacuum-De-Watering was not required and not done at Yelahanka since W/C ration was too low to perform this activity. If higher W/C ratio is adopted in mix design for improving workability this activity can be performed prior to Floating and Trowelling. After uniform spreading of hardner, the concrete surface was “Floated” with tremix skim Floater for top layer. Subsequent two passes of floating was carried out with floater at a interval of 1 to 11/2 hours. Once the Floating was completed, the surface was “Troweled with power trowel for three times at a interval of 2 to 2 to hours depending upon the weather condition. The smooth finished surface was achieved in 10 hours of operation.
Electrically Operated Door Shutters:
The main hangar has been provided with electrically operated door shutters, twelve numbers, each of size 10mx5m. These twelve doors were placed over guide rails at the bottom and supported on guide channels fixed to steel wind girder at the top. The girder & doors structures were designed by M/S Madhu Industries, Bangalore. The total steel used was approx 45 MT. The gantry was fabricated at site in three parts. These three parts were then shifted at location and assembled with welded joints. The gantry was lifted en-block with two cranes of 100 Ton capacity and placed in position. The speed of movement of doors is adjusted for 10m per minute.
Double Storey RCC Annexe:
The conventional annexes on South and North were designed as framed structure with isolated footings. The panel walls were constructed with PCC Solid / hollow blocks. The floor finishes were with rectified ceramic, vitrified tiles and granite slabs in stairs. The railings on verandah were of stainless steel matt finish.
Media Center and Auditorium:
The rear annexe was designed as Pre-Engineered Building structure of approx plinth area 2100Sqm to house two auditoriums of capacity 200 & 50, VIP lounge, class room, communication room, dining hall with Kitchen, store and toilets. Auditoriums are provided with Air conditioning, acoustically treated and provided with state-of the-art Public Address system centrally controlled from control room. The media centres were provided with modern furniture manufactured by M/S Featherlite Industries and M/S Durian Ltd. Air conditioning was designed and erected by M/S Blue Star Ltd. The acoustic treatment was designed by a renowned consultant, Prof B Ramakrishna. All toilets were provided with designer tiles, stainless steel doors and urinals with sensors. The PEB stanchions and Columns are clad with ALUCOBOND cladding material for aesthetics.
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P-5 : FOUNDATION OF PORTALS: PEDESTALS CAN BE SEEN
P-6 : EARTH WORK IN PROGRESS 211-07-31-9628-2131
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P-7: STRIP FOOTING BEING CASTED
P-8 : STRIP FOOTING REINFORCEMENT 211-07-31-9628-2131
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P-9 : ELEMENTS OF PEB STRUCTURE
P-10 : FIXING OF STANCHIONS OVER BASE PEDASTALS 211-07-31-9628-2131
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P-11 : ERECTION OF END TWO PORTALS IN PROGRESS
P-12 : PRECISE SETTING OF RAFTER OVER STANCHIONS 211-07-31-9628-2131
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P-13 : SETTING OF RAFTER OVER STANCHIONS
P-14 : ERECTION OF STANCHIONS AND RAFTER IN PROGRESS 211-07-31-9628-2131
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P-15 : FIXING OF ELEMENTS OF RAFTER WITH BOLTS BEFORE ERECTION
P-16 : PORTAL BRACING IS SEEN DULY ERECTED 211-07-31-9628-2131
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P-17:RAFTER BRACING IN SECOND SPAN WITH ROOF SHEETING IN PROGRESS
P-18 : A VIEW OF PEB STRUCTURE 211-07-31-9628-2131
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P-19 : ERECTED PEB PORTALS
P-20 : AERIAL VIEW OF PEB STRUCTURE 211-07-31-9628-2131
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P-21 : READY MIX CONCRETE BEING PUMPED TO FIRST FLOOR
P-22 : ROOF SLAB OF ANNEXE BEING CAST WITH PUMPED READY MIX CONCRETE 211-07-31-9628-2131
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P-23: WMM IN HANGAR FLOOR BEING LAID WITH PAVER
P-24 : WMM IN RAMP PORTION BEING LAID WITH PAVER & VOBROMAX 211-07-31-9628-2131
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P-25 : STAINLESS STEEL DOORS & DESIGNER TILES IN GENTS TOILET
P-26 : ENTRANCE HALL OF MEDIA CENTER 211-07-31-9628-2131
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P-27: ACOUSTIC BOARDS IN AUDITORIUM
P-28 : INTERLOCKING PAVEMENT TILES AND ALUCOBOND LINING AROUND COLUMN 211-07-31-9628-2131
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P-29 :ALUCOBOND LINING AROUND PEB COLUMNS
P-30 : STRUCTURAL GLASS CLADDING OVER STAIR CASE HALL 211-07-31-9628-2131
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P-31 : COMPLETED GATE STRUCTURES
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Important technical parameters of the completed hangar are given in Table (3) Table: ( 3 ) Parameter of the Hangar PEB
RCC
TOTAL
PLINTH AREA
7061 SQ.M.
3250 SQ.M.
8992 SQ.M.
COST
820 LACS
180 LACS
900 LACS
PA RATE
RS.11613/SQ.M.
RS.5540/SQ.M.
RS.10008/SQ.M.
TOTAL WEIGHT OF PEB MATERIALS
:
910 MT
WEIGHT PER SQ.M.
:
129 KG/S.M.
PRIMARY MEMBERS COLUMNS/RAFTERS
:
310 MT
SECONDARY MEMBERS: PURLINS, STRUTS,
:
57 MT
ROOF SHEETING 6717SMX0.005MX7850
:
264 MT
WALL CLADDING 6200SMX0.005X7850
:
244 MT
GUTTER, DOWN SPOUTS, BOLTS ETC
:
10 MT
BIRD PROOFING:
:
55 MT
DOORS
:
138 MT
TOTAL
:
1098 MT
DETAILS OF PEB MEMBERS:
WIND BRACING ETC:
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CHAPTER-VIII SUMMARY, FINDINGS, CONCLUSIONS AND RECOMMENDATIONS 8.1 SUMMARY/FINDINGS/DISCUSSION ON IMPORTANT TECHNICAL ISSUES:
Smooth Concrete Floor:
As per specifications given in the specifications, hangar floor was to be of Pavement Quality Concrete designed for Flexural strength of 45 Kg/cm2 with rough broomed surface finish. This practice has been followed in almost all the hangars constructed in the past. During visit to the project, Pilots/Aircraft maintenance engineers pointed out that the rough surfaces in hangar floors cause maintenance problems with reference to cleaning of floor off grease / oil etc. They brought out that all over the world, hangar floors are now being provided with smooth floor which attract less dust and are easy to clean. It was desired by them that hangar floor in this project should also be finished smooth for avoiding such problems. A detailed survey was carried out for ascertaining suitable techniques and material which could provide smooth finished floor without causing any shrinkage cracks. Subsequently trials were carried out over floor of existing hangars by M/S Fosroc Chemicals, M/S Sika chemicals and M/S Berger Paints for self levelling epoxy floor coatings. All these products were appearing technically suitable but economically unviable. It was finally decided to obtain smooth surface by using power floats and trowels in combination with floor hardener NITOFLOR STANDARD of M/S Fosroc Chemicals Ltd. applied @ 2.5 kg/sqm. This technique was found effective in achieving an excellent, smooth, high wear resistance floor finish without any shrinkage cracks. Photographs P-(32) to P(35) show various activities of hangar floor which are shown on upcoming pages:
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P-32 : CONCRETE PAVER (M/S MULTIQUIP)
P-33 : PQC FLOOR CASTED IN PANELS 211-07-31-9628-2131
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P-34 : POWER TROWELLING IN PROGRESS
P-35 : JOINT CUTTING IN PROGRESS 211-07-31-9628-2131
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Erection of Gate Structure:
The gate structure was designed as an independent structure for the entire wind load over a large area of 60mX10m. This has necessitated the wind girder depth and weight as high as 4.5m and 45 Tonnes respectively. The girder was fabricated at site in three parts. The erection of Girder as one unit after connecting three parts was done carefully by using three cranes of 100Ton capacity with one crane as stand by. Erection of the gate supporting girder is seen in Photographs P-(36) to P-(39).
P-36 : WIND GIRDER LYING ON GROUND FOR ERECTION 211-07-31-9628-2131
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P-37 : WIND GIRDER BEING ERECTED
P-38 : ERECTION OF WIND GIRDER USING 100 T CRANES 211-07-31-9628-2131
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P-39 : ERECTION OF WIND GIRDER USING 100 T CRANES
Polycarbonate Roof Panels and Dome:
Use of polycarbonate roof panels and dome has been found very effective in improving lighting level inside the hangar apart from improving the front elevation and overall aesthetic of the structure. These panels and dome can be seen in Photographs P- (40) and P-(41) as shown on next page:
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P-40 : COMPLETED DOME AND FRONT VIEW
P-41 : A CLOSE UP OF DOME OF HANGAR MADE OF POLY CARBONATE 211-07-31-9628-2131
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Bird proofing panels fixed directly to flange of Portal Beam: As specified in the CA bird proofing panels made out of square tube section frame and weld mesh were to be fixed with suspenders at suitable intervals. This technique was used in Hangar ‘D’ constructed for 2003 aero show. It was observed that bird proofing in this hangar has developed sag at many places and got de-shaped over short span of time. Photographs P-(42) and P-(43) indicate such sagged panels. Similar type of problems have been experienced at other places as well in bird proofing work with different specifications viz. Angle or Tee section frame with weld mesh or wire mesh fixed to frame with FI sections using suspenders or directly fixed to tie member of trusses. It was thus decided to fix these panels directly to bottom flange. This practice apart from imparting greater stability to bird proofing frame has rendered additional working height inside hangar. Photographs P-(44) and P- (45) indicate the modified arrangement of bird proofing in this project.
P-42 : BIRD PROOFING IN HANGAR “D” WITH SUSPENDERS 211-07-31-9628-2131
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P-43: FIXING OF BIRD PROOFING PANEL DIRECTLY TO FLANGE OF RAFTER IN HANGAR ‘E’
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P-44 : FIRST FLOOR CORRIDOR WITH STAINLESS STEEL RAILING
P-45 : INTERFACE OF PEB STEEL AND RCC STRUCTURE 211-07-31-9628-2131
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Gate structure and Gate panel Design:
Design of gate panels and gate structure including fabrication was done by M/S Madhu Industries Pvt. Ltd. Bangaluru. The gate supporting structure ie wind girder was fabricated out of Tube sections RH 100 to RH 50 size and ISMC 250 sections with total weight of 45Ton. Similarly twelve number gate panels of size 10mx5m were fabricated out of ISMC 250 main frame with ISA 75756 diagonal bracing, each panel weighing to 2.5Ton. Since the wind girder was designed as structure independent of main hangar due to time constraints as already clarified in para( ), its size w.r.t depth, height and size of member has been on higher side. The same could have been reduced if this structure was connected to the adjacent braced rigid frame. Similarly weight of gate panels could have been reduced if fabricated out of built-up section made out of 4 Nos ISA placed at 300mm C/C laced on all faces with 16mm MS rods. Due to time constraint the revision of design was not considered appropriate.
P-46: GATE PANELS BEING ERECTED 211-07-31-9628-2131
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MONITORING OF WORK and QUALITY CONTROL
The progress of work was being monitored right up to top management level. Regular meetings were being held at different levels so as to monitor the progress. Apart from many other progress reports, a daily report up to CE’s Office and a fortnightly progress report up to departmental head was being initiated, intimating the latest progress of the work. Project was visited by several senior officials during the progress of work . A well equipped laboratory was set up by contractor at the site of work immediately after issue of work order. One officer specifically for Lab assisted by one JE was made in charge of the laboratory under direct control of Chief Engineer. Most of the quality control tests were conducted in this laboratory in presence of Engineer and contractors representatives. All field tests were also being carried out by Field lab incharge, contractor and executives jointly. One senior officer from head office was also deputed verify the correctness of test results periodically for ensuring strict quality control.
CONCLUSION:
The time was in true sense an essence of this project since dates for Aero India-2005 exhibition were fixed. In-spite of excessive rains and tight schedule the work could be completed in record time with excellent quality control to the entire satisfaction of users. This was possible due to judicious planning, timely decisions, close interaction between users and engineers and, of course, round the clock close supervision by executives. Technical knowledge and innovative approach applied in the work were quite effective in overcoming day to day problems encountered at site and in improving quality of work. User’s interaction in technical accommodation like hangar is of paramount importance. In this work also a close liaison with users has given important inputs in achieving finished product to their entire satisfaction. The technical issues discussed in this report will prove to be useful in planning and execution of similar projects in future.
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