Internship report on substructure and superstructure works of construction project

Debre Berhan University

Institute of Technology College of Engineering Civil Engineering Department Four Month Internship Report Abdirashid Mohamed Dahir ID: ENGR/952/04

2015 GC 2007 EC

0|Page©Internship Report by Abdirashid Mohamed Dahir -4th year Civil Engineering Student-DBU

We are born of all the things we know!

Copyright ©Abdirashid Mohamed Dahir, 2015

No part of this internship report may be reproduced, transmitted, utilized or stored in any form or by any means without prior written permission from the writer


DECLARATION

I, Abdirashid Mohamed Dahir, hereby declare that this internship report is submitted by me under the guidance of my mentor Alemu Diribsa and supervision of Bashir Mohamed Barik. I assure that the report contains actual events and facts that were observed and performed during my internship practice program. All the contents are my own and have not been submitted to any other institute.

Mentor:_________________________________________ Signature__________ Supervisor:______________________________________ Signature__________ Student:_________________________________________ Signature__________


List of Tables Table-1 Major Activities and Stretch objectives of the Bureau………………..Page 11 Table-2 Customers and Expectations of the Bureau……………………….……....Page 12 Table-3 Design Team…………………………………………………………………………….Page 12 Table-4 Contracts and Construction Administration Team……………………...Page 14 Table-5 Process Owner………………………………………………………………………….Page 17 Table-6 Concrete Cover…………………………………………………………………………Page 35 Table-7 Concrete Classes……………………………………………………………………….Page 35 Table-8 Reinforcing Bars and Their Applications………………………………….…Page 36 Table-9 Recommended Slumps for Various Types of Construction………….Page 49


Table of Contents DECLARATION ............................................................................................................................................... 2 List of Tables ................................................................................................................................................. 3 Acknowledgement ........................................................................................................................................ 6 Executive Summary....................................................................................................................................... 7 ACRONYMS ................................................................................................................................................... 8 Background of the Bureau ............................................................................................................................ 9 1.1 Brief Details ......................................................................................................................................... 9 1.2 Main products and services of Bureau ............................................................................................... 9 1.3 Main Customers and End Users of the Products and Services ......................................................... 12 1.4 Overall Organization and Work Flow ................................................................................................ 12 2- Overall Internship Experience................................................................................................................. 18 2.1 How I got into the company ............................................................................................................. 18 2.2 The sections that I had been working in ........................................................................................... 19 2.3 Introduction to the Sites ................................................................................................................... 20 2.3.1 Introduction to Palace and Staff Residence ............................................................................... 20 2.3.1.1 Construction Materials, Quality Assurances and Tests........................................................... 20 2.3.1.2 Storage Process and Construction Equipment ....................................................................... 21 2.3.1.3 Concrete Mixing ...................................................................................................................... 24 2.3.1.4 Engineering Problems at Presidential Palace Site................................................................... 26 2.3.1.5 Substructure and Foundation Works ...................................................................................... 28 2.3.1.6 Solid Slab and Grade Beams [Staff Residence] ....................................................................... 35 2.3.1.7 Floor System [Presidential Palace] .......................................................................................... 38 2.3.1.8 Roofing System [Presidential Palace]...................................................................................... 42 2.3.1.9 Tests on the Site ...................................................................................................................... 48 2.3.1.10 Total Station Operation ........................................................................................................ 50 3-Overal Internship Benefits ....................................................................................................................... 54 3.1 Improvement of Practical Skills......................................................................................................... 54 3.2 Theoretical Knowledge Upgrading .................................................................................................... 54 3.3 Interpersonal Communication .......................................................................................................... 55 3.4 Team Playing Skills ............................................................................................................................ 55 4|Page©Internship Report by Abdirashid Mohamed Dahir -4th year Civil Engineering Student-DBU

3.5 Leadership Skills ................................................................................................................................ 56 3.6 Work Ethics ....................................................................................................................................... 56 3.7 Entrepreneurship Skills ..................................................................................................................... 56 4-CONCLUSION ........................................................................................................................................... 57 5-RECOMMENDATION ................................................................................................................................ 58 6-REFERENCES ............................................................................................................................................. 59 7-APPENDICES ............................................................................................................................................. 60


Acknowledgement Firstly, all praise due to almighty GOD for the generation of ideas solely expressed in this report, in depth analysis of engineering problems and possible solution, at last the publishing and above all the everlasting mercy. I would like to express my profound gratitude for the excellent guidance, hearty acceptance, constant cooperation and warm welcome of Eng. Asad Omar Hussein, the Deputy Chief of Ethiopian Somali Urban Development, Construction and Industry Bureau. Special thanks also go to Eng. Bashir Mohamed and Eng. Mohamed Omar who tirelessly helped me cope with different engineering problems during my stay with Urban Development Bureau in Jigjiga. Both worked with me as supervisors and I was able to share my ideas on engineering problems with them. I am grateful to my advisor Alemu Diribse who really showed off greater willingness in helping me remain updated and for his corrective measures in the course of the internship program. Lastly, I should not forget to thank Ato Abraham and Highway Engineer Samson Kibret of Best Consulting Engineers P.L.C, the company that undertook the design project of Jigjiga asphalt roads for their encouraging feedbacks and invaluable contribution.


Executive Summary In summary this report sheds light on my internship practice program at Ethiopian Somali Urban Development, Construction and Industry Bureau in Jigjiga, the capital of Zone 5 where I have maintained four-month presence. Primarily, although I was assigned to Roads Construction Enterprise, the delay in the projects forced me to strike contract with the governmental Bureau which welcomed me with open arms upon my application. I translated theories at class into practice not only as intern but also I played consulting role in the construction of Presidential palace in the outskirts of Jigjiga, three storey staff residence in Jigjiga University and the design of four lane-one way urban roads in Jigjiga. In the first part of this report, I have discussed the background of hosting Agency- Urban Development, Construction and Industry Bureau which is among the regional implementing bureaus with the aim of enhancing infrastructure and integrated housing development in the Somali region of Ethiopia. Consulting services and role by the Bureau as client in some construction projects are also part of the first section of this report. Second part of the report divulges my overall internship experience, for instance how got into the company, the section of the company I have worked in, the workflow of the section, tasks being executed, challenges I faced and the possible solutions to the problems encountered during the internship practice program. Third, the detailed report exposes overall benefits I have gained during the internship when it comes to the improvement in practical skills, upgrade of theoretical knowledge, interpersonal communication skills, team playing skills, understanding of ethics and organizational and entrepreneurship skills. Finally, I have given recommendations to the hosting Bureau and concluded my report with paragraphs summarizing practical skills on the sites over the last four months.


ACRONYMS AUTOCAD-Automated Computer Aided Design BSc-Bachelor of Science DBU-Debre Berhan University DPC-Damp Proof Coarse EBS-Easting Back Sight EBCS-Ethiopian Building Code Standard ENG-Engineer ESUDCIB-Ethiopian Somali Urban Development, Construction and Industry Bureau -Yield Strength of Steel bars GC-Gregorian Calendar GPS-Global Positioning System NBS-Northing Back Sight OPC-Ordinary Portland Cement PLC-Private Limited Company PPC-Pozzoloni Portland Cement PVC-Polymerized Vinyl Chloride SAP-Structural Analysis Program UTM-Universal Transverse Mercator


Background of the Bureau 1.1 Brief Details Ethiopian Somali Urban Development, Construction and Industry Bureau is an implementing body tasked with administration of settlements in urban cities, expansion of houses and infrastructure and inter urban rural linkage to play a great role in the region’s economic and social development to reduce poverty. Bureau aspires to establish better construction quality and good urban governance system through rapid and sustainable development. Ethiopian Somali Urban Development, Construction and Industry Bureau leads accountable institution by organizing and integrating supportive community-based organization in public and private sectors while designing sustainable capacity building system which enhances urban good governance, efficient and effective service delivery, building better construction industry and service capacity.

1.2 Main products and services of Bureau  Designing – sub team  Design preparation service  Job list preparation and approval service  Checking and approval of design  Adaptation of design  Consultation service  Contract and construction administrations sub- team  Preparation of bid document  Contract agreement  Selling of bid document  Payment service . Preparation of bid document . Interim payment . Final payment . Payment certificate  Variation work service  Additional work service  Construction material’s price escalation service  Solving conflicts b/n contractors and consultants  Performance bond document service  Temporary & final construction acceptance service  Construction material’s market price assessment 9|Page©Internship Report by Abdirashid Mohamed Dahir -4th year Civil Engineering Student-DBU

 Performance evaluation service  Contactors license service  Consultants license service  Professionals license service  Certificate of occupancy  Answering for technical support  Answering for arithmetic check  Laboratory service  Site surveying service  Soil test service  Construction material test service

Table 1-Major Activities and stretch objectives of the process

Major S/No activities Design 1. preparation

Stretch Objectives Preparing a new design within  High level building 7-20 Mill in 90 days. Quality of 90% 

Middle level building 4-7Mill 60 days. Quality of 90%



Low level building <4 Mill 30days. Quality of 90%



Extra high level building greater than 20 Mill in as per schedule. Quality of 90%

10 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

2.

Design approval

Approving design within  High level building 7-20 Mill in 7 days. Quality of 90% 

Middle level building 4-7 Mill in 4 days. Quality of 90%



Low level building <4 Mill in 2 days. Quality of 90%



Extra high level building greater than 20 Mill in 15 days. Quality of 90%

3.

Bidding process

Selecting and categorization of capable contractors within 15 days using IT technology.

4.

Supervision and inspection process

We make supervision and provide report within 3 days for concerned sector. Quality of 100%.

5.

Payment process

6.

Registration Finishing the registration within ½ day. of contractors& consultants

Finishing the payment and approval within 7 days.


1.3 Main Customers and End Users of the Products and Services Table 2-Customers and Expectations S/No Customers 1.

Regional sector Bureau and Woredas

2.

Contractors and consultant

3.

Investors

Need and expectation      

Approving designs in short period of time. To get completed design which satisfy their need with scheduled tie. Processing and approving of the payment to be fast and transparent. To get capable contractor. To respond claims on time and in transparency way. Project to supervise each activity to get quality building & supervision on projects

   

Payment process to be fast. The site hands over to on time. To get complete design on time. To get fast response to their claims or disputes.



Approving designs on time

1.4 Overall Organization and Work Flow Work flow goes to the following three teams Table-3 Design Team S/N Position name

Minimum requirement

1

Surveyor

Adv. Diploma in surveying



2

Architect

Bsc In Architecture



Respective role

 

remark

Preparation architectural design Check architectural design Prepare design contra document


3

Architect

Bsc In Architecture

  

4

Architect

Bsc In Architecture

  

5

6

7

8

9

10

11

Structural Engineer

BSC In Civil Engineer

Structural Engineer


Structural Engineer


Electrical Engineer

Bsc Electrical Engineer

Electrical Engineer




Electrical Engineer




Drafts Man

Bsc In Drafting Or Advance Diploma With

          





Preparation architectural design Check architectural design Prepare design contra document Preparation architectural design Check architectural design Prepare design contra document Preparation of structural design Prepare project TOR Checking structural design Preparation of structural design Prepare project TOR Checking structural design Preparation of structural design Prepare project TOR Checking structural Preparation of electrical design Checking electrical of design Preparation of electrical design Checking electrical of design Preparation of electrical design Checking electrical of design


3 Year Experience 12

Drafts Man

Bsc In Drafting Or Advance Diploma With 3 Year Experience

13

Drafts Man

Bsc In Drafting Or Advance Diploma With 3 Year Experience

14

Sanitary Engineer

BSC In Sanitary Engineer



Preparation of sanitary design Checking sanitary design

15

Sanitary Engineer




Preparation of sanitary design Checking sanitary design




16

Sanitary Engineer





Preparation of sanitary design Checking of sanitary design

17

Quantity Surveyor

Advance Diploma Civil Engineering Or Related Field

 

Preparation of BOQ Checking BOQ

18

Quantity Surveyor


 


19

Quantity Surveyor


 


Table-4 Contracts and Construction Administration Team S/N Position name

Minimum requirement

Respective role

remark


1

construction engineer

BSC Civil Engineering Or Related Field Advance Diploma Civil Engineering Or Related Field

      

2



3



      

4


BSC Civil Engineering Or Related Field Advance Diploma Civil

 

Evaluation of contracts Supervising construction Checking & approve variation Solving disagreement Checking & approve time extension Performing temporary & final acceptance Registration of construction. Consultants as well as providing professional license

Evaluation of contracts Supervising construction Checking & approve variation Solving disagreement Checking & approve time extension Performing temporary & final acceptance Registration of construction. Consultants as well as providing professional license Evaluation of contracts Supervising construction


Engineering Or Related Field

5





Checking & approve variation  Solving disagreement  Checking & approve time extension  Performing temporary & final acceptance Registration of construction. Consultants as well as providing professional license       

6



      

Evaluation of contracts Supervising construction Checking & approve variation Solving disagreement Checking & approve time extension Performing temporary & final acceptance Registration of construction. Consultants as well as providing professional license Evaluation of contracts Supervising construction Checking & approve variation Solving disagreement Checking & approve time extension Performing temporary & final acceptance Registration of construction. Consultants as well as providing professional license


Table-5 Process Owner S/ N

Position name

Minimum requirement

2

Secretary

Diploma In Secretarial Science

Respective role  







 

Responsible to the process owner Prepare different letter, write and transfer to the concerned bodies. Examine documents, written letters and transfers to the concerned bodies. Give reception to the customer and other stake holders accordingly and make to meet with core process owner. Manage and transfers all materials from the process owner to the concerned body Take attendance from team in the process Perform other assigned work by the process owner


remark

2- OVERALL INTERNSHIP EXPERIENCE 2.1 How I got into the company It was not a painstaking process for me to simply get into ESUDCIB. Before applying to the governmental body, in March 2014 GC I signed an agreement with Roads Construction Enterprise and at the time, the General Manager of the Enterprise Guled Ahmed Ali told me that I will gain practical experience from the construction of rural roads outside the capital of Zone 5 Jigjiga. Working under difficult circumstances is always welcome and Highway sector has an important role to play in Ethiopia and in Africa at large. Shortly after the holistic exam, in line with my previous agreement with Roads Construction enterprise, I directly arrived in Jigjiga to get involved in projects pertaining to the design and construction of roads; unfortunately I couldn’t get into the company since the regional government temporarily put the projects across Zone 5 on hold. It took a few weeks for me to make a shift in hosting company [as per the acceptance of the Bureau] and the roads construction enterprise encouraged me to join the implementing body which was undertaking huge projects in Jigjiga. The following days, I had a meeting with Eng. Asad Omar Hussein, the highest governing deputy chief of the Bureau who immediately assigned me to the site where a new presidential palace were being built under the supervision of professional engineers. As I was intern from Debre Berhan University, I enjoyed wider recognition and open cooperation from the team of engineers with the Bureau. I used to learn a lot about the designs and construction of buildings from them. The presidential palace was under progress and the contractors were erecting superstructure elements, meaning that I was unable to see the substructures, like foundation works. Nonetheless, I managed to work with K2N architecture and Engineering consultancy P.L.C on the foundation of three storey 18-blokcs meant as staff residence in Jigjiga University following consultations with the Bureau. In the last month of the internship program, I had been part of a technical committee appointed to review the engineering report of Best Consulting Engineers 18 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

P.L.C. I drafted a seven page evaluation report on the engineering designs and reports of the consultancy.

2.2 The sections that I had been working in I had been working on the side of the consultant and my role was not only limited to visiting sites and practically understanding the job but my role was also to make some designs, quantity takeoffs and study designs. Among the tasks entrusted in me are as follows: 1-Supervision of Jigjiga Presidential palace, including inspection of construction progress and the quality of construction materials. 2-Reading of Designs of the buildings under construction and ensuring whether the design is met on the site. 3-Cooperating with foremen under the guidance of Bureau supervisor on the prevailing problems. 4-Generation of new ideas and proposal of solutions if challenges come into being on the construction site. 5-Preparation of takeoffs for the plans of new construction projects. 6-Supervision of construction of staff residence in Jigjiga University. 7-Review into engineering report by Best Consulting Engineers P.L.C, on four lane divided urban roads that will be constructed in Jigjiga city. 8- Introduction of comments on the much-needed engineering tasks. 9-As surveyor using Total Station equipment. During my internship program, I paid special attention to:      

Condition of plastering Visible cracks due to the self-weight and live loads imposed on the structure by construction workers Severe failures in the structure The condition of Portland cement Concrete mix Whether foreman assigns workers to their respective tasks


2.3 Introduction to the Sites 2.3.1 Introduction to Palace and Staff Residence

Presidential place and staff residence are found in Jigjiga, the capital city of Somali region of Ethiopia. Presidential palace is now 80% completed and substructure works were completed before my arrival while 3 storey 18 blocks staff residence is under construction and nearly 20% completed. 2.3.1.1 Construction Materials, Quality Assurances and Tests

-Cement -Selected Materials -Fine Aggregates -Coarse Aggregates -Reinforcement Bars -Nails -Tying Wires -Form Works -Timber Scaffolds As I worked on two different sites, construction materials were similar to each other but the most important issue, regarding the tests for quality assurance was matter under spotlight. On Site one where presidential palace is being built tests were either preconducted or suspended due to physical observations being made by engineers. But on Site Two, where staff residence is being built, I found that Addis Ababa-based Engineering Consultancy employed two empirical tests: 1-Slump Test 2-Compressive Strength Test For every concrete mix, the consultancy PLC staffers used to test the compressive strength of the concrete. If the concrete fails to satisfy the required compressive strength, demolition will come into being for the sake of quality assurance. All compressive strength tests were conducted in Dire Dawa. Six test cubes of each (15cm*15cm*15cm) are taken for each test. At least one test is taken whenever the concrete mix is less than 50m3, and at least two tests are taken to test for a concrete mix greater than50m3. Out of the six cubes, three will be tested for 7 days strength which should be greater than 70% of the compressive strength of the 28th day strength, and the rest will be tested for the 28days compressive strength which should fulfil the required strength. 20 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

Criterion for Design 

   

Function- the structure should give any of the services it was intended for. It should be possible to have unrestricted and unhindered use of the structure for the purpose for which it is built. Crack, deflection and vibration of the structure should be within the service limits. Safety- the structure should be safe against any possible failure during its intended time of use. It should fulfill requirements set by building codes. It should follow the codes of practice for loading, materials, design and construction. Durability- the structure should be able to stand for a time it is intended to serve for. Economy-The design work should take into account not only the cost of materials but also the applicability, the time required to build, the cost of temporary structures, the cost of maintenance. Appearance (aesthetic value) - it should have a satisfying appearance/ look. The design should consider the effect of cracking, leaking, staining, flaking, etc.

2.3.1.2 Storage Process and Construction Equipment

Upon my arrival at the site, I decided to learn a lot about the construction materials and equipment since engineers are required to be acquainted with the knowledge of equipment and store keeping on the site. Various materials such as cement, PVC, metallic pipes and paints have varying shelf lives and different ways are employed while keeping them in halls mainly constructed of Galvanized Corrugated Steel Sheet [BWG 34], the low-quality sheets for economic reasons.

Figure 1: Photo 1: Indicates cement bags resting on the ground & Photo 2: Cement Bags placed above the ground at nearly 30cm 21 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

The site engineer told me that the shelf life of cement is 6 months and if it surpasses duration of six months, it can’t be used for the concrete and mortar mixes. The following factors are taken into account while storing concrete in the temporary camps of contractors.  

Flooding/ the depth of flowing water when it rains Humidity and moisture Why placed above the ground? Because cement is more liable to be inundated by liquids including rain water and moist soil on which cement bags rest.

Figure 2: Photo 1 [Presidential Palace] Factors like flooding should be considered and the height depends on the amount of precipitation Photo 2: Like cement, PVC and electrical conduits are not laid on the ground

Below are the construction equipment found on Staff Residence Site


Figure 3: Orange-branded Back Hoe excavates the ground to minimize labour cost and throws excavated soil into the Damp Truck…….R: Electric vibrators help construction workers expand concrete in plastic state, more importantly in this case for the concrete cover of footing reinforcement

Figure 4: Fixed Concrete mixer has the capacity of holding 2 bags of cement, 6 boxes of course aggregates and 4 boxes of fine aggregates at a time for C25 concrete while R: Concrete hauler transports fresh concrete from the fixed mixer to the intended destination

Compactors


Figure 5: Simple compactors reduce the volume of backfill soil by compaction while R: similarly rollers or caterpillars are compactors and a machine that is mainly used for increasing the bearing capacity of soil on roads and sometimes the site of buildings

2.3.1.3 Concrete Mixing

I took a look back at concrete work on the construction site to see if the procedure complies with university lessons, particularly lessons pertaining to construction materials. On the site that I visited [Presidential Palace] the concrete mix was important part since the building was Reinforced Concrete structure [Residential Building plus assembly building].

Figure 6: Crew members await workers collecting fine and course aggregates in estimating box…R: The photographic image presents everybody with 50 x 40 x 18 measuring box that was used during volume batching of concrete mix Batching Al though two types of batching are used: 1) Weight Batching 2) Volume Batching, the most important one, Weight Batching has never been used on my site but Volume Batching was predominant and workers were employing measuring box with dimensions:  

50 cm X 40 cm X 16 cm for C30 Concrete 50 cm X 40 cm X 18 cm for C25 Concrete




50 cm x 40 cm x 20 cm for C15 Concrete

Ratio Proportioning    

1:2:3 for C30 Concrete [Highly Specialized Work] 1:2:4 for C25 Concrete [Strong Work] 1:2:5 for C 15 Concrete [ General Purpose Work] 1:4:6 for Lean concrete [Sub base Material]

To get concrete consisting of 50kg-Net-weight National-branded cement bag, three measuring boxes of coarse aggregates and two measuring boxes of fine aggregates. Procedure of mixing  Approximately 18 liters of water is poured into the concrete mixer  Cement Pack is cut into two pieces to make handling simple and subsequently added to the water

Pozzoloni Portland cement [PPC] Concrete Formula Dry: -1 Part Portland Cement -2 parts medium or coarse sand -3 part Gravel or rock Urban Development Bureau brought National-branded Pozzoloni Portland Cement (PPC) with 32.5 R Strength Class to the site because it is cheaper when compared with Ordinary Portland Cement [OPC] with 42.5 R Strength Class. The pozzolanic materials commonly used are volcanic ash, calcined clay, fly ash, and silica fumes. The Portland Pozzolana Cement is ideal for general construction which does not required high early strength. Commonly, it is ideally suited for constructions such as hydraulic structures, mass concrete works, marine structures, masonry mortars and plastering, under aggressive conditions, and all other applications where Ordinary Portland Cement (OPC) is used.

Typical concrete sets in about 6 hours and develops a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at 1 week, 35 MPa at 4 weeks and 41 25 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

MPa at 3 months. In principle, the strength continues to rise slowly as long as water is available for continued hydration

Figure 7: National-branded Pozzoloni Portland Cement used for concrete on the construction site The construction works did a good job to at least avoid poor handling, placing and compaction of fresh concrete and in less than 30 minutes, the process was over for setting and hardening of plastic material. Curing was also the most important practice after concrete being placed, the curing was aimed at preventing concrete from surface cracks due to the rapid loss of water and increase the strength of concrete. 2.3.1.4 Engineering Problems at Presidential Palace Site

   

On the site of the construction, I saw problems emanating from segregation and bleeding No test was performed on the concrete, e.g slump test for workability The project lacked mix design and perhaps, it could have affected quality control of concrete Vibrators were not used effectively for the compaction of concrete, thus the chance for segregation was high but it also led to slab defects as concrete cover of the upper floor slab became non-existence according to the below photo.


Figure 8: Honey comb [Mortar fails to fill voids between Coarse Aggregate particles] and Voids [Concrete fails to fill areas in the form work] Defects 2.3.1.4.1 Causes

    

Stiff and Unworkable Concrete Segregation Congested Rebar Insufficient Consolidation Improper Placing Practices

2.3.1.4.2 Weak Crushing Strength Coarse Aggregates

On the site, engineer feels that Coarse Aggregate is the most important ingredient in the concrete since it is different from Mortars due the presence of course aggregate. One thing that I can draw from my experience falls into the strength of course aggregate which is required to match the strength of concrete itself. As I have worked with the consulting firm side, I found a course aggregate with low crushing strength due to the following reasons. -It simply crushed when pressed between thumb and a finger -Appearances such as the surface cracks and sieve-like characteristics proved weaknesses


Figure 9: Low crushing strength Aggregate

2.3.1.5 Substructure and Foundation Works

Since I understood a lot about the superstructure, I asked Urban Development Bureau to let me work with K2N Architecture and Engineering Consultancy plc which was undertaking the construction of G+3 Staff residence buildings inside Jigjiga University. I started observing site clearance operation, including Setting out, excavations for footing pads, Placement of lean concrete and formwork of footings, placement of concrete in formwork, attaching columns to footing re-bars, Backfilling, Profile Floor Levelling and Grade Beams. To meet the exact Profile Floor Level [+/-0+00], you need to fix profile boards at a distance of 2m from the outside edge of the masonry wall where the excavation will take place. Perpendicularity is given much attention to avoid disturbances and improper centerlines during the excavation of ground for shallow foundations. Main function of the lean concrete is to provide the uniform surface to the foundation concrete and to prevent the direct contact of foundation concrete from the soil. Lean concrete is used under the foundations. 28 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

2.3.1.5.1 Tasks Executed Minimum Depth of Boreholes for Site Investigation? As a consultant I suggested that the minimum depth of excavation can be derived from this formula

Where D=Depth of Boring S=Number of stories

In our case, we were constructing G+ 3 building [3 Storey building], henceforth. From previous records, we found that the type of soil is block cotton soil, which could result in failure and differential settlement, therefore we agreed to increase the width of footing for punching shear.


It is impossible to achieve a depth of 12.94m: The footing dimensions=1500mm X 1500mm Footing Depth=550mm Foundation Depth=2730mm Rebar Size=Grade 60 14mm Diameter Concrete Cover=50mm Steel Grade= =300 Column Dimensions=400mmX250mm 250mm of working space was needed each side

Figure 10:From physical observation, I understood that the relative density of soil was small [Low Dense Soil], Depth of Foundation could have been increased [Photo 2] & Photo 3 shows lean concrete poured into the excavated holes Development Length Check To achieve higher bond between the concrete and steel, you need to bend the re-bars for bond strength. Why for development Length? In the tension zone, Concrete-Steel interface form Bond Stress, if not achieved bars pull out of concrete and tension drops to Zero. The sufficient length into which bars extend concrete is known as ‘Development Length’. We usually apply this principle when designing Footing re-bars. I have checked the bars of the foundation for development length, which is unavoidable at all costs during the construction of foundation footings. 30 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

Where ᶲ=Diameter of the bars Yield Strength of Reinforcement Bars

On my site: Rebar Size=Grade 60 14mm Diameter For Concrete C-25 2 X Fctd(Design Stress of Concrete in Tension) =Fbd

Fctd=1 Fbd for deformed bars [>Diameter 6) =2x1=2MPa


Figure 11: Footing Re-bars are bent up for bond strength to create strong bond between Concrete and Steel In Ethiopia, the most commonly used steel bars are S-300 with Fyd=260.87MPa


The amount of soil dug up from the site during the excavation is not almost important and to make sure that future backfill soil is good at compaction, Cart Away concept is introduced during the preparation of Quantity Take-off material. Over 80% of backfill constitutes selected materials and expenses are in turn incurred.

Figure 12: Materials are selected for better compaction, strength and good texture

Columns are fixed to the footing bars by transferring lines from string lines to the ground through plumb-bob and nails are also attached to wooden form work. It is noteworthy to mention that Verandas Footing Pads carry smaller load than other footings of the G+3 building.


Figure 13: Columns are directly attached to footing re-bares [Photo 1], Concrete is poured into the footing only [Photo 2] & without casting the column concrete forms the footing pad only [Photo 3] Footings remain 24 hours in the form work, to continue hydration process in order to attain high strength curing lasts seven days and followed by backfilling.

Figure 14: Photos show curing techniques for footing pad and columns


2.3.1.6 Solid Slab and Grade Beams [Staff Residence]

Solid Slabs For any structural element, the following guidelines are important and it should be applied to the structure while designing and constructing.     

Shear is maximum at support Moment is minimum or zero for pinned and roller supported structures at supports Stirrups [Vertical stirrups] that are most commonly used carry shear above the concrete capacity Inclined stirrups not used for buildings prone to seismic loads T and Inverted L beams –T sections are very advantageous in simply supported span to resist positive bending moment. Inverted L sections resist negative bending moment in cantilever beam.

Table-6 Concrete Cover Member

Concrete Cover

Beam

25mm Moderate

Slab

15mm Mild

Footing

50mm Severe

One-way slab: Reinforcement in one direction [Transverse for Bending Moment] but practically it is non-existent due to architectural reasons. Two-way slab: Reinforcement in two directions Main Mesh Reinforcement Secondary Mesh Reinforcement Table-7 Concrete Classes


Table-8 Reinforcing Bars and their applications

Except for 6 mm diameter bars, reinforcing bars have ribs that create strong bond with concrete. Slabs transfer floor loads to the support by flexure and of the three types of slabs namelySolid Slab, Ribbed Slab and flat slabs-I saw Solid slabs which are divided into strips, say middle strip and edge strips and reinforcement is provided in both directions. Maximum bending moment is found in the middle strip where positive reinforcement and T sections are found while 50% of the strips are extended into the support. I learned that negative bars are terminated at a distance of L/3 from the respective centerline of the supports. Engineers prefer yielding steel at first to collapse in concrete. Grade Beams There is a direct relationship between ground floor slabs and grade beams. Grade beams are similar to other beams supporting slabs but needs some structural considerations and important concepts are introduced while on site and also in office.


Figure 15 the Ground is levelled up to Profile Floor Level [PFL] before grade beam is being laid

Once footings and columns are completed, foundation masonry wall constructed of stone and cement mortar is erected. Grade beams directly rest on the masonry wall and now the concrete. Isolation of Ground floor Slab: During my stay on the site, I came across the concept of isolating ground floor slab from the grade beam. Unlike first floor and second floor slabs, ground floor slabs don’t carry flexural stress but since concrete is weak in tension, you need to avoid severe cracking that would result from tension above the concrete capacity and Expansion joint materials are placed between grade beam and ground floor slab. Grade beams are not doubly reinforced structures but hanger bars run longitudinally in the nominal compression zone for vertical stirrups to be fixed and allocated properly. In fact Negative bars are provided in the tension zone like cantilever beams.


Figure 16: Negative bars resist negative bending moment due to the pressure by soil on the masonry wall on which grade beams rest

2.3.1.7 Floor System [Presidential Palace]

During the flooring, I raised a number of questions, particularly the observation of solid floor which direly rests on the ground. For example, the importance of Damp Proof Courses (DPCs) and how such materials help floor system resist moisture and dampness into the pavement. I took a serious note on the following procedures:Floor Layering

Figure 17: Soil constituting a depth of 150mm above the ground level is compacted manually Soil, either Natural or selected soil material is sprayed on the floor area, the depth of the soil is almost 150mm above the ground level and a rod in a can filled with concrete helps construction workers level the soil to a desired depth. 38 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

Figure 18: Trachytic Hardcore materials used as Damp Proof Course (DPC) during floor layering

Figure 19: Basaltic gravel is also used as an alternative Damp Proof Course (Material) over the course of floor layering


Hardcore or from Geologic perspective, Granite rocks are important in the layering of solid floor due their resistance to dampness and moisture. The hardcore layer occupies a depth of 250mm. Hardcore exists in two forms, namely 1) Trachytic Hardcore [Granite] 2) Basaltic Hardcore Rock. Merits of Hardcore on the site 1-Strengthened and solidified the base of the building by resisting the pressure of dead and live loads acting on the building. 2) Saved cost of construction, for example during the application of hardcore, the volume occupied by the hard core if it were to be concrete would have cost more. 3) I do expect in future, it would reduce movement of water up to the floor surface.

Figure 20: After the hardcore is finished, Reinforcing steel with 8mm diameter is applied to the surface to let floor system withstand tensile forces 40 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU

Before the concrete was poured over the hardcore, a process called ‘blinding’ is employed. Since it is quite troublesome placing concrete on the hardcore directly, three options existed for us on the site 1) the use of a thin layer of very dry coarse concrete that could be spread over it, 2) the use of a thin layer of coarse clinker (powder), and 3) the use of ash. This blinding layer, or coat is about 50 mm thick, and on it the site concrete is spread and finished with a true level top surface. The diameter of reinforcing steel used in the field is 8mm while the total depth of floor became 50cm:1) Compacting the selected backfill material with a layer not more than 25 2) 25cm of Hardcore/ 20 Hardcore plus 5cm of blinding material 3) 10cm of concrete

Figure 21: While casting concrete, it is lined just to ensure that alignment is correct and surface is levelled appropriately


2.3.1.8 Roofing System [Presidential Palace]

Roof constitutes the upper most part of the building. It was really carrying a special interest for me to see how roof covering are selected and supports including rafters, kingposts, struts and purlins are built prior to the placement of Galvanized Corrugated Steel Sheets. The most abundant roof covering on my site was Galvanized [Steel with zinc for rusting] Corrugated Steel Sheet and at least I encountered some problems regarding the quality control.

Figure 22: Galvanized Corrugated Steel Sheet, USG where G=Gauge 0.376mm Types of roofs on the site -Corrugated Metal Sheets -RC Slabs -Clay Tiles There have been pitched roofs, closed couple roofs and trussed steel roofs for assembly structures.


Figure 23: The presidential offices exhibit Hip roofs, just pitched since rainfall is abundant in Jigjiga For halls -Steel Truss span-18.4m -Spacing 4.5m


Figure 24: Assembly buildings require steel trusses unlike others due the width of the building

If the roof is to be constructed as a concrete roof, it will be designed as a slab. While if a sloped roof, say with EGA SHEET cover, supported with truss it will requires its own design procedure. For steel truss like this, the truss members should be designed using design software to check the safety of the truss and its ability to withstand excessive deflection. The loads that are considered in the analysis and design of truss include:1-Roof Cover Load 2-Wind Load 3-Live Load [According to EBCS 2] 4-Self Weight of Truss Members and Purlins 5-Additional Imposed Loads [If Any] The loads are applied at joints as concentrated loads and the truss is analyzed. The reactions from the truss have to be transferred to the structure. For steel truss, since it can have a longer span between the trusses, the load transfer will be directly into columns. But in case of wood truss, the span between trusses is limited, so the roof loads will be transferred to beams as a concentrated load at certain intervals.


Figure 25: Photo 1: Steel trusses Photo 2: Welded Steel trusses Photo 3: Less corrugated Ega Sheets, thicker than more Galvanized Corrugated Steel sheet

Figure 26: BWG 34-0.2mm used for stores while USG 28-0.376mm is used as roof covering Drainage System Like the formal structures, buildings require more credible drainage system to avoid failures resulting from poor drainage.


At the construction sites, Flat sheets are either used as gutters or down pipes and let rain water flow through pipe-like systems attached to the side-building.

Parapets

Figure 27: Parapets are part of the structural elements that form a building Photo 1: Before concrete casting Photo 2: After placement of concrete Parapets are structural elements in the building during concrete casting. They are directly attached to the reinforcement mesh of the slab due to the presence of loadings. Among the loads on the parapets are: Dead loads [Self Weight], Hydrostatic Loads [When raining] and occasionally lateral loads resulted by wind loads on the roof covering. After concrete is casted, hollow concrete blocks at a depth of 40cm are constructed to help parapets retain rain water. Dimensions of the blocks [40X20X15 CM].


Gutters

Figure 28 Photo 1: Workers attend to non-corrugated/ Flat sheets to find exact dimensions required Photo 2: Prepared Gutter on roof top Photo 3: Upper most part of a roof covering with opening Photo 4: Hidden Roof gutters due to aesthetic purposes Quantity Take off for roofs Without taking labour and material costs into account, it’s necessary for engineers to understand how to calculate the surface area of roof on a given building. At first, I found the following interesting  

Angle of the Roof, Rise-and-Run of roofs Width of the Roof and Overhang of the roof

Area= Two Sides X Length of the rafter X Length of the Building


2.3.1.9 Tests on the Site

Slump Test

Figure 29      

Photo 1 indicates preparation after [photo 6 resulted in collapsible slump Photo 2 shows concrete poured into the slump cone Photo 3 unveils compaction of concrete with tamping rod Photo 4 exposes how I carefully lifted the cone after the compaction of three layers got finished Photo 5 I measured the slump of the concrete/True Slump Photo 6 is the first test of collapsible slump

For the construction of footing and columns, I decided to perform Slump Test to ensure whether the concrete is workable enough or not.


Apparatus    

   

Slump Cone/Metallic Mould with 20cm bottom diameter, 10 cm top diameter and 30 cm height. Wooden base plate Steel Tamping road with 16mm diameter and 60 cm length Wheelbarrow Procedure I took a sample concrete on wheelbarrow from the mobile concrete truck Prior to the test, wooden base plate was washed with water to avoid moisture absorption I placed three layers of concrete in the slump cone, each tamped 25 times with steel rod I carefully lifted the slump cone, just to avoid unintentional collapse

Result 



First test resulted in collapsible slump due to the following reasons -Poor compaction by the foreman -Large amount of water in the concrete Second test resulted in true slump of 7 cm /70mm satisfactory for footings and columns according to the following table Table-9 Recommended Slumps for Various Types of Construction

TYPES OF CONSTRUCTION

SLUMP CM. Maximum* Minimum

Reinforced foundation walls and footings

8

2

Plain, footings, caissons, and substructure walls

8

2

Beams and reinforced walls

10

2

Building columns

10

2

Pavements and slabs

8

2

Heavy mass concrete

8

2


Recommendation Since the first test led to collapsible slump, the only solution is to leave it and again proportion concrete ingredients. 2.3.1.10 Total Station Operation

Definition: Electronic Survey Equipment is used to perform horizontal and vertical measurements in reference to a grid system (e.g. UTM, mine grid). Well in the first place, it’s noteworthy to mention that different types of Total station are available on markets so in my case, I operated Sokkia CX Series. Like theodolite you need to adjust tripod, optical plummet to the target (Bench March/ Occupy station) and also to use foot screws. Below is the display panel of my total station after I exactly placed it on the occupy station and centred the circular bulb.

Figure 30


Here we have one task to do to achieve higher accuracy; through the foot screws at 180 one needs to eliminate tilt of Y by two foot screws and tilt of X by one foot screw. Again make 90 degree rotation and repeat the same procedure.

Function Keys

Figure 31 Function Keys are important in many ways, particularly in identifying the kind of project you are expected to execute. Below are function and ESC buttons for showing off the pages. 

Create Job[F3], from the job selection, select job with 0 data if not, then go to F1 [Job List] ,delete a job and again choose job

DATA COLLECTION VIA TOTAL STATION  





Select Data Prepare occupy station [Point over which the total station is placed] with Easting, Northing and Z [Elevation], for almost all cases, we employed Garmin GPS to find E=257955, N=1034958 and Z=1672 of occupy station Again on Data, click BS Data to find second reference position, you will see Angle or Coordinate, we do prefer Coordinate Method, and GPS is again used for BS to achieve accuracy, data is inserted into the equipment. EBS=257910 NBS=1034989 ZBS=1670-----Ok button Height of instrument is measured using steel tape and heigh of the prism pole is written in the display screen.


 

To check out your work, now take Back Sight reading, shoot the prism pole and hit F1[REC] to get accurate reading Place your prism pole over various stations by keeping your total station over the occupy station until prism-hold gets lost due to rough terrain and existence of mountains.

DATA TRANSFER

Figure 32 52 | P a g e © I n t e r n s h i p R e p o r t b y A b d i r a s h i d M o h a m e d D a h i r - 4 t h year Civil Engineering Student-DBU







As you can see from the above photographic image, you can transfer the collected data to flash disk or to the computer with the help of USB and specific software. Fortunately, nowadays total stations have own system to let surveyors receive data in a simple manner. Hit F2 [USB], Select S type, Select Save Data, among the different jobs available on the display panel, choose your task and click ok, wait for a while moving into the storage device. Transfer to Excel as CSV [Comma Delaminate] format and save [Below is the data] X 267952.4 267952.4 267952.4

Y 1034958 1034958 1034958

z 1672.285 1672.285 1672.285

267952.4 1034958 1672.285 267952.4 1034958 1672.285


3-OVERALL INTERNSHIP BENEFITS 3.1 Improvement of Practical Skills In the last four months, I was able to improve my practical skills and understand how works are executed on the construction sites. Below are practical skills I gained during the internship program:              

Installation of scaffolds and false work Types of formwork, releasing agents and their design Concrete mixing, procedures, handling, placement and casting The meaning of the term 1:2:3 in concrete mix Reinforcement Placement, types of re-bars, curtailment, and lab length. Casting of solid slabs, design of negative bars and positive bars and storage of concrete and other construction materials. Operation of Total Station Empirical tests on concrete including slump and compressive strength test Roof covering, quality assurance of roof coverings, quantity takeoff, drainage system of buildings and design of steel trusses for assembly buildings Floor systems and the reasons behind reinforcement mesh of ground floor slabs Understanding grade beam and expansion joints Inspection of aggregates Development length in foundation works Construction Equipment and physical observation in line with engineering perspectives Designing in Autocad, SAP, ETABS and EAGLE POINT

3.2 Theoretical Knowledge Upgrading Practical skills on the construction sites upgraded my theoretical knowledge as I came across new components in construction industry, for example:      

The concept of parapets and Grade Beams Generation of scientific reasoning for practical problems Construction Equipment and Materials The concept of cart away in takeoff sheets and estimation of re-bars for structural elements Reading and Understanding working drawings


3.3 Interpersonal Communication The site is far more different from the University where we solely use scientific reasons. I managed to interact with many people with different backgrounds and languages. I had a working relationship with supervisors, office engineers, project managers, foremen and even construction workers. You may find new words at the site but I coped with both the horizontal and vertical communication between different groups involved in the two projects. Benefits of communication skills on the site     

Suggestions and orders for foremen and construction workers Sharing ideas Co-managing daily activities Respects for attitudes Decision-making while resolving engineering problems

3.4 Team Playing Skills I used to join my colleagues from other universities to discuss engineering problems and possible solutions. At the same time, as a team member and fresh consultant with Urban Development, Construction and Industry Bureau I cooperated with professional engineers on a number of occasions by:      

Respecting suggestions Sharing ideas open-mindedly Communicating effectively Approaching issues from a constructive point of view Listening seriously Seeking accuracy at all times


3.5 Leadership Skills During the internship program, I benefited from many leadership skills from the offices in the Bureau to the construction sites. At office, I took a serious note on the orders from Urban Development, Construction and Industry Bureau head to contract administration team and engineers. On the site, orders by project managers for keeping materials properly were important and foremen remained accountable to both engineers of the contractors and consultancy. Controlling everything on the site under the watch of contactor and work flow at office play crucial role in the timely completion of projects.

3.6 Work Ethics In construction industry, you need to develop healthy working environment and double productivity through punctuality, honesty by avoiding corruption and bias, cooperation, office discipline without disturbing working condition and reliability.

3.7 Entrepreneurship Skills Al though I was working on the side of the consulting Bureau, I came across some entrepreneurship skills including resource utilization in profitable manner in a given period of time and the importance of manpower and construction equipment. The obvious goal of the Bureau was to improve the standards in place for housing and construction of high-quality buildings in the Somali region of Ethiopia.


4-CONCLUSION I have found the internship program interesting as it provided me with the necessary skills required by civil engineers at site and in office. It was an opportunity for me to interact with different people including professional engineers who at least contributed their guidance to me. It was something of highly valued to work for Ethiopian Somali Urban Development, Construction and Industry Bureau on the construction of two key projects -Jigjiga Presidential Palace and staff residence in Jigjiga University. The consulting body directed me towards tough tasks but those with appropriate theoretical knowledge could have overcome the engineering problems over the course of the internship. I gained not only practical but also theoretical knowledge by perceiving different challenges on site and putting what I studied at class into practice. At least, if you go on internship with high-class company or institution, you will get acquainted with the translation of something in books into action. I learned what do self-confidence, team playing, organizational skills, upgrade of theoretical knowledge mean to the engineer? Once and for all, let me say internship is far more fascinating than many things and complies with real life situation.


5-RECOMMENDATION Ethiopian Somali Urban Development, Construction and Industry Bureau where I maintained presence for nearly four months needs to increase the number of civil and construction engineers. Despite impressive work flow, the shortage of experienced engineers was challenging matter. The setting up of modern laboratory, publishing of soil testing manual and training of technicians remain crucial because of the critical tasks ahead for the Bureau. The delays in construction could only be avoided if contractors are scolded legally and held accountable for the mishaps. On site two, the staff residence of Jigjiga University, I recommend both the consulting firm and contractor to provide space to practicing students and ease the restrictive control. As long term and short term plan, consultancies are in dire need of relevant expertise and laboratories to come up with quality assurances and scrutinize the contractors whenever problems arise with varying intensities.


6-REFERENCES      

Debre Berhan University, ‘Lecture Notes’,[Unpublished] Ethiopian Somali Urban Development, Construction and Industry Bureau, ‘Company Profile’ 2007 [Unpublished] Foundation Analysis and Design, ‘Joseph E. Bowles’, 5th Edition Ministry of Works and Urban Development, ‘Ethiopian Building Code Standard; EBCS-1-EBCS-8’,1995 S. S Ray, ‘Reinforced Concrete Design and Analysis’, 1995 Techniques of Writing and Editing Educational Materials, ‘Tesfaye Ejigu Tefera’, 1st Edition


7-APPENDICES

Timber Formwork & Steel Formwork

Oil is used as releasing agent during the initial fixing and at a later date when workers remove temporary support from the hardened concrete


If the work can’t be accessed from the ground, construction workers need to use scaffolds to build upper parts


Internship report on substructure and superstructure works of construction project

Recommend Documents