Seismic Analysis and Design of r.c.c Tall Building With Shear Wall

International Journal of Emerging Researches in Engineering Science and Technology-Vol-2-Issue-4-April-2015Technology-Vol-2-Issue-4-April-2015-ISSN: 23939184

SEISMIC ANALYSIS AND DESIGN OF R.C.C TALL BUILDING WITH SHEAR WALL M.RAJIVGANDHI*, S.AKILA** * (Student, Department of Civil Engineering, Regional Centre of Anna University, Coimbatore -641 047) ** (student, Department of civil engineering, RVS college of engineering & technology, Dindigul-624 005) Email: [email protected], [email protected]

Abstract —

In this project, study of G+19 storeyed building in Zone III is presented with some investigation which is analyzed by changing various different location of shear wall for determining parameters like storey drift, storey shear and displacement is done by using standard package STAAD Pro. Shear Walls are specially designed structural walls included in the buildings to resist horizontal forces that are induced in the plane of the wall due to wind, earthquake and other forces. They are mainly flexural members and usually provided in high rise buildings to avoid the total collapse of the high rise buildings under seismic forces. The aim of the project is to analyze and design with different positions of shear wall. By taking up all the above mentioned work, the plan of then proposed building have been done by using AutoCAD & STAAD Pro &ETABS analysis in this project phase I&II KEYWORDS

ETAB v 9.5.0, STAAD Pro, framed structure, Seismic analysis, Shear wall, Tall Building

INTRODUCTION 1.1 GENERAL

RCC tall buildings are adequate for resisting both the vertical and horizontal load. When such building is designed without shear wall, beam and column sizes are quite heavy

carried out by using standard packages STAAD Pro & ETABS. The comparison of these models for different parameters like Displacement, Displacement, Storey Drift and Story Shear has been presented by replacing column with shear wall. Different position and location of shear walls are considered for studying their effectiveness effectiveness in resisting lateral forces.

NEED FOR THE STUDY The aim of the project is to know the behaviour of tall building with with shear wall The main need of the study is to prevent the building from the damage Analytical study – show the results of of displacement and storey drift , spacing of column and the effectiveness of shear wall •

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•

1.2 OBJECTIVE The main objective of this study is to To analyse the response of RC building subjected to lateral loading by using STAAD Pro and E-TABS software. To study the behaviour of the building by providing shear wall at different positions in the RC frame To design the building with shear wall for the best position obtained from E-TABS E-TABS analysis •

•

and there is problem arises at these joint and it is congested to place and vibrate concrete at these places and displacement displacement is is quite heavy which induces heavy forces in building member.

•

Shear wall may become essential from the point of view of

1.3 TALL BUILDING

economy and control of horizontal displacement.

There is no absolute definition of what constitutes a tall

The residential medium rise building is analyzed for earthquake force by considering two type of structural system.i.e. Frame system and Dual system. Effectiveness of

building. It is a building that exhibits some element of "tallness" in one or more of the following following categories •

It is not just about height, but about the context in

shear wall has been studied with the help of four different

which it exists. Thus whereas a 14-storey building

models. Model one is bare frame structural system and other

may not be considered a tall building in a high-rise

four models are dual type structural system. Analysis is

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International Journal of Emerging Researches in Engineering Science and Technology-Vol-2-Issue-4-April-2015-ISSN: 23939184

city such as Chicago or Hong Kong, in a provincial European city or a suburb this may be disti nctly taller than the urban norm. Again, a tall building is not just about height but also about proportion. •

There are numerous buildings, which are not particularly high, but are slender enough to give the appearance of a tall building, especially against low

All permanent constructions of the structure form the dead loads. The dead load comprises of the weights of walls, partitions floor finishes, false ceilings, false floors and the other permanent constructions in the buildings. The dead load loads may be calculated from the dimensions of various members and their unit weights. the unit weights of plain concrete and reinforced concrete made with sand and gravel or crushed natural stone aggregate may be taken as 24 kN/m and 25 kN/m respectively.

urban backgrounds. Conversely, there are numerous big/large footprint buildings which are quite tall but

their size/floor area rules them out from being classed as a tall building. •

If a building contains technologies which may be attributed as being a pr oduct vertical

transport

of "tall" (eg specific

technologies,

structural

wind

bracing as a product of height, etc), then this building can be classed as a tall building. •

IMPOSED LOADS: IS 875 (Part 2) deals with the imposed loads on roofs, floors, stairs, balconies, etc., for various occupancies. There is a provision for reduction in the imposed loads for certain situations, e.g. for large span beams and number of storeys above the columns of a storey. The earthquake code IS: 1893 (Part 1)-2002 permits general reduction in roof and floor imposed load when considering the load combination with the earthquake loading. But the two types of reductions, that is, in IS: 875 (Part 2) and IS: 1893 (Part 1) are not to be taken together.

Although the number of floors is a poor indicator of a tall building due to the differ ent

floor -to-floor height

WIND LOADS:

in different buildings and functions (eg oce versus

Wind is air in motion relative to the surface of the

residential usage), 14 or more stories (or a height of

earth. The primary cause of wind is traced to earth‟s rotation

over 50m/165ft) could perhaps be used as a threshold for a tall building. 1.4 SHEAR WALL

Reinforced concrete (RC) buildings often have vertical plate-like RC walls called Shear Walls in addition to slabs, beams and columns. These walls generally start at foundation level and are continuous throughout the building height. Their thickness can be as low as 150mm, or as high as 400mm in high rise buildings. Shear walls are usually provided along both length and width of buildings .Shear walls are like vertically-oriented wide beams that carry earthquake loads downwards to the foundation. 1.5 LOADS CONSIDERED 1.5.1 Calculation of Loads The loads will include the following: DEAD LOADS:

and differences in terrestrial radiation. The radiation effects are primarily responsible for convection either upwards or downwards. The wind generally blows horizontal to the ground at high wind speeds. Since vertical components of atmospheric motion are relatively small, the term „wind‟ denotes almost exclusively the horizontal wind, vertical winds are always identified as such. The wind speeds are assessed with the aid of anemometers or anemographs which are installed at meteorological observatories at heights generally varying from 10 to 30 meters above ground. DESIGN WIND SPEED (V,):

The basic wind speed (V,) for any site shall be obtained from and shall be modified to include the following effects to get design wind velocity at any height (V,) for the chosen structure: a) Risk level; b) Terrain roughness, height and size of structure; and C) Local topography. It can be mathematically expressed as follows: Where:

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V = V b * kl * k* ks V b = design wind speed at any height z in m/s; kl = probability factor (risk coefficient) k = terrain, height and structure size factor and ks = topography factor

RISK COEFFICIENT (kI Factor):

kI Factor gives basic wind speeds for terrain Category 2 as applicable at 10 m above ground level based on 50 years mean return period. In the design of all buildings and structures, a regional basic wind speed having a mean return period of 50 years shall be used. TERRAIN, HEIGHT AND STRUCTURE SIZE FACTOR (k, Factor)

Terrain - Selection of terrain categories shall be made with due regard to the effect of obstructions which constitute the ground surface roughness. The terrain category used in the design of a structure may vary depending on the direction of wind under consideration. Wherever sufficient meteorological information is available about the nature of wind direction, the orientation of any building or structure may be suitably planned. TOPOGRAPHY (KS FACTOR)

The basic wind speed V b takes account of the general level of site above sea level. This does not allow for local topographic features such as hills, valleys, cliffs, escarpments, or ridges which can significantly affect wind speed in their vicinity. The effect of topography is to accelerate wind near the summits of hills or crests of cliffs, escarpments or ridges and decelerate the wind in valleys or near the foot of cliff, steep escarpments, or ridges. WIND

PRESSURES

AND

FORCES

ON

BUILDINGS/STRUCTURES:

The wind load on a building shall be calculated for: a) The building as a whole, b) Individual structural elements as roofs and walls, and c) Individual cladding units including glazing and their fixings. PRESSURE COEFFICIENTS

The pressure coefficients are always given for a particular surface or part of the surface of a building. The wind load acting normal to a surface is obtained by multiplying the area of that surface or its appropriate portion by th e pressure coefficient (C,) and the design wind pressure at the height of the surface from the ground. The average values of these pressure coefficients for some building shapes Average values of pressure coefficients are given for critical wind directions in one or more quadrants. F= (C pe – C pi) A Pd Where, C pe = external pressure coefficient, C pi = internal pressure- coefficient, A = surface area of structural or cladding unit, and Pd = design wind pressure element Earthquake Load; earthquake shall be calculated using BIS 1893-2002PART Recommendation. Response spectrum method has been used for calculation of earthquake horizontal load using the calculation of natural period. 1.6 Earthquake Resistant Design Now the following steps may be taken: (a) Estimate fundamental time period Ta using empirical expressions given in the Code IS: 1893-10 2002. Ta = 0.075 H0.75, IS: 1893 Cl.7.6.1 for bare frame along each axis Tax = 0.09h/√d along x-axis IS: 1893 Cl.7.6.2 for frame with substantial infills Ta z = 0.09h/√b, along z-axis, IS: 1893 Cl.7.6.2 for frame with substantial infills Where h is the height of the building and d and b are the base dimensions of the building along x and z axis respectively. (b) Calculate the design horizontal Seismic coefficient Ah Now compute the fundamental time periods T/x and T/z for the bare frame along the two axes by dynamic analysis. These are generally found to be higher than Tax and Taz respectively. The design horizontal coefficient Ah is given by Ah = (Z/2). (I/R). (Sa/g) Take Z for the applicable seismic zone (IS: 1893 Cl.6.4.2), Take I for the use importance of the building (IS: 1893 Table 2),Take R for the lateral load resisting system adopted (IS: 1893 Table 7),and take Sa/g for the computed time period values T/x, Tax, T/z and Taz with 5% damping coefficient using the response spectra curves IS: 1893 Fig 2 for the soil

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type observed. Thus four values of Ah will be determined as follows:In x-direction A/hx for T/x & Ahax for Tax In z-direction A/hz for T/z & Ahaz for Taz (c) Calculate the total horizontal shear (the base shear) The design value of base shear VB VB = Ah W as per 1893 Cl.7.5.3. For design of the building and portions thereof, the base shear corresponding to higher of Ahax and A/hx, similarly between Ahaz and A/hz will be taken as minimum design lateral force. (d) Seismic Moments and Forces in Frame Elements: Calculate the seismic moments and axial forces in the columns, shears and moments in the beams by using the seismic weights on the floors/(column beam joints) through an appropriate computer software (having facility for using floors as rigid diaphragm and torsional effects as per IS: 1893:2002). It may be performed by Response Spectrum or Time History analysis. The important point is that according to IS: 1893 Cl.7.8.2., the base shear computed in either of the dynamic method, say V/B shall not be less than VB calculated under Cl.7.5.3 using Ahax and Ahaz. If so, then all shears, moments, axial forces etc worked out under dynamic analysis will be increased proportionately, that is, in the ratio of VB/V/B. (e) Soft Ground Storey It must be designed according to Cl.7.10 of IS: 18932002. 1.7 SCOPE OF THE WORK The aim of the project is to compare the Seismic analysis of R.C.C. Tall Buildings with Shear wall like special moment resistant frame with shear wall as well as with steel bracings, which is effectively suitable for the Coimbatore seismic zone.

earthquake motion depends on distribution of weight, stiffness and strength in both horizontal and planes of building. To reduce the effect of earthquake r einforced concrete shear walls are used in the building. These can be used for improving seismic response of buildings. Structural design of buildings for seismic loading is primarily concerned with structural safety during major Earthquakes, in tall buildings, it is very important to ensure adequate lateral stiffness to resist lateral load. The provision of shear wall in building to achieve rigidity has been found effective and economical. When buildings are tall, beam, column sizes are quite heavy and steel required is large. So there is lot of congestion at these joint and it is difficult to place and vibrate concrete at these place and displacement is quite h eavy. Shear walls are usually used in tall building to avoid collapse of buildings. When shear wall are situated in advantageous positions in the building, they can form an efficient lateral force resisting system. In this present paper one model for bare frame type residential building and three models for dual type structural system are generated with the h elp of ETAB and effectiveness has been checked. CONCLUSION: From all the above analysis, it is observed that in 10 story building, constructing building with shear wall in short span at corner (model 4) is economical as compared with other models. From this it can be concluded that large dimension of shear wall is not effective in 10 stories or below 10 stories buildings. It is observed that the shear wall is economical and effective in high rise building. Also observed that changing the position of shear wall will affect the attraction of forces, so that wall must be in proper position. If the dimensions of shear wall are large then major amount of horizontal forces are taken by shear wall. Providing shear walls at adequate locations substantially reduces the displacements due to earthquake

LITERATURE REVIEW A.“Seismic Analysis of RCC Building with and Without Shear Wall” www.ijmer.com, International journal Modern Engineering Research (IJMER), Page No: 1805-1810, Year of Publishing: May-June - 2013, Author: P. P. Chandurkar, Dr. P. S. Pajgade DESCRIPTION OF THE WORK

Shear wall are one of the excellent means of providing earthquake resistance to multistoried reinforced concrete building. The structure is still damaged due to some or the other reason during earthquakes. Behavior of structure during

B.“ Earthquake Analysis of High Rise Building with and

Without Infilled Walls” International Journal of Engineering and Innovative Technology (IJEIT), www.ijeit.com Page No: 89-94, Year of Publishing: August 2012, Authors: Wakchaure M.R, Ped S. P DESCRIPTION OF THE WORK: The effect of masonry infill panel on the response of RC frames subjected to seismic action is widely recognized and has been subject of numerous experimental investigations, while several attempts to model it analytically have been reported. In analytically analysis infill walls are modeled as equivalent strut approach there are

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various formulae derived by research scholars and scientist for width of strut and modelling. Infill behaves like compression strut between column and beam and compression forces are transferred from one node to another. In this study the effect of masonry walls on high rise building is studied. Linear dynamic analysis on high rise building with different arrangement is carried out. For the analysis G+9 R.C.C. framed building is modelled. Earthquake time history is applied to the models. The width of strut is calculated by using equivalent strut method. Various cases of analysis are taken. All analysis is carried out by software ETABS. Base shear, storey displacement, story drift is calculated and compared for all models. The results show that infill walls reduce displacements, time period and increases base shear. So it is essential to consider the effect of masonry infill for the seismic evaluation of moment resisting reinforced concrete frame. CONCLUSION: Due to infill walls in the High Rise Building top storey displacement is reduces. Base shear is increased. The presence of non-structural masonry infill walls can modify the seismic behavior of R.C.C.Framed High Rise building to large extent. Arrangement of infill wall also alters the displacement and base shear the top of building displacements gets reduces. In case of infill having irregularities in elevation such as soft storey that is damage was occur at level where change in infill pattern is occur. The effect of slenderness ratio emphasion displacement of frame. As the aspect ratio goes on increasing the displacement, base shear and column forces increases.

location of shear wall. In this paper Study of G+5 Storey building in Zone IV is presented with some preliminary investigation which is analyzed by changing various position of shear wall with different shapes for determine parameter like axial load and moments. This analysis is done by using Standard package STADD-pro. CONCLUSION:

Different location of shear wall effect on axial load on the column. In absence of shear wall axial load and moments are maximum on column. Case-3 is safe as compare to case-1 and case-2. Shear walls are easy to construct, because reinforcement detailing of walls is relatively straight forward and therefore easily implemented at site. Thus shear walls are one of the most effective building elements in resisting lateral forces during earthquake. By constructing shear walls damages due to effect of lateral forces due to earthquake and high winds can be minimized. Shear walls construction will provide larger stiffness to the buildings there by reducing the damage to structure and its contents. PLAN OF TALL BUILDING

C. “Design And Analysis Of Multistoried Building With Effect Of Shear Wall” www.ijera.com international Journal of Engineering Research and Applications (IJERA) (ijera),Page No: 223-232 ,Year of Publishing: May - June 2013,Authors: Himalee Rahangdale *, S.R.Satone** DESCRIPTION OF THE WORK:

Shear wall system are one of the most commonly used lateral load resisting in high rise building Shear wall has high in plane stiffness and strength which can be used to simultaneously resist large horizontal loads and support gravity loads. Incorporation of Shear wall has become inevitable in multistory building to resist lateral forces. It is very necessary to determine effective, efficient and ideal

GROUND FLOOR

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Analyze these three building models by different Loading conditions. Dead load Brick wall Floor finish Live Load Wind Load Wind x-direction Wind y- direction Dead Load + Live Load Dead Load + Live Load + Earth Quake Load (X direction) Dead Load + Live Load + Wind Load (X direction) Dead Load + Live Load + Wind Load (Y direction) The load combinations for analysis and design will be taken as follows: The members (beams, columns, shear walls etc.) and their joints will be designed for the worst combination of loads, shears and moments. 

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•

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TYPICAL FLOOR PLAN PROPOSED METHODOLOGY DETAILS STEP 1:

First Create the Model for R.C.C Tall Building by using the Software STAAD Pro V8i Second Create the Model for R.C.C Tall Building with different position of shear wall by using the Software E-TABS The type of building: Apartment Building The Storey Level

STEP 4:

Compare the results of those three analysis while coming the above Step. By using the comparison of results which type of analysis is best for R.C.C tall building to resist the Earthquake load and wind Load. STEP 5: In these analyzing part these parameters to be considered for R.C.C Tall Building and with shear wall modeling Lateral displacement, storey drift, shear force, bending moment, base shear, time period, story drift . AREA DETAILS: Area of the site

: 536Sqm

Area of the Ground floor

: 386.4Sqm

Area of the typical floor

: 386.4Sqm

Area of the Flat A, B, C, D

: 96.6Sqm

STEP 2: METHOD 1: Model with R.C.C Tall building by using STAAD Pro V8i

Building type

: G+19 framed storey

METHOD 1: Model with R.C.C. Tall building with Shear wall by using E-TABS STEP 3:

BUILDING DATA Type of Structure frame

G+19 METHOD: AutoCAD Drawing for Plan, Section, Elevation

:

Multi Storey rigid jointed

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Seismic Zone Layout and elevation Number of storeys Ground storey height Floor to floor Height Depth of Slab External walls plaster Wall load Density of wall Live Load Materials Seismic analysis Method Design philosophy conforming to IS 456 Ductile design Size of exterior column Size of beam Thickness of shear wall Type of soil

: :

III – Coimbatore Apartment Building plan

: : : : :

G+19 3m 3m 150 mm 230 mm thick including

: : : : :

13.6 KN/ m 3 20 kN/m 3 KN/m2 M30 & Fe 415 Response

:

Limit

: : : : :

IS 13920:1993 300 x750 mm 300 x600 mm 230 mm medium

2

state

Spectrum method

CREATING 3D BUILDING MODEL

MODELLING OF BUILDING Modelling of building is done using STAAD Pro software ANALYSIS OF STRUCTURE: Analysis of (G+19) hotel building done using STAAD Pro . STAAD Pro results During analysis in STAAD Pro, following results are obtained. PLAN VIEW OF STAAD MODEL

SELECTING 2D INTERMEDIATE FRAME FOR ANALYSIS

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A G+19 storey frame model building without Shear wall is analyzed using STAAD Pro. Tall building development involves various complex factors such as economics, aesthetics, technology, municipal regulations, and politics. Among these, economics has been the primary governing factor. This new building type itself would not have been possible, however, without supporting technologies. In this study, the ordinary moment resistant frames without the shear walls are designed and analyzed by using Response Spectrum analysis. The dimensions of the elements of frames are taken by considering the structure to be safe. From the analysis, the base shear for structure without shear wall is less due to reduced self-weight compared with the structures with shear wall REFERENCES 1. IS: 456 -2000

“Code of Practice for Plain and Reinforced Concrete”

SHEAR BENDING IN BEAM NO 6025

2.

IS:1893(Part-I)-2002 "Criteria for Earthquake

Resistant Design of Structures (Fifth Revision)” 3.

4.

5.

6.

IS: 875 (part-1)1987 design load (part -1 dead load other than earthquake) for buildings and structure. IS : 875 (part-1)1987 design load (part -2 live load other than earthquake) for buildings and structure IS: 875 (part-1)1987 design load (part -3 wind load other than earthquake) for buildings and structure IS: 1904-1987 “Code of Practice for Structural

Safety of Buildings: Foundation” DEFLECTION IN BEAM NO 6025

7.

8. 9.

10.

11. 12. 13.

IS: 1498-1970 Classification and identification of soils for general engineering purposes (First Revision) IS: 2131-1981 Method of Standard Penetration Test for soils (First Revision) IS:13920-1993, "Ductile Detailing of Reinforced Concrete Structures subjected to Seismic Forces - Code of Practice" IS: 4326-1993, "Earthquake Resistant Design and Construction of Buildings - Code of Practice (Second Revision)" IS-NBC-2005: National Building Code of India. Earthquake Design Concepts – C.V.Moorthy Dr. P.C.Varghese Limit State Design of Structure

CONCLUSION

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14.

Krishna Raju, N., “Design of Reinforced Concrete Structures”, CBS Publishers &

Distributors, New Delhi, 2003. 15. Unnikrishna Pillai, S., Devdas Menon, “Reinforced Concrete Design”, Tata McGrawHill Publishing Company Ltd., New Delhi. 16. Pankaj Agarwal and Manish Shrikhande,

“Earthquake Resistant Design of Structures”, 17. 18.

19.

20.

Prentice Hall of India, 2006 Dr. B.C.Punmia Reinforced Concrete Structures Vol I And Vol II Vaidyanadhan, R and Perumal, P, “ Structural Analysis – Vol. 1 & Vol. 2”, Laxmi Publications, New Delhi, 2003 S.R. Dhamodharasamy & S.Kavitha Basics of Structural Dynamics and Aseismic Design Structural Dynamics-phi publisher, New Delhi, 2003 S. K. Duggal Earthquake Resistant Design of Structures

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Seismic Analysis and Design of r.c.c Tall Building With Shear Wall

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