Effect of Shear Wall on Response of Multi-storied Building Frame

N.L.SawakareD P.G. Student, Department of Civil Engineering Datta Meghe College of

Engineering,Airoli, Navi Mumbai 400708.

sawinls@gmail.com

Dr. H.S. ChoreProfessor and Head, Department of Civil Engineering

Datta Meghe College of Engineering,Airoli, Navi Mumbai 400708

chorehs@gmail.com

P.A.DodeAssistant Professor, Department of Civil Engineering

Datta Meghe College of Engineering,Airoli, Navi Mumbai 400708

padode@rediffmail.com

Abstract—Shear wall is 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 load and support gravity load. In the seismic design of buildings, reinforced concrete structural walls, or shear walls, act as major earthquake resisting members. Structural walls provide an efficient bracing system and offer great potential for lateral load resistance. In this present study, main focus is to determine the solution for shear wall location in multi- storey building.

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 shear wall has been studied with the help of seven different models. Seven different types of Model is used one is bare frame structural system and other three models are dual type structural system. Analysis is carried out by using standard package ETABS. The comparison of these models for different parameters like Story Shear, Story Displacement and Mode shape with respect to Time period has been presented by replacing column with shear wall.

Keywords— Lateral displacement, Shear force, Storey drift, Storey shear, Shear wall, Time period.

I. INTRODUCTION

Reinforced concrete shear walls are used in building to resist lateral force due to wind and earthquakes. They are usually provided between column lines, in stair wells, lift wells, in shafts that house other utilities. Shear wall provide lateral load resisting by transferring the wind or earthquake load to foundation. Besides, they impart lateral stiffness to the system and also carry gravity loads. Shear wall are one of the excellent means of providing earthquake resistance to multi storied reinforced concrete building. The structure is still damaged due to some or the other reason during earthquakes. Behavior of structure during earthquake motion depends on distribution of weight, stiffness and strength in both horizontal and planes of

building. To reduce the effect of earthquake reinforced 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 heavy. 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 six models for dual type structural system are generated with the help of ETABS and effectiveness has been check.

II. BUILDING DESCRIPTION

A building is assumed for seismic analysis that consists of a G+12 R.C.C. Residential building. The plan of the building is regular in nature as it has all columns at equal spacing. The building is located in Seismic Zone III and is assume on hard type soil. The building is 39.0 m in height 30.0 m in length and 20m in width. The important features of this building are shown in Table 1.

TABLE I. SALIENT FEATURES OF THE BUILDING

1. Type of Structure Multi-storey pin jointed frame2. Zone III3. Layout As shown in Figure no 1

4. Number of stories 13 (G + 12)

5. Ground storey height 3.0m

6. Floor-to-floor height 3.0 m

7. External walls 250 mm thick including plaster

8. Internal walls 250 mm thick including plaster

9. Live load 3.0 kN/m2

10. Materials M 30 and Fe 500

11. Seismic analysis Equivalent static method

12. Design Philosophy Limit state method conforming to IS 456 : 2000

13. Size of exterior column 400 x 400 mm

14. Size of interior column 400 x 400 mm

15. Size of beams in longitudinal and transverse direction

230 x 600 mm

16. Total thickness of slab 125 mm

Fig. 1. MODEL I (Bare frame without shear wall).

III. MODEL AND ANALYSIS

Building is modeled using stander package ETAB. Beams and columns are modeled as two noded beam elements with six DOF at each node. Shear wall are modeled using shell element. Equivalent static analysis or linear static analysis is performed on models. Based on analysis result parameters such as storey shear, story displacement, storey drift and the time period is compared with respect to mode shape are compared for each model. Following the model have been consideredModel I: Bare frame without shear wall.Model II: Frame supported by 2Bay shear wall.Model III: Frame supported by L-Type shear wall at all corner side.Model IV: Frame supported on central core shear wall.

Model V: Frame supported on central & L-Type shear wall. Model VI: Frame supported on full shear wall & 4Bay.Model VII: Frame supported on central shear wall

Fig. 2. MODEL II (Frame supported by 2Bay shear wall).

Fig. 3. MODEL III (Frame supported by L-Type shear wall at all cornerside.)

Fig. 4. MODEL IV (Frame supported on central core shear wall.)

Fig. 5. MODEL V (Frame supported on central & L-Type shear wall.)

Fig. 6. MODEL VI (Frame supported on central full shear wall & 4Bay.)

Fig. 7. MODEL VII (Frame supported on central shear wall.)

IV. RESULTS AND DISCUSSION

A. Storey ShearThe variations of base shear in X and Y direction

with different models considered in the study is illustrated in

Figure 8 and Figure 9. From the afore-mentioned figures, it is found that the base shear is on higher side in respect of model 6 as compared to the other cases.

Fig. 8. Base shear in X- direction

Fig. 9. Base shear in Y- direction

B. Storey Displacement

The displacement in X and Y direction, graphical representation is shown in Figure 10 and Figure 11

Fig. 10. Lateral displacement in X- direction

Fig. 11. Lateral displacement in Y direction

From the graphical representation thereof as shown in Figure 10-11, it is found that the building model 6 is stiffer than the other models. Limit of lateral storey displacement as per IS code 1893(part 1) 2002 is H/500.

C.Time Period & Mode Shape

The mode shape with respect to time period for different models shown in Fig.12.

Fig. 12. Mode shape with respect to time period.

From Fig. 12, the fundamental time period is found to be more in Mode shape 1 from model 1. The trend of time period is less in other models considered in the present investigation. As per IS code 1893(Part 1) 2002, the time period should not be more than 0.1times of number of floors in mode shape 1 i.e. 1.2 sec. The model 1 does not satisfy the criteria of mode shape. From Fig. 14 shows the fundamental time in mode shape 1 in model 6 this condition governs the case time period is very less as per compared to other cases.

V. CONCUSION

The behaviors of multistoried building with & without shear wall have been studied in present paper. In this

present paper we got the results from analysis of model for case1 (Model I) its shows the more lateral displacement, mode shape with respect to time period also less base shear this case does not governs the case as per IS code 1893( part1) 2002. From figure 8 & 9 shows base shear is more in X & Y direction as compared other cases .Graphical representation shown the exact result of analysis from we conclude that case 6 (Model VI ) governs the as per codal requirement.

From above results it is clear that shear wall frame interaction systems are very effective in resisting lateral forces induced by earthquake. Placing shear wall away from center of gravity resulted in increase in the most of the members forces. It follows that shear walls should be coinciding with the centroid of the building. For residential building shear walls can be used as a primary vertical load carrying element, thus serving the load and dividing space. 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.

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