8 AJGS Arabian Journal of Geosciences

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Arabian Journal of Geosciences ISSN 1866-7511 Arab J GeosciDOI 10.1007/s12517-015-1903-7

Controlling the earthquake-induced lateraldisplacement of RC buildings using shearwalls: parametric study

Mohamed A. Dahesh, Ahmet Tuken &Nadeem A. Siddiqui

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ORIGINAL PAPER

Controlling the earthquake-induced lateral displacement of RCbuildings using shear walls: parametric study

Mohamed A. Dahesh1& Ahmet Tuken1

& Nadeem A. Siddiqui1

Received: 28 April 2014 /Accepted: 1 April 2015# Saudi Society for Geosciences 2015

Abstract Shear walls are known for their contribution in im-proving the lateral stiffness and thus controlling the story driftof the Reinforced Concrete (RC) buildings against earthquakeloading. Although substantial research is available on shearwall-frame buildings, a detailed parametric study which canhelp the designers and field engineers to obtain an optimumarrangement of shear walls is missing in the literature. In thepresent study, a multi-story RC building, square in plan andassumed to be located in a seismically active city of the King-dom of Saudi Arabia, was laterally stiffened with the shearwalls of different thickness, height, configuration, and open-ing location. The building was then subjected to seismicforces, and the influence of shear walls in controlling the lat-eral response of the building was studied by varying the aboveparameters. The earthquake was considered from one direc-tion only while studying the effect of the first two parameters(i.e., thickness and height) as the building and shear wall ar-rangements were symmetric along the two orthogonal direc-tions. However, in case of third and fourth parameters (i.e.,shear wall configuration and opening location), earthquakewas considered from the two directions separately as the shearwall configuration and opening location were not symmetricin the two orthogonal directions. The results of the presentstudy are very useful for obtaining the optimum amount andarrangement of shear walls in a given RC frame buildingagainst a specified seismic loading.

Keywords Shear wall . Seismic loading .Multi-story RCbuilding . Lateral displacement . Serviceability

Introduction

To have the lateral story drift within the code-specified limitsis one of the major requirements in the seismic design ofmulti-story Reinforced Concrete (RC) buildings. Generallyunder seismic forces of moderate to high magnitude, theserequirements are difficult to satisfy unless a sufficient quantityof shear wall is provided in the building. Shear walls improvethe lateral stiffness of the building and thus control the storydrift of the building substantially. As a result, almost all theseismic codes recommend the employment of shear walls forthe design of RC buildings against seismic forces.

In the recent past, substantial research has been carried outon seismic response of RC buildings with shear walls. Burakand Comlekoglu (2013) evaluated the effect of shear wall areato floor area ratio on the seismic response of RC buildings.They carried out nonlinear time-history analysis for 24 mid-rise building models having shear wall ratios ranging between0.51 and 2.17 % in both directions. In the analyses, sevendifferent earthquake records were used in the evaluation ofthe seismic performance of these buildings. The resultsshowed that to control the lateral story drift, a minimum of1.0 % shear wall ratio was recommended in the design of mid-rise buildings. They also observed that when the shear wallratio is more than 1.5 %, the effect of shear wall on the per-formance was not insignificant.

Chai and Kunnath (2005) outlined a methodology forassessing the minimum wall thickness to ensure that the in-plane lateral strength was fully developed. The results werepresented for a number of parameters including the ground mo-tion intensity, longitudinal reinforcement ratio, floor weight,

* Nadeem A. [email protected]

1 Department of Civil Engineering, King Saud University,Riyadh 11421, Saudi Arabia

Arab J GeosciDOI 10.1007/s12517-015-1903-7

Author's personal copy

wall-to-floor area ratio, and number of stories. The minimumwall thickness was compared with recommendations in currentbuilding codes. Kim et al. (2005) proposed an efficient methodfor a three-dimensional analysis of a high-rise building structurewith shear walls. Three-dimensional super elements for wallsand floor slabs were developed, and a substructure was formedby assembling the super elements to reduce the time required forthe modeling and analysis. Static and dynamic analyses of ex-ample structures with various types of opening were performedto verify the efficiency and accuracy of the proposed method.They concluded that the proposed method is very useful for anefficient and accurate analysis of high-rise building structureswith significantly reduced computational time and memory.

Neuenhofer (2006) investigated the accuracy of a simpli-fied hand method, recommended in several design guidelinesfor practicing structural engineers, for calculating the lateralstiffness of shear walls with openings. Parametric studies wereperformed in which the location and size of the opening aswell as the aspect ratio of the wall were varied. A special-purpose finite-element algorithm was developed and imple-mented in the computing package MATLAB. Results fromfinite-element analysis were compared with those of the handmethod. He found that the hand method enormously overes-timates the stiffness of shear walls with openings.

Tjhin et al. (2007) presented a simple method for theperformance-based seismic design of ductile RC wall

buildings. The method derives its simplicity by relying onthe stability of the yield displacement and the representationof inelastic seismic demand using yield point spectra. The

Fig. 1 3D model of the studied building

Fig. 2 Plan of the studiedbuilding

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design method was based on an estimate of the roof displace-ment at yield. The required base shear strength was determinedusing yield point spectra. The walls were designed for a singlebase shear force that was established based on one or moreperformance objectives, where each performance level wasexpressed in terms of roof drift and plastic hinge rotation atthe base of the wall. A six-story building was used as an ex-ample to illustrate the method, with the hazard represented byeither smoothed design spectra or recorded ground motions.Nonlinear static and dynamic analyses confirmed the adequacyof the method to achieve the intended performance objectives.

Tuken (2004) proposed an analytical method to determinethe sway of a mixed structure (frame+shear wall) subjected toseismic forces. The validity of the analytical method was test-ed on three-dimensional (3-D) buildings of different heights.He also obtained the sway response using SAP2000 and foundthat the sway results obtained by the analytical methodmatches well with the results of SAP2000.

Tuken and Siddiqui (2013) proposed a simple-to-apply an-alytical method to determine the amount of shear walls neces-sary to make reinforced concrete buildings seismic-resistantagainst moderate to severe earthquakes. The method is basedon the following design strategy: (1) The total design baseshear must be resisted by shear walls; (2) equal amounts ofshear walls must be placed in both orthogonal directions of thestructure; and (3) the moment resisting frame elements, whichare beams and columns, must independently be able to resist25% of the total design base shear. For such a system, the ratioof the total area of shear walls to the area of the floor plan hasbeen obtained by equating the total design base shear to the

total shear resistance provided by all shear walls in one direc-tion. Because seismic action may occur in any direction, equalamount of shear walls is recommended to provide in the twoorthogonal directions. A procedure is also presented to checkthe stiffness (or story drift) requirement for the determinedamount of shear walls. The complete analytical procedurewas demonstrated by implementing it on a ten-story 3-D-reinforced concrete building.

Tuken and Siddiqui (2015) proposed an analytical methodbased on Bdual-system^ concept and Saudi Building Code(SBC 301, SBC 304) provisions to determine the quantity ofshear walls which can satisfy the strength, stiffness, and duc-tility requirements imposed by the Saudi Building Code onRC moment-resisting frame buildings. The method also out-lines a detailed procedure for the assessment of displacementand curvature ductility of RC shear wall-moment resistingframe buildings. This formulation is based on plastic analysisand the assumption that the plastic hinge forms at the base ofthe shear wall. The proposedmethodology was then applied toa 10-story RC building containing shear walls. It was shownthat the amount of shear walls which is enough to satisfy thestrength requirements also fulfills the stiffness criteria (i.e.,story drift limitation) required by the Saudi Building Code.It was also proved that the ductility requirements imposed bythe Saudi Building Code can easily be satisfied by using thesame quantity of shear walls.

Above review of literature shows that although a goodnumber of studies are available on shear wall-frame buildings,a detailed parametric study which can help the designers andfield engineers to obtain an optimum amount and arrangement

Table 1 Salient data for thestudied building Parameter Value Remark

Compressive strength of concrete (fc' ) 30 MPa Assumed for all the concrete elements

Yield strength of steel (fy) 420 MPa Assumed for all the steel

Modulus of elasticity of concrete (E) 25,742,960 kN/m2

4700ffiffiffiffiffif0c

qaccording to Saudi Building

Code (SBC) 304 (2007)

Width of typical shear wall (bw) 0.20 to 0.50 m Assumed

Ratio of horizontal webreinforcement of wall to thegross area of wall web (ρn)

0.0025 Minimum value based on Saudi BuildingCode (SBC) 304 (2007)

Story weights (wi) 9.0 kN/m2 Assumed weight of ith story of the building(being the same for all stories)

Occupancy importance factor (I) 1.0 For all buildings and other structures ofcategory II based on Table 1.6-1 in SaudiBuilding Code (SBC) 301 (2007)

Table 2 Seismic coefficients and factors used for the present building

Basic seismic force-resisting system Response modificationcoefficient (R)

System over strengthfactor (Ωo)

Deflection amplificationfactor (Cd)

Special reinforced concrete shear walls 6.5 2.5 6.5

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of shear walls is required. In the present study, a multi-storyRC building, square in plan and assumed to be located in aseismically active city of the Kingdom of Saudi Arabia, waslaterally stiffened with the shear walls of different thickness,height, configuration, and opening location. The building wasthen subjected to seismic forces, and the influence of shearwalls in controlling the lateral response of the building wasstudied by varying the above parameters.

Description of the studied building

A ten-story RC building containing shear walls was selectedfor the present study. The building is square in plan having atotal height of 30 m with 5-bays in each direction and a con-stant floor plan area of 576 m2 at each story. The height ofevery story is equal to 3 m. The building is assumed to befixed at the base. The floors of the building are considered toact as rigid diaphragms. All the columns, beams and slabswere considered to be of the same sizes (columns: 500×500 mm; beams: 250×600 mm; slab thickness: 150 mm).The building was modeled in ETABS-2013 (2013). Figures 1and 2 show the 3D-model and plan of the building respective-ly. Table 1 provides the salient data of the building.

Loads on the building

In the present study, gravity and seismic loads were consid-ered acting on to the building. Gravity loadwas due to the self-weight of the building in addition to the dead and live loads.The seismic loads were obtained using equivalent lateral forceprocedure as described below.

Equivalent lateral force procedure

In the present study building containing the shear walls wassubjected to the seismic base shear, V, in a particular direction.This base shear can be determined using the following equa-tions as per SBC code (Saudi Building Code (SBC) 301 2007).

V ¼ CsW ð1Þwhere, Cs=the seismic response coefficient; W=the effectiveseismic weight.

The Cs, can be determined using the following equation:

Cs ¼ SDSR

I e

� � ð2Þ

where, R=the response modification factor, Ie=the im-portance factor, SDS=the design spectral response accel-eration parameter in the short period range. SDS can becalculated using

SDS ¼ 2

3FaSS ð3Þ

where, Fa=acceleration-based site coefficient (at 0.2-speriod).S=the mapped maximum considered earthquakespectral response acceleration at short periods.

The value of Cs should not exceed the following:

Cs ¼ SD1

TR

I e

� �

But shall not be less than

Cs ¼ 0:044SDSI

Table 3 Details of the parameters studied

Description Model Parameter studied Parametervaried

Shear wallarea (m2)

Shear wall areato floor area ratio (%)

Shear wall is provided in the form of enclosed boxand continued along the full height of the building

Model A Thickness (L=16 m; H=30 m) 0.2 m 3.2 0.56

0.3 m 4.8 0.83

0.4 m 6.4 1.11

0.5 m 8.0 1.39

Shear wall is provided in the form of enclosed boxagain, but continued for different heights along theheight of the building

Model B Height (L=16 m; t=0.2 m) 6 m 3.2 0.56

12 m 3.2 0.56

18 m 3.2 0.56

24 m 3.2 0.56

30 m 3.2 0.56

The shear walls are provided at different locationsbut keeping the area and height of the shear walls same

Model C Configuration Figure 10 5.6 0.97

The shear walls are provided with opening(s)for elevators at different locations

Model D Opening location Figure 13 3.2 0.56

L total length of the shear walls, H height of the building, t thickness of the shear walls

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where, SD1 ¼ 23 FvS1 is the design spectral response acceler-

ation parameter at a period of 1.0 s; T=the fundamental periodof the structure, T=long transition period. F=velocity-basedsite coefficient (at 1.0 s period); S1=the mapped maximum

considered earthquake spectral response acceleration parame-ter. It is worth mentioning that the values of Fa and Fv arebased on the site class (A, B, C, D, E, and F). The site class isclassified according to the site soil properties.

Model A1 (t = 0; ρwf = 0%)

Model A2 (t = 0.2 m; ρwf = 0.56%) Model A3 (t = 0.3 m; ρwf = 0.83%)

Model A4 (t = 0.4 m; ρwf = 1.11%) Model A5 (t = 0.5 m; ρwf = 1.39%)Fig. 3 Models used to study the effect of shear wall thickness

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Selection of ground motion data

The Kingdom of Saudi Arabia has been divided intoseven regions for determining the maximum consideredearthquake ground motion. According to SBC 301, seis-micity can be described through the following parame-ters: maximum spectral response acceleration for shortperiods (SMS) and at 1 s (SM1); spectral response

acceleration at short periods, SDS, and at 1-s periodSD1, site class and site coefficients Fa and Fv, respec-tively; response modification coefficient (R); systemover strength factor (Ωo); and deflection amplificationfactor (Cd). For Haql City, located in Region 1, thevalues of Fa and Fv are 1.15 and 1.838, respectively(SBC 301). The values of SS and S1 were obtained fromthe maps provided in SBC 301. The corresponding

Fig. 4 Lateral displacement profile of the building (model A1: without shear wall)

Fig. 5 Lateral displacement profile of the building (model A5: with shear wall)

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values were 0.866 and 0.281 g, respectively. Using the-se values, the parameters like SMS, SM1, SDS, and SD1can be determined for Haql City as follows:

SMS ¼ FaSS ¼ 1:15 � 0:866 ¼ 0:996SM1 ¼ FvS1 ¼ 1:838 � 0:281 ¼ 0:516

SDS ¼ 2

3SMS⇒SDS ¼ 2

3� 0:996 ¼ 0:664

SD1 ¼ 2

3SM1⇒SDI ¼ 2

3� 0:516478 ¼ 0:344

The parameters R, Ωo, and Cd were determined from SBC301 for special reinforced concrete moment frames. Thesevalues are shown in Table 2.

Parameters studied

In the present parametric study, the building mentionedabove was laterally stiffened with the shear walls of dif-ferent thickness, height, configuration, and opening loca-tion. The building was subjected to seismic forces, andthe influence of shear walls in controlling the lateral re-sponse of the building was then studied by varying theabove parameters (Table 3). In the present study, the se-lected configurations of shear walls are entitled as models(e.g., model A, model B, etc.)

Discussion of results

The effects of (i) shear wall thickness (model A), (ii)shear wall height (model B), (iii) shear wall configura-tion (model C), and (iv) shear wall opening location

(model D) were studied in this section. The earthquakewas considered from one direction only while studyingthe effects of first two parameters as the building andshear wall arrangements are symmetric along the twoorthogonal directions. However, in case of third andfourth parameters, earthquake was considered from thetwo directions separately as the shear wall configurationand opening location are not symmetric in the two or-thogonal directions.

Effect of shear wall thickness (model A)

In this parametric study, the shear wall thickness was variedfrom 0.2 to 0.5 m, and its effect was studied on lateral dis-placement of the building. Due to change in the thicknessfrom 0.2 to 0.5 m, shear wall area to floor area ratio (ρwf)was varied from 0.56 to 1.39 %. The model correspondingto each case was identified by adding a suffix number 1 to 5after the letter A as mentioned below and shown in Fig. 3.

Model A1—frame without any shear wall (t=0; ρwf=0 %)Model A2—frame with shear wall (t=0.2 m; ρwf=0.56 %)Model A3—frame with shear wall (t=0.3 m; ρwf=0.83 %)Model A4—frame with shear wall (t=0.4 m; ρwf=1.11 %)Model A5—frame with shear wall (t=0.5 m; ρwf=1.39 %)

The response curves shown for the case of withoutshear wall and with shear wall (Figs. 4 and 5) clearlyillustrate the influence of shear wall in controlling the

0

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0 10 20 30 40 50 60 70 80 90 100 110 120

Hei

ght

of t

he B

uild

ing

(m)

Story Displacement (mm)

Earthquake in x (or y) direction

Model A.1

Model A.2

Model A.3

Model A.4

Model A.5

Fig. 6 Story displacement in x(or y) direction for models A.1 toA.5

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lateral displacement of the building. This can be attrib-uted to enhanced lateral stiffness of the building due to

the presence of shear walls. Figure 6 shows the effectof thickness (or shear wall area to floor area ratio) on

Model B1 (hw = 6.0 m)

Model B2 (hw = 12.0 m) Model B3 (hw = 18.0 m)

Model B4 (hw = 24.0 m) Model B5 (hw = 30.0 m)Fig. 7 Models used to study the effect of shear wall heights

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the building’s lateral response against the seismic load-ing. These curves illustrate that as the thickness of theshear wall is increasing, the lateral displacement is de-creasing. This is an expected trend which can be attrib-uted to the increase of lateral stiffness of the buildingdue to increase in the shear wall area. Quantitatively,increasing the shear wall area to floor area ratio from0.56 to 1.29 % reduces the roof lateral displacement by

38 to 72 % respectively of the corresponding displace-ment when there was no shear wall in the building.

Effect of shear wall height (model B)

In order to study the effect of shear wall height onlateral displacement of the building, the height of theshear wall was varied from 6 to 30 m, while shear wall

Fig. 8 Plan for models B.1 to B.5

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0 10 20 30 40 50 60 70 80 90 100 110 120

Hei

ght

of t

he B

uild

ing

(m)


Earthquake in x-direction

Model B.1

Model B.2

Model B.3

Model B.4

Model B.5

Fig. 9 Story displacement in x-direction for models B.1 to B.5

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thickness was kept the same. As the thickness and shearwall plan area were not varied, the shear wall plan area

to floor area ratio (ρwf) was constant (i.e., 0.56 %). Themodel corresponding to each case was identified, as

Model C1 Model C2

Model C3 Model C4

Model C5 Model C6

Model C7 Model C8Fig. 10 Models used to study the effect of shear wall configuration

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before, by adding a suffix number 1 to 5 after the letterB as mentioned below and shown in Fig. 7. The

building plan with centrally located closed box shearwall, used in these models, is shown in Fig. 8.

Table 4 Top displacement formodels C.1 to C.8 due toearthquake in x- and y-directions

Model Top displacement (mm)

Earthquake in x-direction Earthquake in y-direction

C.1 26.2 26.6

C.2 100.8 10.0

C.3 116.5 27.3

C.4 101.5 9.7

C.5 114.8 28.0

C.6 93.8 10.0

C.7 98.7 25.3

C.8 31.6 61.3

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ght

of t

he B

uild

ing

(m)


Earthquake in y-direction

Model C1Model C2Model C3Model C4Model C5Model C6Model C7Model C8

Fig. 11 Story displacement in y-direction for models C.1 to C.8

0

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0 10 20 30 40 50 60 70 80 90 100 110 120

Hei

ght

of t

he B

uild

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(m)



Model C1Model C2Model C3Model C4Model C5Model C6Model C7Model C8

Fig. 12 Story displacement in x-direction for models C.1 to C.8

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Model B1—building frame having the shear wall heightof 6 m (i.e., hw=6 m)Model B2—building frame having the shear wall heightof 6 m (i.e., hw=12 m)

Model B3—building frame having the shear wall heightof 6 m (i.e., hw=18 m)Model B4—building frame having the shear wall heightof 6 m (i.e., hw=24 m)

Model D1 (Opening: 0%) (No opening in the front and back shear walls)

Model D2 (Opening: 17%)(Front shear wall has side-openings, but no opening

in the back shear wall)

Model D3 (Opening: 17%)(Front shear wall has central-openings, but no

opening in the back shear wall)

Model D4 (Opening: 17%)(Front shear wall has side-openings up to third

floor; and the back shear wall has side-openings for the remaining floors)

Model D5 (Opening: 17%)(Front shear wall has central-openings up to third

floor; and the back shear wall has central-openings for the remaining floors)

Fig. 13 Models used to study the effect of shear wall opening location

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Model B5—building frame having the shear wall heightof 6 m (i.e., hw=30 m)

The results clearly illustrate that as the shear wallheight increases, the lateral displacement of the buildingdecreases due to increase in the lateral stiffness of thebuilding. Figure 9 shows the variation of lateral displace-ment with the story height. For model B1, when the shearwall height was extended up to two floors, the buildingexperiences quite a high value of lateral displacement(Fig. 9). The displacement was reduced substantiallywhen shear wall height was extended up to eight floors(models B2 to B4). After this, the decrease in the lateraldisplacement with increase in the shear wall height wasnot significant. This illustrates that lower floor shear walls

are much dominant in controlling the lateral displacementthan upper floors of the building. Quantitatively, the de-crease in the lateral displacement due to every 6-m in-crease in the shear wall height is about 30 % up to sixstories. However, after the sixth floor, the same 6-m in-crease in the shear wall height decreases the lateral dis-placement less than 10 %.

Effect of shear wall configuration (model C)

The shear wall location has significant effect on the buildinglateral displacement. In the present parametric study, keepingthe total shear wall-to-floor area ratio as constant (0.97 %),different arrangements of shear walls were selected as shownin models C1 through C8 (Fig. 10). Shear walls are very

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0 10 20 30 40 50 60 70 80 90 100 110 120H

eigh

t of

the

Bui

ldin

g (m

)



Model D.1

Model D.2

Model D.3

Model D.4

Model D.5

Fig. 14 Story displacement in x-direction for models D.1 to D.5

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(m)


Earthquake in y-direction

Model D.1

Model D.2

Model D.3

Model D.4

Model D.5

Fig. 15 Story displacement in y-direction for models D.1 to D.5

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effective when the seismic forces are acting in their plane andnot much effective when the seismic forces are out of theirplane. Table 4 shows the values of roof displacements underdifferent locations of shear walls. For model C1, although thelengths and thicknesses of shear walls are different in the twodirections, their plan areas are the same. This caused a littledifference in the roof displacement of the building. This illus-trates that as long as the shear wall area is the same in earth-quake direction, its effect on the lateral displacement will alsobe almost the same irrespective of its location in the building.For models C2 through C7, the shear walls are provided onlyalong y-direction with no shear walls along x-direction. It isdue to this reason that when the seismic force is acting alongthe y-direction, the roof displacement is very small in thisdirection (Fig. 11) and substantially high in the other direction(i.e., x-direction) as shown in Fig. 12. For model C8, there wasalmost double quantity of shear wall in x-direction comparedwith y-direction which resulted in substantial reduction in theroof displacement in the x-direction. The roof displacement isalmost double in y-direction due to half quantity of shear wallused in the corresponding direction.

Effect of shear wall opening location (model D)

It is very common to have openings in the shear wall to ac-commodate elevators and stair cases. These openings mayaffect the lateral stiffness of the building which may resultsin higher lateral displacement. In the present study, the effectof openings in the shear walls was studied on parametric basis.The openings were provided in the front and back shear wallsalong x-direction only. Five models were selected for thisparametric study as shown in Fig. 13. The opening area toshear wall area ratio along the height in x-direction was keptas 17 % in the models D2 to D5.

Figures 14 and 15 show the variation of story displacementwhen seismic forces were applied separately along x- and y-directions. As the openings were provided only in the x-direc-tion shear walls, the lateral stiffness of the building was pri-marily affected in this direction. The effect was almost negli-gible in the y-direction as there were only openings in the x-direction shear walls (i.e., no openings in the y-direction shearwalls). Figures 14 and 15 show that when there are centralopenings in the first three floors of the front shear wall andthen similar openings in the back shear wall of the remainingfloors (i.e., model D5), the lateral stiffness is least affected.However, lateral stiffness of the building was reduced sub-stantially when side-openings were provided at the same lo-cations as shown in model D4. The figures also show thatwhen the openings are provided at all the floors but only inthe front shear wall as shown inmodels D2 and D3, there is nosignificant difference in the lateral displacements regardless ifthe openings are provided in the centers or in the sides of theshear wall.

Conclusions

The major conclusions drawn from the present parametricstudy are as follows:

& The shear wall area-to-floor area ratio substantially affectsthe lateral stiffness of the building. In the present study,increasing the shear wall area-to-floor area ratio from 0.56to 1.29 % reduces the roof lateral displacement by 38 to72 % of the corresponding displacement when there wasno shear wall in the building.

& As the shear wall height increases, the lateral storydrift decreases due to the increase in the lateral stiff-ness of the building.

& The lower floor shear walls are much dominant in control-ling the lateral displacement than upper floors of the build-ing. In the present study, the decrease in the lateral dis-placement due to every 6-m increase in the shear wallheight is about 30 % up to six stories. However, after thesixth floor, the same 6-m increase in the shear wall heightdecreases the lateral displacement by less than 10 %.

& As long as the shear wall area is the same in earthquakedirection, its effect on the lateral displacement will also bealmost the same irrespective of its location in the building.

& When there are central openings in the first three floors ofthe front shear wall and then similar openings in the backshear wall of the remaining floors, the lateral stiffness isleast affected. However, lateral stiffness of the buildingwas reduced substantially when side-openings were pro-vided at the same locations.

& When the openings are provided at all the floors but onlyin the front shear wall, there is no significant difference inthe lateral displacements whether the openings are provid-ed in the centers or in the sides of the shear wall.

Acknowledgments Thework presented in this paper was funded by theDeanship of Scientific Research, Research Centre, College of Engineer-ing, King Saud University, Riyadh, Saudi Arabia.

References

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8 AJGS Arabian Journal of Geosciences