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International Journal For Technological Research In Engineering Volume 3, Issue 4, December-2015 ISSN (Online): 2347 - 4718 EFFECT OF OPENING ON BEHAVIOUR OF SHEAR WALL Bhruguli H. Gandhi Abstract: Finite Element modellingnow days is an essential approach in analysing and simulating civil engineering problem numerically. In this paper attempt is made to apply the finite element modelling in analysing and exploring the behavior of shear wall with opening under seismic load actions. In modern tall buildings, shear walls are commonly used as a vertical structural element for resisting the lateral loads that may be induced by the effect of wind and earthquakes. Shear walls are generally located at the sides of buildings or arranged in the form of core that houses stairs and lifts. Due to functional requirements such as doors, windows, and other openings, a shear wall in a building contains many openings. The size and location of openings may vary from architectural and functional point of view. In most of the apartment building, size and location of openings in shear wall are made without considering its effect on structural behavior of the building. This study is carried out on 6- story frame-shear wall buildings, using linear elastic analysis with the help of finite element software, STAAD PRO under earthquake loads in equivalent static analysis. The results reveal that stiffness as well as seismic responses of structures is affected by the size of the openings as well as their locations in shear wall. It is also explored that top lateral drift of the system can also be reduced thickening the element in the model around the opening of shear wall Keyword: Shearwall, I. INTRODUCTION Shear wall are specially designed structural walls in building to resist lateral forces that are produce in the plane of wall due to wind, earthquack and other forces. Shear wall is normally behaves like a flexural member. In a tall building use of shear wall avoids total collapse of buildings under seismic forces.The lateral and gravity load-resisting system consists of reinforced concrete walls and reinforced concrete slabs. Shear walls are the main vertical structural elements with a dual role of resisting both the gravity and lateral loads. Wall thickness varies from 140 mm to 500 mm, depending on the number of stories, building age, and thermal insulation requirements. In general, these walls are continuous throughout the building height; however, some walls are discontinued at the street front or basement level to allow for commercial or parking spaces. II. SHEARWALL BUILDING Reinforced concrete (RC) buildings often havevertical platelike RC walls called Shear Walls in addition to slabs, beams and columns. These wallsgenerally start at foundation level and are continuousthroughout the building height. Their thickness can beas low as 150mm, or as high as 400mm in high risebuildings. Shear walls are usually provided along www.ijtre.com bothlength and width of buildings. Shear wallsare like vertically-oriented wide beams that carryearthquake loads downwards to the foundation. Advantages of Shear Walls in RC Buildings Properly designed and detailed buildings with shear walls have shown very good performance in past earthquakes. The overwhelming success of buildings with shear walls in resisting strong earthquakes is summarised in the quote: “We cannot afford to build concrete buildings meant to resist severe earthquakes without shear walls”:: Mark Fintel, a noted consulting engineer in USA. Shear walls in high seismic regions require special detailing. However, in past earthquakes, even buildings with sufficient amount of walls that were not specially detailed for seismic performance (but had enough well-distributed reinforcement) were saved from collapse. Shear wall buildings are a popular choice in many earthquake prone countries, like Chile, New Zealand and USA. Shear walls are easy to construct, because reinforcement detailing of walls is relatively straight-forward and therefore easily implemented at site. Shear walls are efficient, both in terms of construction cost and effectiveness in minimizing earthquake damage in structural and nonstructural elements (like glass windows and building contents). Architectural Aspects of Shear Walls Most RC buildings with shear walls also havecolumns; these columns primarily carry gravity loads(i.e., those due to selfweight and contents of building).Shear walls provide large strength and stiffness tobuildings in the direction of their orientation, whichsignificantly reduces lateral sway of the building andthereby reduces damage to structure and its contents. Since shear walls carry large horizontal earthquakeforces, the overturning effects on them are large. Thus,design of their foundations requires special attention. Ductile Design of Shear Walls Just like reinforced concrete (RC) beams andcolumns, RC shear walls also perform much better ifdesigned to be ductile. Overall geometric proportionsof the wall, types and amount of reinforcement, andconnection with remaining elements in the buildinghelp in improving the ductility of walls. The IndianStandard Ductile Detailing Code for RC members(IS:13920-1993) provides special design guidelines forductile detailing of shear walls. Overall Geometry of Walls: Shear walls areoblong in cross-section, i.e., one dimension of thecross-section is much larger than the other. Whilerectangular cross-section is common, L- and U-shaped sections are also used. Thin-walled hollowRC shafts around Copyright 2015.All rights reserved. 875 International Journal For Technological Research In Engineering Volume 3, Issue 4, December-2015 the elevator core of buildings alsoact as shear walls, and should be taken advantage of toresist earthquake forces. ISSN (Online): 2347 - 4718 Frame (100% opening) Reinforcement Bars in RC Walls: Steelreinforcing bars are to be provided in walls inregularly spaced vertical and horizontal grids. The vertical and horizontal reinforcement in thewall can be placed in one or twoparallel layers calledcurtains. Horizontal reinforcement needs to beanchored at the ends of walls. The minimum area ofreinforcing steel to be provided is 0.0025 times thecrosssectional area, along each of the horizontal andvertical directions. This vertical reinforcement shouldbe distributed uniformly across the wall cross-section. Boundary Elements: Under the large overturningeffects caused by horizontal earthquake forces, edgesof shear walls experience high compressive and tensilestresses. To ensure that shear walls behave in a ductileway, concrete in the wall end regions must bereinforced in a special manner tosustain these loadreversals without losing strength. Endregions of a wall with increased confinement are calledboundary elements. This special confining transversereinforcement in boundary elements is similar to thatprovided in columns of RC frames. Sometimes, thethickness of theshear wall in these boundary elements is alsoincreased. RC walls with boundary elements havesubstantially higher bending strength and horizontalshear force carrying capacity, and are therefore lesssusceptible to earthquake damage than walls without boundary elements. Design and Analysis Data: Size of wall Span :6 meter Height of each floor :3 meter No of Floor :5 no Plate thickness: 0.15m Size of Frame Beam (R1): 0.3 m * 0.45m Column(R2):0.6m * 0.3m Material used : Concrete Forces at each floor 1st floor : Fx = 56 kN : (from G.L) 2nd floor : Fx = 224 kN 3rd floor : Fx = 504 kN 4th floor : Fx = 896 kN 5th floor : Fx = 1000 kN Support at base Fixed Fixed STAAD PRO Cases: Solid wall (0% opening) Concentric opening 20% opening 40% opening 50% opening 60% opening Eccentrics opening (20% opening) Straight opening Zigzag opening www.ijtre.com Copyright 2015.All rights reserved. 876 International Journal For Technological Research In Engineering Volume 3, Issue 4, December-2015 ISSN (Online): 2347 - 4718 Deflection in X direction and % of deflection at different node point As we see Graph-1, is node vs % deflection for straight opening. Graph shows as % of opening increases deflection increases up to 40% in proportion but after that as % of opening increases deflection increases more rapidly. As we see Graph-2 is node vs % deflection for 20% concentric, eccentric, and zigzag pattern. In this 20% opening Eccentric zigzag has lesser deflection and Eccentric Straight has maximum deflection and concentric loading has less deflection than Eccentric Straight. As we see the graph -4 is % opening vs stresses around opening in the shear wall. Till the 40% opening stress around the opening is increasing proportionally after that if we provide 50% opening stress around opening is increasing drastically. As we see the graph -3 is % opening vs bottom stress in the shear wall. Till the 40% opening bottom stress is increasing proportionally after that if we provide 50% opening bottom stress is increasing drastically. www.ijtre.com [1] III. CONCLUSION As we see in the Graph-1 ,% of opening increases deflection increases up to 40% in proportion but after that as % of opening increases deflection increases more rapidly As per Graph-2 for 20% opening Eccentric zigzag has lesser deflection and Eccentric Straight has maximum deflection and concentric loading has less deflection than Eccentric Straight As per Graph-3 as opening increases bottom Stresses also increases proportionally up to 40% then after Stresses increases vastly. Graph-4 shows Stresses around opening, for different opening condition. We can directly judge that after 40% stresses increases more rapidly So, for a given loading up to 40% opening is suitable for shear wall though code says provide opening as per necessity. REFERENCES Can Balkaya, M.ASCE,1 and ErolKalkan, S.M.ASCE2 “Three-Dimensional Effects on Openings of Laterally Loaded Pierced Shear Copyright 2015.All rights reserved. 877 International Journal For Technological Research In Engineering Volume 3, Issue 4, December-2015 [2] [3] [4] [5] [6] ISSN (Online): 2347 - 4718 Walls”,Journal of Structure enng, October 2004 Daniel Carroll, James Loney, Brian Keating, Eoghan Russell, “Shear Walls With Openings” Structural Analysis Lab Muhammed Abbas Husain “Analysis of Shear Wall with Openings using Brick Element” European Journal of Scientific Research,2011 Ardeshir DEYLAMI1 And Hossein DAFTARI2, “ NON-LINEAR BEHAVIOR OF STEEL PLATE SHEAR WALL WITH LARGERECTANGULAR OPENING”,12th WCEE,2000 Fernando Yáñez1, Maximiliano Astroza2, Augusto Holmberg3, Oscar Ogaz4, “BEHAVIOR OF CONFINED MASONRY SHEAR WALLS WITH LARGE OPENINGS”,13th WCEE,2004 IS code:456, IS:13920 www.ijtre.com Copyright 2015.All rights reserved. 878