Shear wall
- 1. INTRODUCTION:- There has been a considerable increase in the construction of tall buildings both residential and commercial and the modern trend is towards more tall and slender structures. Thus the effects of lateral loads like wind loads, earthquake importance and almost every designer is faced with the problems of providing adequate strength and stability against lateral loads. Shear wall system is one of the most commonly used lateral load resisting sy buildings. WHAT IS SHEAR WALL Shear walls are vertical elements of the horizontal force resisting system earthquake loads downwards to the external walls that typically form a box which provides all of the lateral support for the building. They will have the strength and stiffness to resist the horizontal forces seismic force. WHERE SHOULD SHEAR WALLS BE LOCATED Shear walls should be located on each level of the structure including the crawl space form an effective box structure, equal length shear walls should be placed symmetrically on all four exterior walls of the building. Shear walls should be added to the building interior when the exterior walls cannot provide sufficient strength and There has been a considerable increase in the construction of tall buildings both residential and commercial and the modern trend is towards more tall and slender structures. Thus the effects of lateral loads like wind loads, earthquake loads and blast forces are attaining increasing importance and almost every designer is faced with the problems of providing adequate strength and stability against lateral loads. Shear wall system is one of the most commonly used lateral load resisting system in high rise SHEAR WALL:- Shear walls are vertical elements of the horizontal force resisting system earthquake loads downwards to the foundation. In construction, shear walls are straight external walls that typically form a box which provides all of the lateral support for the building. hey will have the strength and stiffness to resist the horizontal forces like wind force and RE SHOULD SHEAR WALLS BE LOCATED? Shear walls should be located on each level of the structure including the crawl space an effective box structure, equal length shear walls should be placed symmetrically on building. Shear walls should be added to the building interior when the exterior walls cannot provide sufficient strength and stiffness. There has been a considerable increase in the construction of tall buildings both residential and commercial and the modern trend is towards more tall and slender structures. Thus the effects loads and blast forces are attaining increasing importance and almost every designer is faced with the problems of providing adequate stem in high rise Shear walls are vertical elements of the horizontal force resisting system. They carry construction, shear walls are straight external walls that typically form a box which provides all of the lateral support for the building. like wind force and Shear walls should be located on each level of the structure including the crawl space. To an effective box structure, equal length shear walls should be placed symmetrically on building. Shear walls should be added to the building interior
- 2. These walls generally start at foundation level and are continuous throughout the building height. Their minimum thickness can be 150mm and maximum 400mm in high rise buildings. Shear walls are usually provided along both length and width of buildings. CLASSIFICATION OF SHEAR WALLS:- a) Simple rectangular types and flanged walls (bar bell type). b) Coupled shear walls. c) Rigid frame shear walls. d) Framed walls with in filled frames. e) Column supported shear walls. f) Core type shear walls. TYPES OF SHEAR WALLS:- a) RC Shear Wall. b) Plywood Shear Wall. c) Mid ply Shear Wall. d) RC Hollow Concrete Block Masonry Wall. e) Steel Plate Shear Wall. RC SHEAR WALL:- It consists of reinforced concrete walls and reinforced concrete slabs. 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.
- 3. In general, the wall reinforcement consists of two layers of distributed reinforcement (horizontal and vertical) throughout the wall length. The minimum area of reinforcing steel to be provided is 0.0025 times the cross-sectional area, along each of the horizontal and vertical directions. RC SHEAR WALL
- 4. PLYWOOD SHEAR WALL:- Plywood is the traditional material used in the construction of Shear Walls. The creation of pre- fabricated shear panels have made it possible to inject strong shear assemblies into small walls that fall at either side of a opening in a shear wall. MIDPLY SHEAR WALL:- The MIDPLY shear wall is an improved timber shear wall that was developed by redesigning the joints between sheathing and framing members, so that the failure modes observed in standard wall. In MIDPLY shear wall design, one ply of sheathing material is placed at the center of the wall between a series of pairs. PLYWOOD SHEAR WALL
- 5. RC HOLLOW CONCRETE BLOCK MASONRY WALLS:- RHCBM walls are constructed by reinforcing the hollow concrete block masonry, by taking advantage of hollow spaces and shapes of the hollow blocks. It requires continuous steel rods (reinforcement) both in the vertical and horizontal directions. RHCBM WALL
- 6. STEEL PLATE SHEAR WALL:- In general, steel plate shear wall system consists of a steel plate wall, boundary columns and horizontal floor beams. Together, the steel plate wall and boundary columns act as a vertical plate girder. The columns act as flanges of the vertical plate girder and the steel plate wall acts as its web. ADVANTAGE OF STEEL PLATE SHEAR WALL TO RESIST LATERAL LOADS:- 1. The system, designed and detailed properly is very ductile and has relatively large energy dissipation capability. 2. The steel shear wall system has relatively high initial stiffness, thus very effective in limiting the drift. 3. Compared to RC shear walls, the steel shear wall is much lighter which can result in less weight to be carried by the columns and foundations as well as less seismic load due to reduced mass of the structure. 4. Compared to reinforced concrete shear walls, steel plate shear walls can be much easier and faster to construct. STEEL PLATE SHEAR WALL
- 7. DUCTILE DESIGN OF SHEAR WALLS:- Just like reinforced concrete beams and columns, reinforced concrete shear walls also perform much better if designed to be ductile. Overall geometric proportions of the wall, types and amount of reinforcement, and connection with remaining elements in the building help in improving the ductility of walls. OVERALL GEOMETRY OF WALLS:- Shear walls are rectangular in cross-section, i.e., one dimension of the cross- section is much larger than the other. While rectangular cross-section is common, L-, U-, H- and I-shaped sections are also used. Thin-walled hollow reinforced concrete shafts around the elevator core of buildings also act as shear walls, and should be taken advantage of to resist earthquake forces. ADVANTAGES OF SHEAR WALLS IN BUILDINGS:- Properly designed and detailed buildings with shear walls have shown very good performance in past earthquakes. Shear walls in high seismic regions require special detailing. However, in
- 8. past earthquakes, even buildings with sufficient amount of walls that were not specially detailed for seismic performance 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. CODES FOR DESIGN OF SHEAR WALLS:- Widely used design approaches for shear walls------------ ACI method (ACI 318-1995) IS 13920:1993 Indians Standard Ductile Detailing of RC members IS 456:2000 Code provides a ductile design to give adequate toughness and ductility to resist severe earthquakes. CONCLUSION:- 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. __________________________________________