REINFORCEMENT IN THE CONCRETE WALLS (SHEAR WALL)

Reinforcement concrete walls in buildings are generally required to carry vertical loads .Some times they are also required to carry moments due to lateral loads action normal to length or normal to thickness of the walls or both. If the lateral loads due to wind or earthquake are acting normal to the depth , the wall may be classified as the Shear wall . Shear walls are used in the multistoreyed buildings with twenty or more storeys . These walls are very effective in resisting severe earthquake forces . In general the wall should have minimum thickness of 100 mm A reinforced concrete wall is classified as a short wall if the ratio of the effective height to thickness is less than 12 , otherwise it is classified as a long wall .A wall behaves in a manner similar to that of a column and, therefore, it should be designed in accordance with the recommendations given for the columns. If walls are subject to axial loads and moments they should be designed as columns under uniaxial loading bending. In case of long walls , additional moments due to slenderness must be accounted for in the analysis .The design of such walls can be accomplished using the axial force moment interaction curves for columns based on the limit state design philosophy. The strength of a wall may be increased depending upon the ratio of its height to length .The length of a wall is its overall length and where the opening occurred the length between the adjacent openings may be considered.The spacing of vertical and horizontal reinforcement may not exceed three times the wall thickness or 450 mm whichever is less .It is suggested that atleast two 16 mm bars must be provided around all doors and window openings.These bars must be extended for full development length beyond the corners of the openings.