SEISMIC ANALYSIS OF BUILDING HAVING SOFT STOREY USING DISPLACEMENT BASED DESIGN

Abstract

This topic reports the method to determine the column size by using displacement based design method of reinforced concrete frame buildings, and then compare the design forces with the is code 1893 (part 1): 2002 solution. A G+8 building frame is taken for the analysis and study of soft storey problem, two methods are properly used (a) is code 1893 (part 1):2002 (b) equal displacement based design. Analysis has been performed without considering the stiffness of infill wall effect in first method and for second method considers the effect of infill walls. The design solution of IS code 1893 (part 1): 2002 are simple and used as 2.5 times storey shear and moments coming by analysis with no infill wall effect. In equal displacement based design method we use the reverse calculation for obtaining the stiffness and finally column size. The designs moments are considered in calculation are coming from the 1st trial column size. The column size then replace in frame and find new moments result. This iteration is going till we get the same column size in two consecutive iterations. The determined column sizes can be effectively used with some minor changes according to the designer’s choices. In the IS code result, the base shear capacity, calculated from the column design moment observed to be 4.8 times higher than that base shear, calculated with a response reduction factor of 5. In Equal displacement based design, calculated from equal displacement based design are 53% of design base shear with response reduction factor 5.