Evaluation of Increasing Coefficient of Fundamental Period of Buildings

Linear Static Analysis is a current approximate method in buildings analysis under earthquake force. One of the effective parameters in determining earthquake forces is building fundamental period. For computation this parameter, different experimental equations are provided on the basis of different structure resisting systems. Also the code has been allowed to increase the fundamental period in special conditions. Since the period changing used in lateral static forces calculation is leaded to change the building calculated earthquake force, so it is clear that taking into account more accurate fundamental period is leaded to better estimating of real earthquake forces. In this research the numbers of steel buildings are chosen from existing buildings and calculated earthquake force from using codes' period and calculated ones from dynamic analysis has been computed and compared so that can achieve the fundamental period allowed increasing coefficient.