Stiffness Determination Method Uniformizing Enveloped Inter-Story Drift Angle in Multiple Seismic Responses

This paper proposes a stiffness determination method uniformizing inter-story drift angle in seismic response using the closed-form representation of a primary mode. The primary modal shapes for the uniform inter-story drift angle are obtained from seismic response analyses on the 120 models and shown with number of building stories and dimensionless height as parameters. In the same way, an equation that estimates the uniform inter-story drift angle is shown with building representative height, natural period, and damping constant as parameters. From the above, the stiffness for uniform inter-story drift angle can be easily obtained without repetitive calculations. This paper proposes a stiffness determination method uniformizing inter-story drift angle in seismic response using the closed-form representation of a primary mode. The primary modal shapes for the uniform inter-story drift angle are obtained from seismic response analyses on the 120 models, and shown with number of building stories and dimensionless height as parameters. In the same way, an equation that estimates the uniform inter-story drift angle is shown with building representative height, natural period, and damping constant as parameters. From the above, the stiffness for uniform inter-story drift angle can be easily obtained without repetitive calculations. Uniform inter-story drift angle in seismic response of buildings is effective in improving structural performance. Because it is expected to prevent pancake collapse due to concentration of deformation, and to decrease the maximum inter-story drift angle by efficient absorption of damping energy in each story. In this paper, inter-story drift angle is controlled by stiffness calculated using the closed-form representation of a primary mode, and the method is applied with the results of time history analyses. Then the primary mode shapes are obtained from the results of time history analyses on 120 model cases, and the values of maximum inter-story drift angle are investigated. The conclusions are obtained as follows.