Earthquake Response of 3D Asymmetric Building with Infill Wall Under Soil-Structure Interaction

Due to encroachment of soil-structure interaction effect, behaviour of structural system response is greatly influenced. The variation in structural response with the variation of soil stiffness during earthquake is the subject of present study. An attempt of studying seismic response behaviour with the inclusion of SSI effect of an asymmetric 3D multi-storey building frame is done in finite element software LUSAS in frequency domain as well as time domain. Moreover, infill wall as diagonal strut is considered to study the comparison of base shear, torsional base shear of infilled frame with bare frame. Site-specific input earthquake motion is obtained through de-convolution using DEEPSOIL, by 1D wave propagation. Natural frequency of both the models (bare frame and infilled frame) with different storey height due to SSI effect is obtained and found that irrespective of storey height infilled frames are stiffer than the other as usual because of which for low rise building, resonance occurs in stiff soil with maximum base shear, whereas for high rise building peak, response occurs in flexible soil. It is observed that due to infill wall though ‘base shear’ was increased but ‘torsional shear’, a common phenomenon of asymmetric building, was reduced. When the soil is soft, ‘torsional shear’ appears lesser than fixed base structure. Therefore, during a site selection, for high rise building soft soil and for low rise building stiff soil should be avoided as much as possible.