Seismic impact between adjacent torsionally coupled buildings

The problem of seismic impact between torsionally coupled multi story moment frame buildings is investigated in this paper. Five pairs of adjacent structures spaced at various separation distances are considered. The buildings are 4-10 stories in height. Although a common plan being symmetric with regard to lateral stiffness is considered, a mass eccentricity variable from zero to 30% of the plan dimension is assumed. By three-dimensional modeling of the nonlinear torsional buildings having common story elevations, the seismic pounding happen anywhere along the adjacent buildings edges. Effect of impact and torsional eccentricity are studied by comparison of nonlinear dynamic responses of buildings at different clear distances under 11 consistent earthquakes. The responses include pounding forces at stories, story drifts, story shears and plastic hinge rotations. It is shown that how pounding incidents increase for larger eccentricities and how pounding occurs even at the clear distances prescribed by seismic design codes. The combined effect of torsional eccentricity and pounding results in amplifying the nonlinear response of structure especially for the peripheral frames.