Based on the power spectrum method of stochastic vibration theory, the seismic response and its computation of two-way
Beam String Structure (BBS) under multi-dimensional earthquake excitation are discussed. By means of an illustrative 90m × 90m
two-way BBS roof, dynamic properties and characteristics of multi-dimensional earthquake responses are presented. Structural
response contributions from different ground motion component and interactions between roof and supporting frame are also
analyzed. Some aspects on seismic computation of two-way BBS are further investigated, including the reasonable number of
participation modes, the impact of initial prestress distributions and the sensitivity of damping ratios. The validity of
multi-dimensional seismic effect combination method, suggested in China Code for Seismic Design of Buildings (GB50011), is also
probed. Unconventional dynamic response characteristics of two-way BBS are emphasized. Some suggestions on the seismic
computation are also ard for the design of two-way BBS.