Response Analysis Of Long-Span Multi-Support Structures Under Multi-Support Excitations

The number of large-span structures is increasing following the development of the economy. Engineers have higher regard for the more rational seismic response analysis of the long-span structure,because the spatial and time interaletion of propagation of earthquake wave makes the input of excitations different at the individual supports of the structure.In allusion to the multi-support excitation of ground motion, this study establishes a differential equation of motion with input of ground motion displacement, deletes the pseudo-static item, and derives the solution of structure response in the linear-elastic phase using the random vibration theory. It analyzes the solution of primary multi-support excitation problem, and raises the problem in the multi-support response spectrum method and its improvement is made. By comparing factors of response peak values of different structures under the same ground motion, this study proposes the concept of generalized factor of peak value and the corresponding calculation method. Meanwhile, it further realizes that normal modal shape has obscure relationship with the multi-support excitation; therefore, this study proposes another concept of shift modal shape. Finally, it compares the structural responses to the consistent and inconsistent excitations and analyzes the seismic responses of large-span structures with the different span lengths.