Analytical solution and characteristics of vertical seismic displacement of truss cable structures

Abstract

So far, there is no analytical solution for the vertical seismic displacement of truss cable structures via modal superposition spectrum method. First, according to the first author’s previous work, the first eight symmetric and anti-symmetric frequencies and corresponding mode shapes are given. Then, the shape curves of maximum vertical seismic displacement of truss cable structure with 40m, 65m and 72m spans are presented by modal superposition spectrum method. Finally, the correctness of the above analytical solutions is verified by the results of FEM simulations. It is found that: (1) the presented analytical solutions of vertical seismic displacement of truss cable structures are of high accuracy and are simple and practical; (2) The maximum vertical seismic displacement curve of the truss cables has three shapes, which depends on the fundamental frequency and spans. It is found that for the truss cables, the maximum seismic displacement does not necessarily occur in the mid-span. This new finding should attract the attention of engineering designer when designing long-span truss cables.