行波效应对大跨度空间网格结构地震响应的影响

Influence of Wave Passage Effect on Seismic Responses of Long-Span Spatial Lattice Structures

建立了一系列的标准正方形平板网格模型,分别采用时程分析法和随机振动虚拟激励法分析了不同跨度的网格模型在不同视波速的行波激励下的地震响应,并与一致激励下的地震响应进行了对比．结果表明,行波效应对网格结构杆件应力的影响随行波视波速的减小而增大,且对不同位置杆件的应力值的影响有所不同;当行波视波速小于500m／s时,行波效应对跨度大于60 m的网格结构控制杆件内力的影响程度大于lO％;当行波视波速一定时,行波效应对杆件控制内力的影响随网格结构跨度的增大而增大,不同地震激励下的行波效应差别很大．可见,行波效应对大跨度空间网格结构地震响应的影响显著;在空间网格结构抗震设计中,当结构跨度大于60 m、行波视波速小于500 m／s时,必须考虑行波效应对网格结构控制杆件内力的影响．

A series of standard square lattice models were built. The seismic responses of the lattice models with different spans under excitation of traveling waves with different apparent velocities were investigated using the time-history method and the pseudo-excitation method for random vibration, and were compared with the seismic responses under uniform excitation. The results show that the wave passage effect on the stresses of bars of the lattice structure increases with the decrease of the apparent velocity of the traveling wave, and the effect is different for the stresses of bars at different positions. When the apparent velocity of the traveling wave is smaller than 500 m/s, the wave passage effect on the stresses of control bars of the lattice structure with span larger than 60 m is more than 10%. When the apparent velocity of the traveling wave is certain, the wave passage effect on the internal forces of bars increases with the increment of the span of the lattice structure, and varies greatly with different earthquake excitations. Some conclusions are given that the wave passage effect on the seismic responses of the long-span spatial lattice structures is significant; in the seismic design of the spatial lattice structures, the wave passage effect on the internal forces of control bars of the lattice structure must be considered when the span of the structure is larger than 60 m and the apparent velocity of the traveling wave is less than 500 m/s.