空间网架结构随机地震动激励下的响应分析

Response Analysis of Spatial Grid Structure Under Random Seismic Excitation

以上海大众仪征五厂的车身车间网架结构为研究对象,采用随机振动法,分别对结构进行独立的3向正交随机地震动激励作用下的动力响应分析.结果表明:该结构具有振型密集、频率变化均匀的特点,在地震动激励作用下可能首先发生扭曲破坏;在水平方向的随机地震动激励作用下,虽然结构整体安全,但是其下弦中的几根杆件发生破坏以及上弦中1号截面杆件的拉压应力值较大.在x和y方向的随机地震动激励作用下,上弦和下弦中1号截面杆件产生的拉压应力值的差值较大,其它截面的杆件应力值的差值较小.

Taking the grid structures of the car body workshop of Shanghai Volkswagen＇s Yizheng fifth factory as research object and using random vibration method, the dynamic responses of the grid structures were analysed under independent three orthogonal random seismic excitations. Analysis results indicate： the structure is characterized by high density vibration modes and uniform frequency varation, which may at first be twisted and destroyed under seismic excitation. Under horizontal random seismic excitations, a few bars at the bottom chord will fail and the draw-press stress of No. I cross-section bar at the upper chord will be relatively great, though the whole structure is safe. Under random seismic excitations in x and y direction,the draw-press stresses of No. 1 cross-section bars at upper bottom chord have a great difference, while the other section bars＇ stresses are of little diversity between each other.