Damage Evolution Of Long-Span Spatial Lattice Structures Under Strong Earthquakes

With the acceleration of China’s urbanization, the long-span spatial structures arebecoming the most popular structure which can meet the needs of big scaletransportation,culture, sports, and exhibition sections. Spatial structures are using widely in gymnasium, exhibition buildings, entertainment center, museums, airport terminal, and railway stations. China is facing a severe reality of high-risk strong earthquake. So it is necessary to enhance the structural earthquake-resistance ability during the designing period. As to spatial structures especially lattice shell, many principles based on structural characteristic responses have been came up to assess the structural earthquake-resistance ability. But the principles only can reflect the aspect of one area. If a macro index which can evaluate the whole structural healthy condition under strong earthquake, it would be a considerable way to evaluate the earthquake-resistance capability efficiently.Modal damage research developed rapidly. Structural stiffness would soften when suffered severe earthquake as showed by post-studies. The soft of stiffness can be reflexed by the modal information of every mode. Damage assessment is researched in this point. This paper will study a global damage model from the aspect of modal damage. As a typical long-span spatial structure, reticulated domes is different from normal building structures while it have more densely-distributed dynamic properties. As these properties haven’t been considered, the existing damage models can’t be used straightly to reticulated domes. A new kind of damage model considering the modal properties is come up in this paper. And the example is been used to illustrate the applicability of the new damage model.The paper has two parts:the modal evolution under strong-earthquake of lattice shells structure and the establishment and validation of multi-modal damage model. The OpenSees program developed by the Pacific Earthquake Engineering Research (PEER) Center is applied to perform the incremental dynamic analysis (EDA) for typical single layer latticed shell, and modal analysis have been done in different working condition. According to the graphing of every mode’s vibration shape in every working condition, the modal evolution of reticulated domes can be revealed. The damage index can be calculated based on the accomplishment of modal evolution analysis. And the result of damage index can express the damage status properly coordinating with structural characteristic responses.