Failure Mechanism Of Single- Layer Latticed Cylindrical Shells Under Severe Earthquakes

The latticed shell structures integrat the advantages of truss structures and thin shell structures, have the rational routine for transfering force and can cover large space. Especially, the capability that latticed shells can be subjected to severe seismic motions is most predominant in all structures. So the latticed shell structures are used widely. But compared with fast development of the latticed shell structures, the anti-seismic theory is still very lagging. Now static stability questions about such structures have been largely settled. However, research on anti-seismic behaviors of latticed shell structures is not enough. This has hindered advanced development of latticed shell structures. To solve these problems, the paper study deeply the failure mechanism of single-layer latticed cylindrical shells subjected to severe seismic motion.At first, large-scale parameter analysis to the single-layer latticed cylindrical shells with 15-meter span and 20-meter span has been executed. Using idealism model and damage cumulative model, large-scale dynamic calculations for single-layer latticed cylindrical shells with different parameters have been analyzed with the variation of rise-span ratio, different length-to-width ratio, surface mass and imperfection in virtue of the whole-course analysis method. The failure modes and critical loads were mastered with the variation of different parameters.Then, according results of parameter analysis, the mathematics model and fuzzy synthetic evaluation method for distinguishing failure modes of single-layer latticed cylindrical shells based on comprehensive fuzzy evaluation in fuzzy mathematics has been established.The mehod considered several parameters such as maxim relative displacement, proportion of 8P, maximum of relative plastic strain-acceleration amplitude. At last, we get a fuzzy synthetic criteria to eatimate the failure modes of structures.The last, based on great computing datas, the damage model of single-layer latticed cylindrical shells which even consider span and length-to-width ratios have been established. Firstly the damage modes of structures with 15-meter span and 20-meter span had been estabilished, according to them we gained a uniform ultimate load intensity under random dynamical load.In addition,a 180m single-layer reticulated domes is be simulated, its anti-seismic performance under frequent,occasional earthquakes and severe earthquakes are fully disussed, the influence of the section of beam, original imperfection, and input of earthquakes to performance of domes are compared, which can be consulted for design in the future.