纤维模型在钢拱桥抗震设计中的适用性研究

Study on Applicability of Fiber Model in Seismic Design for Steel Arch Bridge

为了探讨纤维模型在钢拱桥抗震设计中的适用性以及钢拱桥合理的验算方法,并考察动轴力及钢板局部变形对钢拱桥的影响,以一座跨度为200m的上承式钢拱桥为对象,利用精细的三维有限元计算模型讨论了钢拱桥弹塑性地震反应特性,并在此基础上探讨了采用纤维模型进行抗震验算的适用性。研究结果表明:地震动轴力对钢拱肋极限应变的影响不可忽略;纤维模型仅适用于发生轻微损伤的钢结构弹塑性地震反应的计算;对于截面接近正方形的构件,用破坏区的平均应变指标验算纤维模型的损伤程度是一种可行的方法,但合理的等效塑性域长度还有待进一步研究。

In order to investigate the applicability of fiber model in seismic design for steel arch bridge and the reasonable checking method for steel arch bridge,and to study the influences of dynamic axial force and local deformation of steel plate on steel arch bridge,a deck-through type arch bridge with a span length of 200 m was employed as the research object to study the elastoplastic seismic response using a three-dimensional finite element model.On this basis the applicability of fiber model in seismic checking of steel arch bridge was discussed.The results show that the influence of dynamic axial force on the ultimate strain of the structure cannot be neglected;fiber model is only applicable to elasto-plastic seismic response analysis of steel structure with a slight damage;the average strain of damage zone is a feasible index to check the damage degrees of the members with approximate square sections,but further studies are needed to determine the equivalent length of plastic zone.