斜交装配式简支梁桥地震非均匀碰撞效应

Uneven Pounding Effect of Assembly Skew Simply-supported Beam Bridge Under Earthquake

鉴于地震作用下斜交梁桥的不规则平面旋转位移使得应用接触单元法计算斜交梁桥碰撞效应存在一定的局限性,为了探讨三向地震作用下斜交装配式简支梁桥的地震碰撞力、梁端应力和墩底应力的非均匀分布规律,提出了采用显式动力接触算法计算斜交梁桥地震碰撞效应的数值模拟方法。结果表明:斜交简支梁桥横桥向的碰撞比纵桥向的碰撞更加剧烈;桥台背墙对边主梁的碰撞力大,对中间主梁的碰撞力小;桥面两侧的梁间碰撞力大,桥面中心线的梁间碰撞力小;挡块根部受到的碰撞力大,相应部位的边主梁横向应力大;挡块端部受到的碰撞力小,相应部位的边主梁横向应力小;碰撞对台柱底部几乎没有影响,斜交梁桥的地震碰撞力分布极不均匀,总体上表现出"四角四边大,中间部位小"的特点。

Because of the irregular rotational displacement of skew beam bridge under earthquake , there were some limits to calculate pounding effect with contact element approach .In order to explore the uneven distributing rules of seismic pounding force ,stress at beam end and stress at pier bottom for assembly skew simply‐supported beam bridge under three‐dimensional grounding motions ,the new approach of explicit dynamic contact algorithm was presented . The results indicate that the transverse pounding is more severe than longitudinal pounding .Under collision of back wall of abutment ,the pounding force of edge beam is great while the pounding force of middle beam is small .The pounding force between two beams at both sides of bridge deck is great while that at centerline of bridge deck is small .The pounding force at block root is great and transverse stress of edge beam is great at the corresponding position .The pounding force at block end is small and transverse stress of edge beam is small at the corresponding position .Seismic pounding has almost no influence on the pier bottom .Therefore ,seismic pounding forces of skew beam bridge distribute extremely unevenly ,and have the characteristics of “great at four corners and four sides ,small at middle parts” on the w hole .