“5·12”汶川地震典型桥梁震害分析

Typical Bridge Damage Analysis in "5·12" Wenchuan Earthquake

针对"5.12"汶川地震中公路桥梁破坏严重,且破坏形式在映秀—北川断裂带南北两段出现了显著差异的情况,从震源机制、断裂带运动方式和桥梁结构本身特点等方面分析了产生这一差异的原因;并在汶川地震典型的桥梁震害分析的基础上,对强震区梁桥和拱桥的抗震设防提出了一些建议。结果表明:在断裂带南段由于地震释放能量巨大,断层逆冲作用显著,桥梁结构在强大竖向和水平地震力的共同作用下出现了桥墩、拱圈断裂导致的结构垮塌等强度失效型破坏;在断裂带北段断层右旋走滑作用显著而逆冲作用微弱,桥梁结构在剧烈的地面水平错动下出现了上部结构的落梁和双曲拱的垮塌等位移型破坏。

According to the highway bridges severely damaged in ＂5 ·12＂ Wenchuan Earthquake, there was significant difference in damage style between south and north part of the Yingxiu Beichuan fault, Sichuan Province. The reason was analyzed from several aspects, such as earthquake source mechanism, movement style of the fault and characteristic of the bridge structure. Some suggestions in seismic fortification for girder bridges and arch bridges were given on the basis of the typical bridge damage analysis in ＂5 ·12＂ Wenchuan Earthquake of Sichuan Province. The results show that because of the huge energy and faults thrust in south part, structures sustain huge vertical and horizontal seismic forces at the same time, the damage style of the highway bridges is strength failure, such as collapse caused by rupture of piers or arch rib. While in the north part of the fault, because of the huge right lateral strike slip and the weak thrust, the damage style is displacement failure, such as collapse of the superstructures or the two-way curved arch bridges.