爆炸作用下曲线梁桥的倒塌模式

Collapse Pattern of Curved Girder Bridge under Blast Action

桥梁是交通工程中的重要枢纽结构和社会开放性公共设施,在运营过程中存在意外爆炸和恐怖袭击导致结构损坏甚至倒塌的风险,研究桥梁结构在遭受爆炸冲击后的倒塌模式显得尤为重要。利用流固耦合方法和三阶段方法数值模拟曲线梁桥在桥墩受到爆炸后的破坏效应和倒塌过程。结果表明:200 kg TNT炸药在曲线梁桥中间单柱墩底起爆后,墩柱被迅速逐层破坏,在重力作用下桥梁逐步倒塌,单柱墩是桥梁抗爆防爆设计的关键构件,应加强对墩柱的防护。连续刚构曲线梁桥的倒塌模式会表现出墩柱破坏、梁体下垂、支座处梁底破坏、梁端坠落和梁体在悬臂根部折断等破坏形态。桥台支座是曲线梁桥的重要支撑连接构件,支座或其附近区域破坏是主梁落梁的重要原因,建议在立交桥的抗爆设计中采取强连接约束措施以延缓或防止桥梁倒塌。

Bridges are important hub structures of transportation lifeline engineering and public facilities. Great risks of structural damage or even collapse may be caused by explosion accidents and terrorist attacks in the operation process. Therefore, it is particularly important to study the collapse patterns of bridge suffering the impact of explo- sion. Damage effects and collapse process of curved girder bridge after explosion of the pier are numerically simulated with fluid-structure interaction method and three-stage approach. The results show that after 200 kilograms explosive detonation at the bottom of pier with single column, the pier is quickly destroyed layer by layer and bridge gradually collapses under gravity. Single-column pier is a key component in blast-proof design of bridge and the pier protection should be strengthened. Collapse patterns of consists of pier damage, girder sagging, beam damage at the bearing, beam falling and girder breaking at the end of cantilever in the collapse process of continuous rigid curved bridge. A- butment bearing is the important supporting and connecting member in curved girder bridge. Destruction of bearing or girder near bearing is the important reason of beam falling. The strongly connected restraint measures are recommen- ded in the antiknock design of the overpass to delay or prevent the bridge collapse.