大桥受船撞击灾害的计算机评价方法

A COMPUTER METHOD TO DETERMINE RELIABILITY OF BRIDGE AFTER SAILING SHIP IMPACT

本文提出了一种对撞桥灾害进行评价的计算机方法。首先用非线性有限元法计算由于船撞引起的桥体局部损伤分布，局部损伤用材料损伤在该处的密度表示，材料损伤是塑性应变和塑性应变率的函数，在桥体材料模型中加以反映，通过对有限元计算出的桥体局部损伤数据、现场测量数据和大桥以往累积损伤数据进行分析，利用专家知识库确定大桥目前整体损伤指标，用整体损伤指标表示大桥当前的安全状态，如果整体损伤指标超过给定临界值，则大桥退役或需要进行大的安全防护措施，否则，大桥可以继续服役，但需对其在未来如船撞、地震等可能灾害作用下的安全性能进行预测，如果预测出的安全性偏低，则需要对大桥提前进行维修。用所提出的方法对清江高坝大桥船撞灾害的实例进行了应用，验证了方法的有效性。

A computer method is proposed to determine the reliability of bridge when impacted by a sailing ship in this paper. The local damage distribution in the bridge structure caused by the ship impact is calculated by nonlinear FEM analysis. The local damage is represented by the density of material damage in the local area. The material damage, which is a function of the plastic strain and the plastic strain rate, is included in the bridge material model. The calculated local damage data, test data and the historical damage data of the bridge are analyzed by knowledge-based expert system to give the global damage index of the bridge structure. The global damage index is used to stand for the current safety status of the bridge. If the global damage index is higher than a given critical value, safety control on the bridge is advised to take or the bridge is simply discarded. Otherwise, the damaged bridge could continue to be in service, and its future safety level is predicted by assuming that some possible disasters such as being impacted by sailing ships, earthquake, etc are encountered in future. If the predicted future safety level is low, the damaged bridge should be repaired in advance. Finally, the Qing Jiang Gao Ba bridge was analyzed as an example to show the effectiveness of the method.