Preventing the fall of skew and curved bridge decks during earthquake and predicting the pounding response

在1995年的兵古县-南部地震和1994年的北岭地震中，许多斜桥和弯曲桥的桥面倒塌。通过橡胶支座支撑桥梁，并允许桥面与桥台之间的碰撞，研究了防止桥面结构倒塌的方法。研究的关键是弄清冲击现象，其结果可以预测桥头和桥台的损伤程度，验证所提出方法的可行性。通过仿真分析和试验研究表明，桥台与桥台之间的冲击是一种混沌现象，但在输入强度、间隙和桥台响应三个量之间具有相似性。特别是，间隙是决定最大响应的最主要因素，而甲板的频率特性和地震波对响应的影响不大。由于甲板的冲击是一种混沌现象，响应的时程是不可靠的，但从工程的角度来看，极大值是相当重要的。即使响应是混沌的，最大值也受能量原理的支配，是可预测的。因此，本研究提出了一个满足三个量之间相似性的预测方程。将预测方程与模拟结果和实验结果进行比较，结果与模拟结果吻合较好。因此，该预测方程可以估计地震作用下桥面端部和桥台的损伤程度，可以验证所研制的减震器的有效性，而无需采用复杂的碰撞模型模拟冲击。

During the Hyougo-Ken-Nanbu earthquake in 1995 and Northridge earthquake in 1994, many decks in skew and curved bridges collapsed. The research dealt with preventing the fall of deck structures by the means of supporting the bridges by rubber bearings and permitting pounding between the decks and the abutments. The crucial point in the research is to clarify the pounding phenomena and the result can predict damage level of deck ends and abutments and can verify the possibility of the proposed means.From the simulation analyses and the experiments, the research indicated that the pounding between deck and the abutments is a chaos phenomenon but has similarity between the three quantities of input intensity, clearance and response of a deck. Particularly, the clearance is most dominant in determining the maximum response and frequency characteristics of a deck and earthquake wave do not much influence the response.Since pounding of a deck is a chaotic phenomenon, time history of the response is not reliable but the maximum is rather important in an engineering viewpoint. Even if the response is chaotic, the maximum is governed by energy principle and is predicable. Therefore, the study proposes a predicting equation that satisfies the similarity between the three quantities. When comparing the predicting equation with simulated results and experimental results, the equation well agrees with them. Hence, the predicting equation can estimate the damage level of deck end and abutment during earthquake and can verify the effectiveness of shock absorber developed without simulating the pounding by using complicated model of collision.