中美规范防落梁搭接长度比较与参数分析

Comparison and Parameter Analysis of Anti-falling Beam Overlap Length in Chinese and American Codes

摘要:

地震作用下，桥梁落梁破坏是桥梁失效的主要形式，提供足够的搭接长度是避免落梁破坏最有效的措施之一。基于参数对比和有限元模型，对中美两国规范规定的搭接长度计算要求及其与实际桥梁地震分析结果间的差异进行研究。结果表明：对于直接支承在桥台上的简支桥，公路桥梁抗震规范对搭接长度的规定更加贴合适用、经济的设计理念；通过公路桥梁抗震规范、ASSHTO规范计算所得的搭接长度变化趋势基本一致，但公路桥梁抗震规范规定的搭接长度更保守，ASSHTO规范规定的搭接长度对墩高变化更敏感；公路桥梁抗震规范、ASSHTO规范规定的搭接长度基本上可以满足多数地震作用下（峰值加速度达到0.8g）桥梁不落梁的要求，具有广泛的适用性。

Abstract:

Under the action of earthquake, the falling beam failure of bridge is the main form of bridge failure. It is one of the most effective measures to avoid the falling beam failure by providing the sufficient overlap length. Based on the parameter comparison and the finite element model, the calculation requirements of the overlap length stipulated in the codes of China and the United States, and the differences from the actual bridge seismic analysis results are studied. The results show that for the simple-supported bridge directly supported on the abutment, the seismic code of highway bridge on the overlap length is more suitable and economical to the design concept. The variation trends of overlap length calculated to obtain through the anti-seismic code for highway bridges and ASSHTO code are basically the same. But the overlap length specified in the anti-seismic code for highway bridges is more conservative, and the overlap length specified in ASSHTO code is more sensitive to the change of pier height. The overlap lengths stipulated in the anti-seismic code for highway bridges and ASSHTO code can basically meet the requirements of the bridges not dropping the beams under the most earthquake actions (the peak acceleration reaches 0.8g), and have the wide applicability.