近场脉冲型地震作用下上承式拱桥损伤模式研究

Damage mode analysis of deck-type arch bridge subjected to near-fault pulse-type ground motions

为了研究近场脉冲型地震作用下上承式钢筋混凝土拱桥的损伤模式,采用OpenSEES建立了某实际上承式箱板拱桥的全桥模型,根据N-M相关曲线和能力需求比分别研究了主拱圈与拱上立柱的抗震性能,并基于动力增量分析(IDA)对桥梁的损伤模式进行探讨。研究表明:在纵、横向地震输入下,拱圈的最大弯矩响应均出现在拱脚;当地震沿纵向输入时,较矮拱上立柱的剪力响应较大,而当地震沿横向输入时,拱上立柱将产生双向剪力,且较高立柱的横向剪力大于纵向,较矮立柱的纵向剪力大于横向;主拱圈的潜在抗震薄弱环节是拱脚,且其纵向抗震性能弱于横向;拱上立柱纵向抗震性能优于横向,靠近拱顶的立柱最先发生破坏,且以剪切破坏为主;较高的拱上立柱易发生横向剪切破坏,而较矮的拱上立柱易发生纵向剪切破坏。损伤分析表明,钢筋混凝土上承式拱桥在近场脉冲型地震作用下拱上建筑会先于主拱圈发生损伤。

In order to investigate the damage mode of deck-type reinforced concrete arch bridge subjected to near-fault pulse-type ground motions,the OpenSEES was used to establish the analytical model of an actual deck-type arch bridge with box section.The seismic performance of the arch ring and spandrel columns was examined according to the N-M correlation curves and capacity demand ratios.The damage mode of the bridge was discussed based on the incremental dynamic analysis(IDA).The results show that the maximum bending moment response of the arch ring is found in the springing sections under the excitations of both longitudinal and transverse directions.When the bridge is excited longitudinally,larger shear force responses are found in shorter spandrel columns.When the bridge is excited transversely,bidirectional shear force responses are found in the spandrel columns,and the transverse shear force responses are greater than the longitudinal ones for the higher columns and the opposite trend is also true for the shorter columns.The springing sections are the most vulnerable components of the arch ring,and their longitudinal seismic performance is weaker than their transverse one.The longitudinal seismic performance of the spandrel columns is better than their transverse one.The first damage occurs to the spandrel columns near the arch crown and is subjected to shear failure.The taller spandrel columns are prone to transverse shear failure,while the shorter ones are prone to longitudinal shear failure.The damage analysis shows that the spandrel structure of deck-type reinforced concrete arch bridge will be damaged prior to the main arch under the near-fault pulse-type ground motions.