In-span hinges can facilitate construction processes and diminish the adverse consequences of creep, shrinkage and thermal phenomena, but can also bring about detrimental effects such as impacts, unseating issues and large displacements. The seismic behaviour of concrete bridges has been addressed in previous studies, but it remains unclear how in-span hinges affect the seismic response of irregular bridges. The aim of this research was to determine the seismic performance of irregular multi-frame bridges. To consider a wide range of irregularity, four classes of single- and multi-frame bridges with low to high regularity indices were considered. An innovative parameter, the adjacent frame lateral stiffness ratio (AFSR), was introduced to determine the appropriate position of in-span hinges and investigate the performance of multi-frame bridges. The results showed that the beneficial or damaging effects of in-span hinges on the seismic behaviour of a bridge depend on its level of irregularity. The seismic demands of piers in multi-frame bridges are typically lower than those of single-frame bridges. The results also showed that the piers adjacent to an in-span hinge are more affected by the hinge. It is recommended that in-span hinges are located such that the AFSR approaches unity so as to avoid out-of-phase vibration of adjacent frames and unseating issues.

中文翻译：

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不规则多框架钢筋混凝土桥梁地震响应的数值研究

跨距铰链可简化施工过程并减少蠕变，收缩和热现象的不利后果，但也会带来不利影响，如撞击，不稳固问题和大位移。混凝土桥梁的抗震性能已经在先前的研究中得到了解决，但是尚不清楚跨度铰链如何影响不规则桥梁的地震响应。这项研究的目的是确定不规则多框架桥梁的抗震性能。为了考虑各种不规则性，考虑了四类具有低到高规则性指数的单帧和多帧桥。引入了一个创新参数，即相邻框架横向刚度比（AFSR），以确定跨度铰链的适当位置并研究多框架桥梁的性能。结果表明，跨度铰链对桥梁地震行为的有利或破坏作用取决于其不规则程度。多框架桥墩的抗震要求通常低于单框架桥。结果还表明，跨距铰链附近的墩受铰链的影响更大。建议跨度铰链的位置应使AFSR趋近于一体，以避免相邻框架的异相振动和不安的问题。结果还表明，跨距铰链附近的墩受到铰链的影响更大。建议跨度铰链的位置应使AFSR趋近于一体，以避免相邻框架的异相振动和不安的问题。结果还表明，跨距铰链附近的墩受到铰链的影响更大。建议跨度铰链的位置应使AFSR趋近于一体，以避免相邻框架的异相振动和不安的问题。