长大公路混凝土连续梁桥抗震方案比选

Comparison of Seismic Design Schemes for Long-span Concrete Continuous Hhighway Girder Bridges

长大公路混凝土连续梁桥通常具有全桥连续长度大、联长较长、上部混凝土主梁自重较大、结构较刚等特点,当建于强震区时,其抗震设计是个技术难点。本文介绍了长大公路混凝土连续梁桥的抗震结构、隔震结构和振动控制结构的设计概念,并对3种基本抗震设计概念的适用性进行了评述。基于实桥案例,对当前实际工程中应用最多的抗震结构方案与隔震结构方案进行了技术比选。结构地震反应分析结果表明,与常规的抗震结构方案相比,隔震结构方案可使全桥各联下部结构的纵桥向和横桥向的总地震内力平均降低56%和65%以上。本文还侧重介绍了方案比选中隔震支座的选型问题及初拟铅芯橡胶隔震支座设计参数的简化方法,供同类工程参考借鉴。

A long-span concrete continuous highway girder bridge usually has a large contin uous length and a heavy concrete girder with several bridge units.If it is buil t in a strong seismic zone,its seismic design is difficult.This paper introduc es the design concepts of earthquake-resistant-structure（ERS）,isolation-str ucture（IS）,and vibration-control-structure（VCS） for long-span concrete conti nuous highway girder bridges.The applicability of the three basic design concep ts is reviewed.Both the ERS and the IS design schemes were compared based on a case study.The results show that： comparing with the ERS design scheme,the IS design scheme can in average lower 56% longitudinal and 65% transverse horizonta l seismic force of the bridge substructure.The paper also discusses on the sele ction of seismic isolators,especially on the simplified method for calculating the initial design parameters of lead rubber bearing（LRB） during the concept de sign and preliminary design phases,which provide certain reference significance for similar projects.