摘要
天津大沽桥主跨103米,采用全钢斜拱斜系杆面无顶部水平支撑的结构形式,结构复杂,振型多是空间的,自振频率密集。我国新版桥梁抗震设计规范正在编制,目前我国缺少对这种桥抗震设计的明确规定。参考国内外相关规范,采用两阶段抗震设计,确定了表达两阶段水平和竖向地震作用的反应谱,选择和产生合格的三分量地震地面加速度时程历史;计算了拱圈的几何刚度和斜吊杆的割线刚度对地震反应的影响;用有效振型参与质量分别确定了对顺桥向和横桥向地震作用的振型组合所必须的振型数,和非弹性时程积分的合理步长,表明用前57阶振型进行振型组合,以及0.02秒的积分步长能给出可靠的结果。对大沽桥弹性反应分析,反应谱振型叠加法必须使用CQC组合,还应考虑对三向地震作用的反应的组合。利用作者开发的程序BER2002进行三分量地面运动同时输入下的非弹性时程积分。分别考虑水平主波沿顺桥向和横桥向的反应,取大者。分析表明,大沽桥的设计方案有良好的抗震性能。
Dagu bridge, at Tanjin, is a tied arch bridge with asymmetric and inclined steel box arches and a steel box girder. Due to its structural complexity, the current Chinese design code is incapable of aseismic assessment. With reference to the new versions of foreign design specifications, appropriate design response spectra in three directions and ground acceleration time histories with three components are given. A 3D analytical model including geometric stiffness of the arch and the secant modulus of the hangers is established. The effective modal participation mass is used to determine the minimum number of modes for mode combination of response spectrum analysis and the reasonable time step for the step-by-step integration analysis. It is found that the CQC combination should be used in the response spectrum analysis. The time histories of three groups of simultaneous three-component ground accelerations are used as input for nonlinear response analysis by SAP 2000, ANSYS and an in-house program BER 2002. It is shown that the bridge possesses satisfactory aseismic behavior.
出处
《工程力学》
EI
CSCD
北大核心
2005年第3期152-156,133,共6页
Engineering Mechanics
基金
国家973项目(2002CB412709)
