大跨度钢-混凝土组合人行天桥舒适度分析

Vibration comfort analysis on large-span steel-concrete composite pedestrian

采用调整结构自振频率和限制加速度响应相结合的方法,对惠州市大亚湾大跨度钢-混凝土组合人行天桥进行了人行舒适度分析。基于通用有限元程序MSC.MARC二次开发的子程序,建立组合人行天桥的纤维模型。利用FORCDT子程序描述随时间和空间变化荷载的功能,模拟了不同人行激励工况,按照各国规范中验算人致振动响应的方法,对人行天桥舒适度进行综合评估。通过加速度时程计算,对比分析阻尼比、积分步长、结构质量、人行荷载模式以及桥梁支座处弹簧节点构造等因素对结构动力响应的影响。分析结果表明:该钢-混凝土组合大跨人行桥能够满足各规范对人行舒适度的检验要求,同时在桥梁支座处设置弹簧连接,可使结构加速度响应降低14%,支座反力减小54%,可有效控制结构的人致竖向振动响应。

The method of combining the natural vibration frequency adjustment and the acceleration response control is used to analyze the vibration comfort of the long span steel-concrete composite pedestrian in the Shenzhen Dayawan Development Zone. Fiber model based on the secondary development on the software MSC. MARC is built for the finite element calculation. The FORCDT subroutine function,which allows describing the load dependent on both time and location,is utilized to simulate the human walking. According to the design criteria of China and overseas for evaluating the comfort degree of footbridges, several loading conditions are considered to calculate the vertical acceleration time history. The influences of the damping ratio,integrating step size,structural mass,loading model and the spring connection on the bridge bearing are intensively analyzed. The results indicate that the large-span steelconcrete composite pedestrian satisfy the requirement of comfort degree for human walking. In addition,the spring connection construction is beneficial to the control of the crowd-induced vibration,which reduces the peak acceleration and support reaction by 14% and 54% respectively.