既有铁路钢桁梁桥基准有限元模型建立与验证

为了评估既有铁路钢桁梁桥的工作状态和使用安全，需要建立能够精确模拟结构目前状态的有限元模型。以南京长江大桥为例，根据灵敏度的物理意义，从简单实用的角度出发，充分利用现有的大型有限元分析程序，以结构设计参数为修改参数，以结构自振频率为目标函数对初始结构有限元模型进行修正，最后以结构主要杆件应力时程响应为验证参数建立了能够表征该桥目前状态有限元基准模型，为大桥的状态和疲劳寿命评估提供了科学基础。

Establishment and Verification of the Baseline 3D Finite-element Model of Existing Railway Steel Truss Bridge

In assessment of condition and service safety of existing railway steel truss bridges, it is necessary to establish the 3-dementional finite-element models (3D FEM) which can reflect the actual mechanical behavior. Aiming at the analysis of the Nanjing Yangtze River Bridge ( NYRB) , based on the physical meaning of sensitivity and with the aid of the finite element program ANSYS, a simple and applicable method of model updating is proposed. With the method, the structural model is updated by modifying the parameters of design, and validated by structural natural vibration characteristics and stress-time response of main members. The baseline 3D FEM reflecting the structural current state is then a-chieved. The results obtained provide a reliable research basis for health monitoring, condition assessment and dynamical response forecasting of the BYRB.