Abstract

There are many uncertainties related to existing bridges that are approaching or have exceeded their original design life. Lifetime extension analysis of bridges should be based on validated numerical models that can be effectively established. This paper presents a new procedure to obtain an optimal solution from sensitivity-based model updating with respect to an improvement in the modal properties, such as the natural frequencies and mode shapes, based on realistic parameter values. The procedure combines variations in the ratios of overdetermined systems with different definitions of local parameter bounds in a structured approach using a sensitivity analysis. The feasibility of the procedure is demonstrated in an experimental case study. Model updating is performed on a full-scale steel bridge using the natural frequencies and modal assurance criterion (MAC) numbers, where the numerical model is established by considering general uncertainties and model simplifications to reduce the model complexity. From the optimal solution for the case study considered, an improvement in modal parameters is obtained with highly reliable parameter values. The proposed procedure can be applied to similar case studies, irrespective of the structure under consideration and the corresponding parameterisation to be made, to effectively obtain a validated numerical model.

摘要

现有桥梁正在接近或已经超过其原始设计寿命，存在许多不确定性。桥梁的寿命延长分析应基于可以有效建立的经过验证的数值模型。本文提出了一种新程序，可根据实际参数值从基于灵敏度的模型更新中获得最佳解决方案，以改善模态特性，例如固有频率和振型。该过程使用敏感性分析在结构化方法中将超定系统的比率变化与局部参数界限的不同定义相结合。该程序的可行性在实验案例研究中得到了证明。使用自然频率和模态置信度 (MAC) 数对全尺寸钢桥进行模型更新，其中通过考虑一般不确定性和模型简化来降低模型复杂性来建立数值模型。从所考虑的案例研究的最佳解决方案中，通过高度可靠的参数值获得了模态参数的改进。所提出的程序可以应用于类似的案例研究，而不考虑所考虑的结构和要进行的相应参数化，以有效地获得经过验证的数值模型。通过高度可靠的参数值获得模态参数的改进。所提出的程序可以应用于类似的案例研究，而不考虑所考虑的结构和要进行的相应参数化，以有效地获得经过验证的数值模型。通过高度可靠的参数值获得模态参数的改进。所提出的程序可以应用于类似的案例研究，而不考虑所考虑的结构和要进行的相应参数化，以有效地获得经过验证的数值模型。