采用二维梁修正模型的钢梁-混凝土板组合桥梁的承载力分析

通过试验对钢梁-混凝土板组合桥梁的结构鉴定、基于修正模型的承载力、承载力对分析模型的敏感性进行分析。基于振型、频率、振型阶次等动力性能及静力变形,建立修正模型。用二维梁模型成功模拟了纵梁间横向荷载传递机理、扭转变形及斜桥影响。算得的承载力结果与三维有限元分析接近,而简化的一维杆模型误差却很大。在模型修正的不同阶段,将模型参数分组,这样能提高收敛速度和成功率。虽然可认为横向支撑不参加工作,但在承载力分析中它们却是临界杆。横向支撑的破坏改变了纵梁间的传力机理,可能导致内梁的过早破坏。

Load Rating of Concrete-Deck-on-Steel-Stringer Bridges Using Field-Calibrated 2D-Grid Models

This paper presents and discusses issues related to structural identification,calibrated model-based load rating,and sensitivity of rating to the analytical model,along with experimental studies conducted on an existing concrete-deck-on-steel-stringer bridge.The proposed model-updating procedure uses collected dynamic data(mode shapes,modal frequencies,and order of modes) as well as static deformed shape information.Two-dimensional(2D) grid models were developed to successfully simulate the transverse load transfer mechanisms between girders,torsional flexibility,and effects of skewed bridge architecture.The rating results obtained from the 2D-grid models were close to 3D-FEM-based evaluation,while simplified 1D bar models had serious shortcomings.Grouping the parameters of the analytical model at different stages of model calibration enhanced the speed and convergence success of the objective function.Although cross-braces are considered as non-structural members,they have been found to be the most critical members of the selected bridge during rating studies.Failure of cross-braces deemed to alter the load transfer mechanism between girders and possibly resulting in the premature failures of interior girders.