Parameter Identification Of Boundary Conditions For Bridge Model Based On Temperature Effects

Thermal load is one of the critical loads for bridge analysis,and has a significant effect on bridge structure.Temperature effects is not only related to the bridge stiffness but also related to the boundary conditions.Therefore,it is required to determine the boundary conditions and establish a reliable model for bridge temperature effects analysis.This thesis proposes a new method for parameter identification of bridge finite element model boundary conditions based on temperature effects.First of all,the relationship between the bridge temperature effects and boundary conditions is analyzed.Then,an objective function based on the residuals of temperature effects of experimental structure and model is created.Finally,the parameters of the boundary conditions are obtained by optimizing the objective function using the least squares nonlinear method.The main research work are as follows:1.The thesis systematically analyzes the impacts of the cross section,length,thermal expansion coefficient,elastic modulus and boundary conditions on the temperature effects for beam bridges.In addition,the relationships between boundary conditions and temperature effects are revealed through the temperature effects analysis for beam structure with different boundary conditions.The thesis derived the expression of temperature effects of beam structure with linear and bilinear translational boundary conditions under uniform temperature change.The expression of temperature effects of beam structure with linear and bilinear rotational boundary conditions under linear temperature gradient is also derived in the thesis.2.The thesis provides a new method for parameter identification of boundary conditions of bridge finite element model based on temperature effects.Through numerical simulation analysis for beam bridges with different boundary conditions and subjected different loads,the parameters of the boundary conditions can be effectively identified.3.Finally,the boundary parameters of Yuanze bridge are identified based on the real measured temperature effects.The initial finite element model of Yuanze bridge is established based on the design drawings.The boundary conditions of the bridge are identified based on the measured data and the proposed method.The results show that the temperature effects based on the model with the identified boundary conditions is in a good agreement with the measure data.