Evaluation And Reuse Study Of Existing Prestressed T-beams Based On Dynamic And Static Load Tests

Prestressed concrete T-beams are widely used in small and medium-sized bridges due to their good spanning capabilities,clear mechanical properties,and simple construction methods.However,in the process of long-term use,due to design and construction defects,material performance degradation,improper use,and environment impact,many prestressed T-beams suffer from structural damage and reduced bearing capacity,which affect safety and use.For this reason,more and more attention has been paid to the maintenance and reinforcement,demolition and reconstruction of such existing bridges,and the assessment of its bearing capacity is an important prerequisite for structural reinforcement or reconstruction.This paper is based on the Jiangxi province project of Changjiu Reconstruction and Extension.By selecting typical existing prestressed T-beams and a full-scale dynamic and static load test study is carried out.On this basis,the large-scale finite element program ANSYS is used to develop the finite element model modification and evaluate its bearing capacity.The main work of the thesis is as follows:1.Taking three demolished existing prestressed concrete T-beams with a span of 35 m as the research object,the on-site three-point static load test was used to evaluate the actual bearing capacity of the T-beams;based on environmental incentives,the stochastic subspace method(SSI)and peak picking technique(PP)were used to identify the modal parameters of the T-beam and provides experimental parameters for the subsequent finite element model modification.2.Using the large-scale finite element program ANSYS,based on the selection of suitable elements,material constitutive factors,failure criteria,and boundary conditions,a solid finite element model of prestressed concrete T-beams was established.By comparing the results with field static and dynamic test results,to evaluate the simulation effect of the initial finite element model.3.Based on the established solid finite element model,the direct modification method and response surface method were used to carry out finite element model modification of the bearing capacity calculation model of the demolished prestressed concrete T-beams with a span of 35 m.By comparing with the result of static and dynamic load tests,reliability of two model modification method were evaluated.4.The modified finite element model is applied to analyzed the impact of parameters such as concrete strength,elastic modulus,density,and prestress magnitude and elastic modulus on the carrying capacity.The evaluation index of T-beam recycle is established,andexisting prestressed T-beams have been researched for recycle.