Study On The Failure Mode And System Reliability Of The Prefabricated Prestressed Concrete T-Beam Bridge

The bridge is the key and controlling facility to ensure road unblocked.If the bridge collapses,the road will be affected seriously.Therefore,it's significant to evaluate the reliability of the bridge structure.Studying the failure modes and system reliability of the bridge under the loads can not only provide advices for strengthening design of the bridge,but also avoid ignoring the weak links at the design stage of bridge effectively.The simply supported T-beam bridge is widely used in the middle and small sized bridges because of the advantages of reasonable cross-section design,high speed of construction and light hoisting weight.Therefore,it is of great significance to study the failure mode and system reliability of the prestressed concrete T-beam bridge.In this paper,the failure mode and system reliability of prestressed concrete T-beam bridge are studied.The main work and achievements are as follows:First,in this paper,the basic theory and calculation method of structural reliability are quoted,and the statistical parameters and probabilistic models of random variables related to resistance and load effects are introduced.On this basis,the calculation method is selected,which is suitable for the system reliability of the T-beam bridge.Second,through analyzing the disease and damage characteristics of the existing concrete T-beam bridge structure,the failure criterion of the T-beam bridge structure is obtained,which is used as the basis for judging whether the structure is invalid.Third,selected an engineering case to analysis,used the space grillage method by the finite element software ANSYS to establish the finite element model,and used the double composite element method to simulate the beam section with possible failure,and calculated the internal force of the structure through the different loading modes.Used the global critical strength branch and bound method to search the main failure modes of the structure,and used the JC method to calculate the reliability index and failure probability of each failure mode through programming by the MATLAB software.According to contrast the reliability index of each failure mode under the different loading modes,and the failure response of the T-beam bridge structure under the different loading conditions is obtained.Fourth,calculated the correlation coefficients among failure modes,the high correlation among failure modes is confirmed,and the system reliability of the T-beam bridge structure is obtained by the correlation coefficients among failure modes.Fifth,some of the results of the existing bridge failure test are compared with the research in this paper to verify the feasibility of the finite element analysis method used in this paper.