Reliability Analysis Of Concrete-filled Steel Tube Arch Bridge Under Serviceability Limit State

Based on bridge structure basic reliability theory, aiming at the existing problems when putting reliability analysis theory into engineering use, the BP neutral network and improved JC arithmetic are combined to calculate reliability of concrete-filled steel tube(CFST) arch bridge under serviceability limit state and to provide theoretical reference for CFST arch bridge reliability assessment. The main research contents are as follows:(1) According to the basic definition of limit state, starting from the resistance of structure and load effect, the effect and resistance probabilistic model of CFST arch bridge under serviceability state are cleared and the disadvantages of traditional reliability calculation method on CFST arch bridge structure analysis are discussed. Combined with gradient calculation method, the limit state equation parameter analysis method of CFST arch bridge is obtained.(2) Based on bridge structure basic reliability theory and features of CFST arch bridge structure, combined with neutral network theory, BP neutral network and improved JC arithmetic are used to analyze the reliability of CFST arch bridge under serviceability limit state from both deflection and stress side. Through improved JC arithmetic iteration way, the nonlinear performance function fitted by BP neutral network is solved which could improve the accuracy of structure reliability analysis and accomplish the reliability assessment of CFST arch bridge on structure level. Based on MATLAB calculation program, systemized and modular design method are used to write reliability analysis program, and a simple example is used to test the feasibility and accuracy of the program.(3) Based on reservoir bridge, finite element model is set up and the CFST arch bridge reliability calculation program is written. Using BP neutral network and improved JC arithmetic, the reliability of real bridge is estimated from both deflection and stress aspects and the sensitivity of reliability indexes to serviceability limit state equation is analyzed. Combined with the sensitivity calculation result, random variate number is decreased to simplify calculation process.