Research On Mechanical Property And Reliability Of Long Span Cable Bridge

Cable bridge is a type of suspension bridge which depends on the wire rope, strand and steel beams to suffer the force. With the construction of low cost, short period of projecting, strong carrying capacity and so on. It particularly applies in the mountains and canyons in construction. It introduced by the military during 20th century 70s. Hydropower construction in the southwest region gradually has been widely used after improving. In recent years, it is often constructing cable bridge in order to resolve cross-strain issue temporary access in many mountain highway, railway and hydropower construction, also made good economic. Therefore, the optimization of cable bridge design, finite element analysis, safety and reliability of gradually drawed people's attention.In this thesis, there are three different span cable bridges as project background, introduced the theoretical calculation of cable bridges, numerical methods and nonlinear finite element analysis. Analyzing the cable bridge with damage cable in Yun Nan province by the large number of measured data in field. And simulate the different positions of cable damage under the cable bridge on the mechanical properties of cable by the finite element model. Researched failure caused by the tensile force of full bridge structure of the law of redistribution of internal force of cable.Second, in concluding on the basis of the method of reliability, using the FOSM (JC) method reliability analysis conducted Cable Bridge, The results can be optimized for the cable bridge design and safety analysis provides a theoretical basis, also enriched the cable bridge in the area of reliability analysis of technical information.The major research is as follows:Firstly, in this thesis, the cable bridge in Yun Nan Province as the research background, calculated the cable bridge structure and the main bearing member natural frequency, critical wind speed by linear simplified calculation method.This theoretical calculation can meet the cable bridge of the basic initial design, and can reference works budget of special section of the bridge for selection. And obtained through theoretical calculations and the initial linear of cable bridge, initial cable forces for the next step tramway bridge finite element model of reference, so it can be effectively shorten the modeling time.And through to search a large number of bridges in the specifications, building codes and materials specifications based on the cable, to check the structure of cable bridge on the main stress components, such as cables,beams and so on, and take into account the impact of temperature on the cable bridge.Secondly, in summing up cables on the basis of numerical calculation method, this thesis derived cable element method and parabolic algorithm, and compare the two algorithms in the cable bridge differences between the accuracy of the calculation, get some beneficial conclusions. Thirdly,This cable breakage of cable bridge in Yun Nan Province as the project background, unifies the scene actual situation, simulates the back guy to fall off in the situation finite element model,before and fell off the measured data the back guy to fall off the measured data after the back to carry on the contrastive analysis, summarized obtains the back guy to fall off to the entire bridge's static, the power influence. And after utilizing revises the finite element model, simulates the situation which the different position the back guy expires, the analysis different position back guy's damage, falls off the influence which distributes again to rope way bridge Tension, studies it to the rope way bridge safety performance destructiveness.Fourthly, according to the mechanical characteristics of the cable bridge, cable bridge limit state equation parameters by the tension cable resistance, dead load generated by solar power, solar power generated by the variable load component. The process of reliability analysis in Cable Bridge, since the current value of the relevant norms of reliability, most for the concrete bridge, there is no statistical parameters for the cable bridge;the actual statistical data are also lacking a lot of. Firstly, the finite element model of the cable under the bridge for static analysis, then the finite element results and the basis of reliability theory, referenced to a large number of bridges and building structures with a cable cord in the statistical parameters, analytical and statistical parameters of the cable bridge the mean and standard deviation of variables. Using FOSM (JC) method to calculate the reliability index cable of Cable Bridge.And compiled using MATLAB computer program reliability index, calculated the reliable indicator of changes in Cable Bridge under the safety factor in the different effects and different load ratio (permanent load effect/variable load effect).The results can be optimized for the same cable bridge design and safety analysis provides a theoretical basis.