Structural Optimization Design Based On Probability-Non-probabilistic Hybrid Reliability Model And Its Application In Bridges

There are many uncertain variables and multiple failure modes in bridge structure.When multiple failure modes include both random variables and interval variables,it is difficult to conduct structure reliability analysis.Therefore,it is necessary to establish a hybrid reliability model,which can analyze multi-failure modes,for reliability evaluation and optimization design of bridge structures.Based on probabilistic and non-probabilistic hybrid reliability model,this paper analyzes the hybrid reliability model and structural optimization design under the multi-failure mode.The research points of this thesis are four parts:(1)Hybrid reliability problems which contain random variables and interval variables,the hybrid system reliability model with multiple failure modes was established.With considering the correlation between multiple failure modes,the correlation coefficient matrix was obtained using the linear correlation calculation method.Finally,the study presented the hybrid reliability evaluation methods for series system and parallel system.(2)Based on the random reliability optimization problem of structural quality,a hybrid reliability optimization design of structural quality was proposed.Considering the influence of two uncertain parameters,the optimal solution was obtained by probability and interval operation under the certain constraints.The sequence approximate programming method was used to solve the optimization problem of hybrid reliability optimization design for structural cost,and the efficiency and accuracy of the method were verified.(3)The thesis established the bridge reliability assessment process based on multi-failure modes,and proposed the hybrid reliability optimization design method.The hybrid reliability evaluation of a three-span prestressed bridge under multi-failure modeswas carried out.The evaluation results are used to guide the bridge reinforcement and reconstruction.When the bridges are unreliable based on the evaluation results,the hybrid reliability optimization design method can be used to guide the optimization design of bridge structure reinforcement.