The Sensitivity Analysis Of Concrete Rigid Frame And Cable Stayed Bridge

From the new century, the construction of infrastructure has developed rapadly in china, including the career of bridge engineer. Cable stayed bridge becomes popular among the big span bridges because of its advantage of structure, economic and beautiful shape. Prestressed concrete continuous rigid frame bridge become a contender among middle span bridges because its lager span capacity, beautiful shape and economic.but the rapid development under economic stimulus, briges have lots of injury and disease, which lead to the reduce of structure load bearing capacity and durability, so that its operation cann’t meet the need of social development. To make bridges meet the need of capacity during normal service time, how to discover the structure injury earlie has become an important issue.This thesis chooses a concrete cable stayed bridge and a concrete continuous rigid frame bridge, based on the survey of bridge disease, find the vulnerable section of structure and study its influence on the static and dynamic characteristics.For concrete continuous rigid frame bridge sensitivity analysis example, combined disease investigation through reducing element stiffness simulate various degrees of damage of middle and four points of main span, analysis the sensitive of dynamic indexs to injury. The results show that the sensitivity of each index is different, the indexs based on modal curvature and flexibility matrix are more sensitive to the damage location.For concrete cable-stayed bridge sensitivity analysis example, through reducing the cable area and tension force simulate various degrees of damage, analyze the impact of damage to the beam deflection, cable force and modal frequency. The results show that individual cable damage has little effect on modal frequencies. After cable damage, corresponding to the main beam position will appear abrupt deflection, and a greater impact on the deflection of long cable, cable damage causes adjacent cable force increase, and this impact is local.In this thesis, the sensitivity case analysis, investigate the sensitivity of different indicators for injury. For damage occurs to the main beam, the indexs based on modal curvature and flexibility matrix are more sensitive. For individual cable damage appears more sensitive indexs of static characteristics, little effect on the dynamic characteristics.