Study On The Crack Damage Discipline Of Continuous Rigid Frame Bridge Web Under Seismic Load

The prestressed continuous rigid frame bridge is widely used in the high speed highway of China because of its large span capability and strong applicability.As the time of service increases,the testing of the applicability and safety of a continuous rigid frame bridge is becoming more and more serious.This kind of problem is very common,the box beam craze is most outstandingIn this paper,a continuous rigid frame bridge with a typical crack on a web in a strong earthquake area is taken as an example,The basic theory of fracture mechanics is expounded,The stress intensity factor and J integral for quantitative description of fracture are mainly introduced,The general numerical analysis method for simulating the cracks of concrete bridge structures is systematically analyzed.Because the calculation methods of the reaction spectrum and time history analysis are different,The full bridge numerical model of intact state and the damage state full bridge numerical model and typical crack local sub model are established by using ABACUS finite element software.According to the general process of seismic response spectrum analysis,the response spectrum analysis is carried out on the basis of the established full bridge numerical model,Studying on the effect of cracks on the stress and displacement of continuous rigid frame bridges,.According to the general process of seismic time history analysis method,the time history analysis is carried out on the basis of the established sub model,and the fracture stress parameters such as the stress intensity factor and J integral of typical fracture are calculated,The change rules of these parameters under earthquake load are studied emphatically,and the stability of cracks is judged.The results show that the seismic load stress cracks on the web plates of continuous rigid frame bridge has significant influence on the complicated stress state of crack,lateral effect,engineering background tends to be stable in the stage of E1 web crack at the E2 stage,the crack damage will deteriorate further,need attention,timely treatment.