Time-dependent Reliability Analysis Of Transverse Bent Of Inland River Suspended Vertical Wharf

Due to multiple loads and environmental factors,the material strength of reinforced concrete structures in harbor engineering will decline as time passes by within its design reference period,which means the resistance of structural members will decline as well and results in degradation of wharf's bearing capacity.By taking into consideration of the factors such as load,environment,concrete carbonation and steel corrosion during the wharf's service,this research focuses on the time-dependent reliability of wharf transverse bent's main components——crossbeam,column and pile foundation of one inland river suspended vertical wharf in Chongqing.The main contents and conclusions are as follows:(1)Previous research on time-dependent reliability was compiled and analyzed for the further analysis.(2)This paper analyzes and summarizes the theory of strength degradation and reliability theory of reinforced concrete structures in port engineering,and establishes concrete carbonization model and steel corrosion model according to the working environment characteristics of inland river terminals,and divides them into three types according to different applicable conditions: initial Service period model,concrete carbonation period model and steel rust expansion model.Based on this,the resistance of the main components of the transverse frame at different time points and its statistical parameters are obtained.The calculation results show that the resistance of the component deteriorates with time,and the degradation rate is obviously accelerated in the rust expansion period of the steel bar.(3)Based on engineering example,a static calculation of inland river suspended vertical wharf transverse bent was conducted through ANSYS,in which ship impact force and ship mooring force played the role of leading variable load respectively,and bending moment,shear force and axial force occurring in various loading combinations were analyzed as well.The results support the argument that compared with axial force,bending moment of the structures is more sensitive to the changes of the water level.(4)According to reality theory,limit equation of the harbor engineering structure was established,followed by iterative calculation via MATLAB.In the end,time-related reliability index in different representing date during service of the main members of w harf transverse bent was obtained and analyzed.The results show that the reliability of composing members of the lateral row frame will decline as time passes by.And some of them are strong enough to endure the whole 100 years,which indicates that there is much room for structural optimization.(5)Structure system reliability of lateral row frame was obtained by means of PNET.The column and the pile foundation are highly related,both of which are low related with the crossbeam.The results show that the reliability of the lateral row frame will decli ne as time passes by.And the reliability of the lateral row frame is relatively lower compared with individual beams.The similarity of the development of the reliability of the lateral row frame and its composing members justifies the method of PNET to calculate structure system's reliability.