Study On Reliability Of Reinforced Concrete Railway Bridge

The allowable stress design method introduced from former Soviet Union has been used for railway bridges for quite a long time in China. In1980s and1990s, Ministry of Railway once carried out revision of code for railway design code guided by reliability theory. However, the revised code was not taken into practice for kinds of reasons. The railway has made great progress in recent years, especially the high-speed railway. The traditional design method can not meet the demand for railway bridges design, which leads to the transfer of the design method of railway bridge from allowable stress method to ultimate state method. This paper studied the reliability of reinforced concrete member of railway bridge, also, analyzed the design method of reinforced concrete compression members with bending domestic and overseas. Main content of this paper includes:(1) Based on the allowable stress method in the current Code for the Design on Reinforced and Pre-stressed Concrete Structure of Railway Bridge and Culvert, statistical parameters of resistance of flexural member of railway bridge have been analyzed. This paper studied the reliability index and its variation with the reinforcement ratio as well as the ratio of characteristic value of dead load and live load effect of the RC flexural member of the railway bridge. It’s indicated that the reliability index of the RC flexural member of the railway bridge is in a range of5.8to6.5.(2) This paper studied the statistical parameters of shear resistance and reliability index for different concrete grades, shear span ratio, and transversal reinforcement ratio for RC member of railway bridge based on TB10002.3-2005. It is indicated that the reliability index of the shear resistance of the RC member of the railway bridge varies with shear span ratio and transversal reinforcement ratio, etc. It is in a range of3.5to4.0.(3) This paper made some comparison between TB10002.3-2005(Code for Design on Reinforced and Pre-stressed Concrete Structure of Railway Bridge and Culvert), AREMA (American Railway Engineering and Maintenance-of-Way Association) Manual for Railway Engineering, and EN1992-2:2005for the design methods the compression reinforced concrete members with bending. Analysis shows that the compression members with bending are designed by allowable stress method, service load method or load factor method and ultimate state method based probability theory in Chinese, American and European codes accordingly. To calculate the second-order effect, TB10002.3-2005adopts eccentricity moment magnifying coefficient, AREMA Manual for Railway Engineering take the end moment, stiffness and slenderness ratio into consideration,which is named moment magnifying method. The two methods to compute the second-order effect adopted by Eurocode are based on nominal stiffness and curvature. There are discrepancies in the safety stocks for the design of eccentric compression members based on different codes. The results show that among the specified codes, Eurocode gains the best safety stock, followed by Chinese Code and then American Code.