Limit State Analysis Of Gravity Piers Of Railway Bridges At Domestic And Foreign

At present,the allowable stress method is still used in the design of railway Bridges,but with the continuous development of China’s railway industry and the increasing number of cooperation projects between domestic enterprises and foreign countries,the allowable stress method can no longer meet the needs of technical exchanges between China and the world,therefore,it is urgent to change the design method of railway bridge from allowable stress method to limit state design method.Although many scholars have studied the limit state design method of bridge in European and American norms,there is a lack of limit state analysis of gravity bridge piers.In this paper,the Chinese allowable stress method and the limit state design method of European and American standards are used to carry out a comparative study on the gravity piers of railway Bridges.The main research contents and conclusions are as follows:(1)The design methods of railway Bridges under different codes in China,the United States and Europe are expounded,and the strength standard value,strength design value,elastic modulus and stress-strain relationship of concrete and steel materials under different codes are compared.Finally,the difference analysis of design methods and material indexes of railway Bridges are given.(2)The design load classification of railway Bridges under different codes in China,the United States and Europe is expounded,and the relevant design loads and their load combinations under different codes are compared and analyzed.Finally,the specific value method and load combination form of relevant design loads are given.(3)The design and calculation contents of gravity bridge piers under different codes in China,the United States and Europe are studied.The differences of compression bearing capacity and crack resistance of section of gravity bridge piers are analyzed,and the design expressions of compression load-bearing capacity and crack resistance of section under different codes in China,the United States and Europe are given.(4)By checking and calculating the engineering examples of railway bridge gravity piers,the checking and calculating programs of railway bridge gravity piers under different codes in China,America and Europe are completed.Finally,the checking and calculating results of the load-bearing capacity surplus and crack resistance surplus of the section are given.(5)By checking the load-bearing capacity surplus and crack resistance surplus of gravity bridge pier section under different load combinations,the results show that,for the load combination of main force and additional force,the load combination of control is constant load + single-span heavy load + braking force or traction force +longitudinal wind load for either double-lane or single-lane traffic.(6)By checking the load-bearing capacity surplus and crack resistance surplus of gravity bridge pier section under different codes,the results show that,the safety reserve of gravity bridge pier section under the limit state design method of European and American codes is higher than that of China,and the design of gravity bridge pier requires less concrete material and the economy is better.