常规跨径钢板组合梁桥中欧规范汽车荷载效应对比研究

Comparative Study of Vehicle Load Effect on Conventional-Span Bridge with Steel Plate and Concrete Slabs Composite Girder Described in Chinese Specification and Eurocode

钢板组合梁可充分发挥钢材和混凝土的材料优势,为给我国桥梁设计人员设计海外钢板组合梁桥提供建议,对《公路桥涵设计通用规范》(JTG D60—2015)及欧洲桥规(Eurocode—Basic of Structural Design、Eurocode 1:Actions on Structures—Part 2:Traffic Loads on Bridges)中常规跨径钢板组合梁汽车荷载效应进行对比。分析了中欧桥梁设计规范中汽车荷载模式、横向多车道折减效应、冲击系数、荷载组合等规定的异同,采用2种规范计算常规跨径钢板组合梁在汽车荷载及基本组合、频遇组合作用下的主梁弯矩。结果表明:欧洲桥规规定4种汽车荷载模式,已考虑冲击系数和横向车道折减,中国桥规规定了车道荷载和车辆荷载2种汽车荷载,计算汽车荷载效应后期需考虑冲击系数和横向车道折减;2种规范极限状态和设计状况规定一致,区别在于作用分项系数和可变作用组合系数取值;多片主梁钢板组合梁的边梁弯矩最大,单独考虑汽车荷载时,欧洲桥规计算的主梁最大弯矩比中国桥规大35%~36%;在考虑荷载组合时,欧洲桥规主梁最大弯矩计算结果在基本组合作用下比中国桥规大21%~22%,在频遇组合作用下比中国桥规大6%~9%。

The steel plate and concrete slab composite girders take advantages of the material properties of steel and concrete.In this paper,the vehicle load effect on the conventional-span steel plates and concrete slabs composite girder bridge that are suggested in the Chinese specification(General Specifications for Design of Highway Bridges and Culverts,JTG D 60-2015,Eurocode—Basic of Structural Design and Eurocode 1:Actions on Structures—Part 2:Traffic Loads on Bridges)are compared,to give insight into the design of overseas bridge projects for Chinese designers.The similarities and differences between a series of items in the Chinese specification and Eurocodes were analyzed,including the vehicle load patterns,transverse multi-lane reduction effect,impact coefficient and load combinations,based on which,the main girder bending moment of the conventional-span steel plates and concrete slabs composite girder bridge was calculated in accordance with the provisions in the selected codes,specifically under vehicle loads,under basic load combinations and under frequent load combinations.It is concluded that Eurocodes give four patterns of vehicle loads,taking into account the impact coefficient and transverse lane reduction coefficient,while the Chinese specification stipulates two types of vehicle loads(namely lane loads and vehicle loads),when calculating,the vehicle load effect,the impact coefficient and transverse lane reduction coefficient must be considered in the calculations concerning service stage.All the selected specifications give the same ultimate service state and design service state,whereas the differences between them lie in the values of action partial coefficient and the variable action combination coefficient.In the multi-girder,steel plates and concrete slabs composite girder,the maximum bending moment occurs in the edge girder,when there are only vehicle loads considered,the maximum bending moment of the main girder calculated in accordance with Eurocodes is 35%to 36%higher than that calculated in accordance with Chinese specification.Under the basic load combinations,the maximum bending moment of main girder calculated in accordance with Eurocodes are 21%to 22%higher than that calculated in accordance with Chinese specification,and under frequent load combinations,the values are 6%to 9%higher than that calculated in accordance with Chinese specification.