钢材强度对千米级斜拉桥主梁用钢量的影响

STEEL WEIGHT OF BOX GIRDER WITH DIFFERENT STEEL STRENGTH FOR THOUSAND-METER SCALE CABLE-STAYED BRIDGES

基于主梁设计应力与钢材屈服应力比值相等的原则,对主跨1088m斜拉桥采用不同强度的钢材进行了计算分析,研究了345MPa、420MPa、485MPa和690MPa四种不同强度钢材(桥梁用钢Q345、Q420和高性能钢HPS70W、HPS100W)对扁平钢箱梁自重的影响。计算结果表明:由于加劲板稳定和最小板厚限制的影响,尽管箱梁部分板件的设计应力不是由强度控制设计,但对于千米级斜拉桥采用高强钢材设计,主梁用钢量明显减少,高性能钢材的应用提高了斜拉桥的跨越能力。

The steel weights are compared between the four trial designs of cable-stayed bridges using different steels with yield point of 345MPa, 420MPa, 485MPa and 690MPa, named as Q345, Q420, HPS70W and HPS100W respectively. The trial designs of the bridge having an identical mid-span length of 1088m are considered having an identical relative safety factor described by the ratio of the longitudinal stress calculated to the yield strength of the box girder. The results indicate that the structural self weigth of the girder for thousand-meter scale cable-stayed bridges become lighter by the use of high performance steels and the steel weight can be reduced obviously with the increase of the steel strength, although the design stresses of some plates of the box girder are not govered by the matiral strength due to the influence of the stability of stiffened plate weights and the minimum plate thickness. The application of high performance steels can increase the span ability of cable-stayed bridges.