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现代的大跨经桥梁广泛地采用箱形截面的承重结构,这主要是因为它具有较好的抗横向弯曲和抗扭性能。例如,在同样的外形尺寸和截面面积情况下,箱形截面所能承受的最大扭矩约为工字形截面的15倍以上,因此,在受到偏心活荷载作用时,以采用箱形截面最合宜;其次,由于箱形截面梁具有较大面积的底板,可以用来承受负弯矩时的压应力,故它更适合于悬臂体系和连续梁桥等以负弯矩为主的桥型结构,以及正、负弯矩交替出现的其它桥型。
Modern large-span bridges widely use box-type load-bearing structure, mainly because of its good resistance to lateral bending and torsional properties. For example, with the same overall dimensions and cross-sectional area, the maximum torque that a box section can withstand is about 15 times larger than the I-section. Therefore, it is most appropriate to adopt a box section when subjected to eccentric live load. Secondly, the box girder with larger area can be used to bear the compressive stress under negative moment, so it is more suitable for the bridge structure with negative bending moment such as cantilever system and continuous girder bridge, Positive and negative bending moment alternate bridge type.