波形钢腹板组合槽型梁静载试验与有效预应力分析

Static test and effective pre-stress analysis of composite trough girder with corrugated steel webs

波形钢腹板组合槽型梁是一种新型下承式开口薄壁桥梁结构,对4片按照1/4相似比进行设计的试验梁进行两点对称加载和有限元分析,研究两组试验梁在对称荷载作用下的荷载位移关系、截面应变分布、裂缝发展规律和破坏形态等,分析张拉预应力和释放预弯力后试验梁底板混凝土的有效预压应力。研究表明:竖向荷载作用下试验梁符合平截面变形规律,应忽略波形钢腹板对抗弯刚度的贡献和底板混凝土对抗弯承载力的抵抗作用;试验梁混凝土受压区受限于上翼缘板,其应变分布为梯形而非常规的三角形分布;下承式槽型截面的中性轴偏低,波形钢腹板预弯钢梁反弹能够有效地对混凝土施加预压应力;采用波形钢腹板能有效提高槽型梁的预应力施加效率,文中建议的波形钢腹板组合梁预应力等效荷载法,能准确计算此类结构的混凝土有效预压应力;两组试验梁由于配筋量的不同分别发生塑性和脆性弯曲破坏;波形钢腹板组合槽型梁的自重轻、抗弯刚度较大、具有较好的延性和抗裂性能。

Composite trough girder with corrugated steel web （TGCW） is a new type of through bridge with open thin-walled members. 4 scaled TGCWs with the similarity ratio of 1：4 were tested by two-point symmetric loading and analyzed by the finite element method. The loading-displacement relationship, section strain distribution, cracking development law and failure shape of the 2 group beams are studied. The effective compressive pre-stresses of test beams in bottom slabs were analyzed after the pre-stress were imposed and the pre-bending forces were released. The research results show that the test beams conform to the law of plane section deformation under vertical loads, the flexural rigidity of corrugated steel webs and the flexural resistance of concrete bottom slab can be ignored. The strain distribution of the test beams in compressive zone are trapezoid instead of conventional triangle due to the area limit of top flanges. The neutral axis of trough girders are low, the compressive pre-stress can be imposed to the concrete effectively after rebounding of the reflexed corrugated steel girders, and the corrugated steel webs can enhance the applied effective pre-stress of trough girders. By the proposed pre-stress equivalent load method for composite corrugated steel webs girders, the effective concrete pre-stress can be accurately calculated. Two failure modes for the two group of test beams are plastic and brittle bending failures, respectively, according to the quantity of reinforcement. The concrete cracks extend thorough the bottom slab, and the top flange concrete break to pieces at last. The TGCW is light-weight with great flexural rigidity, good ductility and cracking resistance.