预应力混凝土平面曲线箱梁裂缝

针对预应力混凝土曲线箱梁,产生径向水平压力的平面曲线力筋易使混凝土腹板超载,而造成混凝土破坏,并使力筋拉直等问题,应用翘曲扭转理论,分析了预应力混凝土平面曲线箱梁在张拉平面曲线形纵向力筋时,将在腹板中产生横向力,以及桥墩和桥梁支座约束作用,局部板中力筋的径向力使竖向跨越的腹板产生剪力和弯矩等产生裂缝的原因,提出了在设计与施工中应采取保证力筋的保护层厚度,充分调整力筋曲率的作用,设计计算必须考虑侧向预应力,保证在力筋弯曲的部位、管道不出现尖弯等措施。为平面曲线桥梁的设计与施工提供了一定的理论依据。

Crack of prestressed concrete box girder in plane curve

To prestressed concrete curved box girder, the plane-curved tendon will yield radial horizontal pressure, which will overload the web plate and will bring the problem of destroying the concrete and straightening the tendon. The reasons for crack of the prestressed concrete curved box girder such as the lateral force in the web plate when the plane-curved tendon is stretched, the effects of the bridge pier and supporting's constraint, the shear and moment in the vertical-span web plate because of the radial horizontal pressure of the tendon in the local sheet, were analysed using buckle and torsion theory. The accordingly methods in design and construction such as the assurance of the thickness of covering layer outside the tendon, fully using of the flexure of the tendon, considerations of side direction's prestressed force in design, no cuspidal point in pipes at the place of tendon's curving were put forward, which provide some theoretical reference to the design and construction of plane-curved girders.