20 m跨径的横向张拉装配式空心板桥试设计研究

Trial-design of 20 m Span Prefabricated Voided Slab Bridge with Transverse Post-tensioning

针对装配式空心板桥横向联系不足,易形成单板受力的问题,提出采用横向张拉预应力提高空心板桥的横向连接。针对一座跨径20 m的采用横向预应力的空心板桥开展试设计研究,探讨横向张拉预应力钢筋和预应力大小的布置,提出采用横向预应力的空心板桥的设计计算方法。结果表明,横向预应力钢筋的纵桥向布置:跨径L≤13 m时在两端支点和跨中处各布置一道,共3道;跨径L>13 m时在两端支点、四分点和跨中各布置一道,共5道。横向预应力钢筋的截面高度方向布置:对于截面高度较小的空心板,在截面形心处布置一道横向预应力钢束。对于截面高度较大的空心板,在空心板截面的顶、底缘对称布置预应力钢束,且施加的横向预应力大小相同。结合面抗弯、剪承载力验算结果表明,采用了横向预应力的试设计空心板桥,结合面抗弯、剪承载力满足要求。

Focusing on the problem of the lack of transverse connection of the prefabricated voided slab bridge,easy to behave individually,using transverse post-tensioning to improve the transverse connection of the voided slab bridge is proposed.A trail design study on a 20 m-span voided slab bridge with transverse posttensioning was carried out.The layout of pre-stressed tie bars and the value of the transverse posttensioning were discussed.The design calculation method of the transverse posttensioned voided slab bridge is proposed.The results show that the longitudinal layout can be as follows:when the span L≤13 m,each section is arranged at both ends and the middle of the span,3 sections in the whole bridge.When the span L>13 m,each section is arranged at both ends,quarter points and the middle of the span,5 sections in the whole bridge.Transverse tie bars arrangement in the vertical direction arrangement can be as follows:for the section height of the voided slab is smaller,one transverse tie bar is arranged at the centroid of the section.For the section height of the voided slab is bigger,two transverse tie bars are arranged symmetrically at the top and bottom edge of the voided slab section,with the same pre-stress value.The check calculation results show that the trail design bridge with transverse posttensioning meets the requirements of the bending and shearing capacity of the junction surface.