桥面板徐变对曲线组合梁桥剪力钉受力性能的影响

Creep Effect of Concrete Slab on the Mechanical Behavior of Shear Studs in Steel-concrete Composite Curved Bridge

钢-混组合梁桥中桥面板与钢主梁通过剪力键连接,混凝土板徐变效应会对剪力键内力产生影响。为探究这种影响,以某座钢-混组合曲线梁桥为背景,使用ANSYS建立精细化实体有限元模型,按金属蠕变原理模拟混凝土板徐变效应,在考虑施工阶段的基础上研究混凝土板徐变效应下剪力钉的力学行为。研究表明:钢纵梁处剪力钉横桥向徐变内力约为顺桥向2.0倍,但徐变内力变化趋势均相同即每跨跨中向两侧支点逐渐递增,徐变内力极值均出现在支点湿接缝附近剪力钉上。钢横梁剪力钉横桥向、顺桥向内徐变内力均由横截面中线向两侧逐渐增加,但受“弯扭耦合”影响,横梁内、外侧剪力钉徐变内力相反。徐变影响下全桥剪力钉顺桥向徐变滑移分布较横桥向更加均匀,绝大多数剪力钉顺桥向徐变滑移量仅为横桥向的30%~50%。混凝土板徐变效应对剪力钉内力影响随时间的增加而减弱,内力影响最大是成桥初期3个月;增加混凝土板预制龄期可显著降低成桥时剪力钉的徐变内力,推荐采用龄期为180 d的桥面板,并计入10年徐变效应可满足工程要求。

In steel-concrete composite girder bridge,the bridge deck and steel girder are connected by the shear keys,and the internal force of the shear keys will be affected by the creep effect of concrete.In order to reveal this effect,a steel-concrete composite curved girder bridge was taken as the engineering background,and an ANSYS refined solid finite element model were applied to simulates the creep effect of concrete according to the metal creep principle,and the mechanical behavior of the shear keys under the creep effect of concrete on the basis of considering the construction stage was also studied.The research shows that the creep internal force of the shear keys in the across bridge direction is about 2.0 times that in the along bridge direction,however,the trend that the creep internal force increase gradually from the middle of a span to the support points is the same at both directions,and the extreme value of creep internal force appears on the shear keys near the wet joints of the support points of a span.Besides,the internal creep force of the shear keys in steel beams increase gradually from the midline of cross section to both sides,but the internal creep force of the shear keys in steel beams is opposite due to the effect of bending and torsional behavior in crossbeam.Farther,due to the influence of creep,the creep slip distribution along the bridge direction of the full-bridge shear keys is smoother than that in the transverse direction,and the creep slip of most shear keys along the bridge direction is only 30%~50%of that in the transverse direction.The effect of concrete creep on the internal force of shear keys decreases with the increase of time,and the maximum effect is happened at the first 3 months a of the bridge.Moreover,increasing the precast age of concrete slab can significantly reduce the creep internal force of shear key.Hence,it is recommended to adopt the bridge deck with 180d age,and the creep effect of 10 years can meet the engineering requirements.