钢-UHPC组合桥面闭口纵肋−横隔板接头疲劳性能

Fatigue behavior of closed rib-to-floor beam joint in steel-UHPC composite bridge decks

为研究新型钢-UHPC组合正交异性桥面纵肋−横隔板接头疲劳性能,基于一座现场桥梁,建立精细化双尺度有限元模型,获得构造细节在轮载下的应力响应。分析其力学特性,并采用热点应力法评估其疲劳性能。研究结果表明:纵肋−横隔板接头应力状态复杂,构造细节处存在显著应力集中,为疲劳易损细节。焊缝末端细节以面外弯曲应力为主,包括扭转效应与泊松效应;横隔板侧细节由面内应力和面外应力组成。为进一步改善纵肋−横隔板接头疲劳性能,分析了UHPC刚度效应,并探讨切口尺寸的影响。通过将50 mm厚UHPC层与40 mm切口间隙相结合,使纵肋−横隔板接头实现了无限疲劳寿命,能应用于交通量大的桥梁工程。

To investigate the fatigue performance of rib-to-floor beam(RF)joint in innovative steel-UHPC composite orthotropic bridge decks,based on an in-site bridge,refined two-scale finite element models were established to derive the stress response of structural details under wheel loads.The mechanical behavior was analyzed,and fatigue performance was assessed by using the hot-spot stress method.The results are as follows.The RF joint presents a complex stress state,and significant stress concentration exists in that,which belongs to fatigue-prone details.The weld-end detail is dominated by out-of-plane bending stress,including rotational and Poisson's effects,while the floor beam detail is comprised of in-plane and out-of-plane stress.To further enhance the fatigue performance of the RF joint,the stiffness effect of UHPC layer was analyzed,and the influence of the cutout dimension was discussed.By combining a 50 mm thick UHPC layer with a 40 mm cutout clearance,the RF joint with infinite fatigue life is achieved,which can be applied to the bridge engineering under high traffic volume.