轮载作用下正交异性钢桥面板构造细节受力特征及机理研究

STRESS BEHAVIORS AND MECHANISM OF DETAILS OF ORTHOTROPIC STEEL DECK UNDER WHEEL LOADS

为明确正交异性钢桥面板(OSD)构造细节的轮载局部应力效应及受力特征,开展了横桥向3个典型工况的货车加载试验和有限元分析,记录了货车低速通行下OSD构造细节的应力时程,研究了构造细节轮载应力行为和机理。研究表明:OSD构造细节轮载局部应力效应显著,构造细节的明显加载效应局限在横桥向轮载中心两侧各1倍纵肋中心距范围,表明OSD疲劳研究无须考虑货车左右轮或相邻车道货车并行的叠加效应。在显著局部应力范围内,货车每个车轴在纵肋-面板(RD)构造细节产生一个应力循环;跨肋式是RD、纵肋-横隔板(RF)焊缝和弧形切口(Cutout)构造细节横桥向最不利轮载位置。轮载作用下沿横桥向,RD面板侧以面板受纵肋腹板支承的连续梁受力为机理,纵肋侧以RD两侧面板和纵肋的弯矩平衡受力为机理;纵肋-横隔板纵肋侧(RF-R)构造细节以横隔板支承的连续梁支点负弯矩受力为机理;纵肋-横隔板横隔板侧(RF-F)构造细节以位于横隔板腹板上方受压为机理;弧形切口细节以空腹桁架竖杆受压为机理。明确的轮载应力局部范围和机理,能简化OSD结构疲劳有限元分析,有助于改善OSD结构抗疲劳设计。

In order to clarify the stress local effects and stress behaviors at details of the orthotropic steel deck(OSD)under wheel loads,truck loading tests and finite element analysis were carried out at three typical transverse loading locations.Stress-time histories were recorded at the details of the OSD to investigate their stress behaviors and mechanism under the passage of a truck with a very low speed.The research finds that the details of the OSD impose significant stress local effects under wheel loads,which is limited to the range of one center-to-center rib space on both sides of wheel center in bridge transverse direction is limited in a zone of two center-to-center rib spaces in the transverse direction.Hence,the stress superimposition at the details,simultaneously produced by the left and right wheels of a truck or produced by trucks traveling side-by-side on adjacent lanes,can be ignored.For the area with significant stress local effects,one axle produces an individual stress cycle at the rib-to-deck(RD)detail.The riding-rib-wall loading is the most critical loading locations in bridge transverse direction for the RD,rib-to-floorbeam(RF)welds and cutout details.Under the wheel loads,the mechanism of stress at RD detail is that the deck plate acts as a continuous beam supported by the rib wall,and that the moment on the rib wall satisfies the moment equilibrium condition among both sides of deck plate and the rib wall.The mechanism of stress at the RF weld at the rib side(RF-R detail)is the negative moment acting on ribs at its supports provided by floorbeam.The mechanism of stress at the RF weld at the floorbeam side(RF-F detail)is due to its location at the upper portion of floorbeam web,while the mechanism of stress at cutout detail is the compressive force in the vertical element in the Vierendeel truss model.Understanding the stress local effects and their mechanism can simplify fatigue investigation of the OSD using the finite element analysis,which facilitates the design of the OSD against fatigue damage.