空心板梁桥桥面连续构造的受力特性试验

Field tests on mechanical characteristic of link slab on hollow-cored slab beam bridge

针对现有拉杆式桥面连续构造易发生开裂、渗水等病害,提出适用于空心板梁桥的拱型桥面连续构造形式,并用实桥荷载试验验证了抗开裂的有效性.通过理论计算和数值仿真,确定空心板梁桥拱型桥面连续构造的拱跨、矢高和分隔缝形式.在车辆荷载或负温度梯度作用下,梁端上翘不会引起拱型桥面连续上移,受拉连接钢筋使拱顶产生正弯矩,混凝土受压;在正温度梯度作用下,钢板分隔缝使桥面铺装压应力有效地传至桥面连续混凝土,抵消了拱顶负弯矩所产生的拉应力.试验结果表明,拱型桥面连续可以使拱顶混凝土达到受压状态,且压应力随荷载增大而增大,而拉杆式桥面连续混凝土始终为受拉状态,且拉应力随荷载增大而增大,无黏结钢筋与混凝土之间的滑移失效是拉杆式桥面连续混凝土受拉开裂的主要原因.

The arched link slab on hollow-cored slab beam bridge was proposed to solve the problem that the existed bridge link deck structure is liable to fracture and water seepage.The numerical simulation was modeled to analyze the mechanical characteristic of arched link slab.The proper parameters of the arch span and the arch rise were obtained through theory deduction and numerical calculation.Under the action of vehicle load or negative temperature gradient conditions,the tensile stress was delivered from the link slab to the arch by the longitudinal forced rebars,which produced positive moments and compression on the concrete of arch crown.Under the temperature variation of positive gradient,the pressure force was delivered from the link slab to the arch by the longitudinal forced rebars,which produced negative moments and tensile stress on arch crown.The pressure stress on link slab can be transmitted to the arched link slab through the thin steel plates in the seams to keep the arch crown concrete in compression.The effectiveness of the arched link slab was verified by bridge field tests.The results of experiment and finite element analysis show that the concrete of arched link slab is always in compression under the vehicle load and temperature variation,but the poor slip effect between the debonded reinforced steel bars and the concrete is the main cause of the existed debonded rebar link slub fractured.