16m无筋预应力UHPC简支工字梁抗弯性能足尺模型试验研究

Full-scale Experimental Study on Bending Performance of 16 m Prestressed UHPC Simple I-beams without Reinforcement

以国内首座无筋预应力体系UHPC桥梁——广州北环高速扩建F匝道桥16 m UHPC工字梁-普通混凝土桥面板组合梁为研究对象,进行四点弯曲下的足尺模型抗弯试验研究,测得各级荷载下梁的应变和挠度,以研究无筋预应力UHPC梁的抗弯承载能力,并与有限元计算值进行对比。结果表明:相对于普通钢筋混凝土梁,UHPC梁的开裂大大延迟;裂缝细而密;UHPC工字梁的跨中截面应变满足平截面假定;无筋预应力UHPC工字梁与普通混凝土桥面板之间界面滑移量极小,现浇板与UHPC梁之间连接良好。采用有限元模型对UHPC组合梁进行受力仿真分析,弹性模型在梁开裂前,荷载和变形与试验值吻合较好。结合试验研究和有限元分析,验证了该UHPC组合梁抗弯承载力满足设计要求。

A 16 m UHPC I-beam combined with normal concrete deck slab composite beam used in Guangzhou North Ring Expressway Extension F-ramp bridge is taken as the object of study,which is the first prestressed UHPC bridge without reinforcement in China.Bending test under four-point of full-scale model was carried out to evaluate the bending capacity of the prestressed UHPC beam without reinforcement.Strain and deflection of the beam during loading were measured and compared with the calculated values of finite element.The experimental results show that the cracking of UHPC beams is greatly delayed compared to ordinary reinforce concrete beams.The cracks are thin and dense.The strain of the UHPC I-beams at middle-span section comforms to the plane cross-section assumption.The interfacial slip between UHPC I-beam and the ordinary concrete deck slabs is very tiny,so the connection between cast-in-place slabs and UHPC beams is good.The finite element model(FEM)was built to simulate and analyze the force of the UHPC composite beam.The load and deformation values of the elastic model are in good agreement with the experimental values before cracking.Combined with experimental results and FEM analysis,the bending capacity of UHPC composite beam has been verified to meet the design requirements.