新老结构间超高性能混凝土拼宽接缝技术研究

Study on Technology of Ultra-high Performance Concrete Widened Joint between New and Old Structures

北京路沂河桥采用老桥顶升2.57 m后保留利用、两侧新建拼宽桥的建设方案。标准跨径30 m的小箱梁与60 m+60.69 m的两跨预应力混凝土连续梁属于不同跨径、不同结构之间的拼宽,拼宽时需要采取恰当措施处理不等跨产生的位移差问题。在采用UHPC无缝拼宽时,需要对拼缝进行合理设计才能实现拼宽桥和老桥整体受力,经详细的分析计算,在纵向拼缝处铺装层选用10 cm厚UHPC形成刚接,拼宽桥梁体内预埋门形钢筋,且老桥小箱梁植门形钢筋,使结构形成整体;纵缝上布置5 mm不锈钢板及5 mm橡胶板,铺装钢筋与UHPC内钢筋绑扎,使铺装层形成整体,橡胶板根据不同的受力特点设置不同的厚度,以适应桥梁不等跨产生的位移差。并对拼接结构进行现场足尺加载试验,试验结果与有限元分析结果基本吻合。

The Yihe Bridge on Beijing Road is used of the construction scheme of retaining and using the old bridge after jacking up 2.57 m and building a new widened bridge on both sides.The small box girder with a standard span of 30 m and the prestressed concrete continuous beam with two spans of 60 m+60.69 m belong to the widening between the different spans and the different structures.During the widening,the appropriate measures need to be taken to deal with the displacement difference caused by the different spans.When UHPC seamless widening is adopted,it is necessary to reasonably design the joint in order to realize the overall stress of the widening bridge and the old bridge.After the detailed analysis and calculation,10 cm-thick UHPC concrete is selected for the pavement at the longitudinal joint to form a rigid connection.The embedded portal rebar is arranged in the widening bridge,and the portal rebar is planted in the small box girder of the old bridge to form an integral structure.The 5 mm stainless steel plate and 5 mm rubber plate are arranged on the longitudinal joint.The paving rebar is bound with the rebar in UHPC to form an integral pavement layer.The rubber plate is set with the different thickness according to different stress characteristics to adapt to the displacement difference of the unequal spans of the bridge.The full-scale loading test of the spliced structure is carried out.The test results are basically consistent with the finite element analysis results.