预应力混凝土连续箱梁加固计算研究

Calculation Study on Reinforcement of Prestressed Concrete Continuous Box Girder

徐州一京杭运河桥为变截面预应力混凝土连续箱梁,目前存在较严重病害,桥梁总体技术状况等级评定为4类,主要表现:边、中跨箱梁合龙段底板存在横向及纵向裂缝;边、中跨箱梁腹板厚度渐变段存在斜向裂缝;边跨箱梁合龙段底板存在不同程度空鼓及崩裂现象。结合平面有限元程序SCDS和空间有限元软件ANSYS进行计算分析,模拟桥梁实际通行荷载,分析预应力偏差对结构受力的影响,研究结论验证了桥梁病害产生的原因。在箱梁内部采取主动施加体外预应力以及腹板内、外侧粘贴钢板等措施对结构予以补强。最后通过成桥静、动载试验及运营情况验证了大桥加固计算分析准确,加固措施有效,满足规范要求。

A bridge on Jinghang canal in X uzhou with the main span（ 62 ＋ 100 ＋ 62） mis a variable cross-section prestressed concrete continuous box-girder. At present,there are serious diseases,the general technical condition rating of the bridge is class 4. The main performance included： some transverse and longitudinal cracks at the bottomof the side and middle span box girder closure segments; some slant cracks on the web thickness gradient section of the side and middle span box girder; the empty drumand bursting crack at the side span box girder closure segments. Base on the plane finite element programSCDS and the space finite element programANSYS to simulate the actual traffic load on continuous box girder,the reason of bridge disease is proved by the final research conclusion. The structure is reinforced with the active application of external prestressing steel strand inside the box girder,the web ofinternal and external bonded steel plates. Finally,through a static and dynamic bridge load test and actual operation,the reinforcement calculation is proved accurate and the maintenance reinforcement measures are effective,it meets the specification requirements.