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为了解决在修补钢-UHPC轻型组合桥面结构的UHPC层破损区域时遇到的UHPC层局部拆除和接缝处理难题,提出了一种通过拉拔UHPC层内钢筋来拆除UHPC破损区域的方法,设计了一种将受力钢筋焊接于钢顶板的新型局部修补接缝形式。为了证明拆除方法的可行性,利用足尺试验模型进行了指定区域UHPC层的拆除试验;为了验证新-旧UHPC接缝的受力性能,完成了纵向接缝、横向接缝的强度试验。结果表明:该拆除方法可以快速完成UHPC破损区域的拆除;新型修补接缝方法通过将接缝位置处的受力钢筋焊接于钢面板,有效提高了接缝的抗拉强度;试验测得接缝在纵桥向、横桥向的开裂应力分别为21.8,17.4MPa,接缝开裂应力分别为现浇段开裂应力的73.4%、63.9%,且明显大于传统接缝9.8MPa的开裂应力;通过对洞庭湖大桥进行有限元计算分析得到UHPC层纵桥向、横桥向的最大拉应力分别为15.4,5.4 MPa,小于接缝的实测抗拉强度,新型修补接缝完全满足该桥UHPC层最大拉应力要求。
In order to solve the problem of partial disassembly and seaming of UHPC layer in repairing UHPC layer damaged area of steel-UHPC lightweight composite decks, a method of removing UHPC damaged area by drawing steel bars in UHPC layer is proposed. A new type of partial repair joint was designed to weld the stressed steel bar to the steel roof. In order to prove the feasibility of the demolition method, full-scale test model was used to carry out the UHPC layer removal test in the specified area. In order to verify the force performance of the new-old UHPC joint, the strength tests of the longitudinal joint and the transverse joint were completed. The results show that this method can quickly remove the damaged area of UHPC. The new repaired seam method effectively improves the tensile strength of the seam by welding the reinforced bar at the joint location to the steel panel. In longitudinal bridge and transverse bridge, the cracking stress is 21.8MPa and 17.4MPa, respectively. The cracking stress of joint is 73.4% and 63.9% of the cracking stress of the cast-in-place concrete, which is obviously greater than the cracking stress of 9.8MPa of the traditional joint. Finite element analysis of the Dongting Lake Bridge shows that the maximum tensile stress in the longitudinal and transverse directions of UHPC plies is 15.4 and 5.4 MPa, respectively, which is less than the measured tensile strength of the joint. The new repaired joint completely satisfies the maximum tensile Stress requirements.