大跨度薄腹板T梁体外预应力加固施工关键技术

Key Technology for External Prestressing Reinforcement Construction of Large-span and Thin-web T-beams

以某特大型跨黄河简支T梁新增体外预应力加固工程为例,分析大跨度薄腹板简支T梁体外预应力加固施工工序及关键技术。测量放样通过建立2种不同参考的坐标系进行互相校核以提高体外预应力两端锚点坐标的准确率;锚固块安装通过控制钢筋损伤率、提高压力注胶饱满度以减小施工对原梁体损伤,同时提高锚固块与梁体的粘结固定效果;同步张拉则利用自动化同步张拉控制系统对张拉力值和伸长量进行过程值和目标值双控,以确保薄腹板T梁体外预应力加固施工质量。试验跨的施工验证了各关键工序施工技术及方法的有效性及可靠性。

Taking the newly-added external prestressing reinforcement project of a super large-scale simply supported T-beam across the Yellow River as a case, the key technology for core process on external prestressing reinforcement construction by T-beam with large-span and thin-web were analyzed.The accuracy of the coordinates of the anchor points at the two external prestressing ends is improved by establishing two different reference coordinate systems for cross-checking.The anchor block is installed by controlling the damage rate of the reinforcement and improving the fullness of the pressure injection to reduce the damage to the original beam and to improve the bonding effect of the anchor block to the beam.Synchronous tensioning uses an automated synchronous tensioning control system to control both the process and target values of tension and elongation to ensure the quality of the external prestressing reinforcement of thin-web T-beams.The construction of the test span verified the effectiveness and reliability of the construction techniques and methods for each key process.