悬索桥索夹螺杆张拉施工控制技术研究与应用

为提高悬索桥索夹螺杆张拉施工的质量与效率,在传统螺杆张拉工艺基础上,提出增加螺母转角作为额外的辅助控制参量,优先考虑同步张拉工艺,采用超声技术测量螺杆的张拉回缩损失进而修正施工荷载再完成张拉,以及适度增加有效稳压持荷时间的索夹螺杆张拉施工控制技术。将该技术在五峰山长江大桥进行验证测试和应用,现场结果表明:采用转角辅助张拉能够有效提高螺杆紧固质量,螺杆平均轴力提高到941.0kN;同步张拉避免了轴力重分配造成的轴力损失;修正施工荷载使得螺杆轴力控制偏差不超过5%;稳压持荷大幅加快了主缆的收缩速度;采用该技术进行吊装主梁前的全桥螺杆张拉,抽检轴力均值达到940kN,超出设计轴力170kN,实现了悬索桥索夹螺杆的高质量、高效率紧固施工。

Study of Tensioning Control Techniques for Bolts in Clamps of Suspension Bridge

To improve the tensioning quality and efficiency of clamp bolts in suspension bridge,the rotation angle of nuts is suggested to be enlarged and drawn as an extra auxiliary control parameter,based on the traditional rod tensioning technique.A synchronized tensioning technique is given priority concern.The tensioning and contraction losses of the bolts are measured by the ultrasonic technique,on the basis of which the construction loads are modified so as to complete the tensioning,and the effective time to sustain the pressure and loads during the bolts tensioning should be properly increased.The technique has been experimentally applied to the Wufengshan Changjiang River Bridge.The results from the field show that enlarging the rotation angle to assist the tensioning can improve the tightening quality of the bolts,with the average axial force of the bolt rising to 941.0 kN.The synchronized tensioning prevents the occurrence of axial force loss induced by axial force redistribution.The modification of construction loads ensures the control deviation of the bolt axial force remain below 5%.The contraction speed of the main cables is accelerated by the way of sustaining pressure and loads.The technique was used to tension all the clamp bolts of the bridge before the erection of main girder.According to the random sample checks,the average axial force reached up to 940 kN,which was 170 kN higher than the design axial force.The high-quality and high-efficiency tensioning of clamp bolts of the suspension bridge was realized.