预应力钢绞线初始张拉荷载及持荷稳压时间研究

Study on Initial Tension Load and Load Holding Time of Prestressed Steel Strand

对于大跨径桥梁的超长预应力束,现有规范无法有效控制其初始张拉荷载以及持荷稳压时间,目前已有研究中对初始张拉荷载和持荷稳压时间并未形成统一评判标准.对4座大跨径桥梁14束超长预应力束进行逐级张拉以及持荷稳定试验,结合已有文献中21束钢绞线测试样本,开展预应力钢绞线初始张拉荷载判定及持续稳压时间研究.发现初始张拉荷载及稳压时间随预应力钢绞线长度的增加而增大.对试验结果进行统计分析,提出判定不同长度预应力钢束初始张拉荷载的计算公式和稳压时间计算公式.本文方法和计算公式与现场测试结果拟合情况较好,可用于指导超长束张拉施工.

For the super-long prestressedsteel strand of long-span bridges, the existing codes cannot effectively control the initial stretch load and the load-holding time, and there is no unified evaluation standard for the load-holding time in the existing studies Fourteen extra-long prestressed strands of four long-span Bridges were subjected to step-by-step tensioning and load-holding tests.Combined with the test samples of 21 steel strand in existing literature, the initial stretching load determination of prestressed steel strand and the research on the duration of load-holding time were carried out.It is found that the initial stretching load and the load-holding time increase with the increase of the length of the prestressed strand.According to the experimental results, calculation formulas for determining the initial stretching load and load-holding time of prestressed steel are proposed.The method and calculation formula presented in this paper fit well with the field test results and can be used to guide the construction of super-long prestressed steel strand stretching.