预应力张拉伸长量及回缩量量测方法探讨

Discussion on Measurement Method for Prestressing Elongation and Retraction

钢绞线预应力混凝土在桥梁工程中已普遍使用,连续梁的结构体系中钢绞线作为主要受力部分,钢绞线张拉过程的控制对于整个连续梁的质量起着至关重要的作用.对于预应力张拉施工涉及的理论伸长量、工作长度、张拉伸长值和锚具回缩值的计算与量测,设计图纸中并未给出具体的方法,各家做法存在较大差异,这对预应力张拉质量控制的双控指标的计算和评判会造成不同程度的影响.结合蒙西华中铁路其中4处连续梁钢绞线张拉施工实际操作,针对钢绞线预应力张拉伸长量计算方法的多样性和锚夹具回缩量量测方法的不标准性,对预应力张拉施工过程中钢绞线的受力情况和锚具的位移情况进行分析,并详细介绍了钢绞线理论伸长值的计算方法和钢绞线张拉伸长值及锚夹具回缩量量测方法.

Prestressed concrete with steel strand has been widely used in bridge engineering.The steel strand is the main part of the continuous beam structure system.The control of the tension process of steel strand plays a vital role in the quality of the whole continuous beam.For the calculation and measurement of theoretical elongation,working length,tension length and anchorage retraction value involved in prestressing tension construction,no specific method is given in the design drawings,and there are great differences among different methods,which will affect the calculation and evaluation of double-control indexes of prestressing tension quality control to varying degrees.Combining with the actual operation of tension construction of four continuous beam strands in the Central China Railway of Mengxi,this author analyzed the stress of strands and the displacement of anchors in the process of tension construction,aiming at the diversity of calculation methods for tension length of steel strands and the non-standard measurement methods for retraction of anchor fixtures,and gave detailed analysis.The calculation methods for theoretical elongation of steel strands and the measurerment methods for tension elongation of steel strands and retraction of anchor fixtures were introduced.