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目的确定抛物线形预应力钢绞线理论伸长值的详细计算过程,提出适用于现场施工的预应力钢绞线理论伸长值的简化测量方法.方法基于五根后张无粘结预应力混凝土试验梁的张拉测试试验,结合《公路桥梁施工技术规范》,阐述了后张法预应力抛物线形钢绞线理论伸长值计算方法,分析张拉各阶段的伸长实测值,并对张拉伸长实测值与理论计算值进行比较和分析.结果总结出简化测量方法,对简化后的实测值与原实测值进行比较,最大偏差为1.27%,并且对简化实测值与伸长理论值进行比较,最大偏差为3.74%,小于实际伸长值与理论伸长值的相对允许偏差±6%.结论通过此方法对后张无粘结预应力梁张拉各阶段的实测伸长值进行分析,既可以对施工过程实行有效监控,也可以检验梁中建立的有效预应力能否达到设计的要求.为确保预期的施工质量和满足设计要求提供了方法和依据.
Aim To determine the detailed calculation of the theoretical elongation of parabolic prestressing strand and to propose a simplified method for measuring the theoretical elongation of prestressing strand for on-site construction.Methods Based on five post-tensioned unbonded prestressed concrete Tensile test of the test beam, combined with “Technical Specifications for Highway Bridge Construction”, expounds the theoretical calculation method of the post-tensioned parabolic strand theory, analyzes the measured value of elongation at each stage of tension, The measured value of tensile elongation is compared with the calculated value of the theory.Results Summarized the simplified measurement method, the simplified measured value and the original measured value, the maximum deviation of 1.27%, and to simplify the measured value and the theoretical value of elongation , The maximum deviation is 3.74%, which is less than ± 6% of the relative allowable deviation of the actual elongation value and the theoretical elongation value.Conclusion The measured elongation value of each stage of tensionless post-tensioned prestress beam Analysis can not only effectively monitor the construction process, but also test whether the effective prestress established in the beam can meet the design requirements and provide a method to ensure the expected construction quality and meet the design requirements in accordance with.