后张法预应力T梁钢束理论伸长量计算方法的优化

现行规范公式在计算后张法预应力T梁钢束理论伸长量时,利用钢束直线段长度近似代替钢束的实际长度,给最终计算结果带来误差。本文根据微积分原理,利用钢束理论伸长量分段计算法,对后张法预应力T梁钢束理论伸长量进行优化计算,重点对部颁通用图中不同跨径T梁直线段钢束的常规计算方法进行优化,给出优化前后的误差大小,并发现传统计算方法对20 m和50 m跨径单片T梁钢束伸长量校核结果影响程度较大。建议采用张拉力与伸长量作为“双控指标”,减小计算误差,以有效提高后张法预应力T梁钢束的张拉质量。

Optimum Study on Calculation Method of Theoretical Elongation of Post-tensioned Prestressed T-girder Steel Bundle

For the current norm formula to calculate the theoretical elongation of the post-tensioned prestressed T-girder steel bundle,the actual length of steel bundle is approximately replaced by the length of straight section,resulting in errors in the f inal calculation results.Based on the principle of calculus,the theoretical elongation of post-tensioned prestressed T-girder steel bundle was optimized by using the method of sectional calculation of theoretical elongation of steel bundle.The conventional calculation methods of steel bundles in straight sections of T-girder with different spans in the ministerial general drawing were optimized,the errors before and after optimization were pointed out.The traditional calculation method has a great inf luence on the checking results of the elongation of 20 m and 50 m span single-piece T-girder steel bundle.Using tension force and elongation as double control index can reduce calculation error and effectively improve the tension quality of post-tensioned prestressed T-girder steel bundle.