百米跨PC连续梁桥合理强迫高差分析

An Analysis of the Reasonable Forced Superelevation for a One-Hundred-Meter-Spanned PC Continuous Beam Bridge

合龙是大跨PC连续梁桥重要的施工工序,由于施工实际情况的复杂性,部分桥梁不能有效的保证合龙时自由端高差在规范规定的范围内,此时往往需要采用压重的形式进行强迫合龙。强迫合龙会在结构中产生附加内力从而对结构长期工作性能产生影响,目前规范对合理的强迫高差并未做出规定,导致施工时对压重的取值不够规范。采用理论结合实际的方法,首先总结了造成强迫高差的因素,然后从结构计算的角度将这些因素分为两类,并应用结构力学基本原理推导了强迫合龙对结构位移和内力的影响,讨论了百米跨径PC连续梁桥合理强迫高差的最大值:当合龙段长度为2m时,较为合理的强迫高差上限为5cm。

The closure operation is one of the important construction processes for long-spanned PC continuous beam bridges. Due to the complexity of the actual circumstances of the specific projects,a part of bridges fail to effectively guarantee the final closure when the superelevation of the free end of the bridge goes beyond the requirement of the norm in superelevation, in which case the forced closure is often necessary with the help of weights. The forced closure will generate additional stress in- side the structure that will affect the working performance of the structure in the long run although the present norm does not prescribe the reasonable forced superelevation. As a result,the choice of the value of weights is often not very standard in con- struction. Upon the basis of summing up all the superelevation-causing factors and through the combination of theory with prac- tice,all these factors are classified into two kinds from the angle of the structural calculations. Besides,the effects of the forced closure on the displacement of and the internal forces in the structure are induced in the light of the basic principles of structural mechanics,with the maximum value of the reasonable forced superelevation for a one-hundred-meter-spanned PC continuous beam bridge discussed. It is found that, when the closing distance is 2 metres, the relatively reasonable upper limit of the reason- able forced superelevation should be 5 eros.