预应力连续箱梁桥开裂状态弯矩重分布试验研究

Experimental Study on Moment Redistribution of Cracking Status of Pre-stressed Concrete Continuous Box Girder Bridge

对连续梁的内力重分布的研究,可以帮助更好地分析连续梁的受力性能,而目前国内外对此主要是针对钢筋混凝土结构,对预应力结构尚少有研究。该试验以一个1:4的三跨预应力连续梁模型为基础,以弯矩调幅系数、边支座反力与中支座反力的比值(边/中)为基本参数,通过体外预应力加固前后的对比试验,对连续梁桥弯矩重分布规律进行了研究。试验结果表明:加固后结构的内力重分布较加固前稍大;加载至部分钢筋屈服时,加固前后各跨中最大弯矩调幅系数在-8.34%^-12.62%之间;两墩顶负弯矩区段的最大调幅系数在19.44%~29.59%之间,边/中由初始的32.1%降至28.38%~27.59%。

The study on the internal force redistribution of the continuous girder can provide better help for analyzing the mechanical behavior of continuous girder. However, such study at home and abroad nowadays is mainly on the reinforced concrete structures, and the relevant study on the pre-stressed structures is fewer.Based on a three-span PC continuous girder model in the scale 1:4, and the basic parameters of amplitude modulation coefficient, and the ratio between side support reaction and the central support reaction(side support/central support), the bending moment redistribution law of continuous girder bridge is studied by the comparison tests before and after the external pre-stressing reinforcements. The results show that the internal force redistribution of the structure after reinforced is slightly larger than before reinforcement, the maximum amplitude modulation coefficient of each midspan is -8.34%^-12.62% before and after reinforcements when loading to the partial rebar yield, and the maximum amplitude modulation coefficient of negative bending moment regions on the top of two piers is 19.44% ~ 29.59%. The ratio between the side support reaction and the central support reaction decreases from 32.1% initially to a range of 28.38% to 27.59%.