分段预制拼装预应力混凝土盖梁静力性能试验

Experiment on Static Behavior of Segmental Precast PC Cap Beam

摘要:

为探究采用不同胶接缝构造的分段预制拼装大悬臂PC盖梁在弯剪内力共同作用下的受力性能，结合实际工程，设计制作了1个整体预制大悬臂PC盖梁模型以及3个分别采用大键齿、小键齿和牛腿式接缝构造的分段预制拼装大悬臂PC盖梁模型（模型缩尺比例均为1：5），并完成4个模型全过程的静力加载测试试验，获得梁体开裂荷载、极限承载力以及梁体混凝土应变分布、挠度、最大裂缝宽度等关键结果。试验结果表明：分段预制拼装盖梁模型与整体预制盖梁模型的裂缝分布形态基本相同，破坏时梁体裂缝分布稀疏，裂缝宽度较大，且破坏形式均为弯曲破坏；采用大键齿和牛腿式接缝构造的盖梁模型的开裂荷载与整体盖梁模型相同，而采用小键齿接缝构造的盖梁模型的开裂荷载仅为整体盖梁模型的81%；采用不同接缝构造的盖梁模型的极限承载力均明显低于整体盖梁模型，其中采用牛腿式接缝构造的盖梁模型的极限承载力最大，约为整体盖梁模型的84%；从极限变形能力看，采用牛腿式接缝构造的盖梁模型的极限位移达到整体盖梁模型的75%，而采用大键齿或小键齿接缝构造的盖梁模型的极限位移均低于整体盖梁模型的50%。综合结构静力性能及施工性能，牛腿式接缝构造是推荐采用的分段预制拼装大悬臂PC盖梁的较合理接缝构造。

Abstract:

In order to investigate the static performances of segmental prefabricated large-cantilevered PC cap beams with different epoxy joints under the combined action of bending and shear internal forces， an integral precast large-cantilevered PC cap beam model and 3 segmental prefabricated large-cantilevered PC cap beam models with large key teeth， small key teeth and corbel joints respectively （the scale of each model is 1：5） were designed and manufactured based on a practical engineering. The full-process static loading tests of the four models were conducted， and the key results such as cracking loads， ultimate load capacities， distributions of concrete strains， deflections， and maximum crack widths of the cap beams were obtained. The test results show that： the crack distributions of the segmental prefabricated models are basically the same as that of the integral prefabricated model， and cracks in the cap beams of all test models are sparse and wide during failure； the failure modes of all test models are flexural failure； the cracking load of the cap beam model with large key teeth or corbel joint is the same as that of the integral cap beam model， while the cracking load of the cap beam model with small key teeth joint is only 81% of that of the integral cap beam model； the ultimate bearing capacities of the cap beam models with different epoxy joints are significantly lower than that of the integral cap beam model； among segmental precast models， the ultimate bearing capacity of the cap beam model with corbel joint is the largest， which is about 84% of that of the integral cap beam model； in terms of ultimate deformation capacity， the ultimate displacement of the cap beam model with corbel joint reaches 75% of that of the integral cap beam model， while the ultimate displacement of the model with large or small key teeth joint is lower than 50% of the integral cap beam model. From the test results of static performances and construction performance， the corbel joint is a more reasonable epoxy joint recommended for segmental prefabricated large-cantilevered PC cap beams.