U型UHPC与再生混凝土组合梁受弯性能分析  

Flexural behavior analysis of U⁃shaped UHPC and recycled aggregate concrete composite beams

作　　者：秦朝刚 杜锦霖 吴涛[1] 刘伯权[1] Qin Chaogang;Du Jinlin;Wu Tao;Liu Boquan(School of Civil Engineering,Chang’an University,Xi’an 710061,China)

机构地区：[1]长安大学建筑工程学院,陕西西安710061

出　　处：《建筑科学》2024年第3期110-120,共11页Building Science

基　　金：中国博士后科学基金资助项目(2021T140587);陕西省自然科学基础研究计划项目(2023-JC-YB-326);长安大学中央高校基本科研业务费专项资助(300102282208)。

摘　　要：采用预制工艺,在再生混凝土(RAC)外围复合超高性能混凝土(UHPC),形成U型UHPC与RAC组合截面梁,提升力学性能。以U型UHPC及配筋率为变量,设计了U型UHPC-RAC组合梁。通过四分点抗弯性能试验,分析了裂缝形态和破坏机理,UHPC与钢筋应变和荷载-位移曲线。结果表明:U型UHPC与RAC形成的组合截面配筋梁,弯曲裂缝宽度小,分布均匀且间距小,最终形成1~2条宽度最大的主裂缝,为延性破坏;U型UHPC薄壁可显著提高开裂荷载,增幅约72.1%,而配筋率将屈服荷载和极限荷载分别增加25.4%和35.7%,改善了再生混凝土梁的初始刚度、延性和耗能性能;组合截面内RAC、UHPC与钢筋协同受力,应变线性变化,符合平截面假定;按照叠加原理,简化应力分布曲线,建立了U型UHPC-RAC组合梁的受弯承载力计算公式,计算结果与试验值吻合较好。The precast technology is used to compound ultra⁃high performance concrete(UHPC)around the recycled aggregate concrete(RAC)to form a U⁃shaped UHPC⁃RAC composite cross section beam to improve the mechanical properties.The U⁃shaped UHPC⁃RAC composite beams are designed with the reinforcement ratio in U⁃shaped UHPC.The four⁃point flexural performance test is carried out to analyze the fracture morphology and failure mechanism,the strain of the UHPC and the reinforcements and load⁃displacement curves.The results show that the beams with reinforced composite section have small width,uniform distribution and small spacing of bending cracks,forming 1~2 cracks with the largest width as failure showing ductile failure finally.The U⁃shaped UHPC shell can significantly increase the cracking load by 72.1%,and the reinforcement ratio can increase the yield load and ultimate load by 25.4%and 35.7%,which improve the initial stiffness,ductility and energy dissipation coefficient of the recycled concrete beam.RAC,UHPC and reinforcement in the composite section work collaboratively,and the strain change linearly,which conforms to the assumption of plain section.According to the superposition principle,the stress distribution curve is simplified and the calculation formula of flexural bearing capacity of U⁃shaped UHPC⁃RAC composite cross section beam is established.The calculated results are in good agreement with the experimental values.

关 键 词：超高性能混凝土 再生混凝土 组合截面 破坏形态 受弯性能 

分 类 号：TU375.1[建筑科学—结构工程]