钢筋超高性能混凝土梁受剪性能细观分析  

Mesoscopic analysis for shear behavior of reinforced ultra-high performance concrete beams

作　　者：王照耀 邵珠山 梁兴文[2] 曹振[2] 吴奎 赵楠 WANG Zhaoyao;SHAO Zhushan;LIANG Xingwen;CAO Zhen;WU Kui;ZHAO Nan(School of Science,Xi’an University of Architecture and Technology,Xi’an 710055,China;School of Civil Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China)

机构地区：[1]西安建筑科技大学理学院,陕西西安710055 [2]西安建筑科技大学土木工程学院,陕西西安710055

出　　处：《建筑结构学报》2024年第1期217-229,共13页Journal of Building Structures

基　　金：国家自然科学基金项目(51278402,12202334);陕西省自然科学基础研究计划(2023-JC-QN-549,2022JQ-497)。

摘　　要：为了研究钢筋超高性能混凝土(UHPC)梁的受剪破坏机理,对8根UHPC梁进行了受剪性能试验,设计变量包括钢纤维掺量、剪跨比、纵筋配筋率和箍筋间距。结果表明:钢纤维桥接作用能够显著提高UHPC梁受剪承载力,限制裂缝发展,减小裂缝间距;随着剪跨比增大,受剪承载力减小但变形能力增强;随着配箍率增大,受剪承载力提高,且增设箍筋能够显著改善UHPC梁峰值荷载后的受剪性能,减小斜裂缝宽度和长度;掺入钢纤维和增设箍筋均能够减小斜向变形(垂直于支座与加载点连线方向的混凝土变形),提高UHPC梁开裂后刚度。结合UHPC梁剪切受力特点,分别确定了临界剪切裂缝界面钢纤维、纵筋销栓作用、剪压区混凝土和箍筋等对受剪承载力的贡献,建立了UHPC梁细观多参数受剪承载力计算式。采用该计算式与5种常用计算式对收集的102根UHPC梁受剪承载力进行预测,发现采用细观多参数受剪承载力计算式的预测值与试验结果吻合较好,进而分析了常用设计参数对受剪承载力的影响规律,发现当剪跨比增大时,剪压区混凝土的受剪承载力会显著减小;纵筋销栓作用和临界剪切裂缝界面钢纤维的受剪承载力均随纤维特征值的增大而提高。The shear tests of eight reinforced ultra-high performance concrete(UHPC) beams were carried out to explore their shear failure mechanisms.The designed variables included steel fiber content,shear-span ratio,reinforcement ratio and stirrup ratio.The test results showed that the shear strength of UHPC beams could be significantly increased due to the bridging-effect of fibers,accompanied by controlling propagation and decreasing spacing of cracks.A decrease in shear strength but an increase in deformation capacity of UHPC beams could be obtained,as their shear-span ratio increased.An increase in the shear strength of UHPC beams took place with the stirrup ratio.Simultaneously,the improvement in their shear behavior after peak load and decrease in width and length of the diagonal cracks could be observed after adding stirrups.The diagonal deformation(concrete deformation perpendicular to the direction connecting the support and the loading point) decreased and post-cracking stiffness of UHPC beams increased after using steel fibers and stirrups.According to the shear force characteristics of UHPC beams,the contributions of steel fibers at the critical shear crack interface,dowel action,concrete in the shear compression zone and stirrups to shear strength were determined.Furthermore,a mesoscopic multi-parameter shear strength calculation formula of UHPC beams was proposed.Based on test results of 102 UHPC beams,a better prediction of shear strength of UHPC beams could be obtained using the proposed calculation formula,compared with five previous formulas.Therefore,the effect of some common design parameters on the shear strength was investigated.It found that the shear strength contributed by concrete in the shear compression zone decreased significantly with the increase of shear-span ratio.The increase in fiber characteristic value enhanced both the shear strength provided by the steel fibers at the critical shear crack interface and dowel action.

关 键 词：超高性能混凝土梁 钢纤维 箍筋 受剪试验 细观分析 受剪承载力 

分 类 号：TU375.1[建筑科学—结构工程] TU317.1