基于延性剪切破坏模式的SFRC无腹筋梁受剪承载力分析  

Analysis on Shear Bearing Capacity of SFRC Beams Without Web Reinforcements Based on Ductile Shear Failure Mechanism

作　　者：毕继红[1,2] 王照耀 赵云 霍琳颖 王光宇 Bi Jihong;Wang Zhaoyao;Zhao Yun;Huo Linying;Wang Guangyu(School of Civil Engineering,Tianjin University,Tianjin 300354,China;Key Laboratory of Coast Civil Structure Safety of Ministry of Education(Tianjin University),Tianjin 300354,China)

机构地区：[1]天津大学建筑工程学院,天津300354 [2]滨海土木工程结构与安全教育部重点实验室(天津大学),天津300354

出　　处：《天津大学学报（自然科学与工程技术版）》2021年第5期497-507,共11页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(51227006).

摘　　要：钢纤维混凝土(SFRC)无腹筋梁受剪承载力是结构设计时的关键指标,准确预测其受剪承载力具有重要意义.大量SFRC无腹筋梁受剪性能试验发现由于钢纤维的加入,其破坏模式由脆性的剪切破坏转变为延性剪切破坏.基于SFRC无腹筋梁延性剪切破坏模式及其抗剪机理,提出一种新的受剪承载力计算模型,其中包括骨料咬合力、纵筋销栓作用、斜裂缝截面钢纤维及受压区混凝土的贡献.根据理论分析分别推导了各抗剪机制的计算公式,并通过SFRC无腹筋梁变形协调及受力平衡条件将这些抗剪机制有效结合,给出了SFRC无腹筋梁受剪承载力计算的具体步骤.为了方便工程设计,在提出的受剪承载力计算模型的基础上根据各抗剪机制的受力特点及对于受剪承载力的贡献提出了简化计算公式,简化计算公式力学概念清晰且形式简单.采用提出的计算模型、简化计算公式和5种已有计算模型对收集到的217根SFRC无腹筋梁受剪承载力进行预测并与试验结果进行对比.计算结果表明,斜裂缝截面钢纤维在SFRC无腹筋梁抗剪中发挥重要作用,提出的计算模型与简化计算公式均能够准确地预测SFRC梁受剪承载力,且变异系数小,在不同的剪跨比、轴心抗压强度、纤维特征系数及纵筋配筋率时均能保证较高的计算精度,为SFRC无腹筋梁抗剪设计与分析提供参考.The shear bearing capacity of steel fiber reinforced concrete(SFRC)beams without web reinforcements is a critical parameter in building structure design.Therefore,it is significant to accurately predict the shear capacity accurately.Several experimental studies on the shear behavior of SFRC beams have found that the failure mode of SFRC beams changes from brittle shear failure to ductile shear failure due to the effect of steel fibers.Herein,a novel calculation model is proposed based on the ductile shear failure mechanism to calculate the shear bearing capacity.The model includes the contribution of aggregate interlock,dowel action,steel fibers at the diagonal crack section and the concrete in compressive zone.The formulas corresponding to each shear mechanism are derived respectively based on the theoretical analysis.These shear mechanisms are effectively combined through the deformation and stress conditions of SFRC beams,and the specific steps for calculating the shear bearing capacity are given.Moreover,a simplified formula is proposed for the design of practical projects based on the stress characteristics and the contribution of each shear mechanism to the shear bearing capacity.The shear bearing capacities of 217 SFRC beams without web reinforcements are predicted using the calculation model,the simplified formula,and five existing calculation models,respectively. The results indicate that steel fibers play an important role in the shear resistance of SFRC beamswithout web reinforcements. The proposed calculation model and the simplified formula can accurately predict theshear bearing capacity with a small coefficient of variation,and ensure high accuracy for different calculation parameters.

关 键 词：钢纤维混凝土 无腹筋梁 受剪承载力 骨料咬合力 纵筋销栓作用 

分 类 号：TU375.1[建筑科学—结构工程]