中文摘要：

基于Rankine破坏准则，推导出简化的剪压区混凝土强度破坏准则。考虑尺寸效应，通过极限平衡法，得到有腹筋与无腹筋钢筋混凝土梁抗剪承载力统一计算公式。该公式形式简单，物理意义明确，可以考虑梁的几何尺寸、剪跨比、纵筋率、配箍率、纵筋及腹筋屈服强度、混凝土强度等影响因素。利用国内外409片无腹筋梁和156片有腹筋梁对公式进行验证，表明该公式对加载方式、剪跨比等主要抗剪承载力影响因素涵盖范围较广，可以反应诸多因素的影响规律。与大量试验数据和其他计算模型进行比较，结果表明文中建议的统一计算公式可以较好预测有腹筋和无腹筋钢筋混凝土梁的抗剪承载力。

英文摘要：

Based on Rankine＇ s failure criteria, the simplified failure criterion of the compression zone of intact concrete is established. A unified shear strength formula for reinforced concrete beams with or without stirrups is proposed, considering the size effect. The formula takes several substantial factors into account, such as beam geometry, shear span-to-depth ratio, longitudinal reinforcement ratio, transverse reinforcement ratio, the yield strength of longitudinal and transverse reinforcement, and the concrete strength. Thus it is simply expressed and of clear physical significance, The accuracy of the proposed method is verified through 409 beams without stirrups and 156 beams with stirrups. By comparing with numerous data from shear experiments and other shear strength theories, the result indicates that the proposed ultimate shear strength equation is applicable to reinforced concrete beams with or without web reinforcement.