Models are proposed for the shear strength of joints, for seismic design or assessment. At first Level-of-Approximation, the joint reinforcement and the column axial force are lumped in a single central Tie in the corresponding direction, whose ends are connected through concrete Struts to the two compressed corners of the joint. Concrete strength and Strut widths are independent of strains. At the second Level-of-Approximation, any reinforcement is smeared in the volume of the joint and compressive stresses are taken as uniform in a continuous compression field. Concrete strength is taken to decrease with load cycling and increasing transverse tensile strain. As this approach gives zero strength for unreinforced joints without column axial load, a minimum shear strength is added to that from the compression field model. Its magnitude and the reduction in the strength of the compression field with load cycling, as well as the Strut widths for the first Level-of Approximation, are calibrated using a database of 277 interior and 389 exterior joints tested to shear failure.

中文翻译：

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抗震设计或剪切梁柱节点评估的近似水平方法

模型被提议用于节点的抗剪强度、抗震设计或评估。在第一级逼近中，节点钢筋和柱轴力集中在相应方向的单个中心拉杆中，其端部通过混凝土支柱连接到节点的两个压缩角。混凝土强度和支柱宽度与应变无关。在第二个近似水平下，任何钢筋都被涂抹在接头的体积中，并且压缩应力在连续压缩场中被认为是均匀的。混凝土强度随着载荷循环和横向拉伸应变的增加而降低。由于这种方法在没有柱轴向载荷的情况下为无钢筋节点提供了零强度，因此将最小剪切强度添加到压缩场模型中。