This paper describes an experimental study to evaluate the shear capacity of small to medium height old buildings constructed in Israel more than 50 years ago with poor materials and construction practices resulting in low performance concrete (LPC), also known as plum concrete. Such LPC is characterized by its low compressive strength and in many cases – by the inclusion of large stones (up to ~300 mm) among its coarse aggregates. The tests conducted in this study were aimed at providing assessment of the shear capacity of existing slender LPC walls. The experimental program comprised beams sawed out of authentic samples, which were extracted from old buildings prior to their demolition, as well as larger specimens cast in the laboratory from concrete mixes designed to represent the main characteristics of authentic LPC. Control specimens, made of the lowest standard concrete class, were also tested. The 14 beam specimens failed in shear and their measured load capacities were compared with the shear capacity of beams without shear reinforcement, on the basis of their measured concrete compressive strength as prescribed by Eurocode 2 and ACI 318 provisions. This comparison indicates that the current Eurocode 2 formula, as well as that of ACI 318, provide reasonably conservative estimates for the shear capacity of LPC walls without shear reinforcement. Hence, engineers who lacked any information on how to assess the shear capacity of such low-performance concrete walls can now refer to this study.

本文描述了一项实验研究，以评估50年前在以色列建造的中低高度的旧建筑物的抗剪承载力，这些建筑物的材料和建筑实践较差，导致混凝土的性能低下（LPC），也称为梅花混凝土。这种LPC的特点是抗压强度低，在许多情况下-粗骨料中包含大块石块（最大约300毫米）。在这项研究中进行的测试旨在提供对现有的细长LPC墙的剪切能力的评估。实验程序包括从真实样品中锯出的光束，这些样品是在拆除之前从旧建筑物中提取的，以及在实验室中从旨在代表真实LPC主要特征的混凝土混合物中浇铸的较大样品。还测试了由最低标准混凝土等级制成的对照样品。14个梁标本剪切失败，根据欧洲规范2和ACI 318的规定，将其测得的混凝土抗压强度作为基础，将其测得的承载力与不带剪切补强的梁的抗剪承载力进行比较。该比较表明，当前的Eurocode 2公式以及ACI 318的公式为没有剪力增强的LPC墙的剪力提供了合理的保守估计。因此，缺乏有关如何评估此类低性能混凝土墙的抗剪承载力的信息的工程师现在可以参考此研究。