Limit analysis (LA) is successfully used for investigating the bearing capacity of reinforced concrete (RC) structures. Some cautions must be taken when using this method for RC since the concrete component exhibits a softening behavior with decreasing strength and limited ductility. A commonly adopted provision consists of considering isotropic reduced values of concrete strength to be input in the analysis (empirical effectiveness factors). In this paper, an alternative and completely new approach is proposed and investigated in which concrete strength is weakened in a more targeted manner. To that purpose, the commonly used 3D truncated Mohr-Coulomb (TMC) criterion is adopted to classically describe the compressive, tensile, and shear failure of concrete. However, TMC is here in an original way enriched by additional constraints that allow to account for weakness and anisotropy induced by preferential failure patterns, assumed a priori. The limit analysis approach is then formulated for two dual analyses in the convex optimization framework, making it possible to quantify the numerical error and obtain a lower and an upper bound of the limit load. Numerical examples illustrate the agreement of the formulation with academic results and laboratory tests.

中文翻译：

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沿涂抹裂缝滑动的钢筋混凝土的三维极限分析


极限分析 （LA） 已成功用于研究钢筋混凝土 （RC） 结构的承载力。对 RC 使用这种方法时必须注意一些，因为混凝土构件表现出强度降低和延展性受限的软化行为。一个普遍采用的规定包括考虑在分析中输入的混凝土强度的各向同性折减值（经验有效性因子）。在本文中，提出并研究了一种替代的全新方法，其中以更有针对性的方式削弱混凝土强度。为此，采用常用的 3D 截断 Mohr-Coulomb （TMC） 准则来经典地描述混凝土的压缩、拉伸和剪切破坏。然而，TMC 以一种原始的方式存在，它通过额外的约束来丰富，这些约束允许解释由优先失效模式引起的弱点和各向异性，假设是先验的。然后，为凸优化框架中的两个对偶分析制定极限分析方法，从而可以量化数值误差并获得极限载荷的下限和上限。数值示例说明了配方与学术结果和实验室测试的一致性。