This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

中文翻译：

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带剪切头的钢筋混凝土平板冲孔剪切特性的非线性数值模拟

本文通过详细的三维非线性数值模拟和使用混凝土损伤可塑性模型的参数评估，研究了配备有完整埋入式剪切头的钢筋混凝土平板的结构响应。针对三个测试系列的实验结果对所采用的非线性有限元程序进行了验证。在对数值模型能够紧密预测全部非弹性响应和破坏模式的能力有了信心之后，进行了数值研究，以检查关键材料和几何参数的影响。这些数值评估的结果使得能够根据剪切头与周围混凝土之间的相互作用确定三种破坏模式。根据调查结果，结合以前的研究结果，提出了用于预测此类平板系统的旋转响应以及极限强度的分析模型。还提供了有关钢筋混凝土平板剪头设计的实用建议，包括埋入长度和截面尺寸。本文提出的分析表达式基于广泛的参数评估，与所有类型的剪切头的现有方法相比，显示出提供了更可靠的设计方法，并且适合直接实际应用。