This paper investigates numerically and experimentally the performance of reinforced concrete (RC) beam with unequal depths subjected to combined bending and shear. Such beams can geometrically be considered for unleveled reinforced concrete (RC) floor slab-beam system. However, it may generate critical disturbances in stress flow at the re-entrant corner (i.e. location of drop in beam depth). This research investigates the use of shear reinforcement and geometric properties to enhance cracking characteristics, yielding, ultimate load-carrying capacity, and exhibiting ductile failure mode. Ten reinforced concrete (RC) beams were constructed and tested experimentally considering the following key parameters: recess length, depth of smaller beam nib, and amount and layout of shear reinforcement at re-entrant corner. Finite element analysis (FEA) with material non-linearity was conducted in two RC beams that were tested experimentally to validate the computer modelling. The FEA models were then extended to conduct a parametric study to investigate the influence of geometric parameters (beam shape and width) and amount and arrangement of shear reinforcement on the structural response. Results confirmed that geometric properties and ratio of shear reinforcement at the re-entrant region significantly affect the behavior of reinforced concrete beam with unequal depths in terms of first cracking, yielding level, ultimate load carrying capacity and mode of failure.

中文翻译：

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受扰深度钢筋混凝土梁的试验和数值评估

本文通过数值和实验研究了不等深钢筋混凝土 (RC) 梁在弯曲和剪切联合作用下的性能。这种梁在几何上可以考虑用于未平整钢筋混凝土 (RC) 楼板梁系统。然而，它可能会在凹角处（即梁深度下降的位置）处产生应力流的严重扰动。本研究调查了使用抗剪钢筋和几何特性来增强开裂特性、屈服、极限承载能力和展示延性破坏模式。考虑到以下关键参数：凹槽长度、较小梁尖的深度以及凹角处抗剪钢筋的数量和布置，我们建造了 10 根钢筋混凝土 (RC) 梁并进行了实验测试。具有材料非线性的有限元分析 (FEA) 在两个 RC 梁中进行，这些梁经过实验测试以验证计算机建模。然后扩展 FEA 模型以进行参数研究，以研究几何参数（梁形状和宽度）以及抗剪钢筋的数量和布置对结构响应的影响。结果证实，凹入区的几何特性和抗剪配筋率显着影响不等深度钢筋混凝土梁的初裂、屈服水平、极限承载能力和破坏模式的行为。然后扩展 FEA 模型以进行参数研究，以研究几何参数（梁形状和宽度）以及抗剪钢筋的数量和布置对结构响应的影响。结果证实，凹入区的几何特性和抗剪配筋率显着影响不等深度钢筋混凝土梁的初裂、屈服水平、极限承载能力和破坏模式的行为。然后扩展 FEA 模型以进行参数研究，以研究几何参数（梁形状和宽度）以及抗剪钢筋的数量和布置对结构响应的影响。结果证实，凹入区的几何特性和抗剪配筋率显着影响不等深度钢筋混凝土梁的初裂、屈服水平、极限承载能力和破坏模式的行为。