Experimental Investigation on Effect of Aspect Ratio on Behavior of Isolated Reinforced Concrete Struts

摘要

Strut-and-tie modeling involves simplifying the dispersion of compressive stress within a concrete member. In this paper, an experimental study has been conducted to determine the strength of compressed struts and the dispersion of compression in bottle-shaped struts focusing on the effect of aspect ratio. Sixteen reinforced concrete isolated struts as plain panels were tested up to failure under in-plane point loading. The tested specimens were prepared with various aspect ratios. The behavior of tested beams was investigated and the dispersion of compressive stresses have been examined and compared with an analytical equation of isostatic lines of compression (ILCs) and the provisions of ACI 318-11. The overall shape formed by strut-and-tie modeling (STM) can be useful for designers to estimate the magnitude of the transverse tensile force and more adequate arrangement of required reinforcement in the various geometrical conditions. The results indicate that the dispersion of compression and the shape of the strut-and-tie model are influenced by the aspect ratio of struts. The angle between strut and maximum tensile stress are closer to the results of investigated analytical method than the angle provided by ACI 318-11. Current ACI 318-11 provisions indicate a constant slope of 1:2 for flow of compressive stress without considering the effect of aspect ratio or geometrical properties of strut.