Abstract
Experimental and numerical investigations of the behavior of directly and indirectly loaded flanged reinforced concrete (RC) deep beams cast with self-compacted concrete (SCC) containing recycled concrete as coarse aggregate (RCA) were conducted in this research. Seventeen RC deep flanged beams were designed to fail in shear. These beams were divided into three groups: twelve indirectly loaded beams without shear reinforcement; three directly loaded beams without stirrups; and two indirectly loaded beams with vertical stirrups. These beams were also classified according to the RCA ratio and shear span-to-effective depth (a/d) ratio, which will be detailed later. The RCA ranged from 0% to 75%, while the a/d ratio was taken as 1.0, 1.35, and 1.7. Experimental results show that the use of RCA reduces the cracking and ultimate capacities, and this finding complies with the conclusions of several research studies in the literature as will be detailed later. It was observed that beams with higher RCA exhibited higher deflection, strain, and crack width. Furthermore, by increasing the a/d ratio, the ultimate load was decreased due to the lower contribution of arch action shear transfer in the beam. A web reinforcement spaced at 100 mm and 50 mm increases the ultimate load by 35% and 48%, respectively. Strut and tie model (STM) presented by the American Concrete Institute (ACI) 318-14 and the American Association of State Highway and Transportation Officials (AASHTO LRFD 2012) was used to predict the ultimate shear capacity of the beams. STM predicted lower beam capacity than the experimental result. The ultimate strength calculated using ACI318-14 and AASHTO LRFD 2012 was on average 38% and 52% lower than the experimental data, respectively, which reflects the conservative nature of this approach. Finally, 3D finite element models were created to investigate the responses of the beams. The FE results showed very good agreement with the experimental data, where FE-predicted shear capacities were on average 9% higher than the experimental results.
Highlights
Waste materials (WM) resulting from the demolition of tremendous concrete structures that have reached the end of their lifespan have negatively impacted the environment
In which four groups are indirectly loaded while the fifth group is directly loaded. e parameters considered in this study are the replacement ratio of recycled concrete as coarse aggregate (RCA), shear span–to–effective depth (a/d) ratio, and the web reinforcement
The main bars properly functioned to prevent any anchorage failure. erefore, shear failure due to diagonal cracking results in splitting the beams along the diagonal crack. e crack pattern formed a simple strut configuration with a triangle shape connecting the load application area with the two supports. It was observed from the experimental results for both, directly and indirectly, loaded beams that the compressive strength, modulus of elasticity, and splitting tensile strength were reduced by the increase of the RCA replacement ratio
Summary
Waste materials (WM) resulting from the demolition of tremendous concrete structures that have reached the end of their lifespan have negatively impacted the environment. Erefore, this research presents a detailed study and offers an experimentally quantified approach that can be utilized to implement the effect of indirect loading conditions on the response of deep beams. Studying the effect of indirect loading conditions on the response of RASCC deep beams is underdocumented even in international standards like ACI and AASHTO. Another important feature of this research is the combination of using deep beams prepared using RCA as a partial replacement of NA and utilizing the SCC technique. Another important feature of this research is the combination of using deep beams prepared using RCA as a partial replacement of NA and utilizing the SCC technique. is combination produces more sustainable structural elements and eliminates construction efforts
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