Shear Performance of Hybrid Concrete Deep Beams of Trapezoidal Section

Abstract

The structural behaviour of hybrid reinforced concrete beams of trapezoidal section was investigated in this work. The main aim of study was to investigate the interaction effect of hybrid concrete compressive strength–section geometry variations on beam strength characteristics. The experimental programme included fourteen simply supported reinforced concrete deep beams being prepared and examined under a four-point load setting protocol. All specimens were of 1,000 mm length and of equal cross-sectional area. The specimens were divided into groups according to section shape variations and hybrid compressive strength considerations. Various concrete compressive strengths (70, 50, and 25) MPa were considered, and three different trapezoidal geometries of different alignment side angles (75°, 80°, and 85°) were also adopted, along with two steel rebar ratios (0.008617 and 0.01508). Generally, the experimental results showed that the shear strength capacity increased with increases in the area of high-strength concrete in the compression zone in increments, with improvements ranging from 3.66% to 8.63% as compared to reference specimens of uniform section (rectangular section); the diagonal crack load decreased, however. It was also observed that the hybrid concrete created high ductile behaviour, and the significant failure mode was shear mode without slippage of the hybrid concrete layers. A comparison of results with the hybrid strength reduction index (Ψ=f’cb/f’ct ) showed that as Ψ decreased from 0.714 to 0.357, the average rating varied between 1.15 and 1.22 with respect to rectangular specimens and from 1.07 to 1.13 with respect to trapezoidal sections of uniform strength. An optimum alignment side angle for trapezoidal configuration also appears to be indicated, with the best results for all hybrid strength-trapezoidal sections in specimens where Ө=80°.

A Novel Hybrid Model of Reinforced Concrete Deep Beams With Curved Hybridization

“…In 2014, Hassan [15] testing hybrid deep beams of the two layers of concrete (ultra-high performance concrete UHPC and normal concrete, UHPC used in compression of beams, show that the increase in the capacity of beam by increasing the thickness of the UHPC layer and the proportion of steel fibers used in concrete. Sada and Resan 2021 [16] used the trapezoidal section instead of the rectangular one. RPC (reactive powder concrete) has been used in various types of structural members [17][18].…”