Concrete waste in large quantities has caused environmental damage and requires landfilling places and effort. Therefore, concrete waste has been recycled, and new concrete has been produced, which is called recycled aggregate concrete (RAC). In this work, study the behavior of T-beams with recycled aggregate concrete is investigated, and the parameters studied on T-beams are as follows: (Replacing natural coarse aggregate (NCA) with 100 % recycled coarse aggregate (RCA), increasing the flexural reinforcing ratio (ρw) in percentage (25 % and 50 %), increasing the shear reinforcing ratio (ρv) according to (Ø10@50mm and Ø12@75mm), and increasing the flange reinforcing ratio (ρf) in percentage (50 % and 100 %) to find the effects of these parameters on the longitudinal strain distribution on the top surface of the flange, flange effective width, deflections, and the development of cracks. Eight beams’ specimens are tested, and the results of the tested beams show that; the replacing natural coarse aggregate (NCA) with 100 % recycled coarse aggregate (RCA) leads to a decrease in the longitudinal strains distribution, flange effective width, and increase in deflections. The increase in the flexural reinforcing steel ratio (ρw) leads to an increase in the longitudinal strains distribution, flange effective width, and decrease in deflections. The increase in the shear reinforcing steel ratio (ρv) leads to a very little increase in longitudinal strains distribution, flange effective width, and decrease in deflection, and this parameter effects is very little and can be neglected. Finally, the increase in flange reinforcing steel ratio (ρf) leads to an increase in longitudinal strain distribution and flange effective width and a decrease in deflection

This paper presents comprehensive empirical equations to predict the shear strength capacity of reinforced concrete deep beams, with a focus on improving the accuracy of existing codes. Analyzing 198 deep beams imported from 15 existing investigations, this study considers various parameters such as concrete compressive strength (f′_c), the shear span-to-effective depth ratio (a_v/d), and reinforcement ratios (p_s, p_v, and p_h). Introducing a novel predictive empirical equation, this study conducts a rigorous evaluation using statistical metrics and a linear regression analysis (MAE, RMSE, and R²). The proposed model demonstrates a significant reduction in the coefficient of variation (CV) to 27.08%, compared to the existing codes’ limitations. Comparative analyses highlight the accuracy of the empirical equation, revealing an improved convergence of data points and minimal sensitivity to variations in key parameters. The results proved that the proposed empirical equation enhanced the accuracy to predict the shear strength capacity of the reinforced concrete deep beams in various scenarios, making it a valuable tool for structural engineers. This research contributes to advancing the understanding of shear strength capacity in reinforced concrete deep beams, offering a reliable empirical equation with implications for refining design methodologies and enhancing safety with the efficiency of structural systems.

This study focuses on studying the behavior of fibrous circular short columns (tied and spirally reinforced) using recycled coarse aggregate (f'c, ft, Ec, and fr) by using recycled aggregates with comparison to normal aggregates with and without using steel fibers. For this purpose, ten (10) short columns were cast at five groups each of two circular columns(tied and spiral of 150 mm radius x 600mm height) with different percentages of recycled coarse aggregate (0%, 50%, and 100%) and different percentages of steel fiber (0%, 0.5% and 1%). The study showed that when adding the 50% normal aggregates with 50% recycled aggregates, decreases of (10%, 18%, 30% and 22%) for (compressive strength, splitting tensile strength, flexural strength and elasticity module), respectively were observed, and when replacing the 100% normal aggregates with 100% recycled aggregates, decreases of (30%, 35%, 58% and 63%) for (Compressive strength f'c, splitting tensile strength ft, flexural strength fr and elasticity module Ec), respectively were observed. The changes on the compressive strength of adding steel fibers to the RAC by a proportion of (0.5% and 1 %) resulted in a significant increase of about (14 % and 35 %), respectively.

This paper presents a thorough investigation into the shear strength capacity of reinforced concrete deep beams, with a focus on improving predictive accuracy beyond existing code provisions. Analyzing 198 deep beams from 15 investigations, the study considers parameters such as concrete compressive strength (fc’), shear span to effective depth ratio (av/d), and reinforcement ratios (ρs, ρv, ρh ). Introducing a novel predictive model (Equation 7), the study rigorously evaluates it using nonlinear regression analysis and statistical metrics (MAE, RMSE, R2). The proposed model demonstrates a significant reduction in the coefficient of variation (COV) to 27.08%, surpassing existing codes' limitations. Comparative analyses highlight the model's robustness, revealing improved convergence of data points and minimal sensitivity to variations in key parameters. The findings suggest that the proposed model offers enhanced predictive accuracy across diverse scenarios, making it a valuable tool for structural engineers. This research contributes to advancing the understanding of shear strength in reinforced concrete deep beams, offering a reliable and versatile predictive model with implications for refining design methodologies and enhancing the safety and efficiency of structural systems.

This paper investigates the effect of momentum on the behavior of reinforced reactive powder concrete two-way slabs under impact loading. Five specimens of rectangular simply supported slabs were adopted with dimensions (500x500 mm and 70mm thickness). Each slab was first subjected to impact force and then tested under static force to examine the effect of dynamic load on the strength capacity of slabs. The impact force test was carried out using a free-falling mass called (Stricker), which consists of an iron ball with a diameter 125mm linked to Circular discs grouped together according to the required weight to form a cylindrical shape. The Stricker falling through a circular-section tube guided the drop weight vertically and ensured mid-span collision. The variables investigated in this research were the influence of height of impact (2.1m, 1.8m, and 1.5m), the effect of falling mass (26kg,21kg,16kg). Experimental studies have been carried out to determine the attitudes of each slab, including the impact force, maximum central deflection, residual displacements, reinforcement strain, residual crack width, impulse, momentum, absorbed energy and kinetic energy for the impact test. The first cracking load, crack width, failure load, maximum deflection, and failure modes for the static test. The obtained results demonstrate that decreasing the height of falling mass from 2.1m to 1.5 m caused a reduction in the magnitude of impact force by 34% due to the decrease in velocity. Furthermore, the maximum central deflection is dropped by 29.83 % when the projectile's mass is reduced from 26 kg to 16 kg.