Using post-tensioned metal straps (PTMS) as a method of strengthening reinforced concrete building members is relatively new, however, it has been tested mostly on small specimens. Therefore, this study is an attempt to show the effectiveness of PTMS fully wrapped around medium- scale steel reinforced concrete (RC) beams to enhance their shear strength. For this purpose, four normal RC beams are constructed without transverse reinforcement with dimensions of 160 mm × 240 mm x 1050 mm which are width, depth, and length respectively. To strengthen the beams, PTMS is wrapped fully around the beams at different locations with different strip numbers. It is found that if used properly, PTMS can effectively alter the type of failure of the beams from a brittle shear failure to a ductile bending failure. Additionally, the load-carrying capacity of the beam can increase by 143%, 170%, and 182% by using two, four, and six strips of PTMS respectively. Moreover, the deflection capacity increases by 643%, 557%, and 653% by using two, four, and six straps of PTMS. Finally, after using PTMS on the beam there is a reduction in the number of cracks and the location of their appearance will be localized in the center of the beam.

The efficacy of post-tensioned metal straps PTMS, wrapped around steel channels anchored to normal reinforced concrete (R.C) beams is tested in increasing the flexural capacity of the beams. For this purpose, nine normal R.C beams with dimensions of 160 mm x 240 mm x 2100 mm are constructed to fail in bending. The location and the number of the straps are considered as the main variable. It is found that using PTMS can enhance the load-carrying capacity of the beam by 29% to 63%. The decisive factors affecting the increase are the location of the straps (at the bottom or sides), shape of the flange and web edges (squared or rounded) and alignment of the flanges (vertical or inclined). A complete guide can be found in the paper as it is a novel method of strengthening beams which can be applied to the beams cast in place with integral slabs.

Over one billion tires are disposed into the environment each year and this has become a major environmental issue in the globe. Recycling of these waste tire rubbers in concrete has gained attention from researchers all around the world. In this study, the impact resistance of rubberized concrete exposed to fire is investigated experimentally in the laboratory. For that purpose, sixty specimens were made with five different mixes replacing their sand content partially with different percentages of tire rubber by weight ratios of 0% control, 6%, 12%, 18% and 24%. The water/cement ratio was kept constant at 0.393 in all the mixes. In each mix, fifteen concrete specimens with the size of (150 x 150 x 73) mm were prepared to expose to fire. Every three specimens were gradually exposed to fire for four various durations of (0, 15, 30, and 45) minutes. Each specimen was then tested in a drop-weight impact machine by dropping 2240-gr and 4500-gr hammers from heights of 280 mm and 450 mm. The average impact energy of three identical specimens required for the occurrence of the final fracture was calculated. The investigational results are compared with results of control samples. It is found that the impact energy considerably increased with an increase of the rubber replacement. It is, also, noted that any increase in the burning period of specimens results in a reduction of the impact energy and more early crushing of the rubberized concrete.

The structural performance of two-way reinforced concrete slabs is significantly influenced by the presence of openings, which are frequently required for functional elements like staircases, lift shafts, and utility ducts. These apertures diminish slab stiffness and affect punching shear strength due to their size and placement. This review integrates experimental, analytical, and computational analyses to assess the influence of slab openings on structural performance. It discusses essential factors, including opening dimensions, configuration, positioning, and reinforcement techniques. The predicted reliability of design codes, such as ACI 318-19 (American Concrete Institute), Eurocode 2, and fib Model Code, is demonstrated, with an emphasis on their limitations in addressing opening effects. The results demonstrated that apertures adjacent to columns markedly reduce punching shear resistance by interrupting the critical shear perimeter and exacerbating stress concentrations. Nevertheless, the strategic positioning of reinforcements and the optimization of opening layouts alleviate these consequences. This literature review highlights the need for enhanced design specifications to guarantee safety and performance in reinforced concrete slab systems with apertures.

Fracture analysis of reinforced concrete deep beam strengthened with carbon fiber-reinforced polymer (CFRP) plates was carried out. The present research aimed to discover whether crack propagation in a strengthened deep beam follows linear elastic fracture mechanics (LEFM) theory or nonlinear fracture mechanics theory. To do so, a new energy release rate based on nonlinear fracture mechanics theory was formulated on the finite element method and the discrete cohesive zone model (DCZM) was developed in deep beams. To validate and compare with numerical models, three deep beams with rectangular cross-sections were tested. The code results based on nonlinear fracture mechanics models were compared with the experimental results and the ABAQUS results carried out based on LEFM. The predicted values of initial stiffness, yielding point and failure load, energy absorption, and compressive strain in the concrete obtained by the proposed model were very close to the experimental results. However, the ABAQUS software results displayed greater differences from the experimental results. For instance, the predicted failure load for the shear-strengthened deep beam using the proposed model only had a 6.3% difference from the experimental result. However, the predicted failure load using ABAQUS software based on LEFM indicated greater differences (25.1%) compared to the experimental result.