Many structural elements are subjected to a significant torsional moment that affects the structural design and may require strengthening. This paper presents different effective strengthening techniques to enhance the torsional capacity of reinforced concrete (RC) beams. An experimental and numerical investigation was undertaken to evaluate the efficacy of utilizing various strengthening systems. The experimental program included six full-scale RC beams with a cross-section dimension of (150 mm × 300 mm) and a length of 1500 mm, split into one beam without strengthening as a control beam, and six beams strengthened with various materials. The various strengthening materials were wrapped aluminum strips with anchorage bolts, wrapped stainless steel strips with anchorage bolts, wrapped glass fiber reinforcement polymer (GFRP), one layer of wrapped steel wire, and two layers of wrapped steel wire meshes along the beam. The results showed that the ultimate torque of the beam strengthened by wrapped aluminum strips and the beam strengthened by wrapped stainless steel strips was larger than the control beam by about 32% and 40%, respectively, because the strips acted as an external reinforcement. In addition to the strengthening systems, using aluminum strips and stainless steel strips is effective in raising the capacity to a similar degree despite the high cost of the stainless steel strips. The ultimate torque of the beams strengthened by GFRP, one-layered wrapped steel wire meshes, and two-layered wrapped steel wire meshes along the beam is larger than the control beam by about 62%, 118%, and 163%, respectively, in addition to the ultimate angle of twist, which was larger than the control beam by about 53%, 93%, and 126%, respectively. This showed that the strengthening using the two-layered wrapped steel wire meshes along the beam would be very significant in increasing the ultimate torque strength. Moreover, the strengthened beam by two-layered fully wrapped steel wire meshes along the beam developed the highest ductility factor compared to all strengthened beams; in contrast, the beam strengthened by GFRP had less ductility. To verify the outcomes of the experimental tests, a finite-element program, ABAQUS, was performed. Finally, an excellent agreement between the experimental and numerical results was obtained.

It is thought that rigid pavements are more expensive than flexible pavements. However, when taking into account the element of durability, it was found that rigid pavements are less expensive than flexible pavements and have a service life up to 20 years. The flexible pavements are more suitable for the areas with weak subsoil and poor drainage, but it has a negative impact on the environment. This research presents an experimental and numerical study to explore the behavior of rigid pavement made of different types of concrete under the influence of static loads. The recent experimental study consists of six slabs with dimensions of 600 × 600 × 60 mm made of different types of concrete. Such types are normal-strength concrete (NSC), high-strength concrete (HSC) and strain hardening cementitious composites (SHCC). Based on the findings of this study, it is evident that the slab constructed with SHCC exhibits a 76.6% greater bearing capacity compared to the NSC slab. Regarding cost-effectiveness, the HSC slab was identified as the most economically advantageous option. A point to be noted is that the numerical model using the Abaqus program succeeded in modeling the experimental tested slabs.

The punching shear failure of reinforced concrete (RC) flat slabs is an undesirable type of failure, as it is sudden and brittle. This paper presents an experimental and numerical study to explore the behavior of flat slabs made of different types of concrete under the influence of punching shear. Experimental tests were carried out on four groups of flat slabs, each group representing a different type of concrete: ordinary normal concrete (NC), high-strength concrete (HSC), strain-hardening cementitious composite concrete (SHCC), and ultra-high-performance fiber concrete (UHPFC). Each group consisted of six slabs, one representing an unreinforced control slab other than the reinforcement of the bottom mesh, and the others representing slabs internally reinforced with SHCC-filled steel tubes and high-strength bolts. An analytical equation was used to predict the punching shear capacity of slabs internally reinforced using steel assemblies. A numerical model was proposed using the ABAQUS program, and was validated by comparing its results with our experimental results. Finally, a case study was performed on large-scale slabs. The results showed that using steel assemblies inside NC slabs increased the slab’s punching shear capacity but does not completely prevent punching shear failure. Internally unreinforced slabs made of UHPFC and SHCC were able to avoid punching shear failure and collapse in a ductile bending pattern due to the high compressive and tensile strength of these types of concrete. The proposed analytical method succeeded in predicting the collapse load of slabs reinforced with steel assemblies with a difference not exceeding 9%.

The segments of the precast concrete beams can be assembled by joints have interlaced shear keys. This paper presents an experimental and numerical study of ten samples, six of them were tested under the influence of direct shear; these samples represent reinforced and non-reinforced shear keyed joints made of high-strength concrete (HSC) and ultra-high performance fiber concrete (UHPFC) under the influence of different levels of confining stress. In addition, four beams were tested under the influence of bending, two of them are unconnected control beams made of HSC and UHPFC, and the other two beams are precast segmented and were assembled using reinforced shear keyed joints of the same joints tested under direct shear. All the details of the shear keyed joints are fixed in all samples and they are dry non-epoxy joints, the external prestressing technique was used. Also, Abaqus program was used for numerical modeling of all samples that were tested in the experimental program using the 3D solid element model. The success of the modeling process was verified by comparing the experimental and numerical results as the results of the relationship between load and displacement and also the failure pattern. From the experimental and numerical study, it was found that by reinforcing the shear keys and/or by increasing the confining stress of the joints made of HSC and UHPFC, the shear capacity of the joints is increased. If the value of the used confining stress is constant at a value of 3 N/mm² and by reinforcing the shear keys with reinforcement, the maximum load increases by 18% and 48%, respectively, than its non-reinforced counterparts joints. It was also found that by increasing the confining stress of the reinforced shear keyed joints from 3 N/mm² to 6 N/mm², the maximum load value is increased by 18% and 16%, for HSC and UHPFC shear keyed joints, respectively.

Cast-in-place ground-supported concrete slabs (GSCSs) are used as floors in many facilities such as factories, workshops, garages, and airports (i.e., rigid pavements). These slabs may be subjected to repeated impact loads caused by vehicle loads, the dropping of heavy loads, and aircraft landing loads on runways. This research presents an experimental and numerical study to investigate the behavior of these slabs under impact loads. The experimental program consists of 18 concrete slabs with dimensions of 400 mm × 400 mm × 100 mm. Some variables were studied experimentally, such as the reinforcement ratio of these slabs and the amount of the impact force (represented by the drop height). Unreinforced slabs and slabs reinforced with steel reinforcement or a geogrid mesh made of knitted polyester ribs were tested. ABAQUS software was employed to study the failure mode and crack distribution of these slabs numerically. The accuracy of the proposed numerical model was verified by modeling the tested slabs and comparing the numerical results with the experimental results. From the study results, it is clear that the reinforcement significantly improves the impact performance of GSCSs, transforming their failure behavior from brittle to more ductile and tough. The combined use of impact strength and ductility factors provides an integrated measure of slab performance, offering valuable guidance for the design of protective structures, pavements, and industrial flooring under impact loading.