This article investigates the shear behavior of reinforced concrete beams without transverse reinforcement. Two types of concrete were produced: a Reference Conventional Concrete (RCC) and a Lightweight Self-Consolidating Concrete (LSCC), all with an average 28-day compressive strength (fc) of approximately 30 MPa and characterized by rheological and mechanical tests. Twelve 15 x 30 x 200 cm beams were manufactured for shear failure during a four-point bending test. Concrete properties, longitudinal reinforcement ratios (0.89%, 1.27% and 1.68%) and shear-span to depth ratio (1.87 to 2.71) were determined. The studied beams were compared in terms of cracking pattern, diagonal cracking load, shear strength, specific concrete and longitudinal reinforcement deformation at failure. The strength values obtained experimentally were compared with ABNT NBR 6118 (2014), ACI 318 (2019) and CEN EC-2 (2004). The tested beams of LSCC showed less shear strength when compared to beams of RCC.

In this work, twenty-seven dry joint specimens of prestressed segmental bridges produced using recycled coarse aggregate concrete (RAC) were subjected to push-off tests. The substitution rate of coarse aggregate for recycled aggregate was 100%. The variables observed were the number of keys, including flat, single-keyed, and three-keyed, and the magnitude of the confining stress, varying at 1.0, 2.0, and 3.0 MPa. The slippage between both parts of the joint and the cracking of the specimens were analyzed using the digital image correlation technique (DIC). Equations from the literature were used to predict the shear strength of dry joints with recycled coarse aggregate concrete. The experimental results obtained from the present research were compared to those of other conventional concrete researchers. The results showed that the dry joints produced with recycled coarse aggregate concrete presented a crack formation in conventional concrete joints following a similar mechanism of failure; however, they presented lower strength. Some equations in the literature predicted the strength of dry joints with recycled coarse aggregate concrete. Based on the analysis performed, adopting a reduction coefficient of 0.7 in the AASHTO normative equation was recommended for predicting the shear strength of dry joints when produced with recycled coarse aggregates concrete.

The self-consolidating concrete presents properties that improve the constructive process, it has the main characteristic of flowing under its own weight and completely filling the formwork, without the need of compaction. However, the uncertainty about its shear strength, due to the differences in coarse aggregate volume and size of this concrete compared to conventional vibrated concrete, is one of the main barriers to its acceptance. Self-consolidating concrete mixtures requires generally the reduction of coarse aggregate content and addition of fines materials to obtain flowability and the reduction of particles size directly influences the mechanism of aggregate interlock. In this work, two concrete mixtures, conventional and self-consolidating, were used for casting test specimens, submitted to the direct shear test, in order to evaluate the direct shear strength of these concretes. The results showed a reduction of the shear strength for the self-compacting concrete, attributed to the use of coarse aggregate with smaller particle size, the reduced volume of coarse aggregate and the larger fines content in the mixture. The experimental results were compared with equations proposed in the literature, demonstrating that for self-consolidating concrete these equations underestimate the ultimate shear strengths. Thus, this work contributes to the formation of a database aiming the establishment of equations to estimate self-consolidating concrete shear strength.

This study investigates the corrosion behavior of 5 mm diameter prestressed wires in concrete beams under chloride attack, a prevalent issue for coastal infrastructure. The study simulated aggressive chloride environments to understand their impact on structural integrity and service life. Utilizing a combination of advanced digital image correlation (DIC) techniques and a novel machine learning-based predictive model, the research provides a nuanced analysis of the interplay between stress levels, corrosion rates, and concrete strength. Empirical findings reveal a significant correlation between increased prestress levels and accelerated corrosion, indicating a crucial consideration for the design and maintenance of prestressed concrete structures. Notably, this study found that beams with a 95% prestress level exhibited a corrosion rate of 0.64 mm/year, significantly higher than the 0.37 mm/year for non-prestressed beams. The predictive model’s accuracy was validated with a mean squared error of 0.517 and an R² value of 0.905, offering a valuable tool for quantifying the impact of corrosion. Therefore, the predictive model is a valuable tool for quantifying the impact of corrosion, enhancing the ability to assess and improve the durability of such infrastructure. This study’s insights highlight the necessity for a balanced approach to design and regular monitoring, especially in chloride-rich environments. By helping to develop more resilient construction practices and contributing to sustainable development goals, this study can significantly impact the safety and service life of coastal bridges and structures, aligning with global efforts to create more sustainable and durable infrastructure.

Shear design models in reinforced concrete structures depend on stress transfer through cracks. Such mechanism is influenced by the displacement and roughness of the opposite faces generated during cracking. Shear is reduced when an aggregate particle is fractured leading to a smoother crack as found in lightweight and high strength concrete. This study evaluated the ultimate shear strength of sand-lightweight and conventional high strength concrete as well as the differences in their behavior. Results from Pereira and Soares with 29 push-off test specimens were used. Transverse clamping stress ranged from 4.79 to 12.71 MPa while fcm was 30 and 50 MPa. The experimental results showed significant differences in the concrete studied. A tri-linear model was proposed to calculate the ultimate shear strength. An overall mean value of τu, exp/τu, cal was 0.96.