Hybrid slabs made of carbon-fiber-reinforced polymer (CFRP) and concrete provide a solution that takes advantage of the strength properties of both materials. The performance of the system strongly depends on the CFRP–concrete interaction. This study investigates the shear behavior in the interface of the two materials. Eight full-scale experiments were carried out to characterize the interface shear response of these hybrid elements using different connection solutions. An untreated surface is compared to a surface with aggregates, with a novel system comprising a flexible, straight glass fiber mesh and an inclined glass fiber mesh. The experimental results show that the fabric connection improves the friction between materials and is responsible for the pseudo-plastic performance of the specimens. The inclined mesh produces a more uniform tightening effect compared to the straight mesh. In simulations via the finite element method, we used an adjusted frictional model to reproduce the experiments.

Recent developments indicate that the application of pultruded FRP profiles has been continuously growing in the construction industry. Generating more complex structures composed of pultruded FRP profiles requires joining them. In particular, I-shape glass fiber pultruded profiles are commonly used and the possible joints to connect them should be specifically studied. The mechanical behavior of adhesively and bolted joints for pultruded Glass FRP (GFRP) profiles has been experimentally addressed and numerically modeled. A total of nine specimens with different configurations (bolted joints, adhesive joints, web joints, web and flange joints, and two different angles between profiles) were fabricated and tested, extending the available published information. The novelty of the research is in the direct comparison of joint technologies (bolted vs. adhesive), joint configuration (web vs. flange + web) and angles between profiles in a comprehensive way. Plates for flange joints were fabricated with carbon fiber FRP. Experimental results indicate that adding the bolted flange connection allowed for a slight increase of the load bearing capacity (up to 15%) but a significant increase in the stiffness (between 2 and 7 times). Hence, it is concluded that using carbon FRP bolted flange connection should be considered when increasing the joint stiffness is sought. Adhesively connections only reached 25% of the expected shear strength according to the adhesive producer if comparing the numerically calculated shear strength at the failure time with the shear strength capacity of the adhesive. Apart from assessing adhesive connections, the implemented 3D numerical model was aimed at providing a simplified effective tool to effectively design bolted joints. Although the accurate fitting between experimental and numerical results of the mechanical response, especially the stiffness of the joint, the local failure experimentally observed was not automatically represented by the model, because of the simplified definition of the materials oriented to make the model available for a wide range of practitioners.

In order to combat corrosion issues, several studies on progressively replacing steel reinforcement elements with composite ones have been conducted in recent years. Hybrid steel–concrete thin slabs in which the steel acts as formwork are also candidates for update in the coming years. Achieving a reliable connection between fiber-reinforced polymer (FRP) and cast-in-place concrete is key to promoting this technology. This study analyzed different connection systems and proposes the novel approach of embedding a flexible fiber fabric as a superficially distributed connector between concrete and FRP. Eight specimens with four different connection strategies were tested using an experimental modal analysis and a quasi-static three-point bending test. The impact of the connection system on the vibrational response, flexural ultimate load, moment response, neutral axis position, shear and dissipated energy was obtained and compared. The results show that the use of an embedded mesh increases the frictional mechanism and produces the best performance in terms of load-bearing capacity and ductility.

This research aimed to consider the necessity of studying different dimensions of existing galleries in gravity concreted dams regarding design limitations and the dam sustainability provision. In recent years, structural optimization has been studied extensively with various considerations. Concrete volume in concrete dams is higher than in other concrete dams. Therefore, if the concrete volume of these dams can be reduced without reducing the dam safety and stability, the costs of constructing such dams could be significantly reduced. For this purpose, in this paper, the Pine Flat Gravity Dam has been selected, its numerical model has been constructed and stimulated under the Taft earthquake. There are three types of small, medium, and large size galleries in different positions. The dam reservoir and foundation in the current study have been modeled, and the foundation has been assumed to have no mass. Then the results have been examined. The innovation of this research is in identifying the most optimal shape and position of the gallery in the body of the weighted concrete dam, which is based on stress and strain responses. It can be concluded that while the medium gallery was in the middle of the dam, the optimum condition for reducing concrete was achieved by maintaining the dam stability.

Fiber-reinforced polymer (FRP) has been commonly used to reinforce concrete structures. The kinds of FRP demonstrate an effective alternative to various methods of reinforcement in concrete structures subjected to bad environmental conditions which cause corrosion and damage to concrete. Due to their lightweight, high strength, and high corrosion and fatigue resistance, Fiber Reinforced Polymer (FRP) composites have been widely applied in steel substitution during revitalization interventions. This paper presents numerical three-points bending tests on different models to investigate the effect of the reinforcements; Carbon, Glass, and Aramid fibers to find the corresponding cost of each one. Also, there is an available experimental model for verifying the results of the FEM that demonstrated broad agreement with the experimental statement, concerning the load-displacement curve. After validating the models, alternative designs such as type of the FRP, position of the FRP, and amount of the FRP usage were numerically tested to study the influence of each on the load-bearing capacity. The results showed that the best configuration would be one with GFRP and the load-bearing capacity is around 9 kN in the optimum design.