The effectiveness of concrete confinement by fiber-reinforced polymer (FRP) materials is highly influenced by the orientation of fibers in the FRP laminates. In general, acceptable deviation limit from the intended direction is given as 5° in most design guidelines, without solid bases and reasoning. In this paper, a numerical study using finite element modeling was conducted to assess the effects of small deviations in fiber orientation from the hoop direction on compressive behavior of concrete cylinders confined with FRP. Different fiber angles of 0°, 2°, 5°, 8°, 10° and 15° with respect to hoop direction, unconfined concrete compressive strengths of 20, 35 and 50 MPa, FRP thicknesses of 0.2, 0.5 and 1.0 mm and FRP moduli of elasticity of 50 and 200 GPa were considered. The results showed that total dissipated energy ($E_t$), ultimate axial strain (${\epsilon }_{cu}^{\prime }$) and compressive strength ($f_{cu}^{\prime }$) exhibited the most reduction with deviation angle. For 5° deviation in fiber orientation, the average reduction in $f_{cu}^{\prime }$, ${\epsilon }_{cu}^{\prime }$ and $E_t$ were 2.4%, 2.8% and 4.5%, respectively. Furthermore, the calculated allowable limit of deviation in fiber orientation for a 2.5% reduction in $f_{cu}^{\prime }$, ${\epsilon }_{cu}^{\prime }$ and $E_t$ were 6°, 3° and 2°, respectively, with a 95% confidence.

This article serves as a review of the current challenges in bridge engineering, specifically addressing the transition effect and the utilization of recycled materials. It aims to identify research gaps and propose innovative approaches, paving the way for future experimental studies. As a review article, the authors critically analyze the existing literature on the transition effects in bridge construction, their causes, and their negative impacts. Integral bridges are discussed as a solution designed to work in conjunction with road or rail embankments to transfer loads, minimizing maintenance and construction costs while increasing durability. Particular attention is given to the potential use of modified plastic composites as an alternative material in integral bridge structures. This concept not only addresses the issue of plastic waste but also promotes the long-term use of recycled materials, a key consideration given recycling limitations. This article highlights the importance of the connection between the embankment and the abutment and provides examples of polymer applications in bridge engineering. By outlining the state of the art, this review identifies future development paths in this niche, but promising, field. Almost 240 literature items were analyzed in detail, and works containing 475 different key words contained in about 3500 individual works were used for scientometric analysis. The results of the analysis clearly indicate the novelty of the presented subject matter.

W artykule omówiono recykling opakowań PET, podkreślając jego znaczenie w gospodarce obiegu zamkniętego. Przedstawiono metody przetwórstwa odzyskanego materiału i jego potencjalne zastosowania w różnych sektorach gospodarki. Wykazano znaczenie zasady 6R w integracji gospodarki i promowaniu zrównoważonego rozwoju.

This article provides an in-depth review of selected technical chains, with particular emphasis on link chains and their load transmission mechanisms. It explores structural and functional characteristics, highlighting how chain geometry affects stress distribution, fatigue life, and performance under various loading conditions. The study includes a detailed classification of chains by type, material, and application, ranging from steel-based lifting and transport chains to lightweight, corrosion-resistant polymer types. Manufacturing methods and connection techniques are also discussed, underscoring the importance of proper assembly for mechanical reliability. Special attention is given to the role of materials, particularly the emergence of polymer composites reinforced with glass or carbon fibers, which offer promising alternatives to conventional metals. Although such composites exhibit advantageous properties—such as low weight, corrosion resistance, and energy efficiency—their application remains limited, insufficient load-bearing capacity, and the absence of standardized design guidelines. The review identifies critical knowledge gaps in the field, especially concerning shaping, dimensioning, and normative requirements for polymer-based load-bearing chains. It also highlights the lack of focused research on chain-specific geometries and the need for numerical simulations to optimize link design. The article concludes by emphasizing the importance of developing sustainable, durable, and standardized chain systems—particularly those utilizing recycled or novel materials—to meet both technical demands and environmental goals. This work supports future innovation in the design of advanced chain structures and provides a foundation for expanding the use of high-performance composites in civil and urban engineering applications.

In the article, the authors presented the problem of the transition effect in bridge engineering, its causes, negative consequences, and suggested a solution involving the use of integral bridges with the embankment through a spatial bars structure using reinforced composite polymer material. Integral bridges are designed to collaborate with road or railway embankments in bearing loads. Additionally, their application minimizes maintenance and construction costs while enhancing durability. Current solutions in bridge engineering were described. It is predicted that the presented concept will reduce the amount of plastic waste and contribute to the long-term use of materials. The article emphasized the importance of sustainable development, recycling, and the potential application of substitute materials.