Structural Reinforcement Research Articles

Effect of Water Immersion and Freeze-Thaw Cycles on Pull-off Strength of FRP Epoxy Bonded on Concrete: An experimental study

The durability and performance of Fiber Reinforced Polymer (FRP) composites for strengthening reinforced concrete structures under various environmental conditions are critical for their long-term efficacy. This study investigates the effects of water immersion and freeze-thaw cycles on the pull-off strength of epoxy-bonded FRP concrete slabs, simulating conditions typical for waterfront structures such as piles, beams, and decks. Concrete slabs, fabricated to EN 1766 standards, were reinforced with Basalt (BFRP), Glass (GFRP), and Carbon Fiber Reinforced Polymer (CFRP) sheets using Duratek® AV21 epoxy resin. The samples were conditioned in a controlled laboratory environment (23±2°C, 50±5% RH) for 24 hours before being subjected to water immersion and freeze-thaw cycling tests. Pull-off tests, conducted per EN 1542, revealed cohesive failures in the concrete substrate. The average pull-off strength for the control samples was 3.26 N/mm² for concrete and 3.97 N/mm² for epoxy resin. Water immersion results showed a slight decrease in pull-off strength for CFRP and GFRP, by 9% and 2% respectively, while BFRP exhibited a 14% increase. Freeze-thaw cycling led to increased pull-off strength across all FRP types: 7% for GFRP, 7.3% for BFRP, and 3.75% for CFRP. The findings indicate that water immersion and freeze-thaw conditions have a marginal impact on the pull-off strength of FRP-reinforced concrete. Despite the environmental exposure, all test results remained above the required pull-off strength of 2.5 MPa, demonstrating the robustness of the FRP-concrete bond. The study supports the use of FRP composites for structural reinforcement in harsh environments, highlighting their resilience under adverse conditions. Further research is recommended to explore long-term performance and additional environmental factors to ensure comprehensive durability assessments of FRP-reinforced systems.

Steel grid-reinforced aluminum matrix composite prepared via wire-based friction stir additive manufacturing

ABSTRACT Grid-reinforced metal matrix composites featuring tailorable mechanical properties pose significant challenges to additive manufacturing due to its co-controlling reinforcement structure and interfacial formation issues. Here, a dense steel grid-reinforced aluminum matrix composite was successfully prepared by wire-based friction stir additive manufacturing. No internal defects, like porosity, grid breakage, or interface cracking, were detected, and the reinforcing grids kept a predefined orientation without deviation. A strong interfacial bonding between the deposited layers and the grid was achieved due to sufficient matrix material flow and diffusion behaviour induced by severe plastic deformation. Compared to pure aluminum, the ultimate tensile strength and flexural strength of the as-deposited composite increased by 27.1% and 41.8%, without loss of ductility, by incorporating a 12.3 vt.% of the steel grid. This work provides an efficient approach to fabricating large-scale metal matrix composites reinforced with other high-performance continuous grid, such as metal fibre and carbon fibre grid.

Experimental Investigation of Marine Soil Stabilization with Recycled Aggregates and MgO: Implications for CO<sub>2</sub> Sequestration

Dredged marine soils are increasingly recognized as a valuable resource amidst growing environmental concerns and the need for sustainable waste recycling. This study presents an innovative soil stabilization technique combining recycled aggregate (RA) and magnesium oxide (MgO), with a dual focus on enhancing soil properties and promoting carbon dioxide (CO2) sequestration. The stabilizing effects of RA and MgO were evaluated independently and synergistically under varied curing conditions and durations, with microstructural and mechanical properties analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and uniaxial tests. Carbonation experiments quantified CO2 fixation potential, demonstrating that the formation of hydration and carbonation products, in conjunction with the dynamic moisture content and pH conditions, played a significant role in enhancing the structural reinforcement of the soil. The combined RA-MgO treatment achieved superior mechanical stability (1.28-3.02 MPa) and a CO2 sequestration capacity of up to 11 g/kg without compromising performance. This study highlights the dual environmental and structural benefits of utilising RA and low-content MgO for marine soil stabilization, offering a sustainable pathway to reduce carbon emissions, promote waste recycling, and support resilient infrastructure development.

Factors Influencing the Bond Strength between FRP Bars and Concrete and the Calculation Methods for Anchorage Length

Since the 21st century, developed countries such as Japan, the United States, and Europe have designated Fiber Reinforced Polymer (FRP) as a key industry for development. Currently, FRP sheets, represented by carbon fiber fabric, have become an important material for structural reinforcement and are widely used in the renovation and reinforcement of various civil and industrial buildings. For example, in the early 1960s, the American company Marshall-Vega produced Glass Fiber Reinforced Polymer (GFRP) bars to address the issue of salt corrosion in reinforced concrete structures in coastal and cold regions. In the design of the ArtScience Museum in Singapore, to ensure the integrity and smoothness of the architectural form, facilitate prefabrication and assembly of components, and meet structural, fire safety, and security requirements, the designers evaluated various materials and ultimately selected polyethylene resin-based GFRP panels. This paper employs a literature review methodology, first analyzing the factors that affect the bond strength between FRP bars and concrete, then reviewing standards to understand the calculation methods for anchorage length in different countries, collecting relevant experimental data, and finally analyzing the advantages and disadvantages of various anchorage length calculation methods.

Advancing Structural Reinforcement in 3D-Printed Concrete: Current Methods, Challenges, and Innovations

Advancing Structural Reinforcement in 3D-Printed Concrete: Current Methods, Challenges, and Innovations

Strength Analysis and Reinforcement of 120 m3 Liquid Helium Storage Tank for Transportation Case

To ensure the safe transportation of a 120 m3 liquid hel ium storage tank, based on the analysis of its structure, material, and load characteristics, a finite element model for stress and strength analysis is established and solved by using the coupled thermo-mechanical analysis method for the accelerating and cornering cases experienced by the tank during transportation. The stress and deformation distributions in different transportation cases are analyzed in comparison to the finite element model, and the strength check is carried out for the tank. The study shows that under various working cases, the extreme value of stress of some parts is 267.5 MPa; this does not satisfy the strength requirement, and therefore requires structural reinforcement. The analysis of the reinforcing effect of the reinforcement structure shows that the stress extremes of the dangerous parts of the tanks after reinforcement decreased by 63.7% and 34.7%; the structural strength meets the standard requirements, and the new reinforcement structure only leads to an increase of 6% in the liquid nitrogen consumption of the cold screen, which is a better reinforcing effect.

Tailoring Mechanical Performance in Bulk Nanoparticle-Structured ZnO and Al₂O₃: Insights from Deep Learning Potential Molecular Dynamics Simulations

The rapid advancements in nanotechnology have created unique opportunities to manipulate material properties at the nanoscale, particularly through the design of nanoparticle-structured (NP-structured) materials. Due to their distinctive mechanical and chemical properties, materials composed of nanoparticles, such as ZnO and Al₂O₃, are of high interest for applications in structural reinforcements, electronics, and catalysis. However, accurately predicting the mechanical behavior of NP-structured materials remains a challenge. This study investigates the mechanical properties of bulk nanoparticle-structured (NP-structured) materials composed of ZnO and Al₂O₃ nanoparticles in FCC and BCC configurations. We used deep learning potentials (DLPs) derived from density functional theory (DFT) calculations to comprehensively analyze stress-strain behavior, local shear strain distributions, and elastic properties across various nanoparticle sizes and compositions. Our findings reveal that nanoparticle size and crystalline arrangement are crucial in determining the mechanical performance of these materials. Smaller ZnO nanoparticles exhibit higher yield stress, ultimate stress, and Young's modulus in both FCC and BCC configurations, attributed to their higher surface-to-volume (S/V) ratio. In contrast, larger Al₂O₃ nanoparticles demonstrated superior mechanical properties, especially in FCC configurations, due to the strong ionic bonding and effective stress distribution inherent in Al₂O₃. In ZnO/Al₂O₃ composite systems, we found that the mechanical properties could be precisely tuned by adjusting the nanoparticle size and ratio. Larger nanoparticles in FCC arrangements contributed to higher yield stress and stiffness, while smaller nanoparticles in BCC arrangements provided better overall mechanical performance. This work highlights the potential of DLPs in accurately predicting and optimizing the mechanical properties of NP-structured materials, offering valuable insights for the design of advanced materials with tailored mechanical characteristics.

Enhancing the Performance of Concrete Coupled Shearwall Using Shape Memory Alloys

ABSTRACTUtilizing self‐centering materials, such as shape memory alloys (SMA), as reinforcement in concrete structures can positively influence their performance during and after earthquakes. Despite the high cost of SMAs, their unique flag‐shaped stress–strain behavior and effective energy dissipation make them an attractive material choice in some structures. This study evaluates the application of iron‐based SMAs in enhancing the seismic performance of coupled concrete shear walls. The purpose is to identify optimal SMA placement strategies within the walls' plastic hinges to improve energy dissipation, reduce residual drift, and enhance ductility. This research explores pre‐tensioned and non‐pre‐tensioned SMA configurations through macro‐element modeling and cyclic analysis. Presenting a comparative framework that balances material efficiency and structural performance differentiates this study from prior studies focused predominantly on SMA benefits in isolated structural applications. Two optimization scenarios are proposed: maximizing energy dissipation and minimizing residual drift, and reducing SMA usage while maintaining structural efficiency. The results indicate that pre‐tensioned SMAs in the wall web provide the most significant improvement in seismic behavior, significantly reducing residual drift and increasing ductility. This approach offers a cost‐effective solution for improving earthquake resilience in structures.

Bending performance of concrete beams retrofitted with mechanochromic glass/carbon hybrid composites: Combining structural reinforcement and visual health monitoring

Bending performance of concrete beams retrofitted with mechanochromic glass/carbon hybrid composites: Combining structural reinforcement and visual health monitoring

Comparison of Reinforcement of High Rise Structure in Different Seismic Zones Using Staad Pro

Abstract: In this research design of G+10 High Rise Structure has been analyzed. The earthquake is most dangerous natural hazard in manmade structure. The demand of earthquake resisting building has been increased which can be fulfilled by providing the shear wall , Structure reinforcement and the appropriate sizing of beams and columns in the structure for resisting lateral forces. Shear walls also have high stiffness and strength which can be used to resist horizontal loads and gravity loads making useful in various structural engineering design. The study focuses on G+ 10 high rise structures located in seismic zones II, III, IV and V of India with shear walls at corners of the external walls . A Comparison of reinforcement for both flexural and compression members across different seismic zone is included . The analysis is done by using STAAD-Pro Connect Edition V22 software. The IS codes used for the analysis and designing is IS 1893 (Part-1):2016 (criteria for earthquake resistant design of structures), IS 456:2000 (plain and reinforced concrete) and SP 16: 1980 (design aids for reinforced concrete to IS : 456 )

Deterioration Behavior of Concrete Beam Reinforced with Carbon Fiber-Reinforced Plastic Rebar Exposed to Carbonation and Chloride Conditions.

The absence of carbon fiber-reinforced rebar performance standards in Korea has limited its reliability. This study investigates the durability performance of carbon fiber-reinforced polymer rebar as an alternative to traditional steel reinforcement in concrete structures. Concrete beams reinforced with carbon fiber-reinforced polymer rebar were exposed to chloride environments for durations of 35 and 70 days and then subjected to bending tests to evaluate their durability. The results demonstrate that the strong bond between the carbon fiber-reinforced polymer and concrete effectively prevented brittle fracture, even under exposure to harsh chloride. A scanning electron microscope analysis of the specimens exposed to chloride showed no deterioration of the carbon fiber-reinforced polymer rebar, highlighting its exceptional resistance to corrosion. Furthermore, durability tests were conducted in a carbonation chamber for 8 and 12 weeks, with no signs of degradation in the carbon fiber-reinforced polymer rebar. These findings suggest that carbon fiber-reinforced polymer rebar offers excellent resistance to both chloride-induced corrosion and carbonation, making it a promising solution to enhance the longevity and durability of reinforced concrete structures exposed to aggressive environmental conditions.

Study of structure and properties of steel reinforcement of a periodic profile after alternating bending with tension

Study of structure and properties of steel reinforcement of a periodic profile after alternating bending with tension

Finite Element Modeling of RC Beams Produced with Low-Strength Concrete and Strengthened for Bending and Shear with CFRP and GFRP

In this study, the analysis of reinforced concrete (RC) beams strengthened with Fiber Reinforced Polymer (FRP) composites against bending and shear loads was carried out with the finite element technique, using ABAQUS software, which is widely used in simulating experimental circumstances in numerical studies. It has been reported that buildings in areas damaged by earthquakes are generally constructed using low-strength concrete and inadequate reinforcement. Additionally, construction errors also contribute to reducing the load-bearing capacity of structural elements. For this purpose, nine rectangular cross-section RC beams were experimentally constructed using low-strength concrete and inadequate bending and shear reinforcement. These beams were strengthened by wrapping them in different configurations with Carbon and Glass FRP (CFRP and GFRP) composites to resist shear and bending forces in both transverse and longitudinal directions, and their load-displacement curves were obtained. Subsequently, a three-dimensional Finite Element Model (FEM) was created to validate the experimental results. The FEM validation demonstrated high accuracy in replicating experimental outcomes, emphasizing the influence of mesh size, dilation angle, and concrete constitutive models on simulation fidelity. Parametric studies revealed that increasing longitudinal reinforcement diameters had minimal effect on load capacity but highlighted the critical role of transverse reinforcement, as reducing stirrup spacing significantly improved load-bearing capacity. GFRP-reinforced beams exhibited superior ductility and a 15% higher strength compared to CFRP, suggesting their suitability for applications demanding enhanced displacement capacity. Furthermore, the findings underline the need for refined FEM models to better capture inclined fiber orientations and optimize structural reinforcement strategies.

Leaf traits and insect herbivory levels in two Mediterranean oaks and their hybrids through contrasting environmental gradients.

Insect herbivory has attracted enormous attention from researchers due to its effects on plant fitness. However, there remain questions such as what are the most important leaf traits that determine consumption levels, whether there are latitudinal gradients in herbivore pressure, or whether there are differences in susceptibility between hybrids and their parental species. In this work we address all these issues in two species of Mediterranean Quercus (Q. faginea and Q. pyrenaica) and their hybrids. Over two years, we analyzed leaf emergence and 11 leaf traits (biomechanical, chemical and morphological), as well as the levels of herbivory by insects in leaves of the three genetic groups in different locations distributed along a climatic gradient. The hybrids showed intermediate values ​​between both species in leaf emergence, chemical traits and in structural reinforcement. By contrast, they were more similar to Q. faginea in leaf size and shape. Despite their intermediate leaf traits, hybrids always showed lower losses by consumption than both parental species, which suggests that they possess inherent higher resistance to herbivores, which cannot be explained by their dissimilarities in leaf traits. Within each genetic group, differences in leaf size were the most important determinant of differences in herbivory losses, which increased with leaf size. In turn, leaf size increased significantly with the increase in mean annual temperatures across the climatic gradient, in parallel with herbivory losses. In conclusion, contrary to our expectations, hybrids maintained lower levels of herbivory than their parent species. Given the potential negative effect of leaf herbivory on C fixation, this advantage of the hybrids would imply a threat to the persistence of both pure species. More research is needed to elucidate possible alternative mechanisms that allow maintaining species integrity in the absence of reproductive barriers.

Models of ecological renovation of industrial buildings for the creation of shopping, entertainment or recreational complexes

The article examines the key features of the functional planning and spatial architectural treatment of the typological group of public buildings and structures during renovation of industrial buildings in coastal areas in order to create promising models of two different types of multifunctional spaces: a shopping and entertainment complex, and a public park. Both approaches exploit the structural and spatial advantages of these buildings and modern architectural-ecological techniques, such as: adaptive reuse, structural reinforcement, and integration of natural light and environmentally friendly materials. The key differences lie in their focus: shopping and entertainment centers emphasize commercial activities and leisure through a dynamic shopping environment, while public parks give preference to green areas and outdoor recreation, integrating extensive landscape design and environmental sustainability methods into the project. Overall, these renovation models not only improve the urban environment, but also contribute to the well-being of the population and restoration of the environment in the area.

Mixed DAMP/MAMP oligosaccharides promote both growth and defense against fungal pathogens of cucumber.

Plants recognize a variety of environmental molecules, thereby triggering appropriate responses to biotic or abiotic stresses. Substances containing microbes-associated molecular patterns (MAMPs) and damage-associated molecular patterns (DAMPs) are representative inducers of pathogen resistance and damage repair, thus treatment of healthy plants with such substances can pre-activate plant immunity and cell repair functions. In this study, the effects of DAMP/MAMP oligosaccharides mixture (Oligo-Mix) derived from plant cell wall (cello-oligosaccharide and xylo-oligosaccharide), and fungal cell wall (chitin-oligosaccharide) were examined in cucumber. Treatment of cucumber with Oligo-Mix promoted root germination and plant growth, along with increased chlorophyll contents in the leaves. Oligo-Mix treatment also induced typical defense responses such as MAP kinase activation and callose deposition in leaves. Pretreatment of Oligo-Mix enhanced disease resistance of cucumber leaves against pathogenic fungi Podosphaera xanthii (powdery mildew) and Colletotrichum orbiculare (anthracnose). Oligo-Mix treatment increased the induction of hypersensitive cell death around the infection site of pathogens, which inhibited further infection and the conidial formation of pathogens on the cucumber leaves. RNA-seq analysis revealed that Oligo-Mix treatment upregulated genes associated with plant structural reinforcement, responses to abiotic stresses and plant defense. These results suggested that Oligo-Mix has beneficial effects on growth and disease resistance in cucumber, making it a promising biostimulant for agricultural application.

A problem without a cause: Framing the agenda within sport for development organisations

Critical examinations of the sport for development (SfD) field have highlighted concerns related to an emphasis on individual-level solutions and outcomes and the reinforcement of current neoliberal power structures. As such, the purpose of this paper is to investigate how SfD organisations use their annual reports to frame social problems, define the causes of those problems, the role of sport in crafting solutions to development problems, and make moral judgements related to their work in the SfD sector. Using framing theory as a framework, a qualitative content analysis of the annual reports from 2019 to 2021 of five prominent SfD organisations was conducted. The researchers used an open coding methodology to develop a codebook based on the four functions of framing: defining problems, identifying causes, determining solutions, and making moral judgements. The analysis revealed a lack of consistent salience of social problems except for the COVID-19 pandemic. The causes for these problems were largely ignored within the annual report documents; instead, organisations focused on the solutions they were working to implement. Solutions were framed primarily through the expansion or continuance of their active programming, bolstering the claim that their active SfD efforts are working.

Experimental research of the tensile strength of concrete reinforced with basalt fiber

Non-metallic composite fittings are increasingly used in modern construction due to their high mechanical characteristics, corrosion resistance, durability in concrete and aggressive external environments, and other properties. At the sametime, usually, non-metallic composite reinforcement is used in the form of rods with the main supporting element in the form of basalt, glass, aramid or roving made of other materials, which is thin fibers with a diameter of 7...20 mm.The specified roving, as an element of reinforcement of concrete structures, will be used in the form of fiber to a much lesser extent, although it is a real alternative to traditional steel fiber with all the advantages of fiber reinforcement, to which corrosion resistance is also added. The limited number of experimental explains the current situation andtheoretical studies of non-metallic fiber reinforcement, in particular, tensile strength, which is one of the main advantages of fiber reinforcement of concrete.This article presents the results of experimental studies of the tensile strength of concrete reinforced with fiber from basalt roving with a diameter of 16 μm and a length of 24 mm, which included bending tensile tests of three series of concrete samples with a strength class of compression, respectively, C20/25, C25/30, C30/35 and percentage of fiber reinforcement within 2.0...8%.As a result of the conducted research, it was established that the fiber reinforcement from the baseboard roving leads to an increase in the axial tensile strength of concrete. At the same time, the most intensive increase in tensile strength took place when the percentage of reinforcement was increased in the range of 2.0...4.0%. With a further increase in the percentage of reinforcement in the range of 6.0...8.0%, this growth stopped, which indicates that fiber reinforcement in the range of 2.0...4.0% is the most effective, regardless of the class of concrete in terms of compressive strength.Other things being equal, the increase in axial tensile strength of concrete with an increase in the percentage of fiber reinforcement within the limits of 2.0...8.0% is 15...20% compared to concrete without reinforcement.

3D PRINTING TECHNOLOGY FOR MONOLITHIC BEAMS WITH THE POSSIBILITY OF REINFORCING BARS

The integration of 3D printing technology in construction has the potential to reduce costs and accelerate the construction and installation processes. While this technology is gaining global attention, Ukraine currently lacks regulations governing the design and construction of structures using 3D printing. Additionally, there is a limited experimental base regarding the bearing capacity and deformability of printed structures. This publication proposes a methodology for the production of monolithic beams reinforced with single bars using a construction 3D printer. It outlines the entire process of manufacturing, from the design phase to product fabrication and readiness for experimental research. To carry out the research, the design of the beams was first created using graphic software systems, which facilitated the formulation of tasks for a construction-grade 3D printer, considering the capabilities of this technology. Design and production drawings of the samples are included in this publication. The reinforced monolithic beams were printed using a construction 3D printer by the Ukrainian company 3D TECHNOLOGY UTU LLC, following the developed work algorithm. This methodology enabled the reinforcement of structures with single bars, in compliance with regulatory requirements, while allowing for future experiments. As a result of this work, reinforced monolithic beams were successfully printed using the developed technology. To assess the physical and mechanical characteristics of the materials, samples of cubes and prisms were printed and cast into formwork. Additionally, reinforcement samples were created from the same batch used to reinforce the beams. The proposed technology for producing beams with a 3D construction printer resulted in structures that adhered to previously established design solutions. The detailed sequence for printing beams allowed for effective reinforcement of monolithic beams with single bars.

Development of a Modular Sandwich Panel with a Composite Core of Recycled Material for Application in Sustainable Building.

In recent years, the construction industry has faced challenges related to rising material costs, labor shortages and environmental sustainability, resulting in an increased interest in modular construction cores composed of recycled materials, such as XPS, PUR, PLW and GFRP, from waste from the truck body industry. Two resins, PUR and polyester, were used to bond these recycled composites. Physical, chemical and mechanical analyses showed that the panels formed with PUR resin had superior workability due to the higher open time of the resin, 11.3% better thermal conductivity than the commercial PLW panel (SP-PLW) and reduced porosity compared to those using polyester resin. The mechanical performance of the panels improved with higher structural reinforcement content (PLW and GFRP). Compared to a commercial panel (SP-PLW), the SP-RCM1 recycled panel showed 4% higher performance, demonstrating its potential for sustainable building applications. Thermal and microscopic characterizations showed good adhesion of the materials in the best performing formulations related to higher thermal stability. Therefore, this research aims to demonstrate the feasibility of using waste from the car industry in the manufacture of sandwich panels for modular construction to address these issues.