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Natural fiber-based composites become more popular as the demand for lightweight, high-strength materials for specialized applications grows. Moreover, natural fiber-based composites have greater durability, stiffness, and damping resistance. Researchers developed a wide variety of composites for different applications. This study aims to develop a hybrid composite using Acacia arabica and Sida cordifolia fibers as a reinforcement and epoxy as a resin. The fibers were treated using 5% NaOH solution. Six samples were prepared by varying the proportion of fibers and resin. The performance of the composites was measured by conducting the tensile, flexural, impact, and hardness tests. The alkaline-treated sample with 70% fiber and 30% resin (S6) exhibits a greater tensile strength of 384 MPa which shows much improvement in tensile strength when compared to other samples. The mechanical properties of the hybrid composites are better than many other composites available in literature. The surface morphological analysis and water absorption tests were also carried out. [ABSTRACT FROM AUTHOR]

AbstractThis study used human DNA structure to inspire an innovative design concept. Mechanical testing assessed how design parameters and thermal shock cycles affected it. As thermal shock cycles increase, material characteristics decrease. After sixty thermal shock cycles, tensile and flexural strengths dropped 43.33% and 35.90%, respectively. DNA structures had a better strength-to-weight ratio than solids. After 60 thermal shock cycles, 2 mm ribs, straight ribs, and hexagonal honeycomb ribs had higher tensile and flexural strengths of 9.42 and 20.76 MPa, respectively. [ABSTRACT FROM AUTHOR]

This paper was aimed to study the mechanical properties of Istle fibre composites. The process of fabrication was done by hand layup technique at three different fibre orientations i.e., unidirectional, bidirectional and 45 degrees inclined, and also its effect on tensile and flexural property that was studied in the Instron Testing Machine. The fibre volume ratio was kept uniform for the entire specimen as 50:50. The treatment of istle fibre was done with sodium hydroxide to increase the fibre matrix bonding. The effect of E-glass reinforcement has also been studied in both bending tests and flexural tests. The maximum tensile and bending modulus recorded were from unidirectional fibre specimen. [ABSTRACT FROM AUTHOR]

This article proposes a 6061‐T6 Al alloy and carbon fiber hybrid composite material pre‐curing and forming integrated new process, which can significantly reduce the hybrid composite material processing time, improve the production efficiency, and provide the possibility of hybrid composite materials in automotive parts applications. The process started by placing hand‐stacked carbon fiber reinforced plastic (CFRP) composites on the surface of 6061 Al alloy sheets, followed by bonding and pre‐curing of the CFRP to the Al alloy sheets through two different sets of dies in a hydraulic press, and ultimately full curing in an aging furnace. Mechanical properties of the CFRP/Al hybrid composite material were measured by flexural tests. The results show that the flexural strength of CFRP/Al hybrid composites with different layups ([90]12, [0/45/90/−45]3, and [0]12) was increased by 159%, 93.4%, and 67.9%, respectively, compared with the single 6061 Al alloy. According to the macro‐morphological observation, [90]12 lay‐up parts have the least thinning. According to the microstructure observation, no obvious cracks or voids were found in the [90]12 lay‐up parts. Elongated cracks and void defects could be found in the [0]12 lay‐up parts. For the [0/45/90/−45]3 lay‐up parts, voids are mainly exist in ±45°layups. The results of the spring‐back analysis show that the standard deviation of the formed parts obtained from the three lay‐up methods is within 1 mm, indicating that the forming effect is good. Highlights: New process improves productivity and reduces production costsThe flexural strength of CFRP/Al hybrid parts is greatly improved[90]°12 lay‐up parts have the least thinning and no cracks were foundThe forming precision of the three lay‐up parts is good [ABSTRACT FROM AUTHOR]

Many problems may occur during constructing the reinforced concrete structures during the implementation process, so this study has focused on one of the problems that often occur during implementation, especially in large buildings where these building needs to pump large quantities of concrete at one time, and this is often not possible, so it creates an interface between the old and new concrete is called a construction joint. Also, large areas need reinforcement of large lengths, and here we will need reinforcement splices to obtain the required lengths. Many studies examine these two problems separately, but few of them mean studying them together, that is, the construction joint occurs at the area of reinforcement splices. Therefore, this study dealt with an experimental program from nine concrete beams reinforced with steel to study the structural performance of reinforced concrete elements in the presence of a construction joint (having various interfaces 45º inclined and L-shaped), with reinforcement splice of three different lengths. The results showed that the presence of a construction joint with a reinforcement splice of sufficient appropriate splice length reduced the load capacity by 37% for the inclined joint beam while an insufficient splice length of 180 mm reduced the load capacity by 59% compared to the reference. It is shown that concrete beams lose their ductility in the presence of the construction joint at the splice reinforcement splice reinforcement region. Also, it should be considered the outcome of this study when designing mega-reinforced concrete structures. [ABSTRACT FROM AUTHOR]

The gyroid structure is a bio-inspired structure that was discovered in butterfly wings. The geometric design of the gyroid structure in butterfly wings offers a unique combination of strength and flexibility. This study investigated sandwich panels consisting of a 3D-printed gyroid structure core and carbon fiber-reinforced polymer (CFRP) facing skin. A filament fused fabrication 3D printer machine was used to print the gyroid cores with three different relative densities, namely 10%, 15%, and 20%. Polylactic acid (PLA) was used as the printing material for the gyroid. The gyroid structure was then sandwiched and joined by an epoxy resin between CFRP laminates. Polyurethane foam (PUF) was filled into the gyroid core to fill the cavity on the core for another set of samples. Flexural and compression tests were performed on the samples to investigate the mechanical behavior of the sandwiches. Moreover, the two-parameter Weibull distribution was used to evaluate the results statistically. As a result, the sandwich-specific facing stress and core shear strength from the three-point bending test of the composites increased with the increase in sandwich density. Core density controls the flexural characteristics of the sandwich. Adding PUF improves the deflection at the maximum stress and the sustained load after fracture of the sandwich. Compression strength, modulus, and energy absorbed by gyroid core sandwiches and their specific properties are higher than the PUF-filled gyroid core sandwiches at equal sandwich density. [ABSTRACT FROM AUTHOR]

Featured Application: Additive manufacturing is frequently used in industries that require the manufacturing of special parts, such as aerospace, automotive, medical, and situations where the produced parts need to be connected to each other. This study provides experimental data for integrating fasteners into additive manufactured parts, and the results will guide the design and optimization of the assembly of these parts. This study aims to investigate common fastener implementation methods for parts manufactured with Fused Deposition Modeling (FDM). Although fastener applications for FDM manufactured parts are already in use, the effects of these methods on tensile and bending forces have not been examined. Test samples with different design techniques and infill ratios were produced using Polylactic Acid (PLA), and tensile strength and flexural and tightening torque tests were performed. Four of the of the most preferred fastener applications were studied. Two of the applications use a heat-set insert, and the other two applications use square nuts. Test samples were designed for the applications and printed with three different infill ratios. The production times and material consumption for these different applications were explained and evaluated. Different drawbacks and advantages were investigated for different applications. It has been observed that the strength of the basic heat-set inserts depends on the surface adhesion and is less affected by the filling rate. Advanced heat-set inserts adhere better to the surface, so the infill ratio is the determining factor in strength. The embedded nut methods depend on the infill ratio up to a certain load. As the load increases, the influence of wall thickness becomes increasingly evident. These findings not only contribute to enhancing structural integrity but also offer invaluable insights into optimizing connection methods for diverse applications. [ABSTRACT FROM AUTHOR]

The use of Atmospheric Pressure Plasma Jet (APPJ) technology for surface treatment of carbon fabrics is investigated to estimate the increase in the fracture toughness of carbon-fiber composite materials. Nitrogen and a nitrogen–hydrogen gas mixture were used to size the carbon fabrics by preliminarily optimizing the process parameters. The effects of the APPJ on the carbon fabrics were investigated by using optical and chemical characterizations. Optical Emission Spectroscopy, Fourier Transform Infrared-Attenuated Total Reflection, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy were adopted to assess the effectiveness of ablation and etching effects of the treatment, in terms of grafting of new functional groups and active sites. The treated samples showed an increase in chemical groups grafted onto the surfaces, and a change in carbon structure was influential in the case of chemical interaction with epoxy groups of the epoxy resin adopted. Flexural test, Double Cantilever Beam and End-Notched Flexure tests were then carried out to characterize the composite and evaluate the fracture toughness in Mode I and Mode II, respectively. N2/H2 specimens showed significant increases in GIC and GIIC, compared to the untreated specimens, and slight increases in Pmax at the first crack propagation. [ABSTRACT FROM AUTHOR]

This article is focused on the experimental study of flexural properties in different multi-layer carbon fiber-reinforced polymer (CFRP) composites and correlations with the results of finite element method (FEM) simulations of mechanical properties. The comparison of the results shows the possibility of reducing the number of experimental specimens for testing. The experimental study of flexural properties for four types of carbon fiber-reinforced polymer matrix composites with twill weaves (2 × 2) was carried out. As input materials, pre-impregnated carbon laminate GG 204 T and GG 630 T (prepreg) and two types of carbon fiber fabrics (GG 285 T and GG 300 T (fabric)) were used. Multi-layer samples were manufactured from two types of prepregs and two types of fabrics, which were hand-impregnated during sample preparation. The layers were stacked using same orientation. All specimens for flexural test were cut with the longer side in the weft direction. Pre-impregnated carbon laminates were further impregnated with resin DT 121H. Carbon fabrics were hand-impregnated with epoxy matrix LG 120 and hardener HG 700. To fulfill the aim of this research, finite element method (FEM)-based simulations of mechanical properties were performed. The FEM simulations and analysis were conducted in Hexagon's MSC Marc Mentat 2022.3 and Digimat 2022.4 software. This paper presents the results of actual experimental bending tests and the results of simulations of bending tests for different composite materials (mentioned previously). We created material models for simulations based on two methods—MF (Mean Field) and FE (Finite Element), and the comparative results show better agreement with the MF model. The composites (GG 285 T and GG 300 T) showed better flexural results than composites made from pre-impregnated carbon laminates (GG 204 T and GG 630 T). The difference in results for the hand-impregnated laminates was about 15% higher than for prepregs, but this is still within an acceptable tolerance as per the reported literature. The highest percentage difference of 14.25% between the simulation and the real experiment was found for the software tool Digimat FE 2022.4—GG 630 T composite. The lowest difference of 0.5% was found for the software tool Digimat MF 2022.4—GG 204 T composite. By comparing the results of the software tools with the results of the experimental measurements, it was found that the Digimat MF 2022.4 tool is closer to the results of the experimental measurements than the Digimat FE 2022.4 tool. [ABSTRACT FROM AUTHOR]

In this study, 0, 0.5 and 2 wt% hexagonal boron nitride (hBN) were added to 30 wt% short glass fiber reinforced polyamide 66 (PA 66) matrix (GF30) to fabricate the thermoplastic composite materials. The hBN additives were applied by coating of granules of GF30 materials. The hBN coated thermoplastic materials were produced by plastic injection method. The effect of various weight percentages of hBNs on the flexural properties of thermoplastic composites were examined in the produced samples. The produced samples were subjected to three-point bending tests. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were used to analyse structural and physical properties of the composites. The highest enhancement of flexural properties was obtained from the sample of PA 66/GF30/2% hBN. The samples with 2 wt% hBN showed the best flexural properties with an improvement of 85 and 52% flexural modulus and strength, respectively, compared to the samples without hBN (PA 66/ GF30). According to the obtained results of this study, as the percentage of the hBN weight contents increased, the flexural strengths and flexural modulus increased significantly. It was concluded that hBN coated thermoplastic composite samples demonstrated high improvements for flexural properties at optimum rates of hBN. [ABSTRACT FROM AUTHOR]

A new type composite dowel shear connector was proposed by introducing folded angles in the steel dowels. Four push-out specimens and two composite beam specimens were designed and experimentally studied. The structural behavior and failure mechanism of the composite folded dowel shear connection were investigated. The concrete failure was observed in both push-out and flexural tests, and the folded steel dowels were capable of yielding development. It is found that the bearing capacity and shear stiffness of the specimens with denser spacing dowels were higher than that of specimens with sparser dowels, but the ductility and deformation performance of the specimens with denser spacing dowels were lower than those with sparser dowels. By means of the finite element model simulation, the influence of strength and thickness of concrete slab, strength, thickness and folded angle of steel dowel on the mechanical properties of folded dowel shear connection were analysed. The folded angle could be determined as 20° because of the larger actual effective shear area and bearing capacity. Based on the bearing capacity analysis in terms of the three likely failure modes, such as steel failure, concrete shear failure and concrete pry-out, calculation formula of the shear bearing capacity of the folded dowel shear connection was put forward and verified. The calculated results by the proposed formula were in good agreement with the test results. For the composite beams, the calculated bending moments derived from the transformed section and the plasticity section methods were also in good agreement with the test values. It is suggested that the shear connection degree should be greater than 1 to enable a full composite beam. [ABSTRACT FROM AUTHOR]

Green composites, renowned for their biodegradable and recyclable attributes, have recently gained substantial prominence. Their sustainability, eco-friendliness, and lightweight characteristics position them as a compelling alternative to conventional plastic-based materials. This study delves into the mechanical performance, encompassing tensile, flexural, and Charpy impact test properties, of jute and flax thermoplastic composite laminates. Additionally, it explores the flexural behavior of sandwich composites reinforced with jute and flax fabrics individually. To accomplish this, we manufactured various composite laminates, including jute/PP, flax/PP (64.2 % fiber mass fraction), flax/PP (45.0 % fiber mass fraction), and plasma-treated flax/PP (PTF/PP) composite laminates using compression molding techniques. We also crafted sandwich composites by integrating flax and jute natural fabrics as reinforcements into a polypropylene (PP) matrix for the sandwich surface layer, along with recycled polyethylene terephthalate (PET) foam as the core material. This allowed for a comprehensive comparative analysis of their functional properties. In addition to mechanical testing, the differential scanning calorimetry (DSC) analysis was conducted on various composite laminates to evaluate the crystallinity levels and melting behavior of PP within these diverse formulations. Further characterizations included Fourier transform infrared (FTIR) spectroscopy and digital imaging analysis. Our experimental results unequivocally demonstrated the superior performance of Flax/PP composite laminates over Jute/PP composite laminates in terms of flexural, tensile, and impact properties. In the context of sandwich composites, Flax/PP/PET foam exhibited the highest force resistance, along with superior bending strength and modulus when compared to Jute/PP/PET foam. Notably, Jute/PP/PET foam displayed a higher incidence of delamination and breakage. Interestingly, both sandwich composites demonstrated nearly identical properties in the impact test. Furthermore, plasma treatment of flax composite laminates had a beneficial effect on specific mechanical properties, leading to an 8.6 % enhancement in flexural strength (54.09 MPa) compared to the performance of flax/PP (45.0 % fiber mass fraction) laminate.

Underprivileged people in many parts of Asia, Africa, Europe, and Latin America use earthen dwellings because of environmental and economic advantages. However, such non-engineered structures often encounter unacceptable risks from various natural calamities such as earthquakes, floods, etc. The 3rd January 2017 moderate earthquake in Tripura (NE India) is prime evidence of severe damage to earthen houses in rural Tripura. The present research focuses on enhancing the seismic strength of traditional earthen houses through mechanical stabilization with locally available low-cost sustainable natural fibers (i.e., jute and straw) and stabilizing materials (i.e., clay and lime), respectively. Primarily, the shear and flexural strength of both stabilized and unstabilized model rammed earthen wallettes are investigated experimentally. Thereafter, a 3D finite element (FE) numerical model is developed to verify the sanctity of the experimental findings. The study reveals that fiber-reinforced earthen wallettes, especially jute fiber-reinforced wallettes, exhibited significant improvement in shear and flexural strength including ductility behaviour whereas, clay and lime-stabilized wallettes offered improvement in strength exhibiting brittle failure. Finally, the seismic response of a prototype fiber-reinforced rammed earth wall is evaluated through 3D FE-based numerical modelling considering the input motion of the 2017 Tripura earthquake which also indicated significant improvement compared to the unimproved one. However, from the viewpoint of sustainability, it is concluded that carbon emissions of approx. 38% may be reduced in the case of natural fibers such as jute and straw compared to synthetic stabilizing agents (i.e., lime). Hence, the study promotes the use of low-cost sustainable fibers with a lower carbon footprint and minimum energy consumption in earthen houses. [ABSTRACT FROM AUTHOR]

Precast pile technology is gaining popularity in the construction industry, particularly for deep foundation pits (DFPs). However, challenges persist in achieving optimal force performance and construction efficiency in connecting methods. In this study, we present a novel socket joint design including first and second level connectors, enabling robust connections and efficient installation. A comprehensive large-scale experiment unraveled the joint flexural behavior, exposing an eastic stage dominating over 70% of the process. During loading, bolt pin slippage induced extrusion on the upper and lower flange slabs, leading to yielding and substantial deflection, ultimately surpassing the load-bearing capacity of the joint. Lower bolt pins exhibited apparent shear failure, attributed to their interaction with the lower flange slab. Based on experimental results, the calculation for flexural performance is presented. Furthermore, finite element analysis elucidated the internal forces and deformation characteristics at various stages. Stress redistribution in and around the pins in the tension zone of the joint is an important aspect of joint load failure. These findings highlight the potential of the socket joint in overcoming limitations associated with conventional connecting methods in precast pile technology.

Abstract Accelerated bridge construction (ABC) has many advantages for bridge construction in modern society. While for ABC, the post-cast joint is always the weakest and most critical part. This paper presents a UHPC rhombus-strip-shaped (RSS) joint suitable for ABC. Several model tests were carried out to verify its resistance to flexural and shear. First, large-scale model tests are advanced to confirm its flexural properties. The results show that densified and welded joint interface rebars can significantly improve the ultimate bearing capacity and durability-based cracking stress of the RSS joint beams, and the ultimate bearing capacity can reach 90% of the complete beam. Then the shear-resistance tests were carried out. The results show that the UHPC RSS joint beam has excellent bending-shear mechanical properties and better ductility. Lastly, the ultimate flexural bearing capacity and shear-resistance capacity calculation methods were obtained.

Development of competent composite beam systems has been fostered by the steel industry for structural efficiency. Current flexural design methods were developed primarily for conventional composite systems using a wide-flange section. Posed configuration is characterized by angle shear connectors welded to U-shaped cold-formed steel beams. For verification of code compliance, this study performed 12 composite beam flexural tests. Test parameters considered angle shear connector direction, spacing, and concrete strength. Based on experimental and analytical results, flexural strength prediction by international standards as well as an angle anchor design equation were evaluated. Ensuing thoughts and discussion pertain to the effects of neutral axis depth and partial composite behavior. Findings were deemed beneficial in development of design methods for the posed system. To develop design methods for the posed system, a simplified flexural response analysis model, which relies on just shear connector strength without an exact interfacial shear-slip relationship information, is proposed. [ABSTRACT FROM AUTHOR]

The present study was conducted to clarify the flexural behaviors of the Composite Girders of a Prestressed Segmental Ultra-High-Performance Concrete (UHPC) Channel and a Reinforced Conventional Concrete Deck (PSUC-RCCD). The girders can be used as bridge superstructures with the advantages of structural efficiency, cost-effectiveness, and easy construction. A total of five specimens were tested. Three of them were PSUC-RCCD specimens, including two semi-segmental girders (the channel beams were composed of five segments with dry-joints) and one integral girder (the channel beams were integral ones without dry-joints). The two other specimens were P-UHPC girders composed of PSUC and UHPC deck slabs; one was semi-segmental and the other was integral. The flexural behaviors of the specimens were investigated, including the load-displacement curves, crack distribution, cracking moments, and ultimate flexural capacity. The study compared the influence of the segment number and deck material on the flexural behaviors of semi-segmental girders and introduced and validated methods for calculating the cracking moment and flexural capacity of both semi-segmental and integral sections in PSUC-RCCD and P-UHPC girders. The results show that the entire loading process of all the specimens can be classified into the elastic phase, the cracks development phase, and the failure phase. Compared to the integral girders, the number of segments has little effect on the flexural behavior of the semi-segmental girders, but it has a significant effect on the cracking moments. The cracking moments of the semi-segmental girders is only 0.58~0.60 of the integral girders. Reducing the strength of the deck slab by changing the material from UHPC to CC does not significantly affect their flexural behaviors. Based on the test results, this work proposes a method for predicting the cracking moment and flexural capacity of the semi-segmental girders, the results of which fit well with the test results, and it is applicable in the structural design of such members. [ABSTRACT FROM AUTHOR]

Accelerated bridge construction (ABC) has many advantages for bridge construction in modern society. While for ABC, the post-cast joint is always the weakest and most critical part. This paper presents a UHPC rhombus-strip-shaped (RSS) joint suitable for ABC. Several model tests were carried out to verify its resistance to flexural and shear. First, large-scale model tests are advanced to confirm its flexural properties. The results show that densified and welded joint interface rebars can significantly improve the ultimate bearing capacity and durability-based cracking stress of the RSS joint beams, and the ultimate bearing capacity can reach 90% of the complete beam. Then the shear-resistance tests were carried out. The results show that the UHPC RSS joint beam has excellent bending-shear mechanical properties and better ductility. Lastly, the ultimate flexural bearing capacity and shear-resistance capacity calculation methods were obtained. [ABSTRACT FROM AUTHOR]

This study aims to investigate common fastener implementation methods for parts manufactured with Fused Deposition Modeling (FDM). Although fastener applications for FDM manufactured parts are already in use, the effects of these methods on tensile and bending forces have not been examined. Test samples with different design techniques and infill ratios were produced using Polylactic Acid (PLA), and tensile strength and flexural and tightening torque tests were performed. Four of the of the most preferred fastener applications were studied. Two of the applications use a heat-set insert, and the other two applications use square nuts. Test samples were designed for the applications and printed with three different infill ratios. The production times and material consumption for these different applications were explained and evaluated. Different drawbacks and advantages were investigated for different applications. It has been observed that the strength of the basic heat-set inserts depends on the surface adhesion and is less affected by the filling rate. Advanced heat-set inserts adhere better to the surface, so the infill ratio is the determining factor in strength. The embedded nut methods depend on the infill ratio up to a certain load. As the load increases, the influence of wall thickness becomes increasingly evident. These findings not only contribute to enhancing structural integrity but also offer invaluable insights into optimizing connection methods for diverse applications.

This article is focused on the experimental study of flexural properties in different multi-layer carbon fiber-reinforced polymer (CFRP) composites and correlations with the results of finite element method (FEM) simulations of mechanical properties. The comparison of the results shows the possibility of reducing the number of experimental specimens for testing. The experimental study of flexural properties for four types of carbon fiber-reinforced polymer matrix composites with twill weaves (2 × 2) was carried out. As input materials, pre-impregnated carbon laminate GG 204 T and GG 630 T (prepreg) and two types of carbon fiber fabrics (GG 285 T and GG 300 T (fabric)) were used. Multi-layer samples were manufactured from two types of prepregs and two types of fabrics, which were hand-impregnated during sample preparation. The layers were stacked using same orientation. All specimens for flexural test were cut with the longer side in the weft direction. Pre-impregnated carbon laminates were further impregnated with resin DT 121H. Carbon fabrics were hand-impregnated with epoxy matrix LG 120 and hardener HG 700. To fulfill the aim of this research, finite element method (FEM)-based simulations of mechanical properties were performed. The FEM simulations and analysis were conducted in Hexagon’s MSC Marc Mentat 2022.3 and Digimat 2022.4 software. This paper presents the results of actual experimental bending tests and the results of simulations of bending tests for different composite materials (mentioned previously). We created material models for simulations based on two methods—MF (Mean Field) and FE (Finite Element), and the comparative results show better agreement with the MF model. The composites (GG 285 T and GG 300 T) showed better flexural results than composites made from pre-impregnated carbon laminates (GG 204 T and GG 630 T). The difference in results for the hand-impregnated laminates was about 15% higher than for prepregs, but this is still within an acceptable tolerance as per the reported literature. The highest percentage difference of 14.25% between the simulation and the real experiment was found for the software tool Digimat FE 2022.4—GG 630 T composite. The lowest difference of 0.5% was found for the software tool Digimat MF 2022.4—GG 204 T composite. By comparing the results of the software tools with the results of the experimental measurements, it was found that the Digimat MF 2022.4 tool is closer to the results of the experimental measurements than the Digimat FE 2022.4 tool.

The quest for innovative design of reinforced-concrete to make it more durable, flexible, and sustainable has brought a transition from traditional methods of lap splicing to the use of anchor-head bars. One such innovation is the state-of-the-art Expanded Rib Steel Bar (ERSB) technique which reduces the conventional splice-length and also lessens the stress concentration at the concrete anchor-head contact areas to avoid brittle failure. Leveraging the four-point-bending experimental results of ERSB and two conventional designs, this paper investigates the performance of ERSB using a nonlinear 3D-Finite-Element Model. The results indicate that the proposed FEM reproduces the experimental behavior of ERSB in terms of maximum strength, displacement, ductility ratio, and crack pattern accurately. Moreover, the performance of ERSB is superior than the single-head-anchor bars and similar to that of the reinforced beams without joints. A parametric study then suggests design implications which can be adopted to develop guidelines for designing ERSBs.

In this study, a flexural test and residual stress evaluation using the aspect ratio (65 and 80) and steel fiber content (20, 30, and 40 kg/m3) as variables were conducted according to the EN 14651 standard to investigate the flexural toughness of concrete reinforced with high-performance arched steel fibers. The result of the flexural test show that the residual stress was 114.5% higher in the test specimen with high curvature and high content of arched steel fibers than that in the other conditions. In addition, the energy absorption capacity of arched steel fiber-reinforced concrete increased by 138.88% compared to concrete. [ABSTRACT FROM AUTHOR]

The effect of a recently developed socket-type shear connector (SSC) on the flexural behaviour of a composite basement wall (CBW) was examined in this work. To this end, 12 CBWs composed of cast-in-place (CIP) piles fabricated with H-shaped steel beams or reinforcing steel plates were prepared by varying the arrangement and amount of SSCs. Two-point loading was applied to simply supported CBW specimens. The CBW specimens with more SSCs had a higher effective stiffness in the elastic state and higher moment capacity in the ultimate state, irrespective of the cross-sectional details of the CIP piles. These trends were particularly prominent when a reinforcing steel plate was used in the SSCs. The post-peak behaviour of the CBW specimens subjected to a simulated load with a negative external moment tended to be more ductile. Consequently, a higher degree of composite action was fully exerted on the CBWs with greater numbers of SSCs. Using established equations for the sectional details of CBWs with SSCs, the nominal partially composite to full composite flexural capacity ratios of the CBW specimens subjected to simulated loads with positive and negative external moments were calculated to be, respectively, 0.83 and 0.91 for 0.5ηsc and 0.79 and 0.90 for 0.75ηsc, where ηsc is the normalised shear connector capacity specified in ANSI/AISC 360-16. [ABSTRACT FROM AUTHOR]

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Thin-walled concrete structures with textile reinforcement have a number of advantages over conventional reinforced concrete. This article discusses the manufacturing method and investigates the structural behavior of the arch made of textile-reinforced concrete (TRC). The possibility of manufacturing an experimental arched structure with textile reinforcement is demonstrated. This study includes the arch design, mold preparation and loading test. With the use of a 3D printer, the mold of the arched structure was printed, which made it possible to implement a distributed loading scheme. Three concrete arches including a reference non-reinforced arch and two concrete arches reinforced with glass textiles were designed and tested. The test results showed a slight increase in the strength of the reinforced arch compared to the control non-reinforced arch. The effectiveness of the reinforcement of the arch structure amounts to about 10 % increase in contrast to arches with external reinforcement, where the increase in strength reaches 40–85 %. However, the main advantage of such reinforcement is the significant residual strength of the arch structure, which prevents catastrophic collapse of it. The textile reinforcement continued to hold the failed concrete matrix in contrast to the external reinforcement, where the loss of cohesion leading to delamination could cause the fracture of parts of the concrete.

Fatigue is a sudden failure of components below the maximum strength of the material when subjected to repeated loading. This paper studies the fatigue behavior of basalt, carbon, and glass fibers/epoxy hybrid composites under three‐point flexural loading and a saltwater environment. Five different composite panels were manufactured using the VARTM. The samples were then immersed in a saltwater solution for 60, 120, and 180 days before conducting the tests. Three‐point static and fatigue tests were conducted using UTM as per ASTM D7264‐07 and ASTM D7774‐12. The S‐N and stiffness degradation curves were plotted, and the morphology of the fatigue samples was investigated using SEM. In addition, the ion penetration in the solution was detected with ICP‐OES analysis. The result shows that bending fatigue properties of all composite samples show a degradation as the immersion period increases. This might be due to micro‐hole formation as the ions move from the sample to the saltwater solution. Highlights: Composite specimens were immersed in a saltwater solution for 2, 4, and 6 months.Three‐point bending fixture is used for fully reversed fatigue loading (T‐C).Percentage degradation of fatigue life and stiffness loss increases with the immersion periodSEM image shows delamination, fiber pullout, debonding, and fiber and matrix breakage. [ABSTRACT FROM AUTHOR]

Engineered Cementitious Composite (ECC) is an advanced construction material that combines cement, fine aggregates, and specially designed fibers to create a highly ductile and durable building material. ECC is renowned for its exceptional tensile strain capacity, allowing it to undergo significant deformation while retaining its structural integrity. This characteristic makes ECC particularly suitable for applications where flexibility and durability are paramount, such as in earthquake-resistant structures and infrastructure repairs. This study investigates the tensile and flexural properties of ECC using Polyvinyl Alcohol Fibers (PVA) and compares these properties with those of regular mortar. Various sizes of PVA are available, and for this study, we utilized 12mm PVA fibers. The trial concrete mix design used was M30, with a watercement ratio of 0.3. The mixing process for traditional concrete and ECC is similar. Initially, the dry combination of ingredients is mixed for one to two minutes, followed by the addition of High Range Water Reducer (HRWR), and the mixture is further stirred for an additional three minutes. Finally, fibers are incorporated to achieve a stable condition for mixing. The samples used for testing consisted of 15 beams and 15 cylinders. The beam dimensions were (500 X 100 X 100) mm, while the cylinder dimensions were 100 mm in diameter and 200 mm in height. These samples were tested after 28 days of curing. The experimental findings indicate that PVA-enhanced concrete exhibits greater tensile and flexural strength when compared to conventional concrete, with results varying based on the percentage of PVA used. The split tensile strength of 1.5% PVA ECC cylinders was enhanced by approximately 46.8%. In terms of flexural strength, there was a decrease observed in 0.5% and 1% PVA fiber beams compared to ordinary concrete beams. However, the 1.5% PVA fiber beam exhibited a 43.45% improvement over the 0% fiber beam and showed a 9.4% increase compared to the 2% PVA beam. Additionally, the 1% PVA sample in the soundproof test reduced sound by up to 21.2%. [ABSTRACT FROM AUTHOR]

This paper presents the results of a comprehensive experimental study on the flexural performance of ballastless discrete precast slab tracks with two alternative reinforcement types. These are the precast slab tracks produced using ordinary reinforcement [nonposttensioned (NPT)] and the precast slab tracks produced using post-tensioned (PT) reinforcement. The study aims to compare the flexural performances of NPT- and PT-type slab tracks using three-point bending tests, even though they continuously sit on the ground with different rigidities in real-life applications. The tests performed on four full-scale slab tracks in the longitudinal and transversal directions resulted in the first cracking and the ultimate loads were greater in PT specimens. Also, the maximum crack widths and residual displacements of PT specimens were smaller. Although the aforementioned performance parameters of NPT-type slab tracks are relatively behind those of PT-type slab tracks, their overall response is still acceptable, with the advantages of easier production and lower cost. [ABSTRACT FROM AUTHOR]

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Fiber Reinforced Polymer (FRP) has been established as an effective retrofit material world wide. Its behaviour as retrofit material has been evaluated by several research works. In this research work, the use of FRP for retrofitting of reinforced concrete beams was reviewed and the experimental study was carried out by casting tenR C beams with nominal reinforcement. Except control beams all the beams were strengthened using single, double and triple layer of externally bonded GFRP of varying fiber content measured in grams/ square meter (i.e. GSM) as the main parameter of difference. The RC beams were tested to failure and experimental data was obtained on load, deflection and failure modes of the beams. The efforts have been taken to investigate the effect of different amount of GFRP wrapping on load capacity, deflection and failure modes of the beams.