Ultimate in-plane shear behaviour and reinforcement efficiency of damaged masonry walls strengthened with single-sided TRC overlays

The pursuit of durable, ductile concrete has intensified because steel reinforcement suffers corrosion and durability problems. Glass fiber–reinforced polymer (GFRP) bars offer high strength-to-weight, corrosion resistance, and nonmagnetic properties, yet their low elastic modulus and sudden failure can result in large deflections, wide cracks and sudden collapse of GFRP reinforced concrete. This experimental study examined punching shear capacity and behaviour of two-way slabs reinforced with GFRP bars without shear reinforcement. It assessed whether hybrid reinforcement of GFRP bars in tensile zone and steel in compression zones of a flat slab improves punching shear capacity and failure mode relative to behaviour of GFRP or conventional steel-reinforced slabs only. A total of 26 full flat slab specimens with varied reinforcement ratios were cast and concentrically loaded representing interior columns of slab-column connection; parameters including load–deflection, first-crack load, crack patterns, ultimate capacity, punching shear resistance, and energy absorption were evaluated. Experimental failure loads or punching loads were compared with predicted failure loads using American, British and Canadian design codes as well as one proposed model existing in literature. The results revealed that American (ACI 318-19) code gave a better but conservative prediction of VExpr/VPred of 1.25 (experimental to predicted failure loads ratio) compared with the British (BS 8110) code, Canadian code and the model in literature all of which overestimated the punching capacity of the flat slabs. The study concludes that tensile reinforcement ratio and concrete strength have significant effect on punching capacity of the flat slab while compression reinforcement and hybrid reinforcement with conventional steel in compression zones have insignificant or unclear effect on punching shear capacity of the slab specimens. It is proposed that punching shear equation of ACI 318-19 design code be modified to include the contribution of tensile reinforcement to the punching shear capacity of flat slabs.

Proof load testing on bridges requires high magnitude loads. Stop criteria are used to avoid irreversible damage or failure during proof load testing. These stop criteria are thresholds to measurable parameters during the test. After reaching a stop criterion, the proof load test needs to be terminated. While in the past, stop criteria have been identified as a single level, this research proposes to use a traffic light system for stop criteria: green light (related to the serviceability limit state), yellow light (as an intermediate level) and red light (further testing is not permitted). The green light relates to the development of cracking, whereas the yellow and red light relate to the failure modes of flexure and shear. To develop stop criteria for the brittle failure mode of shear, thresholds are derived from mechanical models, based on strain measurements and crack widths, as well as using acoustic emission measurements. To validate the stop criteria, three series of experiments are analyzed: reinforced concrete slab strips, straight slabs, and skewed slabs. While field validation of the traffic light system is pending, the developed tool is a step forward to safely test concrete bridges without shear reinforcement.

Previous studies on Konstruksi Sarang Laba-Laba (KSLL) foundations have primarily focused on bearing capacity and overall foundation performance, while limited attention has been given to soil–structure interaction, stress distribution, and reinforcement design of KSLL ribs using the Winkler method. This study investigates the stress distribution in KSLL foundation ribs and determines the corresponding reinforcement requirements under different subgrade conditions. A numerical modeling approach was employed using a structural analysis program to simulate KSLL foundations on three soil categories—soft, medium, and stiff soils—with three rib/column connector dimensions of 30 × 30 cm, 50 × 50 cm, and 80 × 80 cm. The analysis was based on the modulus of subgrade reaction (Ks) to represent Winkler-type foundation springs. The results show that Ks increases with soil stiffness, indicating stronger subgrade support in stiffer soils. Soft soil consistently produced the highest normal stress, shear stress, and settlement, followed by medium and stiff soils. The ratio of normal stress between soft and stiff soils ranged from 1.5 to 3.0, while the shear stress ratio ranged from 1.4 to 2.0 at support zones and 1.6 to 1.9 at span regions. The effect of column-size variation on normal stress was relatively limited, although larger column dimensions reduced shear stress at supports by improving force distribution. The required main reinforcement increased with normal stress, reaching 7–8 bars in soft soil, 6 bars in medium soil, and 5–6 bars in stiff soil. Shear reinforcement spacing decreased as shear demand increased, with minimum spacing of 110 mm in soft soil, 150 mm in medium soil, and 260 mm in stiff soil. These findings demonstrate the importance of incorporating soil–structure interaction, subgrade stiffness, and rib-specific reinforcement design in KSLL foundation analysis to achieve safer and more efficient shallow foundation design.

ABSTRACT Sawdust-magnesium oxychloride cement composite (SMOCC) is a novel low-carbon material whose beams exhibit inadequate flexural capacity due to premature sawdust fiber fracture. This study investigates the flexural behavior of SMOCC beams strengthened with FRP. A total of 6 groups of 13 beam specimens with dimensions of 2300 mm × 200 mm × 100 mm were designed for four-point bending loading tests. The design parameters include the type of FRP material (CFRP or BFRP), the number of FRP flexural reinforcement layers (1, 2, or 4), and the configuration of FRP shear reinforcement (4 or 6 stirrups). The results show that FRP reinforcement promotes a more ductile failure compared to unreinforced beams. Increasing CFRP layers improves flexural performance, but excessive layers (more than two) cause over-reinforcement, reducing efficiency. Additional CFRP hoops do not enhance bearing capacity or initial stiffness but effectively improve ductility. CFRP reinforced beams achieve higher peak loads and stiffness than those with BFRP. Strain measurements confirm deformation compatibility between FRP and the SMOCC matrix, validating the plane-section assumption. Theoretical predictions of the flexural capacity of the SMOCC beams based on a sectional analysis were found to be in good agreement with the experimental results and were within 5% on average.

This study investigates the shear behavior of glass fiber-reinforced polymer (GFRP)-reinforced concrete (RC) beams to address challenges associated with their low elastic modulus, absence of yielding, and reduced stirrup efficiency in bending regions. GFRP bars are increasingly adopted as an alternative to steel due to their superior corrosion resistance, durability, and cost-effectiveness. This study focuses on the effects of stirrup type, stirrup spacing, and shear span-to-effective depth ratio on the structural performance of GFRP RC beams. Twelve full-scale beams were tested under four-point bending, incorporating three GFRP shear reinforcement configurations: fabricated closed stirrups, integrated straight bar systems, and discrete vertical bars. Experimental observations were analyzed in terms of failure modes, load-carrying capacity, energy absorption, and deformation characteristics. Results indicate that fabricated F-type stirrups provide the highest shear performance, though their effectiveness is limited by premature rupture at bending points. Site-integrated S- and T-type configurations offer practical alternatives, maintaining structural integrity while mitigating bend-related stress concentrations, but with slightly lower energy absorption and load capacity. Increasing stirrup spacing significantly reduces shear resistance and shifts failure from flexural to shear-dominated modes. Comparisons with widely used design codes and analytical models show that CSA S806-12 provisions offer the most reliable predictions, while other guidelines tend to over- or underestimate shear capacity depending on configuration and a/d ratio. The study highlights the importance of optimizing stirrup type and spacing to enhance the shear performance of GFRP RC beams. Findings provide valuable insights for improving current design methodologies, offering guidance for engineers seeking durable, corrosion-resistant alternatives to steel reinforcement in aggressive environments. This research demonstrates that innovative site-integrated stirrup configurations can bridge practical fabrication constraints without compromising overall shear performance, promoting more efficient and resilient GFRP RC structures.

This study presents a design-oriented numerical case study investigating the punching shear behavior of reinforced concrete flat slabs, focusing on the combined effects of drop panels, shear reinforcement (shear hooks), and slab openings located near slab–column connections. Punching shear is a brittle and critical failure mode, particularly when openings disturb stress flow near columns. A reinforced concrete flat slab with a thickness of 230 mm supported by an interior rectangular column (300 × 800 mm) was analyzed using manual calculations in accordance with ACI 318-19 and numerical modeling using SAFE software. The initial configuration without a drop panel resulted in an unsafe punching shear ratio of 1.36. Introducing a 100 mm drop panel increased the effective depth and critical shear perimeter, reducing the ratio to approximately 1.01, satisfying code requirements. Although the slab became technically safe after adding the drop panel, Ø10 mm shear hooks were provided around the column and near opening edges to enhance ductility, improve crack control, and increase robustness against unexpected load redistribution. A parametric numerical assessment was conducted by varying drop panel thickness, hook spacing, and opening location to examine their influence on punching shear demand. Based on the numerical results, practical design recommendations are proposed, including the use of drop panels at slab–column connections with nearby openings, placing the first row of shear hooks within 0.5d from the column face, and reducing hook spacing to ≤ 0.5d in regions affected by openings. The findings provide direct guidance for structural engineers involved in flat slab design within the framework of ACI 318-19.

Rising construction costs and environmental concerns necessitate the exploration of sustainable alternatives for conventional building materials. This study investigates the influence of palm kernel shell (PKS) on the shear behaviour of reinforced concrete deep beams. A high strength lightweight concrete of grade 40 was prepared using palm kernel shell as coarse aggregate. Three pairs of deep beams, with and without shear reinforcement, of 150 mm width and 350 mm depth, having shear span-to-effective depth ratios of 1.0, 1.5 and 2.0, were prepared for the PKS reinforced concrete deep beams. The beams were cured for 7, 14, 21, and 28 days and tested for ductility and shear strength under three-point loading. The experimental results showed comparatively that the average ductility ratio of the PKS concrete deep beams without shear reinforcement was 1.6 times that of the normal weight concrete (NWC) whilst for the beams with vertical shear reinforcement, the ductility ratio was 1.3 times that of the NWC, showing superiority of palm kernel shell concrete (PKSC) over NWC in terms of ductility. Also, the normalized shear strength of the PKSC deep beams was found to be higher than the NWC samples at all a/d ratios. It was concluded that PKSC deep beams exhibit higher ductility and normalized shear strength characteristics than NWC deep beams which can be considered as a sustainable material.

This study investigates the influence of the longitudinal reinforcement ratio on the flexural behavior of high-calcium fly ash geopolymer concrete (GPC) beams using three-dimensional nonlinear finite element analysis (3D NLFEA). Beams with identical geometry and shear reinforcement were modeled, with reinforcement ratios varied from under-reinforced to over-reinforced conditions. Material properties were based on validated experimental data. Results show that increasing reinforcement enhances flexural strength but significantly reduces ductility and energy absorption. Under-reinforced beams exhibited ductile, tension-controlled failure governed by steel yielding, while over-reinforced beams failed abruptly due to concrete crushing. The transition from ductile to brittle behavior occurs at significantly lower reinforcement ratios in GPC (around ρ = 0.0157) compared to ordinary Portland cement concrete. Based on ductility ratio, energy absorption, and toughness index i10, a maximum reinforcement ratio of ρ ≤ 0.010 is recommended for ductile design of high-calcium fly ash GPC beams.

Abstract Nonlinear finite element modelling is a standard tool for the extension of experimental research programs in the field of the design of concrete load-bearing structures. It allows for the expansion of the database of results obtained by a demanding experimental test in order to monitor quantities that could not be recorded during experiments and thus to formulate further conclusions from the research. The paper deals with an analysis of the shear stress of prestressed concrete beams with shear reinforcement. It is focused on investigating the effect of the magnitude of the axial force on the shear resistance. A beam with a height of 0.6 m and an I-shaped cross-section was analysed. A prestressed beam is used as a typical load-bearing element for the construction of road bridges. Two types of models were used: one considered the reinforcement as a discrete element and the second as a model with a smeared reinforcement. The modelling results confirmed only a small effect of the axial force on the increase in shear resistance.

Shear behavior of prestressed box beams with high-strength shear reinforcement

In West Java Province, the demand for educational facilities continues to increase in line with population growth and the rising need for improved educational quality. The education sector plays a crucial role in supporting national development; therefore, it requires adequate facilities and infrastructure to ensure that teaching and learning activities can be conducted effectively. However, the existing educational facilities are still insufficient to meet current demands. SMP Terpadu AL-Munir, for instance, currently utilizes classrooms owned by the AL-Munir Foundation to support its learning activities. As the number of students, teachers, and supporting staff continues to grow, more representative and properly planned classroom buildings are required in accordance with educational building planning standards. This study aims to analyze and design the structural system of the Classroom Building of SMP Terpadu Al-Munir by utilizing SAP2000 software. The structural model is developed based on reinforced concrete design principles and incorporates a flexible structural system characterized by a high level of ductility. The result is in the design of beams, columns and plates using steel tensile capacity BJTS fy = 420 MPa dan BJTP fy = 280 MPa and concrete compressive capacity fc’ = 25 MPa. with beam design with size B1 = 35 cm x 50 cm with main tensile reinforcement 5 D16 and compression 3 D16, 2D10-100 sliding reinforcement on the pedestal area, 4D10-150 sliding reinforcement in the field area, 2D12 torsion reinforcement in fulcrum area and field, B2= 25 cm x 35 cm with main tensile reinforcement 5 D16 and compression 3 D16. The repeating of Column design is obtained with size K1 = 40 cm x 40 cm column is installed 16D16 flexural reinforcement,and 2D10-100 shear reinforcement in the fulcrum area and 2D10-150 shear reinforcement in the field area.K2 = 35 cm x 35 column is installed 16D16 flexural reinforcement,and 2D10-100 shear reinforcement in the fulcrum area and 2D10-150 shear reinforcement in the field area. K3 = 30 cm x 30 cm column is installed 16D16 flexural reinforcement,and 2D10-100 shear reinforcement in the fulcrum area and 2D10-130 shear reinforcement in the field area. Floor Plate design is obtained with thickness 12 cm with reinforcement in direction x = ∅ 12 -230 and direction y = ∅ 12 – 240, and roof Plate design is obtained with thickness 12 cm with reinforcement in direction x = ∅ 12 -200 and direction y = ∅ 12 - 200.

This study aims to evaluate the feasibility of replacing the minimum shear reinforcement in high-strength self-compacting lightweight concrete (HSLC) beams with hooked-end steel fibers at a volume fraction of 0.75 vol.% and to quantitatively assess the contribution of steel fibers to the shear capacity of the beams. Six HSLC beam specimens were tested to determine load-bearing behavior and failure modes under different reinforcement schemes, including beams without steel fibers or stirrups, beams reinforced with either steel fibers or stirrups, and beams incorporating both steel fibers and stirrups. The experimental results indicate that replacing the minimum shear reinforcement with 0.75 vol.% hooked-end steel fibers increased the flexural capacity, ultimate deflection, and energy absorption capacity by 2.5%, 7.8%, and 16.1%, respectively, thereby confirming the feasibility of using hooked-end steel fibers as a substitute for minimum shear reinforcement. The fiber shear capacity, calculated from experimental data, was compared with various prediction equations. Models containing the fiber factor demonstrated better agreement with test results, showing a minimum difference of 10.1%.

The design of preflex beams is mostly focused on limiting steel and concrete stresses near the span center or at the location of the precambering forces. Verification of shear strength is generally limited to the steel beam web and the identification of the connectors, as well as determining the required amount. In several cases of bridges built at the beginning of this century, fine cracks were found in the compressed concrete bottom flange of the beams, corresponding to a herringbone pattern. In the case of a 55-year-old bridge, a wider longitudinal crack was found in the bottom flange. The study explains these cracking cases based on the internal equilibrium of forces. The origins of the cracks are in the burst effect of the additional bonded prestressing, the spreading across the concrete of the high compression force in the steel lower flange, and the very light shear reinforcement typically used in preflex beams. In addition, recommendations are given to avoid such forms of shear cracks.

Web openings in reinforced concrete deep beams are often necessary for functional purposes but substantially reduce structural performance. Carbon fiber-reinforced polymer (CFRP) strengthening is commonly employed to mitigate these effects. Previous studies typically examined openings in regions without stirrups or assumed closed stirrup configurations, overlooking the frequent stirrup damage that occurs in practice due to the high shear reinforcement in deep beams. In this study, three specimens from a prior experimental program were modeled in ABAQUS, and the numerical results were validated against experimental data. Openings of varying diameters were introduced by cutting reinforcements, and the beams were subsequently strengthened with CFRP laminates, and a parametric study was conducted. Results showed that increasing opening diameter markedly reduces load-carrying capacity and energy absoption, while thicker CFRP laminates partially restore performance. For example, a 300mm opening in a 500mm high unstrengthened beam reduced load capacity by 56% and energy absorption by 87%. Even when the opening diameter was less than one-third of the beam height, 1.8mm CFRP laminates provided only limited improvement. Deep beam performance was strongly influenced by web opening size, and the effectiveness of CFRP strengthening was limited when stirrup integrity was compromised.

This review aims to carefully analyze how Carbon Fiber Reinforced Polymer (CFRP) bars and sheets are used in reinforced concrete, focusing on their strength, durability and ability to support a structure. The analysis compiles recent research to look into the positives and negatives of using CFRP rather than steel as a reinforcement for structures. The main parts of this field are bonding ways, extra costs, effects on the environment and how CFRP performs in various situations. The summary points out that CFRP can considerably increase flexural and shear strength in concrete, resist corrosion and create objects that are both durable and light in weight. Despite the expensive cost, limited information about durability and some bonding-related issues, CFRP systems exhibit encouraging effects in applications like flexural strengthening, shear reinforcement and confining concrete columns. Research and new technologies will likely allow CFRP to be more widely used in the future, solving many infrastructure problems

The shear design of concrete members reinforced with Carbon Fiber Reinforced Polymer (CFRP) bars remains a key hurdle for engineers. This study experimentally investigates the shear behavior of normal-strength concrete members reinforced with CFRP bars without shear reinforcement subjected to monotonic loading. Specifically, this research investigates the effect of anchorage length on shear-dominated behavior, aiming to provide a novel assessment of the interaction between shear and anchorage design—two aspects that have traditionally been treated in isolation in existing studies. The experimental results revealed that all test members, regardless of reinforcement type or anchorage length, exhibited a shear strength ranging from 1.1 to 5.63 times the code-predicted values, confirming the conservatism of current design standards. This pronounced difference in the shear strength of reinforced members is attributed to (1) the unexpectedly significant contribution of dowel action because of the high tensile strength and over-reinforcement ratio, and (2) the inherent conservatism in current code equations for shear capacity. Unlike prior studies that noted conservative shear prediction, this research demonstrated that anchorage length requirements, which are typically linked to flexural design, can be significantly relaxed in shear-dominated members with safety secured. This research highlights the need to refine shear prediction models for CFRP members by incorporating parameters that account for the reinforcement ratio and the unique contribution of dowel action. Furthermore, a revision of anchorage length design standards is justified to develop a more rational and economical design for shear-dominated members.

Reinforced concrete beams are primary structural elements responsible for transferring gravity loads and play a crucial role in maintaining the stability and safety of building structures. In construction practice, variations in concrete strength, reinforcement ratios, and execution irregularities often cause the flexural and shear behavior of beams to differ from design assumptions, making capacity evaluation based on actual section data necessary. This study aims to evaluate the flexural and shear capacity of reinforced concrete beams and to assess the level of capacity utilization under design gravity loads. The research method employs an analytical approachc approach using section geometry, material properties, reinforcement configuration, and gravity loading obtained from design documents. Internal forces are calculated using static equations for simply supported beams, while flexural and shear capacities are determined in accordance with the provisions of SNI 2847:2019 and the load combinations specified in SNI 1727:2020. The results indicate that the factored bending moment of 232.37 kNm and the shear force of 84.88 kN remain below the design capacities φMn of 452.81 kNm and φVn of 206.86 kN, resulting in utilization ratios of 0.51 and 0.41, respectively. The provided flexural and shear reinforcement also satisfies strength and detailing requirements. It is recommended that evaluations based on actual section data be consistently applied to improve design reliability and quality control in reinforced concrete beam construction.

Pontianak City has experienced a steady increase in tourist arrivals, which has resulted in a higher demand for temporary accommodation facilities. In response to this development, this study presents the structural design of an eight-story reinforced concrete hotel building located on Sepakat II Street in Pontianak City. The structure is designed using an Intermediate Moment-Resisting Frame (IMRF) system to ensure adequate performance under seismic loading conditions. The structural design process was carried out in accordance with the applicable Indonesian National Standards (SNI). Structural analysis was conducted using ETABS software to evaluate the building’s behavior under gravity and earthquake loads, while technical drawings were prepared using AutoCAD and SketchUp. The building utilizes concrete with a compressive strength of f’c = 30 MPa and reinforcing steel with a yield strength of fy = 420 MPa. The seismic performance of the structure was evaluated through several parameters, including mass participation ratios, inter story drift limits, natural period verification, and P-Delta effects. The analysis results show that the structural system satisfies all required performance criteria, indicating that the building is capable of resisting seismic forces safely and efficiently. The slab system consists of D10 main reinforcement bars and Ø8 shrinkage reinforcement bars, with slab thicknesses of 150 mm for the roof, 130 mm for typical floors (Levels 1–8), and 160 mm for stair landings. The primary beams (B1) have cross-sectional dimensions of 300 × 600 mm and are reinforced with D19 longitudinal bars, D13 shear reinforcement, and D19 torsional reinforcement. Secondary beams (B2) measure 200 × 400 mm and use D16 longitudinal bars, D13 shear reinforcement, and D16 torsional reinforcement. Columns have a uniform cross-section of 700 × 700 mm and are reinforced with 20D22 longitudinal bars and D13 transverse reinforcement. The foundation system consists of three types of pile foundations using 200 × 200 mm precast concrete piles with reinforced pile caps designed to accommodate varying structural loads.

Abstract The paper presents an investigation of the mechanical behavior of fiber‐reinforced concrete utilizing waste tire and industrially manufactured fibers. The first part of the paper concentrates on material research, indicating that the incorporation of fibers enhances concrete performance, particularly in terms of prismatic compressive strength, which averaged 45.7 MPa, with a notable 14.6% increase observed in specimens 2C. Specimens with a dose of fibers demonstrated a significantly enhanced f R3 , depending on the geometry and end shape of the fibers. The second part examines the shear resistance in reinforced concrete elements without shear reinforcement. Fibers markedly improved shear performance across all mix designs, with specimen 2B realizing a 26.7% increase in shear resistance. Normalized results substantiate the advantageous effects of all tested fiber types. The study concludes that the standard MC 2020 for predicting shear resistance with fibers provides a safe and cost‐effective structural design.