High-strength straight anchor bolts materials require longer embedment lengths in the concrete so the headed bars are employed to significantly reduce the required embedment length of these bars. But they impose concentrated stress on a small concrete surface under the head. In this study, behavior of headed bolts was numerically studied using 3D finite element method (FEM). First, an experimental program consists of four concrete specimens with variations only in head diameter was conducted. Second, FEM program consists of 22 concrete specimens was conducted. The effect of concrete cover thickness around the head was ranging from 85 mm to 510 mm. This variation resulted in a broad range of concrete cover-to-stud diameter ratios from 5 to 30. Additionally, studying the impact of head geometry (hexagonal, square, circular, and pentagonal) was performed. The effect of head diameter from 12 mm up to 50 mm was examined. This study also assessed the effect of using high strength concrete under the head region. The results showed that all specimens exhibited localized compressive failure of the concrete beneath the headed bars. Due to its increased number of sides, the hexagonal head performed better than the square head. When compared to a headed bar with a diameter of 12 mm, the ultimate local pressure of headed bars with diameters of 15, 17, 20, 25, 30, 40, and 50 mm dropped by 53, 60, 68, 76, 78, 87, and 90%, respectively. When the concrete cover-to-stud diameter increased from 5 to 30, there was a noticeable improvement in the final local pressure and the related slip under the rebar head. Overall performance of the bars improved with increase of the members number of the head. When high strength concrete was used under the head, the ultimate local pressure of headed bars increased by 29–152%. Many new formulas were proposed for estimating ultimate local pressure of headed bars.

In reinforced concrete beams, curtailed reinforcement is commonly used to enhance local bending capacity. However, experimental evidence shows that curtailed reinforcement can significantly reduce shear capacity, an effect not accounted for in many shear models, leading to overestimation of shear strength. This highlights a gap in current shear design models and code provisions. This study experimentally investigates the effect of longitudinal reinforcement curtailment and additional stirrups detailing on the shear behavior of reinforced concrete beams with particular emphasis on detailing at curtailment zones, which has not been sufficiently addressed in previous studies. Thirteen beams were tested under three-point bending with a constant shear span-to-depth ratio of aid = 2.5. The investigated parameters included the type of curtailed reinforcement (straight and bent bars with end hooks), the ratio of minimum stirrups, and the amount of additional stirrups provided at curtailment locations. The results confirm that neglecting the effect of curtailed reinforcement leads to unsafe shear behavior, as curtailment without adequate shear reinforcement reduced the first shear cracking load by about 9.5% and the ultimate shear capacity by up to 27.7%, leading to brittle shear failure. In contrast, providing additional stirrups significantly enhanced shear performance by increasing the first shear crack load by 18.4-118.4%, the ultimate load by up to 125%, and the energy absorption capacity by 87-747%, demonstrating the effectiveness of proper detailing strategies at curtailment zones. Bent bar curtailment with end hooks further improved behavior, energy absorption by up to 375%. While the initial stiffness of all beams remained nearly constant, post-cracking ductility and toughness were markedly improved by proper stirrup detailing. Experimental results showed good agreement with theoretical predictions based on ECP 203/2020, while providing new insights for improving shear design provisions and ensuring safer structural performance.

Closed-type winding (CW) ties have emerged to overcome limitations of conventional Glass Fiber Reinforced Polymer (GFRP) ties, particularly overlap slippage and low confinement efficiency. Although their effectiveness under axial loading has been widely reported, their performance under lateral loading across a range of conditions remains insufficiently understood. This study evaluates the lateral behaviour of GFRP-reinforced concrete columns with CW ties, compares their effectiveness with conventional ties, and proposes design recommendations to satisfy both strength and deformation requirements. A numerical model was developed and validated against previous experimental results. Subsequently, a parametric study was conducted considering shear span-to-depth ratio, axial load, concrete strength, tie size, tie spacing, and tie configuration. The results demonstrate that CW ties significantly enhance lateral performance compared with conventional ties. The reduction in deformation capacity caused by low shear span-to-depth ratios and high axial loads was effectively minimised using CW ties. In addition, CW-GFRP ties improved confinement efficiency and reduced the adverse effect of high-strength concrete on deformability. Columns confined with CW ties also showed higher capacity improvement with increasing concrete strength, achieving performance comparable to spiral-confined columns. Tie size and spacing had limited influence on the lateral performance under low column axial loads but became more critical at higher axial loads, improving post-peak stability and enabling a second peak load. The most favourable performance was achieved with a concrete compressive strength of 50 MPa, a tie volumetric ratio exceeding 1.85%, tie spacing equal to 0.25 of the column width, and a hybrid confinement system combining outer square and inner circular ties.

Exposure of wood-concrete composites to moisture leads to wood swelling, cracking, and distortion, negatively affecting load-bearing capacity and bond strength at the interface. This research experimentally and numerically investigates the bond properties between wood and concrete under water immersion. Eighteen composite wood-concrete specimens subjected to double shear push-out tests were evaluated to assess the impact of the bonding method (epoxy alone, steel anchors alone, or a combination of epoxy and steel anchors) on bond characteristics. Additionally, the influence of environmental conditions (dry state or water immersion for 30 days) was evaluated in terms of failure modes, axial load-slip responses, stiffness, and absorbed energy. The cross-sectional area of the wooden element was also considered (30 & times; 100 mm2, 60 & times; 100 mm2, or 100 & times; 100 mm2). In addition to the experimental program, ABAQUS software was used to develop a three-dimensional numerical model to analyze variations in shear stress distribution along the interface based on the bonding method and environmental conditions. The combination of steel anchors and epoxy effectively resisted deformations in the wooden section caused by water exposure, outperforming epoxy alone or steel anchors alone. Specimens bonded with epoxy alone failed due to interfacial debonding, while those bonded with steel anchors alone failed due to concrete crushing. In contrast, specimens bonded with both epoxy and steel anchors delayed failure until the wooden element ruptured. Consequently, the dry specimen with a crosssectional area of 100 & times; 100 mm2, bonded to concrete using both steel anchors and epoxy, recorded the highest ultimate load of 270 kN, whereas the corresponding specimen under water immersion reached 235 kN.

The integration of web openings in reinforced concrete (RC) beams for building services severely compromises shear capacity by disrupting load paths and creating critical stress concentrations. While previous research has focused on external strengthening of traditional RC beams, a significant gap exists regarding the performance of composite beams with embedded steel sections near openings. This study introduces a novel strengthening strategy using internally built-up I-section and T-section steel elements as shear reinforcement. The methodology integrated experimental testing with a validated nonlinear 3D finite element model in ABAQUS to conduct an extensive parametric study. Key investigated parameters included I-section web thickness (0.1–2.5 mm) and flange width (16–64 mm), and T-section compression and tension flange widths (0–64 mm). The key findings were substantial: web openings caused a 14% reduction in strength but a 41% increase in ductility, indicating a brittle failure mode. The incorporation of steel sections effectively reversed this; the I-section (176 × 2 mm web, 40 × 2 mm flanges) in beam BI-W2.0 yielded a remarkable 53.4% increase in ultimate load capacity, outperforming the original solid beam. An optimal I-section web thickness of 2.0 mm was identified, with diminishing returns beyond this point. For T-sections, the tension flange width was far more influential than the compression flange on strength recovery. A fundamental finding was that even a simple steel web alone provided a 43% strength gain, highlighting the critical role of bridging the opening. The reinforcement trade-off was a controlled 16–22% reduction in deflection, enhancing stiffness while maintaining structural safety. The research provides optimized, practical design guidelines for utilizing built-up steel sections to ensure structural integrity in perforated beams, effectively bridging architectural functionality and engineering safety.

Post-installing steel bars—or anchors—using chemical agents is nowadays instrumental in repairing and strengthening existing concrete structures. In this experimental research project, beside three cast-in-place specimens provided with ordinary ribbed bars (reference specimens), eighteen specimens were designed and cast to investigate bond performance of chemically-bonded steel bars placed inside concrete blocks, subjected to a pull-out load. Specimens and reinforcement consisted in concrete cubes (side a = 250 mm) and small bars (diameter db = 10 mm). Concrete strength on cubes was 28 MPa. The parameters under investigation were: bonded length (Lb = 5/10/15 db), drilled-hole diameter (= 1.2/1.6/1.8 db), bar properties (ribbed or threaded surface in the post-installed bars) and adhesive type (Sikadur 31CF and Kimapoxy 165). Bond-slip response, bond strength and bar slip at the peak stress, failure modes, as well as bond ductility and stiffness were thoroughly investigated. As expected, in most of the chemically-bonded and cast-in-place specimens bond failure was by steel yielding within a pull out framework (no cover splitting). For the intermediate and largest hole diameters (= 1.6 and 1.8 db), the load-bearing capacity of post-installed bars was slightly larger than that of ordinary bars. In the specimens with post-installed bars, the bearing capacities with Sikadur 31CF and Kimapoxy 165 turned out to be very close for any bonded length. The bond capacity of post-installed threaded bars was from 12 to 21% less than that of post-installed ribbed bars. Compared to ordinary ribbed bars, bond ductility in post-installed bars was higher (from + 18 to + 25% for Lb = 5 db) or even much higher (from 5 to 10 times for Lb = 10 and 15 db). Finally, to evaluate bond resistance of post-installed bars, a new equation is proposed to take care of all major parameters, based on the test results of this study.

This study investigates a novel concrete-filled aluminum tubular (CFAT) beam design that incorporates perforations in the aluminum tube (AT), which is secured to the concrete core using screw anchorages. A total of twelve specimens, including two with box-shaped sections and ten with U-shaped sections, were tested experimentally under a three-point bending test. The key parameters evaluated included the AT section configurations (box-shaped or U-shaped), the incorporation of screw anchorages, the normalized pitch of transverse strips in the compression zone of U-shaped sections (0.5, 1.0, or 2.0), and the longitudinal strip-to-AT flange area ratio in U-shaped sections (40% or 60%). Furthermore, the failure modes, flexural deflection, flexural strength, flexural stiffness, and ductility of all tested beams are reported. The study found that the governing failure mode of CFAT beams with screws was rupture failure, occurring at the screw rows. Screw anchorages effectively mitigated local buckling and debonding at the AT-concrete interface. Compared with specimens without screw anchorages, those with screw anchorages exhibited significantly higher flexural strength and stiffness. Box-shaped sections showed a 58.97% improvement, while U-shaped sections demonstrated enhancements ranging from 152.47% to 266.86% for normalized transverse strip pitches ranging from 0.5 to 2.0. Furthermore, beams with longitudinal strips exhibited flexural strength enhancements of 166.11% and 163.05% for longitudinal strip-to-AT flange area ratios of 40% and 60%, respectively.

Sometimes only a portion of the surface of a concrete element is loaded, which causes stress concentration in that region. To safely transfer concentric loads to concrete components such as column bases, short cantilevers, superstructure piers, post-tensioned elements, and support anchors, it is imperative to investigate the local compressive characteristics of concrete. To learn more about this subject, further research is required, as there are currently insufficient studies in this field. Therefore, the local compressive behavior of concrete under concentric stresses is the main focus of this work. Concrete is represented as block samples with dimensions of 200 × 200 × 250 mm. A stiff steel plate is used to apply concentric loading on the surface of the samples. The primary parameters are the bearing plate dimensions, shape (square, rectangle, and circular with varying areas), and rectangularity. Additionally, the bearing plate’s movement is examined. The stress-slip curves, ultimate bearing strengths, failures, and related slippages of the tested samples are discussed. The findings revealed that the upper surface of the concrete samples exhibited localized deterioration beneath the bearing plate. Additionally, the ultimate bearing strength of the sample loaded with the 6 × 6 cm square plate was 163% greater than that of the sample loaded with the 10 × 10 cm square plate. Furthermore, the sample loaded with the circular plate with a diameter of 4 cm had an ultimate bearing strength that was 181% greater than the sample loaded with the circular plate with a diameter of 11 cm. It is clear that the samples loaded with a circular plate of varying diameters had an ultimate bearing strength that was 8.5–11% higher than the samples loaded with a square plate of varying lengths.

The behavior of isolated reinforced concrete (RC) footings is strongly influenced by the interaction between the footing and supporting soil, which governs settlement, load capacity, and contact stress distribution. Classical analytical solutions often overestimate edge stresses and fail to account for soil nonlinearity, progressive footing cracking, and stiffness degradation. Experimental studies have shown non-uniform, saddle-shaped stress distributions beneath rigid foundations, yet most research focuses on idealized footings, and conventional design methods typically assume uniform contact stresses, overlooking the evolution of footing stiffness. This study addresses these gaps by developing a validated nonlinear finite element (FE) model in ABAQUS to simulate square RC footings on dense sandy soil under concentric vertical loading. The model was validated against experimental results, showing 1% discrepancy in ultimate load and 3% in settlement. A parametric study investigated the effects of reinforcement ratio (0.26-3.0%), footing thickness (250-500 mm), and concrete compressive strength (20-60 MPa). Increasing reinforcement ratio raised central contact stress by 102%, ultimate load by 111%, and energy absorption by 312%. Increasing thickness to 500 mm improved central stress by 42%, ultimate load by 37%, and energy absorption by 74%, whereas reducing thickness to 250 mm caused reductions of 83%, 61%, and 90%, respectively. Enhancing concrete strength to 60 MPa increased central stress by 152%, ultimate load by 149%, and energy absorption by 367%. The findings highlight the critical role of footing stiffness, cracking, and soil-structure interaction, demonstrating the limitations of uniform stress assumptions and providing practical guidance for safe, efficient, and economical design of RC footings on granular soils.

This study investigates the effectiveness of near-surface mounted wire (NSMW) reinforcement as a shear-strengthening technique for reinforced concrete (RC) deep beams. Eleven specimens, including a control beam, were tested under three-point loading to evaluate the influence of vertical, horizontal, diagonal, and mesh NSMW configurations on shear behavior. The results showed that diagonal and mesh arrangements provided the greatest improvements in shear capacity, with increases of 61.8% and 59.1%, respectively, relative to the control. Vertical reinforcement also enhanced shear resistance by up to 50%, albeit with reduced deflection capacity, while horizontal reinforcement produced more modest gains, with a maximum increase of 34.1%. Among all schemes, the mesh configuration delivered the most balanced performance, achieving a 113.4% increase in energy absorption along with refined crack development. Crack pattern observations confirmed that diagonal and mesh layouts stabilized the compression strut, delayed diagonal cracking, and shifted failure away from the unreinforced shear span, whereas vertical and horizontal layouts were less effective in altering the failure mechanism. Overall, the findings highlight the novelty and practicality of thin-diameter NSMW reinforcement as a versatile alternative to conventional NSM bar techniques for strengthening RC deep beams.

Centrally pull-out experiments were used to investigate the bond behaviour of steel rods implanted in steel fibre reinforced recycled aggregate self-compacting concrete (SSR). SSR, recycled aggregate concrete (RAC), and natural aggregate concrete (NAC) were all looked into. RCA replacement rates of 0, 30, 50, and 100

Reinforced concrete (RC) walls are designed to carry vertical and horizontal loads which may need to be rehabilitated and strengthened to enhance their load-bearing capacity due to increased loading demands, environmental factors, or lateral forces. This study proposes strengthening RC walls using sustainable engineered cementitious composite (ECC) material reinforced with welded steel mesh (WSM). An experimental program was carried out on six RC walls strengthened using the proposed method to explore the effects of the thickness of the ECC layer, and the number of WSM on their axial performance. The ECC strengthening layer was reinforced with one, two, and three layers of WSM. The thicknesses of the ECC layer varied from 10 mm, 15 mm, and 20 mm. It was found that the proposed strengthening method significantly improved cracking control, elastic stiffness, energy absorption, failure modes, and ultimate load capacity. The strengthening technique improved the ultimate loading capacity between a range of 8% to 41%. Similarly, the energy absorption of the wall increases between a range of 60–175%. In addition, nonlinear finite element models were designed and validated against the experimental data. The validated model was used to perform a parametric study.

The integration of utility services in modern buildings often requires longitudinal openings within reinforced concrete (RC) beams. However, these voids, particularly in the compression zone, significantly reduce structural capacity and ductility by decreasing the effective concrete area and inducing stress concentrations. This study investigates the structural behavior of RC beams with longitudinal voids incorporating embedded steel tubes as internal composite reinforcement. An experimental program comprising eleven RC beams tested under four-point bending was conducted and validated using three-dimensional nonlinear finite element analysis. The study examined the effects of void geometry, tube shape, tube orientation, and reinforcement ratio. Results showed that introducing an unreinforced void reduced the ultimate load capacity by 27.5% and caused substantial losses in stiffness and energy absorption compared to the solid beam. In contrast, embedded steel tubes significantly enhanced structural performance through composite action. The best rectangular double-tube configuration increased the ultimate load capacity by 150% relative to the unreinforced void beam, while the circular double-tube system achieved an improvement of 180%. Circular tubes exhibited slightly superior performance due to more uniform stress distribution, whereas horizontally oriented rectangular tubes outperformed vertical ones because of their higher moment of inertia. The developed finite element model accurately predicted the experimental behavior and failure modes. The findings demonstrate that embedded steel tubes provide an efficient and practical solution for improving the performance of RC beams with service-integrated longitudinal voids.

This research experimentally and numerically investigates the feasibility of using low-cost timber plates to enhance the shear behavior of reinforced concrete (RC) beams. Seven simply supported beams with a shear span-to-depth ratio (a/d) of 1.8 were tested under three-point bending, including one control specimen and six strengthened beams. Two strengthening techniques, externally bonded (EB) and near-surface mounted (NSM), were examined using three attachment methods: epoxy only, 10mm diameter anchor bolts only, and a combination of both. A 3D finite element model (FEM) was developed in ABAQUS V2017 to evaluate the influence of increasing the a/d ratio from 1.8 to 3.1 on the ultimate load, stiffness, and toughness of the strengthened beams. Experimental results showed that timber plates, regardless of the strengthening technique, effectively restricted the propagation of the main shear crack and diverted it into multiple secondary cracks. Externally bonded specimens achieved higher ultimate loads than NSM specimens due to the absence of groove-induced reductions in the concrete section. The use of anchor bolts, either alone or in combination with epoxy, prevented debonding and produced the highest ultimate loads, reaching 91 kN and 92 kN, respectively, representing increases of 21.3% and 22.7% over the control beam. Both attachment methods also exhibited stiffness improvements of 10.8% compared to the control beam. Numerical analysis indicated that increasing the a/d ratio from 1.8 to 3.1 led to reductions in stiffness of 43%-47%, ultimate load of 18%-30%, and toughness of 7%-30%.

The primary focus of this work is the behavior of reinforced concrete (RC) slabs, including cut-off apertures supplemented by near surface mounted (NSM) steel rebars with novel scheme. Previous studies have shown that the failure of RC slabs strengthened using NSM is mostly due to debonding at concrete-NSM bar interface; therefore, this study focuses on using a hooked-end NSM bars (HENB) for these slabs around openings. The primary goal of this work is to address the absence of comprehensive research in the literature about the impact of various curtailed reinforcement ratios and the efficacy of end-anchored NSM steel bars. A 4-point flexure test was used to evaluate ten specimens of reinforced concrete (RC) slabs. Every slab is the same length (1000 mm), breadth (300 mm), and thickness (150 mm). The slabs on the tension side were reinforced with deformed steel bars. In order to achieve maximum bending and zero shear, the holes were bored in the middle of the slab span. Three ratios of tensile reinforcing bars have been cut: 20%, 40%, and 60%. NSM bars came in two varieties: straight NSM bars (SNB) and hooked-end NSM bars (HENB). The results demonstrated that using HENB reduced debonding and early failure at the ends of NSM bars which led to a change in the collapse pattern to a more relatively ductile type. As the ratio of curtailed bars increased from 20% to 60%, the cracking capability of slabs decreased by 29.4% and 74.79%, respectively, as compared to solid slabs. Using HENB significantly increased the slabs' cracking load, ultimate capacity, stiffness, deflection, and energy absorption when compared to the same unstrengthened slab. Finally, 3D finite element (FE) modeling software was used to develop a numerical model for every tested sample. The FE results were in agreement with the empirical findings, as evidenced by the average discrepancy ratios of 3.76% between the FE and experimental ultimate loads of the slabs.

The performance and design of reinforced concrete, also known as slender beams are explained in the current study by a number of international codes. Slender beams are essential in modern construction because they preserve structural integrity while allowing for efficient material use. This research conducts a comprehensive comparative analysis of shear design provisions for slender reinforced concrete beams across major international standards, including ECP, ACI, Eurocode, CSA, BS, and JSCE. The innovation lies in systematically identifying differences and commonalities in methodologies related to shear capacity determination, minimum reinforcement requirements, and serviceability criteria. By addressing the current gap of exhaustive analyses needed to standardize criteria and resolve methodological discrepancies, the work aims to enhance the reliability, effectiveness, and uniformity of global shear design processes for slender beams. This comparative approach is intended to assist engineers and academics in making more informed design decisions, thereby improving the efficiency, structural integrity, and safety of slender beam applications in modern construction. In summary, the novel contribution is the exhaustive and systematic comparison of various international design codes concerning slender RC beam shear design. Identification of inconsistencies and variations that affect structural security and design efficiency. Providing insights that could aid in harmonization and standardization of shear design provisions worldwide. Offering recommendations towards achieving more consistent, safe, and economical slender beam designs in contemporary construction.

Abstract This study investigates the flexural behavior of reinforced concrete (RC) footings supported on natural soil and internally strengthened using steel mesh fabrics (SMFs) as a novel alternative to conventional steel bars. Despite the widespread application of SMFs in structural retrofitting, their use as internal tensile reinforcement in RC footings remains largely unexplored. To address this gap, an experimental program involving ten small-scale square footings was conducted to evaluate the influence of SMF quantity, layering patterns, bar-mesh hybrid configurations, and mesh geometry on structural performance under flexure. The results demonstrate that replacing conventional steel bars with SMFs of equal reinforcement weight increased the ultimate load by up to 22.5% and enhanced the energy absorption capacity by up to 237%. Increasing the number of SMF layers raised the ultimate load from 120 kN (one layer) to 175 kN (three layers), corresponding to a 45.8% increase, while ductility decreased due to stiffness growth. Hybrid bar–mesh configurations showed superior performance, where the fan-shaped layout achieved an ultimate load of 161 kN and an energy absorption capacity of 2056 kN·mm, representing increases of 34.2% and 121.6%, respectively, compared to the single-layer mesh specimen. Moreover, partial-area SMF reinforcement beneath the column zone improved load capacity by up to 20% with limited reduction in ductility. Complementary numerical analysis using a validated 3D finite element model was conducted to assess critical variables, including mesh shape, reinforcement layout, and soil–structure interaction. The numerical simulations closely aligned with experimental results, providing deeper insight into stress distribution and deformation behavior. The findings confirm that SMFs offer a structurally efficient and economical alternative for enhancing the flexural performance, ductility, and energy dissipation of RC footings.

Abstract This study investigates the structural performance of over-reinforced concrete (RC) beams incorporating longitudinal compression-zone voids, a solution proposed to improve spatial efficiency for utility integration. However, such voids may significantly reduce strength and promote brittle failure. To address this issue, aluminum tubes (AT) are introduced as internal reinforcement within the voids. An experimental program comprising eleven beams (one solid, five hollow without reinforcement, and five hollow with AT) was conducted. Key parameters included void ratio (3.1–8%), number (single/double), orientation (vertical/horizontal), and AT ratio (0.75–1.8%). Results show that unreinforced voids reduce ultimate load capacity ( $${P}_{u}$$ ) by up to 36.5% and energy absorption (EA) by 44.8%. In contrast, AT reinforcement significantly enhances performance, increasing $${P}_{u}$$ by 57–135% and EA by 126–264%, while improving ductility and delaying brittle crushing. Horizontally oriented ATs achieved superior performance, with up to 10.8% higher $${P}_{u}$$ compared to vertical configurations. Increasing AT ratio (≥ 0.75%) further enhanced post-cracking behavior with minimal effect on initial stiffness. The findings demonstrate that aluminum tubes effectively restore and enhance the structural efficiency of voided over-reinforced beams. For practical applications, void ratios up to 8% are recommended with internal AT reinforcement as a lightweight, corrosion-resistant alternative to conventional external strengthening methods.

The accurate ability to predict the distribution of contact stress under reinforced concrete (RC) footings is important for the safety and serviceability of shallow foundations. Conventional analytical models idealizing the footing as rigid and soil as homogenous fail to capture the stress concentration and redistribution effects, especially under non-uniform loading. Earlier studies are mostly concentrated on sand; however, basalt soil has different mechanical characteristics as it possesses high stiffness, angularity, and interlocking effects. It also ignores stiffness loss due to concrete cracking. This study aims to fill these gaps through an experimental and numerical investigation of RC square footings resting on basaltic soil and the influence of the reinforcement ratio, yield strength of steel and strength of concrete. Within the laboratory conditions, four footings having different reinforcement ratios of 0.19%, 0.36%, 0.54% and 3.43% were tested under monotonic loading. Central and edge displacements were measured. Using a validated finite element model, a parametric study expanded the investigation to include reinforcement ratios of 0.54% to 4.80%, steel yield stresses of 240 MPa to 450 MPa and concrete compressive strengths of 20 MPa to 60 MPa, allowing systematic consideration of these parameters on central contact stress, ultimate load, deformation and energy absorption. The findings revealed that enhancing the reinforcement ratio from 0.54% to 4.80% resulted in an increase of 73.4% in central contact stress, 34.1% in ultimate load, and 55% in energy absorption, respectively. Increase in steel yield stress from 240 MPa to 450 MPa caused a 25.2% increase in central contact stress, 13% in ultimate load and 3.74% in energy absorption in laminated composite panel. The increase of concrete compressive strength from 20 MPa to 60 MPa increased central contact stress by 117.4% ultimate load by 70.4% and energy absorption by 270% showing this factor as dominant. These results show that the performance of footing on stiff basaltic soil mainly depends on the concrete strength and amount of reinforcement whereas careful use of steel yield stress. The insights provided by the study are critical for practical design. Furthermore, non-uniform contact stresses, stiffness degradation, and soil-structure interaction need to be accounted for optimizing strength and ductility.

Web openings in reinforced concrete (RC) beams facilitate building services but weaken shear zones, causing stress concentrations, cracking, and reduced load capacity. While prior studies have explored strengthening beams with openings, little attention has been given to composite beams with multiple openings reinforced by embedded steel elements. This study investigates slender RC beams with multiple web openings, strengthened internally using steel plates as an alternative to conventional shear reinforcement. Nine beam specimens were tested, considering mechanical anchorage, screw parameters, and supplementary reinforcement including vertical posts and upper chord bars. A validated nonlinear finite element model (FEM) complemented the experiments. Results showed that unreinforced openings reduced the ultimate load by 48%, whereas steel plates restored strength and stiffness by up to 83% and 301%, respectively, compared to the unreinforced opening beam. Mechanical anchorage and combined reinforcement further improved energy absorption, nearly restoring solid beam performance. Parametric analysis identified a steel plate thickness of 2.0-3.0 mm as optimal for balancing structural improvement and material efficiency. These findings demonstrate the effectiveness of steel plate strengthening for beams with multiple web openings and provide practical guidance for structural design.