Proposed Design Equation for One-Way RC Walls with Openings Strengthened Using CFRP

Nonlinear Numerical Study of Infilled RC Frames with Openings and Wall-Posts

Masonry infill walls, although commonly treated as non-structural elements in reinforced concrete (RC) buildings, have a significant influence on the lateral response of RC frames. This study investigates the effects of masonry infills, opening configurations, and wall-post systems on the nonlinear lateral behavior of RC moment-resisting frames under quasi-static loading using advanced numerical modeling. Three-dimensional finite element models were developed in ABAQUS and validated against reliable experimental results. The numerical program includes bare frames, fully infilled frames, infilled frames with various opening sizes, and wall-post–strengthened configurations, all subjected to displacement-controlled quasi-static lateral loading up to large deformation levels. The results indicate that masonry infills considerably increase the initial stiffness and lateral strength of RC frames, while simultaneously increasing the potential for brittle behavior and stress concentration in the columns. The presence of openings reduces stiffness and disrupts the load transfer mechanism, leading to localized damage concentration around opening corners. In contrast, wall-post systems effectively mitigate these adverse effects by redistributing stresses, improving damage uniformity, and enhancing post-peak stability. The combined use of wall-posts and infilled walls with openings provides a more controlled lateral response in terms of strength, stiffness, and ductility, highlighting wall-posts as an efficient solution for improving the structural performance of infilled RC frames under lateral loading conditions.

Optimizing Boundary Element Layouts for Blast-Resistant Reinforced Concrete Walls: A Parametric and Fragility-Based Study

This study investigates the blast response of reinforced concrete (RC) walls with varying boundary element (BE) configurations using a validated macro-model implemented in OpenSees. The model, based on embedded layered-shell elements, was verified against independent experimental and numerical benchmarks, demonstrating its ability to capture out-of-plane wall response and BE-specific behavior under blast loading. A systematic parametric investigation was conducted to evaluate the effects of BE placement and thickness, boundary conditions, reinforcement ratios, axial loading, and wall aspect ratios. Results show that a single central BE can enhance blast resistance by approximately 20%, while configurations with two BEs placed at 0.2 times the wall length (BW2) offer the highest efficiency among multi-BE layouts. Increasing the BE thickness to 35 cm provided the best balance of performance and material demand. Vertical web reinforcement significantly improved behavior, while horizontal reinforcement had a limited effect. Higher BE reinforcement ratios further reduced displacements, whereas axial loads reduced global displacement but led to increased localized compressive damage. Fragility curves revealed variations of up to 33.9% in collapse probability across configurations, particularly under moderate impulse levels. Pressure–impulse (P–I) diagrams were developed to enable rapid identification of performance thresholds for different BE arrangements. The findings offer design-oriented guidance for optimizing BE configurations in the blast design of RC walls, with direct implications for improving structural resilience in critical infrastructure.

A Combined Numerical and Experimental Evaluation of the Flexural Performance of Wire Mesh-Strengthened RC Beam

A noble analytical solution for the size of rectangular footing subjected to axial, bending, and surcharge load

This paper introduces a comprehensive mathematical framework for the design of rectangular reinforced concrete footings under axial load, surcharge, and biaxial moments, accounting for both fully and partially supported contact conditions. The proposed method presents a set of closed-form equations obtained via integration, which incorporate changes in soil pressure distribution resulting from eccentric loading. As the noble contribution, a key parameter named compression fraction λ, is added to differentiate between complete and partial soil-footing interaction. The model incorporates surcharge—a component overlooked in previous formulations—and generalizes the concept of equal width typically employed in footing design. Parametric analyses reveal the model’s responsiveness to fluctuations in vertical load, moments, soil bearing capacity, and aspect ratio. Results indicate consistent and rational tendencies, with the footing area expanding under elevated loads or diminished bearing capacity, and contracting with increased soil strength. A comparison with Landeros’s model demonstrates that the proposed method produces more economical designs, with footing area reductions of up to 49.91%. The incorporation of surcharge and the capacity to manage partial compression render the presented equations a reliable and effective resource for structural engineers pursuing precise and material-efficient footing designs under complex loading scenarios.

Experimental-numerical analysis of thin-walled box structures with integral corrugated stiffeners, subjected to torsion

The study presents the results of model experimental investigations and nonlinear numerical analyses of thin-walled, two-segment box structures with various configurations of integral corrugated stiffeners. The models for experimental testing were fabricated using additive manufacturing techniques. Five variants of the structure were examined, including a reference configuration without reinforcement. The experimental investigation was carried out using a dedicated test rig. Numerical representations of the investigated models were developed and subjected to nonlinear analyses using finite element method-based software. The adequacy of the numerical results was assessed through comparison with experimental data. The objective of the study was to determine the effect of different forms of the proposed structural solution on the magnitude of the critical load and the nature of post-buckling deformation.

Numerical Evaluation of Failure Modes in Perforated Beams with Hexagonal Openings

Perforated and castellated steel beams are widely used due to their high structural efficiency; however, the presence of web openings introduces complex failure modes, such as Vierendeel bending and web-post buckling, which are not observed in solid-web sections. In this study, the influence of geometric parameters on the load-bearing behavior and failure mechanisms of perforated beams with hexagonal openings was systematically investigated. Nonlinear finite element analyses were performed on eleven models, including ten perforated beams with varying opening angles (ranging from 40° to 63°) and numbers of openings, as well as a solid-web reference beam. The numerical modeling approach was validated against experimental data from the literature to ensure the reliability of the results. All models were designed with a constant overall depth, allowing the effects of opening geometry to be isolated from those associated with increased section depth in conventional fabrication methods. The analysis results indicate a direct correlation between beam geometry and failure mode. The primary parameter controlling the transition from ductile, high-capacity flexural failure to brittle, low-capacity shear failure (Vierendeel bending or web-post buckling) is the dimensionless ratio 2dt/dg, where dt is the net section depth and dg is the total beam depth. Models with higher 2dt/dg ratios (such as 0.50 and 0.42) reached 86–92% of the capacity of the solid-web beam by developing a ductile flexural mechanism. In contrast, models with a lower 2dt/dg ratio (0.33) exhibited early brittle failure through the Vierendeel mechanism at 72–79% of the reference capacity, independent of opening angle. The opening angle (θ) was determined to be a secondary parameter. It is concluded that optimizing the 2dt/dg ratio is essential for achieving ductile failure in perforated steel beams and avoiding premature Vierendeel failure.