Yazid Hadidane

Following our earlier work on reduced beam section (RBS) connections, this study examines a new set of corrugated-web cell configurations for steel moment-resisting connections. A finite element model, validated against four experimental investigations reported in the literature, was used herein to assess the effects of cell geometry, transverse depth, and position relative to the column face on load-carrying capacity, deformation capacity, and damage evolution. The results show that the proposed configurations alter the stress distribution and shift the plastic hinge away from the beam–column joint, thereby decreasing the stress concentration in critical areas. Structural performance was highly sensitive to the interaction between cell geometry and its position along the beam. The curved cell configuration performed best when located near the column face, whereas the angle-shaped and trapezoidal configurations performed better farther from the column face, with the angle cell configuration giving the best overall response among all four. Comparatively lower efficiency was observed with the double curved configuration. To gain further insight into the viability of the proposed approach, the optimal designs derived from simplified beam analyses were then incorporated into a validated two-story steel sub-frame model. These results confirm that the selected geometric properties remain effective at a larger structural scale, preserving the beneficial effects observed in the beam-level analysis. These results demonstrate the potential of the proposed system to improve steel moment-resisting connections and provide a basis for further research on optimizing more advanced connection design techniques.

Progressive collapse represents a critical failure scenario in steel moment-resisting frames, especially when beam sections are intentionally weakened through flange cuts or web openings. While previous studies reported that circular openings were the most effective configuration among various shapes, the present study investigates whether semi-circular openings, when combined with reduced beam sections (RBS), can provide superior performance. A finite element model was developed in ABAQUS/Explicit v2016 and validated against experimental results to ensure reliability. Parametric analyses considered both circular and semi-circular openings with diameters of 80 mm and 110 mm, placed at various distances from the RBS centerline (L = 0, 65, 140, and 180 mm). The results show that openings located too close to the RBS zone (L = 0 mm and L = 65 mm) significantly reduced strength and suppressed catenary action. Conversely, larger spacings (L = 140 mm and L = 180 mm) enhanced load capacity and ductility by promoting stress redistribution. Importantly, semi-circular openings consistently outperformed circular ones in the present investigation. In particular, the SC3-140-110 specimen achieved the highest peak load (248.7 kN) and the strongest catenary action contribution (227.6 kN), demonstrating superior robustness against progressive collapse. These findings highlight the technical advantage of semi-circular openings as an effective detailing strategy for improving the collapse resistance of steel moment frames.

This research focuses on the optimization of formulation, characterization, and damage analysis of plant fiber-reinforced polyester resin composites (jute and date palm). To better understand the characteristics and mechanical behavior of these materials, this study investigates the influence of resin content and plant fibers on the physico-mechanical behavior of the resin composites. Resinous composites consisting of polyester resin and raw earth were studied using a novel formulation based on an empirical method that follows the principle of earth saturation with polyester resin. Saturation was achieved with a 28% content of polyester resin, which appeared to be an optimal blend for the earth–resin composite. Plant fibers were randomly incorporated as reinforcement in the composites at various percentages (1%, 2%, and 3%) and lengths (0.5 cm, 1 cm, and 1.5 cm). Mechanical tests including bending, compression, and indentation were conducted to evaluate the mechanical properties of the composites. Analysis of fracture morphology revealed that the deformation and rupture mechanisms in bending, compression, and indentation of these composites differ from those of traditional concrete and cement mortar. The obtained results indicate that the composites exhibit acceptable performance and could be favorably employed in the rehabilitation of historic buildings.