Construction and demolition waste (CDW) is a major and increasing environmental problem that is little used in concrete manufacturing, especially crushed clay brick. In this study, the mechanical and durability performance of concrete made of crushed clay brick aggregate (CBA) as a partial volumetric replacement of natural coarse aggregate (NCA) at the replacement level of 0%, 25%, 50%, 75% and 100% has been evaluated. The proportioning of all the mixtures was designed for a nominal 28-day cube strength of 30MPa, the brick aggregate was soaked for 24 hours and dried to a saturated surface-dry (SSD) condition before mixing to account for the effect of water absorption by the aggregate. The fresh and hardened properties were evaluated by slump test, 7 days and 28 days compressive strength, splitting tensile strength at 7 days and at 28 days, ultrasonic pulse velocity (UPV) at 28 days and water absorption at 28 days. As the amount of CBA increased, the workability, strength, and UPV decreased consistently while the water absorption increased. In addition, slump dropped from 78 mm at 0% replacement to 26 mm at 100%, and 28-day compressive strength decreased from 35.6 MPa to 17.7 MPa (a 50.3% reduction), while splitting tensile strength dropped from 2.85 MPa to 1.96 MPa (a 31.2% reduction), suggesting that tensile capacity was relatively less affected by the incorporation of CBA. The UPV decreased from 4.87 km/s to 3.21 km/s and water absorption increased from 4.19% to 7.44% with the same range, and the inverse relationship between compressive strength and water absorption has been identified. Better balances between mechanical adequacy and sustainability gains were obtained for 25% CBA replacement while 50% and higher replacement levels showed significant loss of performance, limiting their use to non-structural applications.
The study presents a comprehensive finite element (FE) analysis of the structural response of battened-up carbon-steel columns subjected to combined axial and lateral low-velocity impact loads (ILs). The study demonstrated that 120 numerical models were created using ABAQUS/Explicit and analyzed four critical design elements: web stiffener shapes, cross-sectional shapes, edge stiffener shapes, and axial load ratios. The confirmation of the numerical models showed that they accurately predicted both overall and local failure. The parametric study shows that CDV (double V-shaped) web-stiffened columns had the highest total axial reaction capacity, reaching a maximum marginal load that is 87.4% higher than that of C-shaped columns. Edge stiffeners, especially type-3 double-edge stiffeners, improved the column's behavior under lateral ILs by increasing stability and load-carrying capacity by 71.4%; thus, local buckling was also deferred. Axial load ratios had a major effect on the impact performance of the columns, with the highest ratio always increasing the columns' capacity, depending on the stiffened design type. The cross-sectional shapes may change the performance features of the columns, either positively or negatively, depending on the arrangement; in well-stiffened designs, enhanced benefits have been reported. This research has been instrumental in advancing the optimization of battened built-up columns under dynamic and accidental loading scenarios.
To address the core issues of construction and seismic performance in prefabricated steel structure projects, this paper uses the Building Information Modeling cloud platform as the foundation to connect the four major stages of design, production, construction, and acceptance. A closed-loop framework integrating seismic performance and construction coordination is developed. Experimental results show that this method significantly improves construction accuracy control. The overall fluctuation of hoisting deviation ranges from 0.28% to 0.35%. The deviation of steel column verticality before acceptance remains stable at 0.81‰±0.02%. The deviation rate of a 60-day construction period is only 2.1%±0.2%, and the average rectification rate of three categories of quality issues reaches 99.1%±0.3%. The waveform matching accuracy between the Building Information Modeling seismic waveform detection and the actual waveform reaches 99.2%, and the peak load of the steel truss reaches 285.6 KN. In summary, this method effectively solves the problems of poor implementation of seismic performance and low efficiency in process coordination. It significantly enhances construction quality, coordination efficiency, and seismic safety of prefabricated steel structure projects, providing support for broader application.
Numerous confinement techniques have been proposed to enhance the strength and ductility of circular concrete-filled steel tube (CFST) columns. This study introduces an innovative confinement method for short circular CFST columns incorporating internal spiral plate stiffeners. The rectangular spiral plates are attached to the inner surface of the steel tube such that their flat faces remain in direct contact with the tube wall. This configuration minimizes obstruction to concrete flow and ensures proper compaction without void formation during casting. The spiral plates were connected to the steel tube using intermittent external fillet welding and tested under axial compression to evaluate their influence on load-carrying capacity and deformation behavior. A detailed finite element (FE) model was developed to complement the experimental program and to investigate the effects of key parameters, including spiral pitch, plate width, and weld spacing, on axial performance. The results demonstrate that incorporating spiral plate stiffeners increases the ultimate strength by an average of 16% compared to conventional CFST columns. Strength enhancement ranged from 5% to 55% as the spiral pitch decreased from 150 mm to 25 mm, while reducing weld spacing from 180° to 30° improved strength by 6–10%. A normalized spiral pitch (p/D) ≤ 0.5 provided effective confinement, resulting in stable post-peak behavior and mitigation of local buckling. Increasing the spiral plate width up to 40 mm enhanced axial strength by approximately 22%, highlighting its contribution to improved load resistance. Furthermore, the spiral plates were effectively delayed and uniformly distributed local bulging along the column height.
Traditional steel shear walls (SSWs) with flat infill plates have been widely used in regions of high seismic hazard due to their high strength and energy dissipation capacity. However, premature buckling of flat plates reduces their structural performance, motivating the development of trapezoidal corrugated steel shear walls (CSSWs). To further address the limitations of single corrugated walls, double corrugated steel shear walls (DCSSWs) were introduced, followed by hybrid flat-corrugated steel shear walls (FCSSWs), which combine a flat plate with a trapezoidal corrugated plate. This study numerically investigates the lateral behavior of three SSW systems: single CSSWs, DCSSWs, and hybrid FCSSWs. Finite element models are developed using ABAQUS and analyzed under lateral loading. The effects of geometric parameters are examined by considering aspect ratios (L/h) ranging from 0.67 to 2 and corrugation angles of 30 degrees, 45 degrees, and 60 degrees. The results indicate that dual-layer systems (DCSSW and FCSSW) significantly improve structural stability compared with single-layer CSSWs. Among the examined systems, the FCSSW exhibits the most stable nonlinear response, showing no strength degradation up to a 2% story drift. In contrast, the CSSW and the DCSSW with a 30 degrees corrugation angle experience noticeable strength degradation. In terms of peak strength, the FCSSW consistently outperforms the CSSW, with the maximum increase (approximately 15.1%) observed at lower aspect ratios. The DCSSW achieves the highest ultimate strength, exceeding that of the FCSSW by 1.6-4.3% and the CSSW by 3.4-12.3%. Initial lateral stiffness is comparable among all systems, with only minor differences observed.
