This study investigated the post-fire resistances of 6063-T5 aluminium alloy angle section stub columns (SCs). The post-fire mechanical properties of 6063-T5 aluminium alloy were assessed using tensile coupon tests. Instead of exhibiting a yield plateau, the stress–strain curves indicated a shift from an elastic to a strain-hardening phase. The impacts of elevated-temperature exposure on the residual elastic modulus were negligible. Strength properties decreased while ductile properties increased within the elevated-temperature range of 200 to 450 °C, with a subsequent strength increase observed beyond 450 °C. After the SC tests, gradual decreases in ultimate resistance were observed within 200–450 °C, followed by an increase beyond 450–500 °C. These trends in the ultimate resistance closely paralleled those strength characteristics observed in the stress–strain curves. As regards the failure mode, all specimens experienced local buckling after exposure to the range of elevated temperatures. The failure mode, ultimate resistance, and load–end shortening curve were used to evaluate a numerical modelling approach that was created to simulate the residual resistance of SCs after exposure to different elevated temperatures was applied. The EC9, ADM-2020, AS/NZS 1664, and GB 50429-2007 were among the design approaches that were evaluated using the experimental and numerical data. Due to the increased strain-hardening behaviour caused by elevated temperatures, the existing design methods proved excessively conservative when applied to the direct prediction of ultimate resistances of 6063-T5 aluminium alloy angle section SCs. The modified design provisions in light of the observed post-fire strain-hardening behaviour improved the accuracy in predicting the residual bearing capacity of 6063-T5 aluminium alloy angle section SCs, which showed better agreement with test and numerical results, offering enhanced applicability for post-fire design.

Bimetallic steel, as a layered composite material formed by metallurgically bonding two dissimilar metals, combines the excellent corrosion resistance of the cladding layer with the superior mechanical properties (such as high strength and toughness) of the base layer. It has been widely applied in demanding fields like marine engineering, the petrochemical industry, and energy equipment, where comprehensive material performance is critical. This paper provides a structured review of the research progress and application status of bimetallic steel. First, mainstream fabrication techniques, such as explosive welding and roll bonding, along with their effects on interfacial bonding quality, are analyzed. Subsequently, key material characteristics, including welding performance, mechanical properties, and corrosion behavior, are discussed. Furthermore, the component-level bearing performance and failure mechanisms under various loading conditions are evaluated. Finally, by synthesizing existing research, current knowledge gaps in areas like long-term service life assessment, adaptability to extreme environments, and efficient intelligent manufacturing are identified, and future development trends are outlined. This review provides important academic reference and engineering guidance for deepening the understanding of bimetallic steels and promoting their safer, more reliable, and cost-effective application in major engineering projects.

Lunar regolith simulant (LRS) geopolymers are promising construction materials for lunar in situ resource utilization, but their brittle behavior and limited crack resistance restrict their structural applications. This study investigated the effect of basalt fiber length on the mechanical properties, failure modes, stress–strain behavior, constitutive relationship, and microstructure of CQU-1 LRS geopolymers. Basalt fiber-reinforced LRS geopolymers were prepared under weak alkali activation and high-temperature curing at 80 °C. The basalt fiber content was fixed at 0.1%, and six fiber lengths of 0, 6, 9, 12, 15, and 18 mm were considered. Compressive and flexural tests were conducted after curing for 1 d and 7 d, and the normalized stress–strain curves were fitted using the Saenz L.P., Carreira D.J., and Zhenhai Guo models. The results showed that basalt fiber length significantly affected the mechanical performance of LRS geopolymers. An appropriate fiber length improved strength, stiffness, ductility, and post-peak load-bearing capacity, whereas excessively short or long fibers weakened the reinforcing effect. The 15 mm fiber group exhibited the best overall performance. After curing for 1 d, its compressive strength reached 2.23 MPa, 49.7% higher than that of the control group, and its elastic modulus increased approximately 2.5-fold. After curing for 7 d, its compressive strength reached 13.44 MPa, 32.0% higher than that of the control group. The Zhenhai Guo model provided the best fit for the stress–strain curves. SEM-EDS analysis showed that basalt fibers improved interfacial bonding and promoted gel enrichment near the fiber–matrix interface. Overall, 15 mm was recommended as the optimal basalt fiber length for CQU-1 LRS geopolymers under the conditions used in this study.

The residual mechanical properties after fire exposure form the basis for evaluating the structural performance of aluminium alloy components subjected to fire without collapse. This research investigated the impact of low cooling rates on the residual mechanical properties of 6063-T5 aluminium alloy after various cooling methods were utilized. A total of 48 tensile specimens were subjected to controlled elevated temperatures (ETs) ranging from 200 to 500 °C for 30 min soaking, followed by two cooling regimes: cooling in air (CIA) and cooling in furnace (CIF). For both CIA and CIF conditions, an increase in ETs led to a gradual increase in ductility, particularly elongation at fracture. Moreover, the effects of ETs on the fracture performance were discussed. Key mechanical parameters—namely nominal yield strength, ultimate tensile strength, elastic modulus, and strain at ultimate strength—were quantified across ETs and cooling methods, which were compared among different aluminium alloys. Empirical predictive equations were developed to capture the temperature-dependent degradation trends of mechanical properties, and a plasticity Ramberg–Osgood model was proposed and validated against test data. The metallographic microstructure of 6063-T5 aluminium alloy after different ETs revealed that the evolution of precipitate was the primary contributor to strength degradation. Finally, finite element simulations of aluminium plate girders after various ETs were conducted, which incorporated the proposed constitutive model and replicated the degradation trends observed in tensile tests. These findings provide a reliable foundation for implementing the proposed model into finite element simulations and structural assessment tools for post-fire aluminium alloy structures.

High-strength steel has attracted increasing attention in civil engineering because of its high strength-to-weight ratio and potential for material-efficient design. This narrative review, supported by a structured literature search, summarizes recent advances in the material behaviour, durability and structural performance of high-strength steel. The discussion covers constitutive behaviour, fatigue and fracture, corrosion degradation, high-temperature and post-fire properties, residual stresses, structural members and connections. Existing studies show that increasing steel strength is commonly accompanied by reduced ductility and strain-hardening capacity, while local buckling, residual stress, welding-induced heterogeneity, fatigue damage, corrosion and thermal degradation remain important design concerns. The accuracy of current design provisions varies with steel grade, product form, section geometry, failure mode and exposure condition, and direct extension from conventional steels is not always appropriate. Future research should emphasize coupled degradation mechanisms, consistent material characterization, broader experimental validation and design models with clearly defined applicability limits.