Performance Optimization Strategy for Steel-Concrete Composite Structures: Post-Fire Load-Bearing Capacity and Deformation Control

High-Strength Steel in Civil Engineering Structures: A Review of Material Behaviour, Durability, Fatigue and Component Performance

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.

Comprehensive Design and Structural Analysis of Steel-Fiber-Reinforced Concrete Tunnel Linings for Railway Infrastructure

The structural performance and durability of tunnel linings are critical for the safety of modern railway infrastructure. This study presents a comprehensive analysis of steel-fiber-reinforced concrete (SFRC) tunnel linings using a hybrid analytical and data-driven framework. The primary objective is to evaluate the effectiveness of SFRC in enhancing structural behavior under complex loading conditions. An integrated ORCA cyclic generative adversarial monitoring (OCGAM) framework, combining ORCA-based optimization with generative adversarial networks, is proposed to model and predict crack development, stress–strain response, and service life of tunnel linings. The framework incorporates key factors such as train-induced dynamic loads, soil–structure interaction, and seismic effects. Numerical simulations demonstrate that SFRC tunnel linings significantly reduce crack width, improve load-bearing capacity, and enhance durability compared with conventional reinforced concrete. The OCGAM framework further enables efficient prediction of structural responses with higher computational accuracy and reduced error rates than traditional analytical approaches. Although the study is limited to simulation-based validation, the results highlight the potential of combining optimization techniques with machine learning for advanced structural assessment. The proposed methodology provides a valuable tool for the design and monitoring of resilient and sustainable railway tunnel systems, and future work will focus on validation by experiments.

Investigation of Expansion Characteristics and Analysis-Oriented Stress–Strain Constitutive Model of Steel-Tube-Confined Recycled Aggregate Concrete

The use of recycled aggregate concrete (RAC) enables the valorization of construction waste and supports carbon-reduction strategies. However, long-term service-induced deterioration means that recycled aggregates and their interfacial transition zones inevitably contain defects, which severely restrict the safe application of RAC in load-bearing structures. Notably, although RAC reduces embodied carbon by recycling construction waste, steel tube manufacturing introduces an additional carbon footprint; such carbon trade-offs can be well compensated by the improved structural efficiency and extended service life of steel-confined concrete, achieving superior whole-life carbon benefits. In the present study, a steel-tube-confined recycled aggregate concrete (STCRC) composite system is proposed. Through designed external confinement, the stress state of the internal concrete is altered from uniaxial compression to triaxial compression, thereby enhancing its axial load-bearing capacity. Axial compression tests were performed on 36 short column specimens of steel-tube-confined concrete (STCC) composed of C30 aggregate concrete and Q235 steel tubes with three wall thicknesses (4.5 mm, 6 mm, 8 mm). Further parametric finite element analyses with 16 calculation cases were conducted to quantify the effects of higher concrete strength grades (C40 and C50) and of steel tube strength grades. The evolutionary characteristics of the load-displacement response, the axial stress–lateral strain relation, and the lateral strain–longitudinal strain were systematically investigated across various parameters. Test outcomes indicate that steel tube confinement significantly restrains lateral dilation of RAC and enhances its ductility and ultimate bearing capacity, with higher confinement efficiency observed for RAC than for natural aggregate concrete (NAC). Numerical results further identify the differing sensitivities of NAC and RAC to variations in tube wall thickness, steel yield strength, and concrete strength grade. Using combined experimental and numerical datasets, a peak stress modification factor is proposed, and a tailored stress–strain constitutive model for STCRC is developed and validated. The research findings provide theoretical guidance for the design of axially compressed short columns made of prefabricated recycled concrete.

A Review on Fiber-Reinforced Polymer Strengthen Steel–Concrete Composite Beam

Evolution of Mechanical Properties and Modeling Analysis of CFRP-Confined Concrete-Filled Steel Tubes after Exposure to Fire

Research on the Hysteresis Performance of Welded Hollow Spherical Joints under Low Temperature

The extreme cold environment has a significant impact on the mechanical properties of welded hollow ball nodes, which are crucial components in large-span steel structures. In this paper, based on the comprehensive test data of drum-shaped welded hollow sphere nodes from Beijing Daxing International Airport, a sophisticated finite element model incorporating welding residual stress is established. Through detailed static loading analysis and systematic hysteresis performance studies, the research thoroughly explores the influence mechanisms of low temperature on node bearing capacity, deformation capability, and energy dissipation performance. The investigation reveals that while the bearing capacity of the nodes increases significantly in low-temperature environments, both their plastic deformation capacity and energy consumption performance are notably reduced. These findings provide valuable theoretical references for the design and optimization of large-span mesh frame structures in cold regions, enabling engineers to better account for temperature effects in structural calculations and safety assessments. The results have important implications for improving the reliability and durability of steel structures in extreme cold environments.