Mechanical properties and connection methods of steel-timber composite beams: a systematic review

Steel-timber composite (STC) beams, as a structural form that combines high strength with sustainability, have demonstrated significant potential for application in green and prefabricated building systems. This paper provides a comprehensive review of STC beams, including their typical connection types, key mechanical properties, common failure modes, and long-term service performance. It also summarizes the current development and applicability of finite element modelling strategies and theoretical analysis methods. The findings indicate that the connection configuration plays a decisive role in determining the composite beam's stiffness, load-bearing capacity, and ductility. Factors such as connection type, spacing, orientation, and interaction with wood grain direction significantly affect the structural response. Moreover, the γ method, elastic analysis models, and the additional curvature method are widely adopted in theoretical studies, each presenting trade-offs between computational accuracy and efficiency. This review further highlights the limitations of current design practices and, based on the latest literature, outlines future research directions in standardized design approaches, long-term performance evaluation, multi-scale modelling techniques, and the development of innovative connection systems. These insights aim to support the engineering application and design optimization of STC structures through both theoretical advancement and practical guidance.