A literature review on the ambient and post- fire behavior of load transfer mechanisms in columns

Abstract

The definition of load transfer mechanisms between beams and columns is one of the main challenges in the development of composite and hybrid structural systems. While traditional shear connectors such as stud bolts are well-established, new alternatives, particularly composite dowels, have recently gained attention due to their potential for improved constructive efficiency. However, the behavior of shear connectors in general after fire exposure remains insufficiently studied, especially when these connectors are used as load transfer mechanisms in post-fire conditions. Assessing residual load-bearing capacity is crucial in buildings subjected to fire, as it supports structural integrity analyses and contributes to reducing the interventions required during the repair process. Despite this importance, the literature reveals gaps regarding the residual strength of shear connectors after fire and their interaction with the degraded mechanical properties of concrete and steel, as these directly influence the performance of such mechanisms. Therefore, this study analyzes main parameters affecting the behavior of shear connectors under ambient and post-fire conditions, with special emphasis on composite dowels, and reviews residual properties of steel and concrete after high-temperature exposure and cooling. The results aim to clarify possible failure modes after fire exposure and contribute to the improvement of design and assessment methods for load transfer mechanisms in fire-damaged columns.