ABSTRACT
The structural behaviour of buildings under fire has historically received significant research attention and their fire resistance design benefits from comprehensive advisory documents. However, the same cannot be said of non-building structures such as cable-stayed bridges whose structural fire protection requirements are not explicitly covered by building regulations and are typically driven by property protection and business continuity requirements. The structural fire protection of cables in cables stayed bridges often requires a thermal response assessment of the cables. The thermal response of cable stays is often based on very simple heat transfer models.
This paper presents the outcome of a comprehensive series of transient 2D heat transfer analyses on a realistic cable cross-section under a selection of heating regimes which aim to investigate the sensitivity of the thermal response to the position of the cable relative to the fire and smoke plumes. The paper also proposes a novel method for modelling the thermal response of cables including the heat transfer mechanisms between individual strands of the cable stays.
The study illustrated that the thermal response of cable strands is sensitive to input parameters and therefore highlights the importance of using both a realistic cable cross-section configuration in addition to accurate heat transfer characteristics. The study undertaken illustrates that the simplified lumped capacitance assumption commonly used in thermal response assessment of cable stays is not always appropriate.
