ABSTRACT
Composite floors comprise a reinforced concrete slab on thin metal steel deck, supported on a network of secondary and primary beams (beams and girders).
Traditionally, all these support beams have required insulation to avoid collapse in severe fires. However, a severe fire in a steel frame building with composite floors but without the insulation occurred in 1990 in the UK, resulting in minor damage only, enabling the floor and building to be repaired and returned to service. This unexpectedly robust performance has led to a comprehensive fire research programme, led by fire engineering researchers principally in the UK and Europe, to understand the behaviour of these composite floor systems with selected unprotected supporting beams in severe fires and to enable the development of design guidance and detailing requirements.
New Zealand has been at the forefront of the design and detailing development of these floor systems, culminating in the introduction of two way floor systems for dependable response in fully developed fires into the draft DR AS/NZS2327 Composite Structures standard, with anticipated publication in mid-2017. This includes the Slab Panel Method, which is widely used in the design of composite floor systems in New Zealand.
This paper covers the development of that method and introduces an application example. It will cover the principal areas of future research required for these systems and describe fire testing planned nationally and internationally, including a testing program underway at the NIST National Fire Research Laboratory in Maryland, USA in which full scale testing of composite beams with slab is being undertaken in 2017 followed by two way floor systems testing in 2018.
