Experimental and numerical investigation of post-tensioned concrete flat slabs in fire

Purpose This paper aims to understand the structural fire performance of two-way post-tensioned flat slabs, particularly their deformations and load-carrying mechanisms in fire, and to explore the behaviour of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons in fire. Design/methodology/approach Four tests of post-tensioned high-strength self-compacting concrete flat slabs were conducted under fire conditions. Numerical modelling using the commercial package ABAQUS was conducted to help interpret the test results. Findings Two of the specimens with lower moisture contents demonstrated excellent fire resistance performance, while the others with slightly higher moisture contents experienced severe concrete spalling. Originality/value The test results were discussed in respect of thermal profiles, deflections, crack patterns and concrete spalling. The performance of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons under fire conditions was better understood.postprin

Virtual hybrid simulation of beams with web openings in fire

Purpose: Perforated composite beams are an increasingly popular choice in the construction of buildings because they can provide a structurally and materially efficient design solution while also facilitating the passage of services. The purpose of this paper is to examine the behaviour of restrained perforated beams, which act compositely with a profiled slab and are exposed to fire. The effect of surrounding structure on the composite perforated beam is incorporated in this study using a virtual hybrid simulation framework. The developed framework could also be used to analyse other structural components in fire. Design/methodology/approach: A finite element model is developed using OpenSees and OpenFresco using a virtual hybrid simulation technique, and the accuracy of the model is validated using available fire test data. The validated model is used to investigate some of the most salient parameters such as the degree of axial and rotational restraint, arrangement of the openings and different types of fire on the overall fire behaviour of composite perforated beams. Findings: It is shown that both axial and rotational restraint have a considerable effect on time-displacement behaviour and the fire performance of the composite perforated beam. It is observed that the rate of heating and the consequent development of elevated temperature in the section have a significant effect on the fire behaviour of composite perforated beams. Originality/value: The paper will improve the knowledge of readers about modelling the whole system behaviour in structural fire engineering and the presented approach could also be used for analysing different types of structural components in fire conditions

The Temperature-dependent Cone Calorimeter: An Approximate Alternative to Furnace Testing

ABSTRACT: This article discusses how a modified (variable heat flux) Cone Calorimeter can be used to approximately replicate heating regimes in standard furnace testing. The method is not exact as there are a number of physical differences between the two systems that are not accounted for, and the cone heater is unable to deliver sufficient heat flux to replicate aggressive furnace environments such as the hydrocarbon heating regime. Intumescent coatings testing is used (on an I-beam and a flat plate in the cone) to demonstrate the efficacy of the technique. The method as described relates to an internal furnace test (on an I-beam), but it is easily modifiable to other test scenarios such as a door test. Similarly, although the example discussed considers intumescent coatings testing, it is expected that a wide range of sample media could be tested in this way. That stated there are a range of limitations to this technique that need to be appreciated. KEY WORDS: intumescent coatings, testing, furnace testing, cone calori-meter. *Author to whom correspondence should be addressed