Restraint of fire‐exposed concrete floor systems

Lim, Linus; Buchanan, Andrew; Moss, Peter

doi:10.1002/fam.854

Cited by 22 publications

(28 citation statements)

References 7 publications

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“…The program was developed for analysing steel or composite structures, but the shell element in SAFIR has been proven to also accurately predict the fire behaviour of RC slabs [13]. A previous study showed that SAFIR can successfully predict the structural behaviour of hibond slabs (proprietary composite slabs) using a combination of shell and beam elements [14], which is the basic idea behind the proposed model in this study.…”

Section: Introductionmentioning

confidence: 99%

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Hollow‐core concrete slabs exposed to fire

et al. 2008

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SUMMARYThe aim of this paper is to provide recommendations to designers and to propose a simple method for designers to model the structural behaviour of hollow-core concrete (HC) floor slabs in fire. The proposed finite element model incorporates a grillage system using beam elements to capture the thermal expansion of the precast units in both directions, with the topping concrete over several precast units modelled by shell elements. The research reported herein compares the proposed model with various fire test results of HC slabs. The simulation outcomes show good agreement with the experimental results.Several HC slab flooring systems tested previously at the University of Canterbury for seismic purposes were simulated using this modelling scheme. Various supporting schemes have been considered, and the results show that different arrangements of axial and rotational restraint at the supports can significantly influence the fire performance of the concrete slab floors.

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Section: Introductionmentioning

confidence: 99%

“…A previous study has demonstrated that two-way supported RC slabs have better fire resistance than one-way supported slabs due to the membrane action [13]. Besides, restraint due to the surrounding structure has been proven to have a favourable effect on the performance of the HC floor system in fire [18].…”

Section: Introductionmentioning

confidence: 99%

Hollow‐core concrete slabs exposed to fire

et al. 2008

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“…Additional analyses with varying levels of axial restraint increased the fire resistance to over 90 minutes, and over 120 minutes in some cases [2]. The effect of axial restraint on fire resistance depends greatly on the height of the line of action of the restraint force, as discussed by Lim et al [16].…”

Section: Single-bay Beammentioning

confidence: 91%

Effect Of Top Reinforcing On The Fire Performance Of Continuous Reinforced Concrete Beams

Bernhart¹,

Buchanan²,

Dhakal³

et al. 2005

Fire Safety Science - Proceedings of the Eigth International Sy

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This paper examines the behaviour of continuous reinforced concrete beams exposed to fire on three sides, in order to investigate the effect of different lengths of the top reinforcing bars over the supports. The study was performed with 2D finite element analysis using SAFIR. The effect of continuity was investigated with rectangular crosssection beams spanning over two and three bays subjected to the ISO 834 fire. Compared to a single span beam, the continuous beams resisted the fire exposure for a longer period of time. It was found that different lengths of the top reinforcing bars resulted in different failure mechanisms, but did not greatly affect the fire resistance of the beams. The influence of the full process of fire development was analysed using the ISO fire for 30, 60 and 90 minutes followed by a decay phase. Structural failure only occurred if the fully developed phase of the fire continued until very close to the failure time reached with no decay phase.

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“…Traditionally, simply supported precast prestressed hollowcore slabs in New Zealand have been widely used as shown in Figure 1 [12], [13]. The simple connection details comprised of the floor unit seated on a mortar bed, core end plugs to prevent concrete from entering the cores, and conventional starter bar reinforcement in the topping slab [1].…”

Section: Simple Connection Detailmentioning

confidence: 99%

Modelling the Fire Resistance of Prestressed Concrete Floors using Multi-Spring Connection Elements

Min

Dhakal

Moss

et al. 2012

Journal of Structural Fire Engineering

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Despite big advances in analytical modelling of the performance of structures exposed to fire, there has been difficulty in modelling the fire performance of precast prestressed concrete floor slabs in multi storey buildings. The fire resistance of these floor systems is heavily influenced by the end connections and the stiffness of the surrounding structure, both of which must be considered in any analysis.Previous "traditional" studies have modelled the floor slabs with beam or shell elements in which the end nodes share the nodes of the beam elements representing the supporting beams. This is acceptable for cast-in-situ or precast flooring system without prestressing, but leads to a major problem for precast prestressed flooring systems where the steel tendons terminate at the end of the flooring units, because the approach of sharing nodes of the supporting beam and floor assumes that these tendons are anchored into the supporting beams.In order to solve this problem, a "multi-spring" connection element has been developed. The multi-spring connection element consists of several parallel axial springs sandwiched between two rigid plates. Each spring represents either a steel reinforcing layer or a segment of concrete in the floor cross-section. The concrete springs have compression-only properties. This multi-spring connection is placed between the end nodes of the floor and the nodes of the supporting beam. With this element, it is possible to terminate the prestressing tendons at the end node of the floor elements and to anchor only the topping reinforcement into the supporting systems predicted using the traditional approach and the newly developed multispring connection, with applications to different forms of precast concrete floors in multi storey buildings.

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Restraint of fire‐exposed concrete floor systems

Cited by 22 publications

References 7 publications

Hollow‐core concrete slabs exposed to fire

Hollow‐core concrete slabs exposed to fire

Effect Of Top Reinforcing On The Fire Performance Of Continuous Reinforced Concrete Beams

Modelling the Fire Resistance of Prestressed Concrete Floors using Multi-Spring Connection Elements

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