Fire engineering design of composite floor systems for two way response in severe fires

Clifton, G Charles; Abu, Anthony; Gillies, A. G.; Mago, Nandor; Cowie, Kevin

doi:10.1201/9781315107202-39

Cited by 5 publications

(5 citation statements)

References 1 publication

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“…However, further development of the FBE model in three dimensions is required. Once this is developed, the FBE formulation could be used in conjunction with the slab panel method (SPM; Clifton, 2006), as a feasible modelling tool for structural fire analyses in performance-based design of structures.…”

Section: Resultsmentioning

confidence: 99%

Implementation of the fire beam element method into OpenSees for the analysis of structures in fire

Volkmann

Walls

Koker

2020

Advances in Structural Engineering

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The fire beam element method is a tool for structural fire analyses that simplifies a structure into a skeletal frame consisting of only beam and column elements. It considers a shifting neutral axis of each beam element, which is updated throughout an analysis. This method was implemented in the OpenSees software environment by adding two subclasses: one for the fire beam element added to the element class, and one for the member section, in which the neutral axis is iteratively adjusted for non-uniform temperature profiles. To validate the implemented model, three benchmark case studies were sourced from literature: (1) a heated cantilever beam with an analytical solution, (2) a steel beam in a furnace with high axial and bending forces and (3) a two-dimensional steel frame in a fire with complex behaviour such as non-linear heating, restraint and buckling. For (1) the fire beam element predicts deformations identical to an analytical solution. For (2) the fire beam element method simulates deformations with good accuracy across the entire time domain relative to experimental data, and simulations in the literature using Vulcan, although with experimental deflections typically being underestimated. For (3) fire beam element predictions are compared to experimental data and models developed in CEFICOSS, ABAQUS, SAFIR and LS-DYNA. Trends are typically accurately captured, with percentage differences varying. Runaway failure is predicted with 2 min of experimental data. A sensitivity analysis of the fire beam element model on mesh size of elements and fibres showed the runtime to be more sensitive to the number of elements than the number of fibres per element.

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Section: Resultsmentioning

confidence: 99%

Implementation of the fire beam element method into OpenSees for the analysis of structures in fire

Volkmann

Walls

Koker

2020

Advances in Structural Engineering

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“…Although the secondary beam remained unprotected and lost much of its flexural capacity during the test, the composite floor with the reinforcement of 142 mm 2 /m resisted the imposed load (equivalent to 56% of live loads at ambient temperatures) through tensile membrane action. The Slab Panel Method (SPM), the Steel Construction New Zealand (SCNZ) design software program developed by Clifton et al [22], was used to predict the behavior of the floor assembly tested in this study. This program incorporates an updated tensile membrane model from that proposed by Bailey [23][24] and the yield line theory by Park [25].…”

Section: Discussion On Slab Reinforcementmentioning

confidence: 99%

Behavior of Composite Floor Assemblies Subject to Fire: Influence of Slab Reinforcement

et al. 2021

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A series of fire experiments are being conducted on the 2‐story steel framed building with composite floors in the National Fire Research Laboratory. This paper presents a brief overview of experimental design and discusses some results of the first test conducted on 6.1 m by 9.1 m composite floor assembly exposed to a standard fire. The test floor slab was constructed with lightweight concrete cast on 7.7 cm deep formed steel deck units and welded wire fabric (60 mm/m2) as the minimum shrinkage reinforcement required in the U.S. practice. The structural steel beams and girders were sprayed with a cementitious fire resistive material for a 2‐hour restrained fire resistance rating. While the test floor assembly resisted mechanical loads (2.7 kN/m2) applied using hydraulic actuators, its underside was exposed to a natural gas‐fueled compartment fire that was equivalent to the standard gas temperature‐time relationship. The study revealed that the test floor assembly could withstand an imposed load at a large vertical deflection on the order of span / 16, but the concrete slab failed due to limited ductility and strength prior to 2 hours in a standard fire. Simple post‐test predictions were performed incorporating tensile membrane action in the floor slab to compare with the measured behavior. Limited comparisons discuss the contribution of steel decking and slab reinforcement to the load‐carrying capacity of a floor assembly in fire.

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“…With several iterations performed for the selection of slab reinforcement using the Slab Panel Method (SPM) [21] which has been used in the New Zealand (NZ) practice, the following two schemes were considered for the Test…”

Section: Design Basis Of Composite Floor Test #2mentioning

confidence: 99%

Fire resilience of a steel-concrete composite floor system :

Choe¹

2022

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The National Institute of Standards and Technology is currently conducting a series of large compartment fire tests to investigate the behavior and fire-induced failure mechanisms of the full-scale composite floor assemblies with the two-story steel gravity frame, two bays by three bays in plan. This report presents the experimental design and results from the second fire experiment (Test #2) conducted at the National Fire Research Laboratory. The Test #2 was aimed to investigate the influence of the slab reinforcement on the structural integrity of the 9.1 m 6.1 m steel-concrete composite floor subjected to combined mechanical loads and compartment fire exposure. The fire test bay was situated on the ground floor in the middle edge bay of the two-story test building. The floor slab in the test bay was reinforced with the No.3 deformed bars placed 30 cm on center (230 mm2/m). The test floor was hydraulically loaded to 2.7 kPa to mimic the code-prescribed gravity loads for fire conditions. The natural gas burners created a peak gas temperature exceeding 1100 C below the test floor. The test fire lasted about 131 min, but the hydraulic loading was not removed until the test floor cooled down over 2 hours. This experimental study confirmed that the steel reinforcement played a vital role in maintaining the integrity of the composite floor under prolonged compartment fire exposure. The mid-panel vertical displacement increased at a rate less than 1 mm/ C as the protected steel beams were heated to 850 C on average. The peak vertical displacement of the test slab was recorded 475 mm surpassing the displacement limit prescribed in the standard fire test. Although the test slab developed extensive surface cracks, it successfully contained the test fire underneath while sustaining the imposed loads simultaneously. The test floor retained the post-fire flexural strength exceeding 90 % of the ambient design strength of the composite secondary beam prior to fire exposure. The experimental results presented in this report can be used for validation of predictive models to perform parametric studies incorporating the variability in the steel reinforcement scheme (area, spacing, and material) for safer and cost-effective composite floor construction for fire safety.

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Fire engineering design of composite floor systems for two way response in severe fires

Cited by 5 publications

References 1 publication

Implementation of the fire beam element method into OpenSees for the analysis of structures in fire

Implementation of the fire beam element method into OpenSees for the analysis of structures in fire

Behavior of Composite Floor Assemblies Subject to Fire: Influence of Slab Reinforcement

Fire resilience of a steel-concrete composite floor system :

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