Restraint in Fire Tests of Concrete Floors and Roofs

Selvaggio, S; Carlson, Clinton

doi:10.1520/stp41304s

Cited by 5 publications

(3 citation statements)

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“…Lower Young’s modulus resulted in higher residual modulus, which corroborates to the findings of Xiong and Liew [ 69 ] and Ali et al [ 70 ]. Fire tests in prestressed concrete beams performed by Selvaggio and Carlson [ 71 ] revealed that a combination of a high modulus of elasticity with reduced tensile and compressive strengths of concrete contribute to the lack of resistance to bursting stresses that leads to concrete spalling.…”

Section: Resultsmentioning

confidence: 99%

Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete

et al. 2020

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This paper investigates a potential application of hard-to-recycle plastic waste as polymeric addition in high strength concrete, with a focus on the potential to mitigate heat-induced concrete spalling and the consequent effects on the mechanical properties. The waste corresponds to soft and hard plastic, including household polymers vastly disposed of in landfills, although technically recyclable. Mechanical and physical properties, cracking, mass loss, and the occurrence of spalling were assessed in high strength concrete samples produced with either plastic waste or polypropylene fibers after 2-h exposure to 600 °C. The analysis was supported by Scanning Electron Microscopy and X-Ray Computed Tomography images. The plastic waste is composed of different polymers with a thermal degradation between 250 to 500 °C. Polypropylene (PP) fibers and plastic waste dispersed in concrete have proved to play an essential role in mitigating heat-induced concrete spalling, contributing to the release of internal pressure after the polymer melting. The different morphology of plastic waste and polypropylene fibers leads to distinct mechanisms of action. While the vapor pressure dissipation network originated by polypropylene fibers is related to the formation of continuous channels, the plastic waste seems to cause discontinuous reservoirs and fewer damages into the concrete matrix. The incorporation of plastic waste improved heat-induced concrete spalling performance. While 6 kg/m3 of plastic increased the mechanical performance after exposure to high temperature, the incorporation of 3 kg/m3 resulted in mechanical properties comparable to the reference concrete.

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Section: Resultsmentioning

confidence: 99%

Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete

et al. 2020

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“…Development of a varying degree of applied restraint against thermal expansion in standard fire tests was assumed to be the main reason for such variations . Additionally, during this time, there were debates about the feasibility of simulating realistic restraint within a test furnace . The 1969 proposed revision received the greatest support from the committee members and was first adopted in the 1971 edition of ASTM E119 .…”

Section: Origin Of Restraint Classificationsmentioning

confidence: 99%

“…Additionally, during this time, there were debates about the feasibility of simulating realistic restraint within a test furnace. 13 The 1969 proposed revision received the greatest support from the committee members and was first adopted in the 1971 edition of ASTM E119. 14 Apparently, results and observations from fire tests performed at Ohio State University with sponsorship from the American Iron and Steel Institute (AISI) played a significant role in the success of the 1969 proposal.…”

Section: Origin Of Restraint Classificationsmentioning

confidence: 99%

Rectification of “restrained vs unrestrained”

LaMalva¹,

Bisby

Gales

et al. 2020

Fire and Materials

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Summary For furnace testing of fire‐resistant floor and roof assemblies in the United States, the ASTM E 119 standard (and similarly the UL 263 standard) permits two classifications for boundary conditions: “restrained” and “unrestrained.” When incorporating tested assemblies into an actual structural system, the designer, oftentimes a fire protection or structural engineer, must judge whether a “restrained” or “unrestrained” classification is appropriate for the application. It is critical that this assumption be carefully considered and understood, as many qualified listings permit a lesser thickness of applied fire protection for steel structures (or less concrete cover for concrete structures) to achieve a certain fire resistance rating if a “restrained” classification is confirmed, as compared with an “unrestrained” classification. The emerging standardization of structural fire engineering practice in the United States will disrupt century‐long norms in the manner to which structural behavior in fire is addressed. For instance, the current edition of the ASCE/SEI 7 standard will greatly impact how designers consider restraint. Accordingly, this paper serves as an exposé of the “restrained vs unrestrained” paradigm in terms of its paradoxical nature and its controversial impact on the industry. More importantly, potential solutions toward industry rectification are provided for the first time in a contemporary study of this paradigm.

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New Criteria for Fire Endurance Tests

Bono

1970

Fire Test Performance

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The long accepted test procedure for determining the fire endurance of floor and roof assemblies, as described in ASTM Standard Methods of Fire Tests of Building Construction and Materials (Designation: E 119), is being questioned seriously. Skepticism has developed because the performance under fire exposure of structural members and assemblies has not corresponded with anticipated performance based on established properties of materials at elevated temperatures. The difference between predicted results and actual results is attributed to the test procedures used to implement provisions in the Standard which require restraint of the test specimen and imposition of loads to develop working stresses. Restraint of the test specimen has contributed so substantially to the performance that normal structural criteria such as deflection and collapse appear to be of limited value in judging fire endurance. Research projects have established that significant improvement is brought about by the presence of restraint during fire tests. Individual steel beams have resisted collapse in fire tests for a 25 percent longer time when tested under restraint as compared with simply supported tests. Concrete members have shown in excess of 400 percent increase in fire resistance in comparative tests. Certain constructions employing continuity and cantilevered sections have shown improved fire resistance as compared with simply supported structures. Various revisions of the criteria in ASTM Methods E 119 have been proposed. Each of these, developed in 1964, 1965, 1967, 1968, and 1969, provided partial solutions. With the exception of the 1969 proposal, which is before ASTM Committee E-5 at this writing, some features of each proposal have been criticized. The concepts of these proposals are examined in this paper, with a summary of the prevailing views. The impact on future designs of building construction for fire resistance and on the costs of building construction are so great as to make any changes in criteria a most important and difficult decision.

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Restraint in Fire Tests of Concrete Floors and Roofs

Cited by 5 publications

References 0 publications

Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete

Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete

Rectification of “restrained vs unrestrained”

New Criteria for Fire Endurance Tests

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