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A platform for research: civil engineering, architecture and urbanism
Fire exposed simply supported wooden I-joist in floor assemblies
A numerical study was conducted with the objective of determining cross-sectional and strength and stiffness properties of I-shaped joists subjected to charring under ISO 834 standard fire exposure. The outcome of this work should be design parameters in terms of Eurocode 5 (EN 1995-1-2) for I-joists in bending where the tension flange is on the fire exposed side of the joist; these are the time of start of charring, charring depths and modification factors for strength. The I-joists are assumed to be integrated in floor assemblies consisting of joists, linings made of gypsum plasterboard or wood-based panels, cavities completely filled with batt-type rock or glass fibre insulation, and a decking. Heat transfer analyses were performed using SAFIR. This software permits us to study the effect of the lining falling off at specified times that are known from full-scale testing or using the criterion of insufficient penetration length of fasteners into unburnt wood. For the determination of the notional charring depth in the flange and the modification factors of the whole cross-section, a computer program CSTFire, written as a Visual Basic macro embedded in Excel, was developed, using the temperature output from the heat transfer calculations and relative strength and stiffness values given by EN 1995-1-2, i.e. compressive strength, tensile strength and moduli of elasticity in compression and tension. The notional charring depth is determined such that the notional residual cross-section of the flange remains rectangular and the section modulus of the I-section is unchanged. The effect of various parameters on the notional charring rate is shown, such as charring phases (i.e. a distinction is made regarding whether the I-section is initially unprotected, protected by a lining, or unprotected after failure of the lining), flange dimensions and depth of cross-section. Modification factors for bending and shear strength are shown as functions of the notional charring depth for different charring phases. In order to ...
Fire exposed simply supported wooden I-joist in floor assemblies
A numerical study was conducted with the objective of determining cross-sectional and strength and stiffness properties of I-shaped joists subjected to charring under ISO 834 standard fire exposure. The outcome of this work should be design parameters in terms of Eurocode 5 (EN 1995-1-2) for I-joists in bending where the tension flange is on the fire exposed side of the joist; these are the time of start of charring, charring depths and modification factors for strength. The I-joists are assumed to be integrated in floor assemblies consisting of joists, linings made of gypsum plasterboard or wood-based panels, cavities completely filled with batt-type rock or glass fibre insulation, and a decking. Heat transfer analyses were performed using SAFIR. This software permits us to study the effect of the lining falling off at specified times that are known from full-scale testing or using the criterion of insufficient penetration length of fasteners into unburnt wood. For the determination of the notional charring depth in the flange and the modification factors of the whole cross-section, a computer program CSTFire, written as a Visual Basic macro embedded in Excel, was developed, using the temperature output from the heat transfer calculations and relative strength and stiffness values given by EN 1995-1-2, i.e. compressive strength, tensile strength and moduli of elasticity in compression and tension. The notional charring depth is determined such that the notional residual cross-section of the flange remains rectangular and the section modulus of the I-section is unchanged. The effect of various parameters on the notional charring rate is shown, such as charring phases (i.e. a distinction is made regarding whether the I-section is initially unprotected, protected by a lining, or unprotected after failure of the lining), flange dimensions and depth of cross-section. Modification factors for bending and shear strength are shown as functions of the notional charring depth for different charring phases. In order to ...
Fire exposed simply supported wooden I-joist in floor assemblies
König, Jürgen (author)
2006-01-01
Local 7234
Paper
Electronic Resource
English
Fire Resistance of Wood Joist Floor Assemblies
| British Library Online Contents | 2008