Although a few fire experiments have been carried out on load-bearing cold-formed steel (CFS) wall systems, the understanding of their fire performance is still limited, and further parametric analysis on the basis of such experiments is expensive and time-consuming. This paper presents a simplified numerical approach to predicting the thermal and mechanical responses of CFS wall systems in fire. Thermal physical property experiments were carried out to measure the essential material properties. With those material properties as inputs, a one-dimensional thermal response model was developed to predict the heat transfer across the cross section of CFS wall systems. Both heat convection and radiation were considered in the thermal boundary conditions. The governing equation was expressed in the form of implicit finite-differential equations and solved using the Gauss-Seidel method. The model predictions of temperature responses of CFS wall systems were in good agreement with the measured temperature...

Thermal and Mechanical Modeling of Load-Bearing Cold-Formed Steel Wall Systems in Fire

Aluminium alloys as structural material: A review of research

Light Gauge Steel Framing (LSF) walls made of cold-formed and thin-walled steel lipped channel studs with plasterboard linings on both sides are commonly used in commercial, industrial and residential buildings. However, there is limited data about their structural and thermal performance under fire conditions while past research showed contradicting results about the benefits of using cavity insulation. A new composite wall panel was recently proposed to improve the fire resistance rating of LSF walls, where an insulation layer was used externally between the plasterboards on both sides of the wall frame instead of using it in the cavity. In this research 11 full scale tests were conducted on conventional load bearing steel stud walls with and without cavity insulation, and the new composite panel system to study their thermal and structural performance under standard fire conditions. These tests showed that the use of cavity insulation led to inferior fire performance of walls, and provided supporting research data. They demonstrated that the use of insulation externally in a composite panel enhanced the thermal and structural performance of LSF walls and increased their fire resistance rating. This paper presents the details of the LSF wall tests and the thermal and structural performance data and fire resistance rating of load-bearing wall assemblies lined with varying plasterboard-insulation configurations under two different load ratios. Fire test results including the time–temperature and deflection profiles are presented along with the failure times and modes.

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Experimental study of load bearing cold-formed steel wall systems under fire conditions

Experimental study on post-fire mechanical properties of high strength Q460 steel

Post-fire mechanical properties of high strength Q690 structural steel

Finite element modelling of load bearing cold-formed steel wall systems under fire conditions

Cold-formed steel members are widely used in residential, industrial and commercial buildings as primary load-bearing elements. During fire events, they will be exposed to elevated temperatures. If the general appearance of the structure is satisfactory after a fire event then the question that has to be answered is how the load bearing capacity of cold-formed steel members in these buildings has been affected. Hence after such fire events there is a need to evaluate the residual strength of these members. However, the post-fire behaviour of cold-formed steel members has not been investigated in the past. This means conservative decisions are likely to be made in relation to fire exposed cold-formed steel buildings. Therefore an experimental study was undertaken to investigate the post-fire mechanical properties of cold-formed steels. Tensile coupons taken from cold-formed steel sheets of three different steel grades and thicknesses were exposed to different elevated temperatures up to 800 °C, and were then allowed to cool down to ambient temperature before they were tested to failure. Tensile coupon tests were conducted to obtain their post-fire stress–strain curves and associated mechanical properties (yield stress, Young׳s modulus, ultimate strength and ductility). It was found that the post-fire mechanical properties of cold-formed steels are reduced below the original ambient temperature mechanical properties if they had been exposed to temperatures exceeding 300 °C. Hence a new set of equations is proposed to predict the post-fire mechanical properties of cold-formed steels. Such post-fire mechanical property assessments allow structural and fire engineers to make an accurate prediction of the safety of fire exposed cold-formed steel buildings. This paper presents the details of this experimental study and the results of post-fire mechanical properties of cold-formed steels. It also includes the results of a post-fire evaluation of cold-formed steel walls.

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Experimental investigation of post-fire mechanical properties of cold-formed steels

Local buckling studies of cold-formed steel compression members at elevated temperatures

Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load-bearing and non-load bearing structural elements. These buildings must be properly evaluated after a fire event to assess the nature and extent of structural damage. If the general appearance of the structure is satisfactory after a fire event then the question that has to be answered is how the structural capacity of cold-formed steel members in these buildings has been affected. Elevated temperatures during a fire event affect the structural performance of cold-formed steel members even after cooling down to ambient temperature due to the possible detrimental changes in their mechanical properties. However, the post-fire behaviour of cold-formed steel members has not been investigated in the past and hence there is a need to investigate the post-fire mechanical properties of cold-formed steels. Therefore an experimental study was undertaken at the Queensland University of Technology to understand the residual mechanical properties of cold-formed steels after fire events. Tensile coupon tests were conducted on three different steel grades and thicknesses to obtain their stress-strain curves and relevant mechanical properties after cooling them down from different elevated temperatures. It was found that the post-fire mechanical properties of cold-formed steels are different to the original ambient temperature mechanical properties. Hence a new set of equations is proposed to predict the reduced mechanical properties of cold-formed steels after a fire event.

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Shanmuganathan Gunalan

Papers

Experimental study of load bearing cold-formed steel wall systems under fire conditions

Finite element modelling of load bearing cold-formed steel wall systems under fire conditions

Experimental investigation of post-fire mechanical properties of cold-formed steels

Local buckling studies of cold-formed steel compression members at elevated temperatures

Post-fire mechanical properties of cold-formed steels