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Light gauge steel-framed (LSF) walls, commonly made with lipped channel studs and gypsum plasterboard sheathing, are increasingly being used in low to mid-rise buildings. Improvements have been made with respect to fire, wind/seismic and energy performance of LSF walls with the use of improved stud sections, wall configurations, different sheathing members, and insulation materials. Although the provision of sheet steel as sheathing has been found to improve the in-plane shear capacity of LSF walls, its effects on the fire performance of load bearing walls remain unknown. Three full-scale ISO 834 standard fire tests were conducted in this study to investigate the fire performance of axially loaded gypsum plasterboard and steel sheathed LSF walls made with web-stiffened studs. The results revealed that compared to the commonly used lipped channel stud, the web-stiffened stud is capable of withstanding a 57% greater axial compression load, yet yield the same fire resistance level (FRL), when sheathed only with two layers of gypsum plasterboard. Under the selected load ratio, the addition of steel sheathing caused only marginal improvements in the stud temperature development, resulting in minor improvements to the FRL of load bearing walls. However, the axial load bearing capacity improvement caused by the inclusion of steel sheathing allowed the web-stiffened stud to withstand a 10% greater axial compression load compared to the plasterboard only wall. more...

Light gauge steel framed (LSF) walls are used in fire compartmentation to prevent the spread of fire, smoke and toxic gases. The fire behavioural characteristics of non-load bearing LSF walls are different from those of load bearing walls. In non-load bearing LSF walls, fire penetration to the ambient side is to be prevented for insulation and integrity criteria whereas in load bearing walls, steel studs need to be protected from heat for structural adequacy also. This paper investigates the fire resistance of non-load bearing and load bearing LSF walls with and without cavity insulation. It presents the details of a series of standard fire tests conducted to investigate the effect of cavity insulation in both load bearing and non-load bearing LSF walls. The use of cavity insulation increased the fire resistance level (FRL) of non-load bearing walls, while it significantly reduced the FRL of load bearing walls. A finite element parametric study was then conducted for LSF walls lined with both single and double layers of plasterboards. Both thermal and structural fire performance results of LSF walls from finite element analyses are presented and compared in this paper. These results showed that FRL of cavity insulated non-load bearing LSF walls increases by 10–20 min, while it is significantly reduced for load bearing LSF walls with load ratios below 0.7. This study highlights both the beneficial and detrimental effects of cavity insulated LSF walls exposed to fire. more...

Light gauge steel frame (LSF) walls are commonly used in modular based mid-rise building construction. They are lined with single or two layers of gypsum plasterboards and used with or without cavity insulation or noggings. These wall lining materials delay the temperature rise of the studs by acting as a thermal barrier and prevent steel studs from being exposed to fire. The wall studs are made of low and high strength steel studs and LSF wall lining manufacturers’ data manuals give the same fire resistance levels for both grades of steel studs. Low and high strength steels are made of different chemical compositions, which influence the fire performance of LSF walls. This paper presents the details of a series of standard fire tests of load bearing LSF walls conducted to investigate the effects of using low and high strength steel studs in Australia. Structural finite element models of fire tested walls were then developed using appropriate elevated temperature mechanical properties, validated using the fire test results and used in a parametric study of LSF walls made of both low and high strength steel studs. The results showed that FRL of low strength steel stud walls is reduced by about 25% in the common load ratio range in comparison with high strength steel stud walls, while their critical hot flange temperatures are reduced. These differences are due to the variations in their elevated temperature mechanical properties caused by the material composition. Reliable fire performance results of both low and high strength steel stud walls from finite element analyses and fire tests are presented and compared in this paper. This paper highlights the importance of using accurate elevated temperature mechanical property reduction factors in numerical analyses and design of LSF walls. more...

Light gauge steel frame (LSF) walls are commonly used in single and two storey residential and commercial buildings and modular based mid-rise building construction. They are lined with single or two layers of gypsum plasterboards and used with or without cavity insulation or noggings. This paper presents the details of a series of standard fire tests of load bearing LSF walls used in low-rise building construction to investigate the effects of using low strength steel studs, noggings and cavity insulation. The presence of cavity insulation significantly reduced the fire resistance level (FRL) of load bearing walls while the use of noggings increased the FRL, and these findings are considered valid for both low and high strength steel stud walls. Structural finite element models of fire tested walls were then developed using appropriate elevated temperature mechanical properties, validated using the fire test results and used in a parametric study of LSF walls made of both low and high strength steel studs. The results showed that FRL of low strength steel stud walls is reduced by about 25% in the common load ratio range in comparison with high strength steel stud walls, while their critical hot flange temperatures are reduced. These differences are due to the variations in their elevated temperature mechanical properties caused by the material composition. Reliable fire performance results of both low and high strength steel stud walls from finite element analyses and fire tests are presented and compared in this paper. This study has highlighted the importance of using accurate elevated temperature mechanical property reduction factors in numerical analyses and design of LSF walls. more...

Cold-formed Light gauge Steel Frame (LSF) walls lined with plasterboards are increasingly used in the building industry as primary load bearing components. Although they have been used widely, their behaviour in real building fires is not fully understood. Many experimental and numerical studies have been undertaken to investigate the fire performance of load bearing LSF walls under standard fire conditions. However, the standard fire time-temperature curve given in ISO 834 [1] does not represent the fire load present in typical modern buildings that include considerable amount of thermoplastic materials. Some of these materials with high in calorific values increase the fire severity beyond that of the standard fire curve. Fire performance studies of load bearing LSF walls exposed to realistic design fire curves have also been limited. Therefore in this research, finite element thermal models of LSF wall panels were developed to simulate their fire performance using the recently developed realistic design fire time-temperature curves [2]. Suitable thermal properties were proposed for plasterboards and insulations based on laboratory tests and available literature. The developed finite element thermal models were validated by comparing their thermal performance results with available realistic design fire test results, and were then used in a detailed parametric study. This paper presents the details of the developed finite element thermal models of load bearing LSF wall panels under realistic design fire time-temperature curves and the results. It shows that finite element thermal models of LSF walls can be used to predict the fire performance including their fire resistance rating with reasonable accuracy for varying configurations of plasterboard lined LSF walls exposed to realistic design fire time-temperature curves. more...

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), Griffith School of Engineering, Science, Environment, Engineering and Technology, Concrete structures regularly require strengthening due to various reasons. These structures include bridges, buildings and infrastructure, across numerous sectors and industries. Based on the load-carrying capacity of structures and proposed future applications, a vast array of strengthening methods may be utilised. Due to rapid advancements in construction materials, technology has led to the achievement of being able to secure safer, more economical and functional buildings. Of the innovative materials, Fibre Reinforced Polymer (FRP) appears to be an encouraging solution for the retrofitting and strengthening of Reinforced Concrete (RC) structures because of its unique properties. These properties include: high strength-to-weight ratio; high fatigue endurance; environmental degradation and corrosion resistance. FRP is also durable and very flexible for application to the various shapes of structural members. Further, it is easy to install, with a negligible increase in structural size and weight. The application of FRP is dependent upon the type of structural member plus its behaviour. It can be used to enhance the load capacities (axial, flexural, or shear), ductility, rigidity, the remaining fatigue life as well as the durability against harsh environments. more...

During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy. more...

Light gauge steel frame (LSF) wall systems are increasingly used in residential and commercial buildings as load bearing and non-load bearing elements. Conventionally, the fire resistance ratings of such building elements are determined using approximate prescriptive methods based on limited standard fire tests. However, recent studies have shown that in some instances real building fire time-temperature curves could be more severe than the standard fire curve, in terms of maximum temperature and rate of temperature rise. This has caused problems for safe evacuation and rescue activities, and in some instances has also lead to the collapse of buildings earlier than the prescribed fire resistance. Therefore a detailed research study into the performance of LSF wall systems under both standard fire and realistic fire conditions was undertaken using full scale fire tests to understand the fire performance of different LSF wall configurations. Both load bearing and non-load bearing full scale fire tests were performed on LSF walls configurations which included single layer, double layer, externally insulated wall panels made up of different steel sections and thicknesses of gypsum plasterboards. The non-load bearing fire test results were utilized to understand the factors affecting the fire resistance of LSF walls, while loading bearing fire test results led to development of simplified methods to predict the fire resistance ratings of load bearing LSF walls exposed to both standard and realistic design fires. This paper presents the results of full scale experimental study and highlights the effects of standard and realistic fire conditions on fire performance of LSF walls. more...

Fire safety has become an important part in structural design due to the ever increasing loss of properties and lives during fires. Conventionally the fire rating of load bearing wall systems made of Light gauge Steel Frames (LSF) is determined using fire tests based on the standard time-temperature curve in ISO834 [1]. However, modern commercial and residential buildings make use of thermoplastic materials, which mean considerably high fuel loads. Hence a detailed fire research study into the fire performance of LSF walls was undertaken using realistic design fire curves developed based on Eurocode parametric [2] and Barnett’s BFD [3] curves using both full scale fire tests and numerical studies. It included LSF walls without cavity insulation, and the recently developed externally insulated composite panel system. This paper presents the details of finite element models developed to simulate the full scale fire tests of LSF wall panels under realistic design fires. Finite element models of LSF walls exposed to realistic design fires were developed, and analysed under both transient and steady state fire conditions using the measured stud time-temperature curves. Transient state analyses were performed to simulate fire test conditions while steady state analyses were performed to obtain the load ratio versus time and failure temperature curves of LSF walls. Details of the developed finite element models and the results including the axial deformation and lateral deflection versus time curves, and the stud failure modes and times are presented in this paper. Comparison with fire test results demonstrate the ability of developed finite element models to predict the performance and fire resistance ratings of LSF walls under realistic design fires. more...

Actualment l’aplicació més freqüent que se li dona a les bales de palla en edificació és la d’aïllament de façanes, principalment, degut al baix coeficient de transmissió tèrmica del material. En aquest cas, les bales únicament tenen l’objectiu de farcir el mur i es deprecia la capacitat resistent que pugui tenir el material. Aquesta tesina, pretén donar a conèixer les excel•lents propietats estructurals dels murs de càrrega conformats amb bales de palla. Per tal de garantir la resistència al foc exigible, aquests murs hauran d’estar revestits amb algun material de cobertura, el qual col•laborarà amb l’estabilitat general del mur de forma conjunta amb les bases de palla. L’estudi neix a partir d’una profunda investigació d’assajos realitzats arreu del món amb l’objectiu d’establir un punt de partida que sigui la base d’un anàlisi fiable i real del comportament dels murs, utilitzant aquesta tècnica constructiva, també anomenada sistema Nebraska. Es realitzen models de càlcul de murs amb elements finits, sota l’acció d’un esforç axial, tallant i una combinació d’ambdós, els quals a la vegada es modelen sota diferents hipòtesis de llums i plantes amb l’objectiu d’establir uns rangs de confort i seguretat en la construcció amb bales de palla estructural. more...

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