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3-ply cross-laminated timber (CLT) is used to investigate the thermo-mechanical performance of intermediate-size assemblies comprised of T-shaped welded slotted-in steel doweled connections and CLT beams at ambient temperature (AT), after and during non-standard fire exposure.

The first set of experiments was performed as a benchmark to find the load-carrying capacity of the assembly and investigate the failure modes at AT. The post-fire performance (PFP) test was performed to investigate the residual strength of the assembly after 30-min exposure to a non-standard fire. The fire-performance (FP) test was conducted to investigate the thermo-mechanical behavior of the loaded assembly during non-standard fire exposure. In this case, the assembly was loaded to 67% of AT load-carrying capacity and partially exposed to a non-standard fire for 75 min.

Embedment failure and plastic deformation of the dowels in the beam were the dominant failure modes at AT. The load-carrying capacity of the assembly was reduced to 45% of the ambient capacity after 30 min of fire exposure. Plastic bending of the dowels was the principal failure mode, with row shear in the mid-layer of the CLT beam and tear-out failure of the header sides also observed. During the FP test, ductile embedment failure of the timber in contact with the dowels was the major failure mode at elevated temperature.

This paper presents for the first time the thermo-mechanical performance of CLT beam-to-girder connections at three different thermal conditions. For this purpose, the outside layers of the CLT beams were aligned horizontally.

1. Load-carrying capacity and failure modes of CLT beam-to-girder assembly with T-shaped steel doweled connections at ambient temperature presented.

2. Residual strength and failure modes of the assembly after 30-min partially exposure to the non-standard fire provided throughout the post-fire performance test.

3. Fire resistance of the assembly partially exposed to the non-standard fire highlighted.

Load-carrying capacity and failure modes of CLT beam-to-girder assembly with T-shaped steel doweled connections at ambient temperature presented.

Residual strength and failure modes of the assembly after 30-min partially exposure to the non-standard fire provided throughout the post-fire performance test.

Fire resistance of the assembly partially exposed to the non-standard fire highlighted.

Thermomechanical behavior of intermediate-size beam-to-wall assemblies including Glulam-beams connected to cross-laminated timber (CLT) walls with T-shape steel doweled connections was investigated at ambient temperature (AT) and after and during non-standard fire exposure.

Three AT tests were conducted to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Two post-fire performance (PFP) tests were performed to study the impact of 30-min (PFP30) and 60-min (PFP60) partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were exposed to fire in a custom-designed frame, then cooled and loaded to failure. A fire performance (FP) test was conducted to study the fire resistance (FR) during non-standard fire exposure by simultaneously applying fire and a mechanical load equal to 65% of the AT load carrying capacity.

At AT, embedment failure of the dowels followed by splitting failure at the Glulam-beam and tensile failure of the epoxy between the layers of CLT-walls were the dominant failure modes. In both PFP tests, the plastic bending of the dowels was the only observed failure mode. The residual strength of the assembly was reduced 14% after 30 min and 37% after 60 min of fire exposure. During the FP test, embedment failure of timber in contact with the dowels was the only major failure mode, with the maximum rate of displacement at 51 min into the fire exposure.

This is the first time that the thermomechanical performance of such an assembly with a full-contact connection is presented.

The purpose of this paper is to investigate the thermo-mechanical behavior of intermediate-size glued-laminated beam-to-girder assemblies connected with T-shaped slotted-in steel doweled connections at ambient temperature (AT), after and during non-standard fire exposure.

AT tests were performed using a universal testing machine (UTM) to evaluate the load-carrying capacity and failure modes of the assembly at room temperature. Post-fire-performance (PFP) tests were conducted to study the impact of 30-min and 60-min partial exposure to a non-standard fire on the residual strength of the assemblies. The assemblies were subject to fire in a custom-designed frame, then cooled and loaded to failure in the UTM. A fire-performance test was conducted to investigate the fire-resistance during non-standard fire exposure by simultaneously applying fire and mechanical load with the custom frame.

At AT, embedment failure of the dowels followed by brittle splitting failure were found to be the dominant failure modes in the beams. In the PFP tests, embedment failure and plastic bending of the dowels were the only observed failure modes. The residual strength of the assembly was reduced by 23.7% after 30-min and 47.8% after 60-min of fire exposure. Ductile embedment failure of the timber in contact with the dowels was the only failure mode observed during the fire-performance test, with the maximum rate of displacement at 57 min into the fire.

Data are presented for full-contact (no gap) connections in Glulam assemblies. PFP results are first to be published.

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Light-Gauge Steel Frame (LSF) structures are popular in building construction due to their lightweight, easy erecting and constructability characteristics. However, due to steel lipped channel sections negative fire performance, cavity insulation materials are utilized in the LSF configuration to enhance its fire performance. The applicability of lightweight concrete filling as cavity insulation in LSF and its effect on the fire performance of LSF are investigated under realistic design fire exposure, and results are compared with standard fire exposure.

A Finite Element model (FEM) was developed to simulate the fire performance of Light Gauge Steel Frame (LSF) walls exposed to realistic design fires. The model was developed utilising Abaqus subroutine to incorporate temperature-dependent properties of the material based on the heating and cooling phases of the realistic design fire temperature. The developed model was validated with the available experimental results and incorporated into a parametric study to evaluate the fire performance of conventional LSF walls compared to LSF walls with lightweight concrete filling under standard and realistic fire exposures.

Novel FEM was developed incorporating temperature and phase (heating and cooling) dependent material properties in simulating the fire performance of structures exposed to realistic design fires. The validated FEM was utilised in the parametric study, and results exhibited that the LSF walls with lightweight concrete have shown better fire performance under insulation and load-bearing criteria in Eurocode parametric fire exposure. Foamed Concrete (FC) of 1,000 kg/m3 density showed best fire performance among lightweight concrete filling, followed by FC of 650 kg/m3 and Autoclaved Aerated Concrete (AAC) 600 kg/m3.

The developed FEM is capable of investigating the insulation and load-bearing fire ratings of LSF walls. However, with the availability of the elevated temperature mechanical properties of the LSF wall, materials developed model could be further extended to simulate the complete fire behaviour.

LSF structures are popular in building construction due to their lightweight, easy erecting and constructability characteristics. However, due to steel-lipped channel sections negative fire performance, cavity insulation materials are utilised in the LSF configuration to enhance its fire performance. The lightweight concrete filling in LSF is a novel idea that could be practically implemented in the construction, which would enhance both fire performance and the mechanical performance of LSF walls.

Limited studies have investigated the fire performance of structural elements exposed to realistic design fires. Numerical models developed in those studies have considered a similar approach as models developed to simulate standard fire exposure. However, due to the heating phase and the cooling phase of the realistic design fires, the numerical model should incorporate both temperature and phase (heating and cooling phase) dependent properties, which was incorporated in this study and validated with the experimental results. Further lightweight concrete filling in LSF is a novel technique in which fire performance was investigated in this study.

The fire resistance of wooden structures is commonly based on the calculation or measurement of the char layer. Designers usually estimate the char layer at the surface of a structural element by using analytical models. Some of these charring models can be found in regulations, as Eurocode 5. These analytical models, quite simple to use, are only reliable for the standard fire curve. In that case, the design of the structure is qualified as “prescriptive-based design” and can lead to oversizing the structure. Optimization of a structure can be achieved by using a “Performance-based design”, where realistic fire scenarios are taken into account by means of more or less complex models [parametric fires, two-zones models, computational fluid dynamics (CFD)]. For these so-called “natural fires”, no model for charring is available. The purpose of this paper is to present a novel methodology for applying a performance-based design to a simple timber structure.

This paper presents the development of a numerical model aiming to simulate the thermal transfer and charring in wood, under any type of thermal exposure, including non-standard fire curves. After presenting the physical background, the model is calibrated and compared to existing experimental studies on wood samples exposed to different fire curves. The model is then used as a tool for assessing the fire resistance of a common wooden structure exposed to standard and non-standard fire curves.

The results show that the fire resistance is obviously dependent on the choice of the thermal exposure. The reliability of the model is also discussed and the importance of taking into account particular reactions in wood during heating is underlined.

One aim of this paper is to show the opportunity to apply a performance-based approach when designing a wooden structure. It shows that more knowledge of the material behaviour under non-standard fires is still needed, especially during the decay phase.

The purpose of this study is to investigate the influencing factors on the charring behaviour of timber, the char layer and the charring depth in non-standard fires.

This paper summarizes outcomes of tests, investigating the influences on the charring behavior of timber by varying the oxygen content and the gas velocity in the compartment. Results show that charring is depending on the fire compartment temperature, but results show further that at higher oxygen flow, char contraction was observed affecting the protective function of the char layer.

In particular, in the cooling phase, char contraction should be considered which may have a significant impact on performance-based design using non-standard temperature fire curves where the complete fire history including the cooling phase has to be taken into account.

Up to now, some research on non-standard fire exposed timber member has been performed, mainly based on standard fire resistance tests where boundary conditions as gas flow and oxygen content especially in the decay phase are not measured or documented. The approach presented in this paper is the first documented fire tests with timber documenting the data required.

Large timber buildings, formed from both light and heavy timber construction, are becoming increasingly common in Europe. Many multiple-occupancy timber buildings, such as apartment blocks, are now constructed to greater heights and in densely populated urban locations. The fire-resistance performance of such timber buildings is generally related to the standard fire test. Alternatively, EN 1995-1-2 may be used to demonstrate fire resistance by means of calculation or numerical modelling. The latter is currently limited to standard fire exposure. In addition, modelling approaches are often avoided as many numerical codes do not normally offer the capability to model timber exposed to fire. The most obvious barrier is incorporating the different tensile and compressive strength/stiffness degradation with increasing temperature. Unlike many other structural materials, it is not possible to define a single relationship between timber Modulus of Elasticity (MoE) and temperature. When timber design is advanced to a ‘performance-based’ level further complexities will arise. For example, the definition of structure temperatures for non-standard fires is a difficult task, and assessment of strength/stiffness degradation on the basis of temperature alone is not sufficient due to char formation. As a result, when cooling is considered, material properties based upon stress state, temperature and temperature history are needed.

To address the above limitations, a number of developments, which can be used with general FEA software, such as DIANA, to design timber structures for fire, are presented. The developments are incorporated via user-supplied subroutines written in FORTRAN code. The routines include code for determining MoE and strength based upon stress state, temperature and temperature history. They are implemented as part of a total strain-based constitutive model. The implementation of the routines is demonstrated using a simple continuous beam. The example is also used to demonstrate how compartmentation provisions and aspects of whole building behaviour can be used to better design large-section timber buildings. Comparisons are made with simple empirical approaches presented in EN 1995-1-2. Extensions to ‘performance-based design’ using parametric fires are also discussed.

This paper aims to deal with the experimental and numerical investigations of the fire protection performance of a waterborne intumescent coating (IC) on structural steel in case of natural fires. Based on own small-scale laboratory tests, an advanced numerical model is developed to simulate the fire protection performance of the investigated coating in case of arbitrary fire scenarios. The insulation efficiency of the coating is described within the model by temperature and heating rate-dependent material properties, such as expansion factors, thermal conductivity and heat capacity. The results of the numerical model are compared to own large-scale fire tests of an unloaded I-section beam and column.

As natural fires can show arbitrary regimes, the material properties of the waterborne IC are investigated for various heating rates. Based on these investigations, a material model for the IC is implemented in the finite element program ABAQUS. With the help of user subroutines, the material properties of the coating are introduced for both the heating and cooling phase of natural fires, allowing for two- and three-dimensional thermomechanical analyses of coated steel elements.

The results of the performed small-scale laboratory tests show a heating rate-dependent behavior of the investigated coating. The mass loss as well as the expansion of the coating change with the heating rate. Moreover, the material properties obtained on small scale are valid for large scale. Therefore, a material model could be developed that is suitable to reproduce the results of the large-scale fire tests. Additionally, with the help of the numerical model, a dimensioning approach for the dry film thickness (DFT) of the investigated coating is derived for arbitrary natural fires.

The material properties presented in this paper are only valid for the investigated waterborne IC and the parameter area that was chosen. However, the developed modeling approach for the fire protection performance of ICs is general and can be applied for every coating that is part of the intumescent product family.

Until now, only few research works have been carried out on the fire protection performance of ICs under non-standard fire exposure. This paper deals extensively with the material properties and the material modeling of a waterborne IC exposed to natural fires. Especially, the laboratory examinations and the numerical simulations are unique and allow for new evaluation possibilities of ICs.

The purpose of this study is to investigate the performance of fire protective materials in protecting steel section. A new indexing system is introduced, named as fire endurance index (FEI), which can be used to evaluate the performance of fire protective materials.

In this study, experiments were carried out using W4 × 13 steel section. Eight samples were prepared; one was a bare steel section without any coating material, and seven were prepared using four types of materials such as vermiculite-gypsum plaster, gypsum plaster, concrete cover and glass wool-concrete cover for fireproofing of the sections. An enclosed electric coiled furnace was used for heating the samples for a certain period. The duration of protection was determined, and the FEI of the materials was calculated. The higher the index value is, the better the performance.

The results demonstrate that the glass-wool-concrete cover offered the best performance at high temperature among the four types of materials. In the experiment with glass-wool-concrete cover, the furnace temperature reached 750°C, whereas the steel temperature reached only 100°C. The FEI of the coatings were calculated. Among the eight samples, glass wool-concrete cover also achieved the highest index value.

The experimental work was performed using a limited number of specimens. Furthermore, the robustness of the indexing system needs to be evaluated with other materials and a wide range of heating rate and temperature. This study sets the foundation for future work.

The findings of this research may contribute to a better understanding of the performance of the materials used as fire protective coatings. This might be helpful for the researchers and practitioners in their design and implementation of legislation of fire safety codes.

Understanding the performance of the fire protective coatings will help in evaluating the fire resistance capabilities of the materials to use for the structural steel members, which may protect collapses and disasters of buildings.

This paper deals with the performance of four types of materials, that can be used as fire protective coatings for structural steel members. Furthermore, the FEI explicitly indicated their performance with numerical values. In this study, the heating of the specimens was performed using a non-standard fire curve based on the concept that naturally occurring incidents of fire do not follow the standard fire curves.

The Southern African Institute of Steel Construction has developed a novel cellular beam structure (CBS) for multi-storey buildings that is entirely devoid of concrete. Channel sections between the cellular beams support a complex sandwich flooring system, which contains a fire-resistant ceiling board, metal sheeting, an interior fibre-cement board and an access-flooring system. As for all structures, the CBS requires a fire rating. This paper aims to investigate the thermal behaviour of the CBS using numerical modelling and experimental fire testing, as it has a unique setup.

Experimental fire tests on the flooring system were conducted to validate finite element models, which were developed in ABAQUS. These models were then extended to include floor beams and the structural steelwork.

Good correlations were found between the experimental and numerical results, with temperature variations typically in the range of 0-5%, although with localised differences of up to 20%. This allowed larger finite element models, representing the sandwich floor system of the CBS, to be developed and analysed. A 1-hour rating can be obtained by the system in terms of insulation and integrity requirements.

The CBS allows for more economical steel structures, due to the rapid construction of its modular panels. A suitable fire resistance will ensure the safety of the occupants and prevent major structural damage. Steelwork and flooring temperatures are determined which has allowed for global structural analyses to be carried out.

The originality of this study lies in thermal analysis and testing of a new cellular beam flooring system, through determining behaviour in fire, along with beam temperatures.