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Numerical investigation of the fire resistance of protected cross-laminated timber floor panels
No full textSeveral experimental investigations have been performed on timber elements to determine their fire resistance. However, the numerical modelling is nowadays an effective and inexpensive alternative method to investigate the behaviour of timber structures in fire conditions. Once validated on experimental data, finite element models can be used to understand more in detail the experimental behaviour, and then employed to carry out parametric studies where geometrical, mechanical and thermal properties are varied.
After an extensive discussion on the state-of-the-art in numerical modelling of timber members and connections in fire conditions, the paper presents a two-dimensional model implemented in ABAQUS software package to simulate fire tests of cross-laminated timber (XLAM) floor panels protected with different cladding systems. The temperature distribution within the XLAM cross-section and the fire resistance of panels loaded out-of-plane were predicted through thermal and thermo-mechanical analyses, respectively. Since the stiffness and strength degradation of wood with temperature is still subject of research, a parametric study with different degradation laws was carried out. Numerical predictions were compared with experimental results showing acceptable accuracy, particularly when the degradation laws of the EN 1995-1-2 were used. The comparisons also show the need to model correctly the failure of the protective cladding for an accurate prediction of the thermal behaviour
"Finite element modelling of cross-laminated timber floors exposed to fire"
No full textThe paper presents a finite element model implemented in Abaqus software package to
investigate the thermal and structural performance of protected and unprotected cross-laminated timber (Xlam) floor panels loaded out-of-plane and exposed to standard fire. The temperature-dependent relationships for wood properties proposed by the European code for fire design of timber structures were adopted in the modelling. The ‘concrete damaged plasticity’ model readily available in Abaqus was used to describe the non-linear mechanical behaviour of timber. The falling-off of the protective layer was simulated numerically as observed in the experiments. The numerical results in terms of temperature and stress distributions along the depth of a Xlam panel
highlight the effect of the protective layer on heat transfer and consequently on stresses. By comparison with experimental results, an accurate prediction of the fire resistance of Xlam floor
panels was attained
"Finite element modelling of cross-laminated timber floors exposed to fire"
No full textThe paper presents a finite element model implemented in Abaqus software package to
investigate the thermal and structural performance of protected and unprotected cross-laminated timber (Xlam) floor panels loaded out-of-plane and exposed to standard fire. The temperature-dependent relationships for wood properties proposed by the European code for fire design of timber structures were adopted in the modelling. The ‘concrete damaged plasticity’ model readily available in Abaqus was used to describe the non-linear mechanical behaviour of timber. The falling-off of the protective layer was simulated numerically as observed in the experiments. The numerical results in terms of temperature and stress distributions along the depth of a Xlam panel
highlight the effect of the protective layer on heat transfer and consequently on stresses. By comparison with experimental results, an accurate prediction of the fire resistance of Xlam floor
panels was attained
"Numerical and experimental evaluation of the temperature distribution within laminated veneer lumber (LVL) members exposed to fire"
No full textThe fire resistance evaluation of a timber member is an important and complex problem of structural design. In order to solve this problem, it is crucial to have reliable information on the temperature distribution within a timber cross-section exposed to fire, and to develop a numerical model for the prediction of such a quantity. The paper reports
the experimental-numerical comparisons in terms of temperature distribution within a timber member made from radiata pine LVL (laminated veneer lumber) exposed to fire. The experimental tests were performed at the University of Canterbury and BRANZ
(New Zealand) on 146x60, 300x105 and 360x133 mm LVL members. The temperature
distribution was monitored using several thermocouples. The numerical results were
obtained using the Abaqus FE code with different conductive models. The Eurocode 5 and Frangi’s proposals led to similar results characterized by acceptable approximation
close to the surface. Since the accuracy reduced for deeper fibres, a new proposal based on a different variation of the conductivity with the temperature was made. The proposal led to acceptable approximation throughout the tested cross-sections
"Numerical and experimental thermal-structural behaviour of laminated veneer lumber (LVL) exposed to fire"
No full text“Comparison between the conductive model of Eurocode 5 and the temperature distribution within a timber cross-section exposed to fire.”
No full text“Comparison between the conductive model of Eurocode 5 and the temperature distribution within a timber cross-section exposed to fire.”
No full text"Numerical and experimental thermal-structural behaviour of laminated veneer lumber (LVL) exposed to fire"
No full textBehaviour of loaded cross-laminated timber wall elements in fire conditions
No full text, , , Wall memberCross-laminated timber (CLT) is increasingly being used in medium-rise timber buildings for a number of reasons, such as rapidity of construction, cost effectiveness and robustness. Like for other building materials, verification of the load-bearing performance in fire conditions is an important issue. Experimental fire tests
have been performed on loaded CLT wall elements at research institutes in Sweden and Italy. In total, three large-scale and four medium-scale tests have been carried out. The aim was to gain information about initially protected and unprotected elements, to be used for classification and also for validation of calculation models. In the test series, reference tests at normal temperature were included to obtain information (e.g. stiffness, strength) about the material tested in fire conditions. In addition,
model-scale fire tests were performed to investigate the loss in stiffness resulting from fire exposure and the effect of different protection types. Loaded fire tests varied in the range of 41.8 min to 120 min, depending on the CLT structure, the level of load,
and the type of protection. Data on temperature within specimens and residual cross-sections were collected. Charring rates evaluated from experimental results were comparable with values proposed by Eurocode for the design of timber structures. Conservative solutions were obtained by using simplified design methods and comparing
their results to test results and results of advanced modelling. It was shown that the load-bearing performance of CLT may show abrupt changes due to its layered structure. It is strongly recommended that a minimum residual depth depending on the CLT structure should be required in order to ensure robust building products
“Fire resistance of cross-laminated timber panels loaded out-of-plane.”
No full textThis paper describes bending tests at ambient temperature and large-scale fire tests of cross-laminated timber (Xlam) floor panels. Three specimens exposed to standard fire curve were loaded out-of-plane with different levels of uniformly distributed load, and in two cases collapse was reached. Other unloaded panels were protected using different cladding systems with the aim to investigate their thermal behavior. Experimental data obtained from the tests and discussed within the paper includes modulus of elasticity and bending strength at ambient temperature, temperature distribution, charring depth, charring rate, residual cross section, midspan deflection, and time to failure in fire conditions. This data was compared with numerical results obtained by implementing a finite-element model in Abaqus software package for sequential thermal and structural analyses, demonstrating the accuracy of the model. The overall fire performance of
the Xlam panels was satisfactory; times to failure of 99 and 110 minutes were found, respectively, for the unprotected and protected panels loaded with 21% of the mean failure load at ambient conditions
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