At the Institute of Structural Engineering (IBK) of ETH Zurich, the fire behaviour of timber-concrete composite slabs made with beech laminated veneer lumber (LVL) (BauBuche) was investigated. This composite slab is made of a thin plate (depth: 40 mm or 80 mm) using beech LVL and a concrete layer on top (depth: 160 mm or 120 mm). The beech plate acts both as formwork and as tensile reinforcement. This innovative slab system was implemented for the first time in the ETH House of Natural Resources at ETH Zurich. This paper summarizes the results of two largescale fire tests on loaded timber-concrete composite slabs exposed to standard ISO fire. Both fire tests show that the timber-concrete composite slab using beech LVL reaches sufficient fire resistance and integrity for 90 min and 60 min, respectively.
There is a need to evaluate timber-concrete composite (TCC) systems under fire conditions to understand how shear connectors will perform and might affect the fire performance and the composite action of the assmebly. This project evaluates the fire performance of TCC assemblies based on their structural resistance, integrity and insulation when exposed to a standard fire, as well as how mass timber and concrete interact. This study involves full-scale fire resistance tests on wood-concrete composite floors using two types of shear connectors.
Three timber-concrete composite floor assemblies were evaluated for fire performance to understand how shear connectors might impact heat transfer into the assemblies. The floor assemblies tested included a CLTconcrete floor with self-tapping screws, a screw-laminated 2x8-concrete using truss plates, and a LVL-concrete using...
This research investigates the fire behaviour of laminated veneer lumber elements
and cross-laminated timber panels. The study focused on some research questions
regarding the fire resistance of unprotected and protected timber structural elements,
the possibility to predict accurately the fire behaviour of timber elements through numerical modelling, and the accuracy of analytical estimations of fire resistance using simplified design methods. Experimental tests of small and large specimens exposed to fire on one or more sides and subjected to different types and levels of load were performed. The results highlight the good performance of timber structural elements in fire conditions. The collected data were used to validate two- and three-dimensional models implemented in the general purpose finite element code Abaqus. Thermal and mechanical analyses were carried out to estimate the temperature distribution within unprotected and protected cross-sections
of different sizes, the fire resistance and the displacement of timber elements loaded inplane and out-of-plane
The wood engineering community has dedicated a significant amount of effort over the last decades to establish a reliable predictive model for the load-carrying capacity of timber connections under wood failure mechanisms. Test results from various sources (Foschi and Longworth 1975; Johnsson 2003; Quenneville and Mohammad 2000; Stahl et al. 2004; Zarnani and Quenneville 2012a) demonstrate that for multi-fastener connections, failure of wood can be the dominant mode.
In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum or the summation of the tensile and shear capacities of the failed wood block planes. This results in disagreements between the experimental values and the predictions. It is postulated that these methods are not appropriate since the stiffness in the wood blocks adjacent to the tensile and shear planes differs and this leads to uneven load distribution amongst the resisting planes (Johnsson 2004; Zarnani and Quenneville 2012a).
The present study focuses on the nailed connections. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small dowel-type connections in timber products is thus proposed. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections (Zarnani and Quenneville 2013b).
A wood-concrete composite deck is presented, where wooden beams are placed in the compression side and the concrete layer is in the tension side. The main motive for this unusual setup is the better fire resistance of the system. The composite system was investigated under fire conditions. Experimental investigations were conducted on a small section of the structure in order to analyze the behaviour of the system. The specimen was subjected to the ISO-834 standard temperature-time curve with the concrete slab exposed to fire. Subsequently, the experiment was modeled using a commercial software package, and a transient thermal analysis was performed with temperature dependent material properties. The temperature profiles for all the materials are adequately comparable from both the investigations, i.e. experimental and numerical. The validated numerical model allows modifying geometrical parameters and determining fire-resistance ratings of different system configurations.
Use of structural composite lumber products is increasing. In applications requiring a fire resistance rating, calculation procedures are used to obtain the fire resistance rating of exposed structural wood products. A critical factor in the calculation procedures is char rate for ASTM E 119 fire exposure. In this study, we tested 14 structural composite lumber products to determine char rate when subjected to the fire exposure of the standard fire resistance test. Char rate tests on 10 of the composite lumber products were also conducted in an intermediate-scale horizontal furnace. The National Design Specification/Technical Report 10 design procedure for calculating fire resistance ratings of exposed wood members can be used to predict failure times for members loaded in tension. Thirteen tests were conducted in which composite lumber products were loaded in tension as they were subjected to the standard fire exposure of ASTM E 119. Charring rates, observed failure times in tension tests, and deviations from predicted failure times of the structural composite lumber products were within expected range of results for sawn lumber and glued laminated timbers.
In many mass timber buildings, CLT or nail laminated timber (NLT) floors are designed with a concrete topping to improve acoustic separation, reduce vibration or act as a fire barrier. Little research has examined the fire behavior of these floor systems, but some preliminary tests involving LVL show that they may be able to meet three-hour fire resistance ratings, which could potentially open up the use of mass timber in Type I buildings, representing a large market opportunity. This project will test the behavior of composite floors under fire loading conditions considering the following parameters: shear connector type, mass timber panel types and thicknesses and concrete thicknesses. It will also test and validate an innovative fire research methodology using radiant panels.
The key objective of this study is to analyze full-scale fire-resistance tests conducted on structural composite lumber (SCL), namely laminated veneer lumber (LVL), parallel strand lumber (PSL) and laminated strand lumber (LSL). A sub-objective is to evaluate the encapsulation performance of Type X gypsum board directly applied to SCL beams and its contribution to fire-resistance of wood elements.
The test data is being used to further support the applicability of the newly developed Canadian calculation method for mass timber elements, recently implemented as Annex B of CSA O86-14.