Timber under real fire conditions – the influence of oxygen content and gas velocity on the charring behavior

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

Load-Carrying Capacity of Timber Structure Bolt Connection Subjected to Double Unequal Shears

The paper deals with load-carrying capacity of bolted connections subjected to unequal double shears with thin plates as outer members and inner timber member. There are derived equations which describe the load-carrying capacity of this connection type in the ultimate limit state.

Calculation and Reliability Assessment of Timber Structure Bolt Connection Subjected to Double Unequal Shears

The paper shows the calculation and reliability assessment of bolted connections subjected to unequal double shear with thin plates as outer members and inner timber member. The concrete example is calculated and explained.

Reliability of Timber Structure Bolt Connection Subjected to Double Unequal Shears

The paper deals with reliability in ultimate limit state of timber structure bolted connections subjected to unequal double shear with thin plates as outer members and inner timber member. There are derived equations for calculation of the reliability of this connection type in the ultimate limit state.

Numerical and Experimental Evaluation of the Temperature Distribution Within Laminated Veneer Lumber (LVL) Exposed to Fire

The 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 146×60, 300×105 and 360×133 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.