STUDY OF THE FIRE PERFORMANCE OF HYBRID STEEL-TIMBER CONNECTIONS WITH FULL-SCALE TESTS AND FINITE ELEMENT MODELLING

Connection design is critical in timber buildings since the connections tend to have lower strength than the structural members themselves and they tend to fail in a brittle manner. The effect of connection geometry on the fire performance of a hybrid steel-timber shear connection is investigated by full-scale testing. These tests were conducted by exposing the test specimens to the standard time-temperature curve defined by CAN/ULC-S101 (CAN/ULC-S101, 2007). Test results showed that the fire resistance of these connections depends on the load ratio, the type of connection and the relative exposure of the steel plate to fire. Finite element models of the connections under fire were constructed using ABAQUS/CAE and these were validated using the test results. These numerical model results correlate well with test results with ±8.32% variation.

REUSED TYRE POLYMER FIBRE FOR FIRE-SPALLING MITIGATION

<p>Polypropylene fibres (PPF) are used in concrete principally to reduce plastic shrinkage cracking, but also to prevent explosive spalling of concrete exposed to fire. In the EU alone, an estimated 75,000 tonnes of virgin PPF are used each year. At the same time an estimated 63,000 tonnes of polymer fibres are recovered from end-of-life tyres, which are agglomerated and too contaminated with rubber to find any alternative use; currently these are mainly disposed of by incineration. The authors have initiated a study on the feasibility of reusing tyre polymer fibres in fresh concrete to mitigate fire-induced spalling. If successful, this will permit replacement of the virgin PPF currently used with a reused product of equal or superior performance. A preliminary experimental investigation is presented in this paper. High-strength concrete cubes/slabs have been tested under thermo-mechanical loading. This study has shown promising results; the specimens with the tyre polymer fibres have shown lower vulnerability to spalling than those of plain concrete.</p>

CHARACTERISTIC VALUE OF THE RANDOM FIRE LOAD DENSITY, Probability-based specification depending on the way how the building compartment is used

<p>The algorithm that allows to specify the characteristic value of the random fire load density, depending on the way how the considered building compartment is used, is presented and discussed in detail. The proposed computational procedure is based on a probabilistic approach, the alternative in relation to the traditional methodology according to which the results obtained from the inventory of such a compartment are a basis for the evaluation. It is assumed that the sought value is estimated as the upper quantile of a <em>Gumbel</em> probability distribution which is set at an appropriate level of the probability of its up-crossing. The formal model described in the paper is referred to the two selected and qualitatively different design techniques which are used in practice. The first one is based on the recommendations contained in the Eurocode EN 1991-1-2, whereas the second - on the rules specified in the standard NFPA 557.</p>

PERFORMANCE BASED COUPLED CFD-FEM ANALYSIS OF 3-BAY HIGH INDUSTRIAL HALL UNDER NATURAL FIRE

In this paper, the main emphasis is put into showing differences between standard fire design of structural elements and performance based approach, that takes into account analysis of structure under natural fire. The exemplary structure is a 3-bay 65,0x110,0 m in plane and 22,0 m high industrial hall with heavy cranes. Because of the significant volume with respect to fire load, there is a low probability that the fully developed fire can occur, nonetheless regarding technological process, a significant local fire could take place and affect the neighbour structure. The most complex approach used in this work is based on coupled CFD-FEM analysis of influence of local fire onto structure.Fire exposure of structural elements is calculated by the coupling scripts, taking into account real heat exposure of section by using adiabatic surface temperature approach.

SANDWICH PANELS – BEHAVIOR IN FIRE BASED ON FIRE RESISTANCE TESTS

<p>Sandwich panel is the material that is easy and quickly to install. Basing on a great experience in the area of determination of the fire resistance class of construction building elements the authors describe the properties and behavior of building elements made of the sandwich panels exposed to fire. The article presents the results of fire resistance tests carried out in accordance with EN 1364-1 non-bearing walls made of sandwich panels with use of different cores.</p>The following parameters were analyzed: temperature rise on unexposed side (I – thermal insulation), integrity (E) depending on the orientations and on the width of the sandwich panels, deflection depending on the thickness of the boards. Conclusions were made on the base of the analysis from fire resistance tests.

PERFORMANCE-BASED FIRE DESIGN OF STEEL STRUCTURES OF HELSINKI OLYMPIC STADIUM

This paper presents an overview of the fire safety analysis conducted for the steel trusses of Helsinki Olympic Stadium stand. The analysis were conducted using advanced calculation models (FDS and SAFIR). It is shown that the predefined design solution (R60 fire protection with sprinklers) can be replaced by fire protection to class R15 (no sprinkler system) without sacrificing safety when some other passive protection means are applied. The good design solution in this case required highly iterative design process and smooth co-operation between client, architects, structural engineers and fire safety consultants.

PERFORMANCE BASED DESIGN OF UNBRACED STEEL FRAMES EXPOSED TO NATURAL FIRE SCENARIOS

<p>According to the Eurocode 3 Part 1-2 (EN1993-1-2) (CEN 2005b), it is possible for structural engineers to consider physical based thermal actions and to do performance based design instead of using prescriptive rules based on nominal fire curves. However, some uncertainties remain in the use of such approaches. This study focus on the clarification of the use of the simplified design methods to assess the fire resistance of unbraced steel frames exposed to fire. On the other hand, a recent study (Couto et al. 2013) suggests the use of a buckling coefficient of 1.0 for all the columns except those belonging to the first storey of a pinned framed where 2.0 should be taken instead and it is unclear if the consideration of such values for the buckling lengths is adequate when using performance based designs.</p>In this study, a comparison is made between simple and advanced calculation models and it is demonstrated that the simple design methods, using the suggested buckling coefficients to calculate the fire resistance of the frames are safe sided when compared to the use of advanced calculations using the finite element method (FEM).

FIRE DYNAMICS IN FAÇADE FIRE TESTS, Measurement, modeling and repeatability

Presented is a comparison between full-scale façade tests where SP Fire 105 and BS 8414-1 were used regarding repeatability and the use of modelling to discern changes in the set-ups. Results show that the air movements around the test set-up (the wind) may have a significant impact on the tests and that the heat exposure to the façade surface will among other depend on the thickness of the test specimen. Also demonstrated was that good results could be obtained by modelling of the façade fire tests giving us the opportunity to use these methods to determine the effect of a change in the experimental setup.

THE MECHANICS OF TENSILE MEMBRANE ACTION IN COMPOSITE SLABS AT HIGH TEMPERATURES

<p>The mechanics of tensile membrane action of thinlightly-reinforced concrete slabs has been re-examined during the last two years.The re-examination is based on large-deflection plastic yield-line analysis, applied to flat slabs. As deflection increases beyond the optimum yield-line pattern, tensile membrane action is mobilized and further load carrying capacity is provided. This paper represents an extension of this re-examination to include composite slabs at high temperatures. As temperature increases, the unprotected downstand steel beams significantly lose capacity, allowing for further deflection until the overall capacity degrades to the applied load. Tensile membrane action then allows further increase of steel temperature until a maximum is reached.</p>

CAPACITY BUILDING IN HIGHER EDUCATION, Resilience improvement in Balkan region

In order to improve the resilience of the region to hazards, it is necessary to provide the required number of experts that is to modernize and develop higher education at the regional higher education institutions in the field of Disaster Risk Management and Fire Safety Engineering. A master study program should be developed to satisfy various criteria, according to regional needs for resilient society, such as the shift from reactive to proactive actions, developing a culture of prevention in built environment and learning to live with risks. Final goal is to produce capable experts, to be able to withstand difficult requirements of today and tomorrow. Compliance of the regional master program with similar programs, developed in the EU countries, strengthens the capacity of individual countries and the region as a whole in the process of European integration.