• Advances in concrete construction
• /
• v.6 no.6
• /
• pp.631-643
• /
• 2018

The focus of this paper is given to the investigation of mechanical properties of steel fibre reinforced self-compacting concrete after being exposed to fire. The research programme covered tests of two sets of beams: specimens subjected to fire and specimens not subjected to fire. The fire test was conducted in an environment mirroring one of possible real fire situations where concrete surface for an extended period of time is directly exposed to flames. Micro-cracking of concrete surface after tests was digitally catalogued. Compressive strength was tested on cube specimens. Flexural strength and equivalent flexural strength were tested according to RILEM specifications. Damages of specimens caused by spalling were assessed on a volumetric basis. A comparison of results of both sets of specimens was performed. Significant differences of all tested properties between two sets of specimens were noted and analysed. It was proved that the limit of proportionality method should not be used for testing fire damaged beams. Flexural characteristics of steel fibre reinforced self-compacting concrete were significantly influenced by fire. The influence of fire on properties of steel fibre reinforced self-compacting concrete was discussed.

• Computers and Concrete
• /
• v.31 no.5
• /
• pp.371-384
• /
• 2023

Precast roofing systems employing prestressed elements often serve as smart structural solutions for the construction of industrial buildings. The precast concrete elements usually employed are highly engineered, and often consist in thin-walled members, characterised by a complex behaviour in fire. The present study was carried out after a fire event damaged a precast industrial building made with prestressed beam and roof elements, and non-prestressed curved barrel vault elements interposed in between the spaced roof elements. As a consequence of the exposure to the fire, the main elements were found standing, although some locally damaged and distorted, and the local collapse of few curved barrel vault elements was observed in one edge row only. In order to understand and interpret the observed structural performance of the roof system under fire, a full fire safety engineering process was carried out according to the following steps: (a) realistic temperature-time curves acting on the structural elements were simulated through computational fluid dynamics, (b) temperature distribution within the concrete elements was obtained with non-linear thermal analysis in variable regime, (c) strength and deformation of the concrete elements were checked with non-linear thermal-mechanical analysis. The analysis of the results allowed to identify the causes of the local collapses occurred, attributable to the distortion caused by temperature to the elements causing loss of support in early fire stage rather than to the material strength reduction due to the progressive exposure of the elements to fire. Finally, practical hints are provided to avoid such a phenomenon to occur when designing similar structures.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.1
• /
• pp.69-75
• /
• 2017

In fire design for floors, the three criteria of stability, integrity and insulation are required for the specified fire resistance duration. Among these, stability is not easy to confirm. For solid prestressed concrete slabs of uniform thickness, Eurocode 2 provides tabulated data and specifies an axis distance to the centroid of strands to achieve particular fire resistance ratings, but it is not clear if this data can be used for a wide range of different prestressed slab profiles. In order to verify the current code-fire ratings for precast prestressed slabs, both simple and advanced calculation methods are investigated. This paper examines the use of calculation methods, accounting for the real behaviour of unprotected simply supported prestressed concrete slabs exposed to the standard ISO 834 fire. The calculated fire resistance of each prestressed concrete slab is compared with tabulated data in Eurocode part 1.2, with detailed discussion.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 1997.11a
• /
• pp.44-48
• /
• 1997

The Swedish Fire Research Board was established in 1979 to initiate and fund relevant fire research efforts. The Board is responsible for a long term research programme revised every third year, and the Board is one of two major Swedish sponsors of all fire research. Beside the Board we also have the Swedish National Rescue Services, funded by the government. BRANDFORSK gives very high priority for the industry and the insurance company and the need they express for fire research. Research that the Rescue Services Board are funding is mainly focusing the need for the fire department. The Swedish Fire Research Board, BRANDFORSK, is the joint agency of the Swedish government, the insurance industry and the business sector, for the initiation, funding and supervision of different kinds of fire research. Work is directed by a Programme Board and is performed in the form of projects at universities, research institutes, state authorities and private firms. The Secretariat of BRANDFORSK shares the premises of the Swedish Fire Protection Association, SFPA, and the SFPA is the principal and the party which enters into agreement with the State. The programme for the period 1997-1999 has been drawn up on the basis of both damage development and the trends in society which can be noted, and the evident fire problems of the interested parties and their need for fire research. The inputs in the programme have been broken down seven problem areas. In every problem area different project areas are set out, and these primarily specify the aim of the work. Our seven problem-areas are; Costs and benefits of fire protection measure. The role and behaviour of people and organizations Fire In buildings Fire in underground facilities Rescue operations fire in industries Fire and the environment. In comparison with previous fire research programmes, cost/benefit studies have been accorded higher priority, and this is also reflected in other problem areas. Grater Emphasis

• Fire Science and Engineering
• /
• v.12 no.4
• /
• pp.31-40
• /
• 1998

Very often, whether accidentally or intentionally set fire, according as building are elevated, varied or complicated day by day. It is of primary importance that we have a treatment of fire damaged structure. In general, strength and elasticity modulus of heated concrete are reduced. Product background of cement, sand and coarse aggregate differ from country to country, so that thermal behaviour of concrete make a difference in high temperature. To cope with demand, this paper is a study on relation to microstructure and strength reduction. In consequence of experiments, concrete exposed to high temperature are estimating the reduction of mechanical properties in comparison with microstructure characteristics which are abtained from the SEM/EDX, XRD and DSC-TG analysis of heated specimens under various temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.10
• /
• pp.821-827
• /
• 2003

Reduced-scale experimental study was carried out on the heat flow behavior which flows under the sloped ceiling in underground fire. Temperature and flow velocity were measured to characterize the ceiling jet along the sloped stairway ceiling. The methanol fuel was used as a model fire source giving 2.2 and 3.4 kW, with changing the slope angle of stairway adopting of 15, 25, 35, and 45 deg. Based on the experimental data, excess temperature and velocity along the sloped stairway ceiling were examined which are usefully applicable to estimate the activating conditions of heat detector and sprinkler head mounted on the sloped ceiling. Excess temperature in upper exit of the sloped stairway was also examined to analyze the soffit which delays the smoke diffusion. The result shows that the activating conditions of heat detector and sprinkler in the sloped stairway ceiling have to be considered differently in a point of about 30 deg.

• Steel and Composite Structures
• /
• v.9 no.2
• /
• pp.89-101
• /
• 2009

This paper presents a simplified model to study post-buckling behaviours of the axially restrained steel column at elevated temperatures in fire. The contribution of axial deformation to the curvature of column section is included in theoretical equations. The possible unloading at the convex side of the column when buckling occurs is considered in the stress-strain relationship of steel at elevated temperatures. Parameters that affect structural behaviours of the axial restrained column in fire are studied. The axial restraint cause an increase in the axial force before the column buckles; the buckling temperature of restrained columns will be lower than non-restrained steel columns. However, the axial force of a restrained column decreases after the column buckles with the elevation of temperatures, so make use of the post-buckling behaviour can increase the critical temperature of restrained columns. Columns with temperature gradient across the section will produce lower axial force at elevated temperatures.

• Fire Science and Engineering
• /
• v.26 no.1
• /
• pp.23-30
• /
• 2012

The temperature development of a structural element is dependent on section factor, which is estimated as a ratio of the fire-exposed perimeter to the cross-section area. Hence, with the higher section factor, the faster temperature development of the section os observed. Composite beam member, partially embedded asymmetry H beam, has a good fire resistance to the cross-section. The study was intended to conduct with change with section factor. The experimental result of section type which the Slim Beam Floor is bottom flange reinforced method.

• Fire Science and Engineering
• /
• v.25 no.5
• /
• pp.8-13
• /
• 2011

High strength concrete is the occurrence of explosive spalling associated with high temperature such as a fire. The spalling causes the sever reduction of the cross sectional area with the exposure of the reinforcing steel, which originates a problem in the structural behaviour. The purpose of this study is to investigate the mechanical properties of lightweight mortar using perlite and polypropylene fiber for fire protection covering material. For this purpose, selected test variables were the ratio of water to cement, the ratio of cement to perlite, contents of polypropylene fiber. As a result of this study, it has been found that addition of perlite and polypropylene fiber to mortar modifies its pore structure and reduces its density. And it has been found that a new lightweight mortar can be used in the fire protection covering material.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2008.11a
• /
• pp.479-483
• /
• 2008

There are no International Standards or Criteria pertaining to fires inside tunnels at the moment, but there are some fire-related regulations in some advanced countries such as Germany and the Netherlands where some fire-related studies have been expedited. Germany has established regulations related to the safety of structures by stipulating Fire Curves of RABT and EBA Tunnels. Also, the Netherlands has established the resistance capacity of structures by stipulating RWS curve so that they can prevent the adjacent area from being damaged due to a tunnel collapse. Hydrocarbon Fire Curve is the standard assessing the behaviour of a structure in a serious fire, by increasing the heating speed and the maximum temperature of ISO 834 Curve, while MHC Fire Curve, which was established in France, realizes more serious fire conditions. In this study, we aimed to develop the basis of full-sized experiments, with which you can assess the fire-resisting capacity against the fire strength of concrete PC panel lining, through the realization of various tunnel fire curves as mentioned above, by developing the heating furnace suitable for the requirements of Fire-Resisting Standards, with which you can assess the fire damage of tunnel concrete lining. We have developed various conditions of the heating furnace and the method to install a thermo couple within the furnace based on EFNARC and KS F2257-1. We have also conducted a calibrating experiment in order to secure its reliability.