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Article
Publication date: 17 July 2017

Hirokazu Ohashi, Shinya Igarashi and Tsutomu Nagaoka

As forestry contributes to the reduction of greenhouse gases by CO2 fixation, in recent years, use of wood in buildings has attracted all over the world more attention. However…

Abstract

Purpose

As forestry contributes to the reduction of greenhouse gases by CO2 fixation, in recent years, use of wood in buildings has attracted all over the world more attention. However, construction of large wood structures is almost inexistent within urban areas in Japan. This is due to the Japanese law on fire protection of wood buildings in cities, which is considered very strict with severe requirements. This paper aims to present a research work relative to the development of one-hour fire-resistant wood structural elements for buildings in cities. The developed elements are composed of three layers made of laminated timber.

Design/methodology/approach

These wood structural elements, made of glued laminated timber with self-charring-stop, have sufficient fire resistance during and after a fire and comply with the strict Japanese standard for wood structural elements, which stipulates that such elements have to withstand the whole dead-load of concerned buildings after fire. To comply with such requirements, new elements of glued laminated timber with self-charring-stop layer were developed, and their performance was confirmed. Several fire-resistant tests conducted on columns, beams, column-beam joints, connections between beams and walls and beams with holes were carried out.

Findings

All tests proved that the elements have sufficient fire resistance. No damage was found out at the load-bearing part of the elements after testing. As the developed elements have two layers protecting the load-bearing part, the temperature in the load-bearing part could be retained below 260°C (carbonization temperature) and provide the elements with a sufficient fire resistance for 1 h.

Practical implications

These wood structural elements have already been applied in six projects, where large-size wooden buildings were constructed in urban areas in Japan.

Originality/value

The proposed structural elements use a novel technique. Every wooden element is composed of three layers made of glued laminated timber. The elements have a typical performance of self-charring-stop after fire without need for water of firefighters. More technologies related to these elements, including column-beam joints and beams with holes and effect of crack, were also developed to design and construct safe wooden buildings.

Details

Journal of Structural Fire Engineering, vol. 9 no. 2
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 12 December 2016

H. Kinjo, T. Hirashima, S. Yusa, T. Horio and T. Matsumoto

Based on heating tests and load-bearing fire tests, this paper aims to discuss the charring rate, the temperature distribution in the section and the load-bearing capacity of…

Abstract

Purpose

Based on heating tests and load-bearing fire tests, this paper aims to discuss the charring rate, the temperature distribution in the section and the load-bearing capacity of structural glued laminated timber beams not only during the heating phase during a 1-h standard fire in accordance with ISO 834-1 but also during the cooling phase.

Design/methodology/approach

Heating tests were carried out to confirm the charring rate and the temperature distribution in the cross-section of the beams. Loading tests under fire conditions were carried out to obtain the load-deformation behavior (i.e. the stiffness, maximum load and ductility) of the beam.

Findings

The temperature at the centroid reached approximately 30°C after 1 h and then increased gradually until reaching 110-200°C after 4 h, during the cooling phase. The maximum load of the specimen exposed to a 1-h standard fire was reduced to approximately 30 per cent of that of the specimen at ambient temperature. The maximum load of the specimen exposed to a 1-h standard fire and 3 h of natural cooling in the furnace was reduced to approximately 14 per cent. In case of taking into consideration of the strength reduction at elevated temperature, the reduction ratio of the calculated bending resistance agreed with that of the test results during not only heating phase but also cooling phase.

Originality/value

The results of this study state that it is possible to study on strength reduction in cooling phase for end of heating, timber structural which has not been clarified. It is believed that it is possible to appropriately evaluate the fire performance, including the cooling phase of the timber structural.

Details

Journal of Structural Fire Engineering, vol. 7 no. 4
Type: Research Article
ISSN: 2040-2317

Keywords

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