In the project FIRSTIMB, leaded by the researchers Manuel L. Romero and Ana Espinós from ICITECH, an innovative demountable structural system based on steel-timber composite beams was investigated and tested under severe fire conditions. In particular, a novel type of bolted shear connectors previously developed by colleagues from the University of Luxembourg (Prof. Christoph Odenbreit) was used. The characterization of these shear connectors in fire was necessary for their future introduction into the market.
The studied shear connection systems allow the timber slabs to be easily detached from the steel beams for their proper disassembly and subsequent reuse or recycling at the building end-of-life, thereby contributing to the circular economy in the construction sector through the demountability of the structural system. Additionally, this innovative construction system can help in achieving significant reductions of the carbon footprint by means of using timber slabs in the composite floor.
The demountable shear connectors showed an excellent performance under normal design conditions (ambient temperature), which was verified through full-scale beam bending tests and push-out (shear) tests, carried out at the facilities of ICITECH.
Moreover, the system was capable to perform adequately in the fire situation, which was verified by means of full-scale beam fire tests conducted in a standard furnace at the external facilities of AFITI (“Asociación para el Fomento de la Investigación y la Tecnología de la Seguridad contra Incendios”).
To provide the composite beams with sufficient fire resistance, it was necessary to design a passive fire protection system that maintained the sustainability and demountability criteria, avoiding the use of sprayed mortars or intumescent coatings. The designed system allows reducing the carbon footprint as compared to other conventional solutions without compromising structural fire safety.
By means of the performed fire tests, it was verified that the demountable steel-timber composite beams were capable to meet the fire safety requirements, far exceeding the initially set objective of 90 minutes fire resistance (R90) and even being able to withstand 120 minutes (R120) standard fire exposure under demanding load levels.
It was hence proved that the proposed innovative demountable flooring systems make it possible to bring together sustainability and fire safety, showing to be a feasible solution for the transition towards a more environmentally friendly construction model.
Full video for dissemination of the FIRSTIMB project results:
https://doi.org/10.6084/m9.figshare.31268095
Project TED2021-130580B-I00 funded by MCIN/AEI/ 10.13039/501100011033
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