Hygromorphic Timber

Abstract

Due to carbon emissions and increased global temperatures, the need for carbon neutral materials is rising. As of 2024, the use of timber is growing rapidly. Still, timber is not the preferred material in the construction sector. As modern architecture is getting more complex geometries, 'fluid' construction materials like steel and concrete dominate the building sites. As timber has a straight geometry, making curved and complex shapes is not desirable. However, timber is a porous and hygroscopic material, it can absorb water from its surroundings and become more flexible. This characteristic has been utilized for over many centuries. By processing glulam or lvl beams or columns with steam or adhesives and clamps, curved structural elements can be manufactured. However, these bending methods are energy- and work-intensive and result in products which are not sustainable in terms of re-usability, recyclebility, etc. Furthermore, curved structural elements can be more efficient in terms of load distribution and material usage than the rectangular and straight counterpart. This thesis aims to research and develop complex structural curved floor elements produced with passive self-shaping.
After an initial bi-layer self-shaping test, multiple different typologies were designed, tested and compared with a conventional capped ceiling. Interconnections, treatment processes, assembly orders and timber species were investigated. For an efficient capped ceiling floor element, the curvature height to width ratio should be between 1/8 and 1/12. The elements designed and tested with both a water and a moisture treatment showed a maximum ratio of 1/45 or 26.8% of the 1/12 ratio. Meaning that it is possible to manufacture and produce a complex self-shaping floor element. There is much potential for the structural floor elements to reach the 1/12 ratio, however this could not be achieved during this research thesis.