Structural floors from timber cut-offs

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Journal Title

Journal ISSN

Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

Date

2024-08-19

Department

Major/Subject

Civil Engineering

Mcode

Degree programme

Master's Programme in Building Technology (CIV)

Language

en

Pages

66

Series

Abstract

This study explored the potential of utilising short timber cut-offs for creating a structural floor system, employing the principle of reciprocal frame (RF) – a self-supporting structure. The main idea behind the research was to reduce construction waste by using materials that will otherwise end up as waste. The research had two main goals: to design and build a structural floor system using short timber cut-offs, and to assess the structural performance of the floor system and the viability of this method by comparing its performance to a comparable CLT floor panel. The designed floor system spanned an area of 2.8m x 4.2m, built using timber cut-offs varying in length between 0.3m to 1.6m. Form finding was first conducted to determine the RF layout, followed by designing beam cross-section and screws. Individual timber boards were then allocated within the frame. A combination of experimental testing and analytical modelling was performed to evaluate the structural performance. Static load testing was conducted to determine the maximum load capacity and displacement. Beam testing was first performed to understand the behaviour of the layered beam, and these results were used with the analytical model to estimate the floor’s maximum load. The research identified screw withdrawal as the dominant failure mode, suggesting that connection optimisation can improve the structure. Deflection was also revealed to be more pronounced in the shorter direction of the floor, highlighting the need for reinforcement in that direction. Furthermore, whilst the floor system underperformed com-pared to a comparable CLT panel in all structural properties, it offers a significant weight advantage. Overall, the study demonstrated the potential of utilising short timber cut-offs for structural floor systems, promoting sustainable construction through circular economy. Further research could explore optimisation strategies and extend the scope of testing to address the current limitations.

Description

Supervisor

Fink, Gerhard

Thesis advisor

Ruan, Gengmu

Keywords

reciprocal frame, timber cut-offs, regular, modular, slide-in connections

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