Whole Timber Construction: A State of the Art Review

Forests worldwide are overstocked with small-diameter trees, putting them at increased risk of disease, insect attack, and destructive high-intensity wildfires. This overstocking is caused primarily by the low market value of these small-diameter trees, which are generally unsuitable for sawn timber production and yield low prices when sold for biomass fuel, paper, or fibre-based engineered timber products. Considerable research in recent decades has demonstrated the potential for these small-diameter trees to be used in minimally processed round segments as structural elements in buildings, bridges, towers, and other infrastructure. Recent structures have also demonstrated the use of trees with major curvature and branching, which are also of low market value, in their round form as primary structural elements. Such “whole timber” construction serves as a low-cost, low-impact building system while providing revenue to forest owners to conduct harvests of low-value trees as required for sustainable forest management. This paper reviews developments in whole timber construction, presenting new non-destructive evaluation techniques, digital survey, design and fabrication methods, new processing technologies, and a diverse range of novel connection types and structural systems. It is shown that the key materials characterisation, processing, and design challenges for whole timber construction have been largely addressed, and that whole timber has the potential to be an important complement to other timber products in construction globally in the coming decades. It is recommended that future work focus on exploiting new digital technologies and scaling whole timber structural applications through increased prefabrication

Whole Timber Construction: A State of the Art Review

Forests worldwide are overstocked with small-diameter trees, putting them at increased risk of disease, insect attack, and destructive high-intensity wildfires. This overstocking is caused primarily by the low market value of these small-diameter trees, which are generally unsuitable for sawn timber production and yield low prices when sold for biomass fuel, paper, or fibre-based engineered timber products. Considerable research in recent decades has demonstrated the potential for these small-diameter trees to be used in minimally processed round segments as structural elements in buildings, bridges, towers, and other infrastructure. Recent structures have also demonstrated the use of trees with major curvature and branching, which are also of low market value, in their round form as primary structural elements. Such “whole timber” construction serves as a low-cost, low-impact building system while providing revenue to forest owners to conduct harvests of low-value trees as required for sustainable forest management. This paper reviews developments in whole timber construction, presenting new non-destructive evaluation techniques, digital survey, design and fabrication methods, new processing technologies, and a diverse range of novel connection types and structural systems. It is shown that the key materials characterisation, processing, and design challenges for whole timber construction have been largely addressed, and that whole timber has the potential to be an important complement to other timber products in construction globally in the coming decades. It is recommended that future work focus on exploiting new digital technologies and scaling whole timber structural applications through increased prefabrication

Form-Fitting Strategies for Diversity-Tolerant Design

Conventional structural design proceeds by establishing a rough geometry for a structure, determining internal forces, and sizing members to resist these forces. This design process assumes effectively infinite supplies of standardised elements. There are some cases, however, where structural materials are available in strictly finite quantities, or may not be processed into standard sections. In these instances, conventional design approaches are slow or ineffective, requiring time-consuming trial and error to develop viable designs, or not finding solutions at all. This paper proposes new computational design strategies to help designers match finite sets of diverse structural elements with desired structural forms. The methods proposed build on algorithmic techniques developed for the Bin- Packing Problem. Two key applications are discussed: the reuse of steel elements from deconstructed structures, and the use of unsawn round timbers in spatial structures

Curved-crease origami face shields for infection control

The COVID-19 pandemic has created enormous global demand for personal protective equipment (PPE). Face shields are an important component of PPE for front-line workers in the context of the COVID-19 pandemic, providing protection of the face from splashes and sprays of virus-containing fluids. Existing face shield designs and manufacturing procedures may not allow for production and distribution of face shields in sufficient volume to meet global demand, particularly in Low and Middle-Income countries. This paper presents a simple, fast, and cost-effective curved-crease origami technique for transforming flat sheets of flexible plastic material into face shields for infection control. It is further shown that the design could be produced using a variety of manufacturing methods, ranging from manual techniques to high-volume die-cutting and creasing. This demonstrates the potential for the design to be applied in a variety of contexts depending on available materials, manufacturing capabilities and labour. An easily implemented and flexible physical-digital parametric design methodology for rapidly exploring and refining variations on the design is presented, potentially allowing others to adapt the design to accommodate a wide range of ergonomic and protection requirements

Curved-crease origami face shields for infection control

The COVID-19 pandemic has created enormous global demand for personal protective equipment (PPE). Face shields are an important component of PPE for front-line workers in the context of the COVID-19 pandemic, providing protection of the face from splashes and sprays of virus-containing fluids. Existing face shield designs and manufacturing procedures may not allow for production and distribution of face shields in sufficient volume to meet global demand, particularly in Low and Middle-Income countries. This paper presents a simple, fast, and cost-effective curved-crease origami technique for transforming flat sheets of flexible plastic material into face shields for infection control. It is further shown that the design could be produced using a variety of manufacturing methods, ranging from manual techniques to high-volume die-cutting and creasing. This demonstrates the potential for the design to be applied in a variety of contexts depending on available materials, manufacturing capabilities and labour. An easily implemented and flexible physical-digital parametric design methodology for rapidly exploring and refining variations on the design is presented, potentially allowing others to adapt the design to accommodate a wide range of ergonomic and protection requirements

New structural systems in small-diameter round timber

Thesis: S.B., Massachusetts Institute of Technology, Department of Architecture, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (page 51).Trees, when used as structural elements in their natural, round form, are up to five times stronger than the largest piece of dimensioned lumber they could yield. Additionally, these whole-timbers have a lower effective embodied carbon than any other structural material. When combined into efficient structural configurations and joined using specially-engineered connections, whole-timber has the potential to replace entire steel and concrete structural systems in large-scale buildings, bridges, and infrastructure. Whole-timber may be the most appropriate structural solution for a low-carbon and fully renewable future in both developed temperate regions and the developing Global South. To reduce barriers to adoption, including project complexity and cost, a standardized "kit of parts" in whole-timber is proposed. This thesis proposes new designs for the first and most important element of this kit: a structurally independent column in whole-timber. A 20' compound column in whole-timber is prototyped at full-scale. New, simple calculation methods are developed for estimating the buckling capacity of tapered timbers. Based on conservative assumptions, the embodied carbon of whole-timber column systems is shown to be between 30% and 70% lower than conventional steel systems.by Aurimas Bukauskas.S.B

Prefabricated Engineered Timber Schools in the United Kingdom: Challenges and Opportunities

Due to changing demographics, the UK faces a significant shortage of school places. The UK government aims to build large numbers of new schools to meet this demand. However, legally binding carbon emissions mitigation commitments might limit the ability of the government to adequately meet this demand on-time, on-budget, and within sustainability targets. This paper assesses the opportunity for prefabricated engineered timber construction methods to help meet the demand for new primary and secondary school buildings in the UK within these constraints. Building on a study of past government-led school building programmes and the state-of-the-art developments in engineered timber construction, this paper outlines the benefits that an engineered timber school building programme could have on a sustainability and procurement level. A strategy is then proposed for the wider adoption of engineered timber for the construction of school buildings in the UK, including detailed guidelines for designers and policymakers. The study concludes with recommendations for the adaptation of this strategy in different countries, depending on context-specific requirements, therefore promoting a generalised adoption of sustainable and efficient construction processes

Inventory constrained funicular modelling

This paper investigates the development of a digital form finding model that combines the generation of funicular geometry with a material inventory constraint. The model provides a flexible design tool that facilitates exploration of structural form whilst simultaneously satisfying two rationalizing criteria. It maintains an equilibrated structure derived from funicular geometry; and optimally assigns an inventory of parts with natural dimensional variation to this funicular geometry. The combined goal for the design outcome is to achieve material efficiency through both structurally rational form, and minimization of material waste. The material chosen for the inventory is below-grade sawn timber1, being lightweight but with high levels of naturally occurring structural variability. Sawn timber boards that are rejected for structural application due to their frequent structural defects (knots, checks, splits etc.) can readily yield usable short length structural members, once the defects are removed. In doing so, this provides a unique inventory of random short members. These short members are well suited to articulated structures, which, by employing an inverted funicular geometry, only incur axial stresses and can employ simple non-moment timber connections. This research has been undertaken for the design of the pavilion for the “Working Group 21 – Advanced Manufacturing and Materials” exhibition at the IASS Symposium 2019

Inventory constrained design of a timber funicular structure

This research investigates the development of a digital form fnding model that combines the generation of funicular geometry with a material inventory constraint. The model provides a fexible design tool that facilitates exploration of structural form whilst simultaneously satisfying two rationalizing criteria. It maintains an equilibrated structure derived from funicular geometry; and optimises the assignment of a unique inventory of timber members having natural dimensional variation. The combined goal for the design outcome is to achieve material efciency through both structurally rational form and minimization of material waste. The material chosen for the inventory is utility-grade sawn timber, being lightweight but with high levels of naturally occurring structural variability. Sawn timber boards that are rejected for structural applications due to frequent structural defects (knots, checks, splits etc.) represent up to 50% of the sawn product produced by Australian sawmills, and are destined for under-valued non-structural use, chipping or burning. Yet these boards can readily yield usable short length structural members, once defects are removed. In doing so, the process creates a unique inventory of random short members. These short members are well suited to articulated structures, which, by employing an inverted funicular geometry, only incur axial stresses and can employ simple (non-moment resisting) timber connections. This form fnding tool and a frst prototype pavilion are proofs of concept for viable structural application of what is otherwise a signifcant source of waste in the timber industry