Timber-Only Structures and Architecture

Gengmu Ruan

Ph.D. candidate at the Department of Civil Engineering

Aalto University


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Timber-Only Structures and Architecture: using salvaged timber and wooden nails only

About the Project

This research focuses on integrated sustainable, structural, and architectural design concepts for timber-only structures, more specifically, structures made from salvaged timber and wooden nails only.

Relation to BuildDigiCraft

The key elements discussed in the current PhD research are connection, material, structure, and architecture (form). A sequence of “Material and connection first, structure second, architecture third” is applied. The process follows a feedback loop idea, which results in lessons learnt (knowledge achieved) from each step backwards through the interconnections in between, as shown in Fig.1. Specifically, the material ised here is salvaged timber, and the connection uses wooden nails only.
Knowledge-wise since this process covers the fields of timber engineering, architectural design and sustainability, a comprehensive understanding on the individual aspects and the interconnections in between is required.

Figure 1. An idea of feeding back process applied in the current research [1]

Due to the fact that there are increasing barriers between structural engineers and architects in contemporary building design process, this research also addresses this issue and discusses an integrated structural and architectural design concept.

The required skills in this research are mainly in architectural design, structural engineering, and wood crafting. Accordingly, the tools used in this research are, digitally: Rhinoceros, Grasshopper, RFEM, Abaqus, Matlab, AutoCAD; Physically: wood milling machine, nailing machine, loading devices.

Regarding Baukultur, a subjective definition can be explained as the buildings which perform a high-quality fulfillment of the requirements in environmental and social sustainability as well as human’s physical and psychological needs.

Research Background

Nowadays, increased demand for timber construction has been proposed as a possible solution for environmental sustainability because of timber’s renewability and the capacity to store carbon. However, nowadays most of the existing timber structures are connected by metal fasteners, which means it still uses a relatively large amount of metal products in timber constructions.

Simultaneously the building sector, which is thought to be one of the major contributors to environmental pollution, energy consumption and waste, is on the move to a new more conscious and environmentally compatible thinking. The use of natural resources, short transport, unmixed material, respectively easy to separate and therefore to reuse material, are just few of the most important keywords in this context.

Because of research in this field and mindset, the exploration of timber-only structures and architecture is proposed. In the field, this research will pay a special focus on timber-only connections, structure members and/or entire structures.

Scale, Aim & Goals

This research project investigates the use of wooden nail connections and salvaged timber in timber-only structures and architecture. Material properties, structural behaviors of possible connections and the entire structure, as well as architectural and structural benefits and limitations will be explored.

Basically, the goal is to deeply understand the wooden nail connection, to develop it within proper structural forms, then to utilize them into timber-only structures and architecture in an elegant, ecological, and efficient way.


1. Literature Review
Literature related to the aspects of wooden nails, salvaged timber, numerical simulation, integrated architectural and structural design as well as digital prefabrication will be reviewed.
2. Experimental Method
Single and multiple connections, mock-ups, prototypes, and entire structures will be constructed and experimentally tested. Structural properties, e.g., bending strength of nail-only beam, will be examined.
3. Analytical and Numerical Modeling
Numerical modelling and simulation of nailed beam, finite element method (FEM) of structural elements, scripting, and parametric design of structures as well as digital fabrication will be explored. Statistical methods will be used for evaluating the results of the experiments and performing sensitivity analysis on analytical models.

Outcomes and Results

The goal of the proposed research is to provide solutions for the usage of wooden nail and salvaged timber as a design driver of timber-only structures and architecture. The structural analysis of the nail and nail patterns in dependence on used (salvaged) material will give information on feasible ways of using this novel sort of connection. This will serve as a basis of exploration of the design-space, meaning searching for the freedom and limits in use and resulting architectural expression.
From the architectural bottom-up approach, namely from the detail to assembly strategy and fabrication to the built space, a new material-logic respectively aesthetics is expected. This will be show-cased by prototyping, design, and realization of experimental structures, which are footed on above-mentioned findings. Simultaneously this research will contribute to a sustainable building strategy, satisfying structural requirements while opening new avenues in architectural design.

As periodic outputs, some design-build projects have been prototyped and realized. A preview of the projects is shown in Fig. 2.

Figure 2. Design showcases: (a) modular elements for Kouvola trail project, (b) a partly curved plaza for Kouvola trail project, and (c) a planar reciprocal frame unit which consists of four beam elements

Discussion and Future Vision

Our results will have an impact on different levels from material technology to structural and architectural systems to computational tools to contructability processes. Overall, the outcomes of this study will also positively be contributed to the deeper understanding on the potential of timber-only connections, as well as the connection between structures and architecture.

Related Publications

[1] Ruan, G.: Master Builders revisited – The importance of feedback loops: a case study using salvaged timber and wooden
nails only. Architectural Research in Finland, 6(1), 2022. (Accepted for publication)
[2] Ruan, G., Filz, G.H. and Fink, G.: Shear capacity of timber-to-timber connections using wooden nails. Wood Material
Science & Engineering, 17(1):20-29, 2022.
[3] Ruan, G., Filz, G.H. and Fink, G.: An integrated architectural and structural design concept by using local, salvaged timber.
In: Proceedings of IASS Annual Symposium 2020/21 and the 7th International Conference on Spatial Structure – Inspiring
the Next Generation, 534-545, 2021.
[4] Fink, G., Ruan, G. and Filz, G.H.: Sustainable design concepts for short span, timber-only structures. In: Proceedings of
IASS Annual Symposium 2019 and Structural Membrane 2019 – Form and Force, 634-641, 2019.