ITECH Research Pavilion 2024

The ITECH Research Pavilion 2024 presents an innovative approach to bio-based hybrid architecture, featuring a first-of-its-kind system that combines timber and natural fibres. The novel process explores the architectural possibilities that arise from the complementary characteristics of both materials. In this context, timber’s compressive strength and shape flexibility are strategically integrated with natural fibres’ tensile abilities and versatility, enabling new directions in the design and fabrication of lightweight and performative hybrid structures. The project introduces the co-design of new computational design methods and multi-robot fabrication processes tailored to leverage the inherent characteristics of each material. The proposed timber-fibre hybrid approach not only pushes the boundaries of material innovation but also offers a regenerative pathway towards climate-positive practices in construction.  The research builds upon a series of successful pavilions developed at the Institute for Computational Design and Construction (ICD) and the Institute of Building Structures and Structural Design (ITKE) at the University of Stuttgart. The project was designed and fabricated by students and researchers from the ITECH master's program at the Cluster of Excellence "Integrative Computational Design and Construction for Architecture (IntCDC)" at the University of Stuttgart.

In the context of environmental crisis and resource depletion, architects must not only strive to mitigate the impacts of their designs but also aim for more holistic approaches that help restore and improve the natural environment. Transitioning from synthetic materials and energy-intensive manufacturing to renewable resources and more efficient fabrication methods is essential. However, this transition should avoid dependence on a single natural material to prevent potential harm to biodiversity and disruption of ecological balance.

Timber has been a fundamental construction material for centuries and has recently resurged in the industry due to its exceptional carbon storage potential and its role in reducing the carbon footprint of building construction. The increasing demand for timber, particularly in the European construction sector, requires a substantial increase in local wood harvests, while factors such as climate change, rising global temperatures, and pest infestations have adversely destabilised timber production in recent years. The growth speed and inherent variability in the supply of naturally grown materials underscores the need for a diversified use of biomaterial systems within the building industry. While typical softwood requires 30-60 years to reach a harvestable cross-section suitable for industrial use, fibre crops can be grown in significant quantities within approximately 120 days. Fibre crops' rapid growth cycle and land efficiency position them as strong candidates to support a broad biomaterial building culture.

Research on fibre-polymer composites (FPC) has successfully demonstrated its ability to form highly performative, lightweight structures with synthetic fibres. In recent years, research has also shown the potential of natural-fibre polymer composites (NFPC) to form load-bearing structures. Flax fibres, locally sourced in central Europe, exhibit a lower environmental impact and superior mechanical properties to other natural fibres. By combining flax fibre-polymer composite with timber, this project showcases the benefits of integrating these materials into a hybrid system, aiming to diversify the use of natural resources.

In an effort to identify more environmentally friendly substitutes for petroleum-based polymers, a partially bio-based resin was employed for the first time in a project of this scale. An epoxy resin containing 56% bio-based material was chosen after an extensive investigation of suitable matrix systems. This step represents progress towards building on an architectural scale with a fully bio-based NFPC.

The hybrid system is a result of an in-depth investigation conducted in the ITECH Master program of the morphological possibilities arising from the combination of timber and NFPC. The system concept integrates both materials, considering their formal, fabrication, and structural opportunities to form large-scale building elements.

Timber's volumetric nature is explored as roof plates, providing enclosure,  while their easy workability enables the milling of the plate's edges to become an interface with the fibres. In the traditional coreless filament winding process, the fibres are placed around mechanical anchors fixed on a temporary structure, known as a frame, generally made of steel. In this case, the timber itself replaces the temporary steel frame, becoming an embedded frame for the fibres. During the fabrication process, the timber supports the fibres, and once they are cured, both materials work together, becoming mutually supportive and essential in maintaining the structure's spatial integrity. This approach extends the timber's functionality beyond its traditional structural role, improves off-site fabrication efficiency, and minimises manufacturing waste.  

Structurally, timber's capacity to deal with compression is paired with fibre's tensile strength, informing the material allocation and the geometrical arrangement throughout the system. The final spatial arrangement between timber and fibre illustrates the distribution of forces in a constant interplay of material interdependence and collaboration.

The developed system unfolds as two component types: columns and roof plates, enabling the structure to expand vertically and horizontally. The columns are formed by placing groups of timber struts in a radial spatial arrangement, where timber acts as compression rods and fibres as tension cables and external bracing, ensuring structural redundancy and stability.  The roof plates are composed of a set of timber struts fixed under a timber plate, a fibre cord, and a fibre mesh. The system allows the timber plate and struts to be primarily under compression and the bottom fibre cord under tension.   

Connections are designed to facilitate disassembly between components, enabled by detachable joints and the reduction of mechanical connections through embedded joints. Cross-screwed lap joints connect the timber plates, while fibre stitches enable on-site connections between fibre edges through bolted joints. Within each component, embedded connections at the end of the struts and on the finger joints facilitate the interface between fibre and timber.

The integrated co-design process synthesises the developed concepts into an iterative digital workflow. This workflow incorporates the geometry resulting from an initial global form-finding process with detailed fibre syntax, connection design, and considerations from robotic fabrication constraints and assembly logic. Ultimately, the digital workflow generates fabrication files from a streamlined design-to-assembly process, leveraging the individual materials' structural, fabrication, and construction potentials to create a complex, high-performance morphology.

Over the past decade, research on Coreless Filament Winding (CFW) has progressed significantly, demonstrating a high degree of robustness and flexibility as a fabrication method for lightweight fibre structures. The design space of such structures can be expanded by multi-robot CFW setups, which offer new opportunities in geometry, complexity, and fibre interaction. Previous projects have explored collaborative robotic setups for various purposes, including extending the robotic fabrication envelope and supporting opposing sides of a steel frame.

This project employs a multi-robot collaboration to address the challenge of using timber as an embedded frame. Specifically in the columns, slender timber struts are used as a frame for the fibres, which could break if tension is applied unevenly. A dual robot winding setup is employed to tackle this challenge, ensuring that both robots wind simultaneously on opposite sides of the same strut. This strategy is primarily used for the initial layers until all struts are wound on both sides and secured evenly by the fibres. This project represents the first use of a parallel winding setup to fabricate a full-scale structure.  

The collaborative setup includes two industrial robotic arms, one on a linear track and the other stationary. The motions of both robots were coordinated with the external axis supporting the structure, allowing dual winding to occur synchronously, resembling a choreographed performance. Specialised tools were developed to optimise the path planning considering the specific types of material interface. Due to the simpler geometry of the roof plate components and the fact that struts were fixed on one side of the plates, a single robotic winding setup was used for the fabrication of all five roof plates. The entire production occurred at ICD's Computational Construction Lab (CCL) in Wangen, Stuttgart. Each column required approximately 14 hours to be wound, while the plates took an average of 8 hours each. Following each winding session, the components were cured in a customised oven.

The ITECH Pavilion 2024 was developed to demonstrate the potential of bio-based hybrid systems in architecture. It leverages the qualities of natural fibre composites and timber to create a highly performative and regenerative hybrid system.

The pavilion's global design consists of a three-legged canopy expanding single and multi-way spans through a highly dematerialised structure. The structural capacity is engineered to withstand 1.5 times its self-weight, in conjunction with 1.5 times the wind load, accounting for both uplift and horizontal forces.  The final geometry was discretised, considering timber’s optimal grain directions and the desired spans. This resulted in three column components, two two-way spanning, and three one-way spanning roof plates. These components effectively transfer forces through the cross-section of the hybrid system, adhere to the fabrication setup limitations, and converge at a maximum angle of ten degrees to facilitate rainwater drainage. After fabrication, a full-scale test assembly of the pavilion was conducted upside-down in the CCL lab to assess fabrication tolerances. This process also allowed for the winding of the detachable fibre stitches before shipping them to the site.

The pavilion is located at the University Campus' Stadtgarten, covering an area of 45 square meters and weighing 966 kg. The main spans cover 5 and 7.5 meters. A total of 41.5 km of flax fibre rovings, 1.75 m³ of 42mm thick 3-layer softwood timber plates, and 0.096 m³ of hardwood struts were used. The assembly process used a mini spider crane to lift the components and a telescopic platform to support vertical construction reachability. The main structure was assembled in two days, with an additional week to complete the roof membrane and foundation. 

Within a familiar architectural typology, the pavilion's unique hybrid system unfolds as an intricate interplay of materials. The final system explores an expanded geometric space for fibre structures, made possible by the strategic arrangement of both materials in space. It defies conventional ideas of form and structure, resulting in a novel yet grounded material and architectural experience. As a research demonstrator, the pavilion represents a step toward a new biomaterial culture that integrates the strength of timber with natural fibres into a cohesive structural system. By leveraging the complementary properties of these two materials, the research aims to address sustainable construction solutions and expand the design possibilities of bio-based hybrids in architecture.

Institute for Computational Design and Construction – ICD

Rebeca Duque Estrada, Fabian Kannenberg, Prof. Achim Menges

Institute for Building Structures and Structural Design – ITKE

Tzu-Ying Chen, Yanan Guo, Prof. Dr.-Ing. Jan Knippers

Concept & System Development:

ITECH Class of 2024: Kalaivanan Amudhan, Hamed Behmanesh, Clara Blum, Yağmur Bulut, Cornelius Carl, Paula Castel, Minghui Chen, Luisa Claus, Matthias Hornung, Che Chen Hu, Mohammad Mahdi Jafari, Simon Joller, Donghwi Kang, Arindam Katoch, Niki Kentroti, Rabih Koussa, Otto Lindstam, Luiza Longo, Samuel Losi, Laura Marsillo, Gonzalo Muñoz Guerrero, Kumaraguru Rangaraj Venkatachalam, Markus Renner, Seyedehgelareh Sanei, Jonathan Schill, Zahra Shakeri, Shirin Shevidi, Ceren Tüfek, Aysima Yavuz, Ali Zolfaghari.

Robotic Fabrication:

ITECH Class of 2024: Kalaivanan Amudhan, Hamed Behmanesh, Clara Blum, Yağmur Bulut, Cornelius Carl, Paula Castel, Luisa Claus, Che Chen Hu, Mohammad Mahdi Jafari, Simon Joller, Donghwi Kang, Niki Kentroti, Otto Lindstam, Luiza Longo, Samuel Losi, Laura Marsillo, Gonzalo Muñoz Guerrero, Kumaraguru Rangaraj Venkatachalam, Zahra Shakeri, Shirin Shevidi, Ceren Tüfek, Aysima Yavuz, Ali Zolfaghari.

With support of: 

Philip Duncan, Sven Hänzka, Harrison Hildebrandt, Renan Prandini, Michael Preisack, Michael Schneider, Katja Rinderspacher & Christoph Zechmeister

Student assistance: YuLun Chiu, Kai-Jie Kwang & Nicolas Pousa

Supported by: 
Deutsche Forschungsgemeinschaft (DFG), ARRTSM, Safilin, University of Stuttgart, Cluster of Excellence Integrative Computational Design and Construction for Architecture - IntCDC