What it does
Temporary folding infrastructure that converts to permanent structural concrete formwork.
Temporary structures are essential for emergency infrastructure response, but they contain a tragic design paradox: the better the temporary structure, the less incentive there is for communities to replace and rebuild permanent infrastructure. It is a problem that our team members were first exposed to in the first year of our engineering degree, with a design project that required us to design a deployable emergency bridge. In the following years of study, we’ve each developed and specialised in various knowledge areas: user-centred design, composite-reinforced structures, origami-based structural design. However our interest in emergency-response infrastructure has been sustained as the relevance of both global and local-scale events, such as recent Brisbane flooding, has continually exposed us to the need for better rebuilding technologies. We therefore revisited the design problem with the benefit of our combined our individual expertise. We developed a new structural formwork technology that enables the creation of functional temporary structures that can also scaffold permanent structures. "The Crease Bridge" is the first application of this technology: a portable bridge that can be instantly deployed in flooded regions for emergency pedestrian and light vehicle thoroughfare (access/evacuation) and following emergency use, can be used to case a permanent concrete bridge.
How it works
The Crease Bridge is formed from a triple-layered morphing shell structure. Each layer is composed of a continuous glass-fibre reinforced sheet (GFRP) which is resin-impregnated to form hard regions corresponding to plates in an origami pattern. Patterns in each of the three layers are designed have compatible folding motions and so the whole assembly can fold from a flat (packaged) to arch (deployed) state. This deployment happens in two stages: an initial in-plane expansion (Stage 1 deployment) and a subsequent rolling into the faceted arch form (Stage 2). If pinned at the base, the faceted arch has load-carrying capacity sufficient for pedestrian and light vehicle loads. Between each of the three layers (bottom face, core, and top face) runs continuous hollow channels. It can therefore act as encasement for concrete (Stage 3) which creates a final form with excellent long-term durability and strength. The cost associated for the installation of a permanent bridge is therefore reduced as the need for concrete formwork is removed. Additionally, the unique geometry of this bridge allows for concrete to be cast directly into compressively-loaded top channel (between core and top face) while the bottom GFRP face acts to resist tensile loads, reducing the required volume and weight of the concrete and further substantially reducing the cost of permanent bridge installation. The Crease Bridge has the additional benefits of quick assembly by hand tools only, delivery in a small lightweight package, and the ability to be moved without specialised equipment. However the two key features of being able to cast a permanent structure from the temporary, if deemed necessary, and being able to reduce the expense of such a structure with a structurally-efficient combination of concrete and GFRP, means that it is successful in addressing the current problems in transitioning from temporary to permanent infrastructure.
The initial development of the project involved research into the applied use of folded or origami-based designs as a solution to the problems associated with current formwork technologies. We identified problems including a lack of portability, time (and expense) to erect, and gradual degradation of formwork material resulting in construction waste. These highlighted the need for a design that is effective in terms of its sustainability and convenience. From here, recent research at the University of Queensland into structural plate assemblies was investigated to explore material folding techniques and designs that would be strong and simple to erect in emergency situations as well as being useful in the long term by allowing the encasement of concrete. Early stages of the design process focused on using plywood, as this was similar to existing formwork technologies, however experimentation revealed that timber forms became weak when hinged. Integration of additional research at UQ allowed us to use composite assemblies, which were easier to hinge and could act as tension reinforcement for the concrete configuration, thus removing the need for reinforcement steel. After some trial and error we were able to develop a method to ‘blank-out’ hinges from the resin impregnation and so to keep them soft and foldable, as well as a simple hand-stitching method to join the three layers of the folded assembly. Thus, we achieved a final design that satisfied our original goals in a number of ways, as it was lighter, easier to construct and also less expensive to manufacture. Ongoing development is focused on analysis and construction of full-scale prototypes suitable for structural testing.
How it is different
The Crease Bridge has not been entered into any other awards or competitions.