Context + Material

The design and structural potentials offered by active elastic bending of materials led us to investigate bending active as a structural system. We were curious to investigate how this stored energy could be used to create novel structural systems and the challenges these systems posed.

In pole vaulting we observed how elastic deformation of a pole was utilised to transfer kinetic energy to potential energy. The deformation brought about by the storage of this potential energy led us to further investigate pole vaulting. 

We first began by learning about the history of pole vaulting and in particular the evolution in the materials used in the sport. Starting with bamboo, moving toAluminium, evolving to glass fibre and settling on carbon fibre : the poles material changed drastically but retained key performance criteria.

We quickly realised that these very criteria were both relevant to pole vaulting and our potential architectural application of pole bending. These were weight, strength and flexibility. We then further observed the stages of a pole vault to better understand how the pole is utilised and to what effect.

CRFP HAT was thus selected as our material of choice. As a two part carbon fibre reinforced polymer, It gave us a lot of flexibility in its fabrication and potential customisation. It also possessed a high ratio of Flexural strength to Flexural Young’s modulus.  

abstracting system

In our initial exploration we decided on a strategy to retain the potential energy of the pole. This was done by the addition of a cable system at one end of the element and a fixed connection at the other. This initial setup enabled us to understand the fundamentals of our system. 

In our initial setup we choose to simulate variation in bending capacity in Kangaroo physics by breaking an element into segments of varying distances. The total length of the element, the number of segments and the position from which the element was pulled were kept as controlled variables.

Having understood a single element we then began exploring branching of the element first in Kangaroo and later in Sofistik.

For the FEM we took a segment of our global structure ( 3 branches) to analyse how one branch may behave. Each branch segment was analysed as individual beams. This imperfect model led us to rethink our approach in simulating the system, being aware of our limited grasp of SOFISTIK. This led us to explore this in a physical model.

By physcially computing our structure we were able to understand how it would react during bending. Although the material and scale were not identical to the ones we envisaged using for the pavilion we were quickly able to test and observe the potential failures and successes of our system. 

In this physical model we modelled a section of the structure as we had in the SOFISTIK analysis. To simulate neighbouring branches, we used a glass fibre rod with a bigger cross section. 

During the experiments we were also able to see the effect of having sliding connections vs stiff ones to connect branching elements. From this we then realised it was crucial to understand the system whollistically and thus returned to an FEM model.

A critical observation from this experiment was the ballooning of the whole structure when pulled down. This was also observed during our physical model trials. The cause of this was attributed to the nature of the branch-to-branch connection, which were fixed.

We then replaced these fixed connections with sliding ones. Due to the complexity of our geometry the FEM approach showed its limitations as well as our own as novice users. This led us to return to particle spring system where we were able to model these connections with far greater ease.