Poly-Pocket is a sticky spiral staircase of tensioned spring-capsules. The Individual components are held together using only tension members and friction enhanced by the “stickyness” of soft pvc plastic. The sticky pvc is laid over stiff polypropylene, which uses tension forces to hold the surfaces in active bending.

The video above shows the assembly process of the final model from our weekend workshop. The video below shows the process of computer-aided structural analysis, via the gh add-on Karamba. The Galapagos Solver of gh was used to find the lowest structural utilization among the possible combinations of geometric variables. The variables are applied to a single component, which associatively updates the global geometry.

[formula used for testing: (utilization percent range)*(square of utilization percent maximum)]

As stated above, the stair’s design follows principals from studies in the translation of soft materials to structural materials. These studies produced components which can oppose compressive forces, and implied a set of rules related to geometry, scale, and material properties. In the first case (pictured below), we see the technique of active bending used to enhance the 3-dimensional rigidity of an other wise flexible 2-d PVC sheet.

The second component (below) exhibits a different type of material manipulation based on the properties of sheet rubber, and seeking geometries which will compliment these properties. By understanding the relationship between tension-enhanced ‘vaulted’ geometries and the resultant spring-back effect observed in plastics, we can draw conclusions about the aggregation of both components.

The use of tension in connecting these components vertically takes advantage of both the spring-back effect and the surface ‘stickiness’ of plastic materials to create frictional resistance to shear forces without the use of direct connections between the surfaces of adjacent plastics.

Our first prototype made from wood clearly showed us that active bending with only one element is hard to do.

So we combined the first element with a second element, where both are bended true interlocking with each other providing stress with the structure. The elements interlock in four points providing five distances we could play with.

In Karamba we compared three different sections to find witch positions are optimal for a structural stair.

From the numbers generated by the software it was clear that the first section performed better than the others.

Making the model using the section positions showed us that in fact the structure was performing better. However there was still something missing.

Using galapagos we tried to find the further best geometry but the result was unsuccessful, so we come back to the first result.

After the beam analysis we found the better geometry for the row support, in order to reduce the My.

Connecting the sides of the steps with rope provided the missing overall stability of the system.

Conclusion: Going back and forth from physical model to digital model showed us the benefits of using both instead of just one for the optimization of a structure. Combining the strong sides of both methods is the wright way.

Our base structure was arches joined in a zip-way. We created a surface between and got a vault structure in case of better understanding of structural behavior.

SELF LOAD-FIXED SUPPORTS

SELF LOAD-PINNED SUPPORTS

1 APEX PT LOAD-FIXED SUPPORTS

1 CENTRAL PT LOAD-FIXED SUPPORTS

1 APEX PT LOAD-PINNED SUPPORTS

1 CENTRAL PT LOAD-PINNED SUPPORT

Displacement:

Looking at the displacement grafs we can see where is structure’s deformation affected by load. In the diagrams we can understand that

the deformations of the structure are not only in the place where the load is placed, but also in places of arches tension according to

supports.

Stress Vector:

The stress vector lines show the movement of forces between the load and supports. In the diagrams we can see that the stress lines

gradually spreaded from the load to sopports and the most tension achieve closer to supports.

Utilization:

It shows the performance of the material. Looking at the diagrams we can see that material work in the placement of load and closer to

supports.

CHANGED SUPPORTS

SELF SUPPORTED-FIXED SUPPORTS

SELF SUPPORTED-PINNED SUPPORTS

Understanding of structural behavior by changing of supports place:

In diagrams you can see that moving the supports in different axes the most tension of structure is always closer to the base points of supports.

Link :exp_03

Link : exp_02

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The first idea was to create a staircase which we could use as a cantilever from a middle support and creating the steps by folding the same element. From there we developed a new staircase using the folding where was needed as structure we tested several pieces made by hand until we found the best shape and structure.

We managed to find the right solution by experimenting with the physical model, letting us know how the structure worked and helping us identify more precisely where the moments of weakness and strength where working or not.

After designing and looking how it behaves in a physical way, we introduced the digital model to be analysed in karmba.