structural bending tests...

as Fibre-C has been developed as a cladding material, not a structural material, we have had to have some tests done. In particular, because the tests that have been done by Rieder in the past, have only tested it's structural capacity perpendicular to the layout of the fibres, while we will be loading the forces in the axis of the fibres.

So today we began the structural bending tests at the labs in Aachen, Germany. According to AKT the tests have been going well...we have no bending failure and no problems with buckling or shear failure. AKT will provide some numbers on capacity of the profiles and further analysis.

In the meantime, here's a video from the testing labs posted for us on youtube...you'll see a big crack begin to appear eventually, but no structural failure!!

FEM Analysis...

AKT has run an initial FEM analysis on the roof structure, and well...we've got a bit of work to do.
Though significantly lighter than conventional concrete, the Fibre-C is still concrete, and the self-load of the material is a bit more than our geoemtry can handle at the moment. Basically, with the tilt/lean of the roof structure, the self-load of the structural material, and the non-continouous nature of the structure....our notch joints are taking a hell of a load. The moment forces that these joints are taking is very high. We are also experiencing high stresses and deformation in the profiles due to bending in their weak axis. AKT has told us we need to reduce the stresses by a factor of about 6 (no kidding...my stress factor has got to be +100 these days).

We've got a few options for reducing these stresses, but it looks like it's going to be a combination of them all:

1. Decrease the tilt angle of the roof structure. By reducing the angle by 15 degrees we gain a factor of 2. We also lose some of the dynamic formal movement and drama of the structure.

2. Introduce bracing, especially at the sides of the pavilion. This could be done by infilling flat sheets of fibre-c stiffeners between profiles at various locations. This could also detract from the visual and structural purity of the pavilion.

3. Add more primary ribs at the side faces. This might alter the visual effect of the moire pattern, but could also be interesting if done as a gradient of spacing. I also find it interesting to architecturally express where the structure is performing the most.

4. Increase thickness of material at primary ribs to 13mm, and decrease thickness of material at secondary profiles to 10mm (reducing the self-load).

As I said, we've got some work to do. All of these decisions need to be looked at before we can make a call on them. We need to maintain our design concept, while finding a structural solution that suits. But in particular...we need to so so ASAP!

Here's a look at the revised wire model with spliced profiles and intersection nodes we sent over to AKT today for a quick analysis. In this version, we have reduced the tilt angle by 10 degrees on the front face, and 5 degress on the back.
On another note, once again we have also revised the bench geometry again. Don't worry, it won't be the last time. As you can see below, we are using the 3.6m x 1.2m standard sheet size of Fibre-C as the module for sizing our profiles.
In light of this, we have now lowered the height of the seatback/counter, so that it drops within the 1.2m width of the sheet material. this allows us to cut the entire bench profile in the primary direction, in one continous piece. this is a very minor change, but one which saves us huge amounts of hassle and detailing.

meeting of the minds...

a photo from AAlog.net of our meeting yesterday with our structural engineering team and pavilion organizer Yusuke Obuchi. AKT is currently conducting analysis on the structural capacity of the pavilion and will also be conducting a series of tests on a few options for joint arrangements. From left to right Hanif Kara, Oliver Bruckermann, Jugatx Ansotegui, Alvin Huang, Alan Dempsey (photo taken by Yusuke Obuchi).

"DRL TEN Pavilion meeting at Adam Kara Taylor’s office on Farringdon St."

"The winning design team members Alan Dempsey (DRL ‘02) and Alvin Huang (DRL ‘04) met with AKT’s engineers Hanif Kara, Oliver Bruckermann and Jugatx Ansotegui and DRL’s Yusuke Obuchi today and discussed structural details of DRL TEN Pavilion. For more details on the pavilion, check out the pavilion blog: http://cspacepavilion.blogspot.com/"

structural optimization...

To optimise the structural performance, and reduce the possible range of tolerances on the joints, we are developing the pavilion as three distinct, but interwoven structures that will be spliced together:

1. Roof canopy
2. Seating
3. Deck

We have also modified the geometry and the sections so that all section cuts are now completely planar. This will help reduce the complexity and tolerances for assembling something with over 1500 joints. Still trying to get that number down too, without losing the density of the structure.

To do so, we are working on a structural pattern that will break the continuous spans of the sectional profiles shown in the images below into sectional lengths based on the standard dimensions of fibre-c panels (5mx1.2m and 3mx1.2m).

Here's a few screen shots of the revised roof geometry and sectional profiles: