Friday, February 22, 2013

Facade modelling - the Core and Outrigger

22 Feb 2013: Its been a busy day for the Tall Building students. Phil headed a seminar of almost 2 hours just on elevators and escalators! Then our minds turned to 'Case Studies' in which each student will give a presentation for 10 mins (in March). The rest of the day was spent on DMT (Design Materials and Technology) or FCT (Facade Technology).

The Floating Clouds group have chosen to make a model demonstrating 'Core and Outrigger' and DNC has provided quite a lot of help from his garage, cutting up spare plywood shelves and roof slates to make some components. The group are also using rubber bungee as the 'columns' for the tensile facade. This is a start to making the first test model, threading the wood blocks onto the bungee.

They are putting slate floors in at intervals to provide some distributed weight. They are intending to build a lattice trussed outrigger and belt truss in two places.

Another group, the Bluesky Dreamers are intending to make their model in aluminium and clear plastic, and this will represent the Megabraced facade idea. The sponges are going to be held in water containers, so we can consider passive damping.

As the model mounts up, it is really unstable and requires a large team of very pretty girls to keep it upright. The men either stand around taking photos or stacking more dangerous weights on top, typical!

We can now make it stable by adding the tensile facade, and 8mm bungee is perfect, secured with metal eyes and figure-of-eight knots. But it is still not safe enough.

We now try additional facade columns, on the long and sort sides, and try to make the tension in each column approximately equal.

It is now standing upright, but a steadying hand is still helpful. The blocks have wood swarf on them after drilling and should have been cleaned off - the micro-gaps between the blocks cause too much sway.

Its going to be stored for the night, but is a little bit reluctant to be carried! and like a disobedient cat it 'jumps out of their hands' Miaow!

We can reduce the instability by cleaning the blocks and gluing them into pairs, thus reducing the number of gaps from 48 to 24. Here they are, drying overnight, with the bungee providing some pressure to help the glue set.

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