Planning

Compression forces acting downwards create outward tension forces on the bottom surface. Therefore reinforcment needs to be used in ar-eas of high tension such as above doorways to carry this force around the gap and down into the ground.

Task: To build the tallest tower possible using only wooden blocks and rubber bands that will allow access for a small toy deer.

Potential Issues:

Possible Solutions:A door way can be built up by gradually bringing the layers of bricks on top of two pillars, forming a pyramid shape. This sollution is quite fragile and may not be able to support the tension forces created at the top of the gap by the compres-sion forces from above.

A pole could be created by connecting three blocks with rubber bands that would be able to carry the forces around the doorway and down to the ground.

Another option we considered was creating square shaped blocks and connecting them with rubber bands, as we found this structure much stronger than thin pillars.

To create the rest of the tower we decided to stack the blocks and offset the joints so there were no week sections where all the gaps were alligned. We decided a square shape with round-ed corners would be easier to create and stron-ger as there are no edges. We also decided to curve inwards each of the sides to counteract any external forces that may have been present. Materials:

We determined that the blocks were all a constitent, flat shape and were relatively light, meaning they are easy to stack without needing to be attached and will not create too much compression force. Howev-er, we found that using rubber bands to attach multiple bricks togeth-er decreased this ability to stack the blocks, therefore we looked into ways of avoiding the use of rubber bands in the construction.

Constructing the tower

We began by gradually build-ing up the walls, leaving a gap at the front that would just allow the deer to move in and out.

We decided to make the base quite large, as this would allow for more height as we were planning on reducing the size of the tower the high-er we got and we realised we had enough blocks to do this. In hindsight, it was unnecesary for it to be this large.

We deciided not to conit-inue buiding up the tower the whole way round, as this would reduce the amount of compression force on the doorway and would allow us to gain height more quickly. This did however make the ex-posed sides vulnerable to tip-ping in or out and so we had to be careful to build directly up.

We had some difficulty creat-ing the doorway over the en-trance and a small portion did collapse. However, we learnt from this and maganged to gradually build across the top by ensuring each piece that we insterted was counter-balacnced.

As shown above, the compression forc-es travel down the tower in a zig-zag path though the overlaps in bricks. At the opening, forces are diverted out-wards and carried down to the ground.

Testing the towers stabilty

One of the other groups used the same

building technique, but had fully en-

closed the tower.

We found that the tower was able to

hold a significant amount of weight

when placed carefully on top, as the

weight spread down the tower.

As seen in the picture on the right, the

tower was not built up perfectly straight,

meaning the weight was not distributed

evenly, putting more pressure on one

side. Had this not happened, the tower

would have been able to hold an even

larger weight.

The tower collapsed when more bricks

were poured on top, rather than gently

placed. This is because the falling blocks

created unbalanced forces on parts of

the tower.

Deconstructing the tower

After completing the tower, we began to take out pieces to test its stabilty and identify the collapsing point.

We found that quite large sections of blocks could be removed without the tower collaps-ing, however it did greatly reduce its structural stabilty.

The tower collapsed once we removed all of the blocks on one half as the remaining side had nothing to support it and evidently wasn’t built perfectly straight.