1
00:00:02,780 --> 00:00:01,250
wanted to do for a while has

2
00:00:05,900 --> 00:00:02,790
demonstrated the effects of slender

3
00:00:08,390 --> 00:00:05,910
column column buckling especially in the

4
00:00:10,879 --> 00:00:08,400
context of World Trade Center seven now

5
00:00:13,539 --> 00:00:10,889
here I've got the equivalent of a column

6
00:00:17,000 --> 00:00:13,549
which is this piece of steel here and

7
00:00:20,150 --> 00:00:17,010
these things here are the equivalent of

8
00:00:23,450 --> 00:00:20,160
floors which are bracing the column on

9
00:00:25,849 --> 00:00:23,460
the sides at the column itself this

10
00:00:29,060 --> 00:00:25,859
piece of steel is free to move up and

11
00:00:33,680 --> 00:00:29,070
down and on the bottom it's simply

12
00:00:37,010 --> 00:00:33,690
resting on the concrete and so what I'm

13
00:00:39,920 --> 00:00:37,020
gonna do is demonstrate how much for so

14
00:00:43,190 --> 00:00:39,930
I could put on top of this I'm gonna do

15
00:00:44,500 --> 00:00:43,200
is balance a plank on this and the other

16
00:00:47,029 --> 00:00:44,510
end of the plank will be on this

17
00:00:49,100 --> 00:00:47,039
stepladder and then I'm going to put my

18
00:01:01,360 --> 00:00:49,110
body weight on that and see if it

19
00:01:05,270 --> 00:01:01,370
supports it so that is quite easily

20
00:01:13,780 --> 00:01:05,280
supporting a very dynamic load for me

21
00:01:19,660 --> 00:01:13,790
and it is not buckling at all the

22
00:01:23,240 --> 00:01:19,670
demonstration is that this is not braced

23
00:01:25,100 --> 00:01:23,250
then it's actually it's extraordinarily

24
00:01:27,050 --> 00:01:25,110
weeks you can hardly sport any way to

25
00:01:31,039 --> 00:01:27,060
stall it but I can I can bend it with

26
00:01:32,840 --> 00:01:31,049
just perhaps ten pounds of weight and

27
00:01:35,690 --> 00:01:32,850
once it is buckles it's hardly supports

28
00:01:38,450 --> 00:01:35,700
any weight when it's in this structure

29
00:01:41,480 --> 00:01:38,460
here when it's actually raced along its

30
00:01:43,249 --> 00:01:41,490
length by the seven or flaws that we