Erm, because I'm (almost) never wrong?Originally Posted by Andy McGregor
not quite right, the keystone was originaly bigger because as the load increased it would in effect strengthen the archOriginally Posted by El Salsero Gringo
this was designed out of the arch as expertise grew
but in a flat arch (which is what we are discussing here) the key stone is not present, and the principle of remaining in compression is removed by the join in the middle - we are discussing a collapse here!!
a voussoir is another name for a brick
a guaged voussoir is a shaped brick designed for an arch to keep the mortar joints a constant thickness, the builders of old would 'rub' the bricks to create the correct shape
peter
sorry I do not have any books to refer to so can't include pictures
Erm, because I'm (almost) never wrong?Originally Posted by Andy McGregor
Really ...Originally Posted by ESG
Originally Posted by Lounge Lizard about ESG's post
what is not quite right AndyOriginally Posted by Andy McGregor
peter
It does seem rather too flat at the top for its own good, doesn't it? And the "knitting" along the top seam doesn't look like it would take any serious load in bending to hold the arch up.Originally Posted by Lounge Lizard
So your first three hinge points are the centre joint and the two places where the slabs sit on the foundations. Then they added a load of weight on top, the thrust line wandered out of the material of the arch, which developed some serious tensions in it's underneath surface, leading to cracking and the development of another hinge point (or two) causing the arch to collapse.
Maybe they did something silly like build the foundations a wee bit too far apart?
hehehehe
I'd love to know what the report of the enquiry says.
Edited to add:
here's an interesting technical article on the cause of the collapse, from the New Civil Engineer website.
Last edited by El Salsero Gringo; 9th-July-2005 at 07:08 PM.
Before I read the report - I figured out why the arch has to be so flat. Whilst the infill is being deposited virtually all of the force will be directed laterally inwards, and the tunnel has to withstand that. It seems very important that the construction is carefully controlled and monitored to ensure that the filling process does not place undue stress on the concrete. Now to read it ...
There are currently 1 users browsing this thread. (0 members and 1 guests)
Bookmarks