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500 Crawford: Multifamily At 500 Crawford St.


lockmat

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  • 2 weeks later...

Not sure if someone has mentioned this, but it seems they're focusing on the south side of the garage first so that they can start leasing more quickly than if they did both sides at the same time. Dirt is the only thing on the north side so far.

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Not sure if someone has mentioned this, but it seems they're focusing on the south side of the garage first so that they can start leasing more quickly than if they did both sides at the same time. Dirt is the only thing on the north side so far.

 

Yeah I noticed that as well. Makes sense too because that's the side which will get the most foot traffic.

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  • 3 weeks later...
  • 2 weeks later...

LOL. See those DOKA shoring posts in the foreground on your second photo? Those are Floor prop Euro Tops by DOKA. We use them on some projects. See the flange mid-height with the bolt keeping them together? 

 

Theyve stacked the shoring posts to reach the elevation they wanted.

 

Big no no. In fact, really dumb. 

 

http://www.doka.com/_ext/downloads/downloadcenter/999801702_2010_09_online.pdf

 

Page 10 of the technical data sheet:

 

 

Do not attempt to use floor props

one on top of another.

 

 

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And just to add, Buckling force of a beam/column thats axially loaded is a function of the length Squared. So by stacking their shoring posts like so, they effectively doubled the length, and reduced the buckling force by a factor of 4. So, according to their technical data sheet, the capacity is 40 KN, which, in Imperial is 9000 lbf (or 9 kip shoring post). By doubling the height of the shoring post--- they basically turned it into 2000- 2500 lbf shoring post: Assuming it as sufficient lateral stability to maintain that load. Of course Doka wouldnt sign off that...

 

 

Who the hell signed off on that?    :lol:

 

 

 

 

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alright, picture your typical grade school ruler. 

 

I have a 6'', a 12'' and then a yard stick(36 inch).

 

 

Imagine it has a rectangular cross section.

 

 

Imagine for a moment you place each end of the ruler into the palm of your left and right hand and pressed together. At 36'' that ruler starts to bend outward (or inward) --- That is buckling. 

 

Buckling force(in general mechanics of materials: more on this later) is equal to  pi*E*I/(KL)2. Buckling force is the force it takes for the 'column' to start deflecting laterally. 

 

PI of course is 3.14

E is known as Young Modulus, which is a measurement of the stiffness of a uniform elastic material. The values of wood are based on the species and vary a decent amount. For steel and Aluminum there are tables providing these values.

I is known the second moment of area, or moment of inertia. Which is based on the cross sectional shape of the object in question. This value can either be derived with calculus, or for simpler shapes (like rectangles or circles), looked up in tables. 

K is a constant value. That changes based on how the column is supported. I won't go into each value, but for simplicity sake, its 1.0 

L is the value of non-Braced Length. So in each case the value is 6, 12, and 36.

 

Okay, now since all 3 rulers are the same species of wood. Same cross sectional area. Same bracing method. The only thing that is different in each of them is L.

 

6 Inch

 

Buckling Force= piEI/36in2

12 inch


Buckling Force= piEI/144in2

36 inch

 

Buckling Force= piEI/1296in2

 

Lets say Mr Bigfoot works out in the gym and presses the ends of the 6'' ruler together with 150 lbs of force and snaps the 6'' ruler. It does a number on your hand though... and cuts your palm. To do the same with the 36 inch ruler... you need 4.1 lbs of force to break the yard stick assuming same material and cross section. 

 

Now, I indicated before in general mechanics of materials. That equation only  works off of the ideal assumption that the geometry is the same throughout. These guys doubled the length of their "ruler" or shoring post. And theyre banking on that little dinky bolt in the middle to resist all the stress of the lateral deflection. Shoring posts are designed many times so that negligible deflection occurs. These guys stacked the shoring posts, increased the likelyhood of deflection occuring: bad new

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