Tilt Up Panel 3

[PowerRanger]

Hi fellows

I am just designing some tilt up panels, around 7m high. Just want to ask is there any limitation from the panel size? what does the design dimension depend on? The one I know is depending on the crane capacity. Also, is there any information about the lifting position? I am going to use the edge lifting method, two anchores will be use, any infomation about the spacing to the edge, anchor's maximum spacing, etc.

Thank you for you help.


PowerRanger

 

[UcfSE]

On the design side there is no explicit limitation on panel size in the code but if you want to use the approximate analysis methods in the ACI 318 the slenderness ratio (kl/r) must be less than 100 as stated in 10.11.5. Above that limit you must perform a second-order analysis taking everything into consideration as listed in 10.10.1 I believe. Of course crane capacity may limit sizes as well.

 

[JAE]

We usually limit the thickness to be at least (panel height) / 50

 

[JedClampett]

Everyone I've ever talked to about tilt-up design says to limit the panel weight to 40 tons. That's the limit most contractors like to deal with.
To get your sizes, the thickness is determined by the vertical span as stated above. The height is the height and the width is determined by limiting the weight.

 

[LPPE]

Also look at stresses in the panel at the lift points. The stress on the panel will probably be different when the crane picks it up as to when its part of the wall and seeing wind/gravity loads. It would be a bummer to design a panel that works well in place, only to see it split to pieces when the crane picks it 1 foot off the ground.

 

[PowerRanger]

Actually i want to ask, is there any limitation of the spacing between the lifting point. For example, two edge lifting point, what is the min. and max. spceing to the end of the wall, and to each other. Also, If i want to consider it as a one way slab when lifting up from the ground, should I need to design more Reo at the lifing edge side to create a strong band?

 

[haynewp]

When I used to design lift points, I would try to balance the moments in the cantilevered part and the span between the lift points.

There is a guide to tilt up lift construction that is small and not that expensive. I thought it was by Hugh Brooks but I am having trouble finding in online. I used to use this reference for lift points. You will still need to calculate the cracking moment and I would make sure you don't exceed this anywhere in the panel. I would not won't to bust the panel during lifting and have somebody calling me about it from the field.

I will try to look some more for you for this book, I don't have it. But it is important to not exceed the cracking moment.

 

[JedClampett]

PowerRanger, don't complicate your life. The manufacturer's of the lifting hardware will design the lift points. Just call out in your specifications that the lift points and rigging to be by the contractor.

 

[AggieYank]

I agree with Jed. We design the tilt up walls for being in place. We state on our specifications that lifting points, and steel reinforcement required for lifting are to be provided by another engineer. Its my understanding that the tilt up wall hardware providers have engineers on hand who deal with this stuff all the time.

 

[blake989]

The manufacturer of the lifting device will provide the information you need for your conditions, check with a company named Meadow-Burke. To locate them, first look at stresses in the panel, then access during the lift until it is in place, then watch your spacing for rigging, there are certain angles between the lifting lines you can not be less than (i.e. the lines cannot be too flat).

AggieYank, how do you guys and the other engineers cooridinate your reinforcing drawings? Does that method work out O.K.?