Tilt-Up Wall Design 1

[oengineer]

I have been assigned the task of designing a Tilt-Up Wall. I am familiar with reinforced concrete design, but this is my first time performing a Tilt-Up Wall design. This wall will just be for one side of a building. The rest of the entire building is Pre-Engineered Metal Building. What are the necessary thing to consider? What design aides and/or books are available? Any comments and suggestions are appreciated.

 

[oengineer]

So far, I am just aware of Engineering Tilt-Up book & ACI 551 R-92(Reapproved 1997, 2003)TILT-UP CONCRETE STRUCTURES.

 

[JAE]

We usually would start with a minimum wall thickness based on H/50 as a start.
If the wall is insulated then you have two ways to go - the two laminations of concrete work compositely using specialized ties, or, you have one lamination that is the structural concrete portion, taking all the load, and the outer lam is simply a concrete veneer - again tied back to the interior lam but not intended to act compositely.

With openings - you have to ensure you transfer both gravity and lateral forces around the openings.

Also be sure to consider second order effects for thin walls - utilizing cracked or partially cracked section properties in your design.

Some engineers simply design the as-built conditions and leave the actual shop drawing, detailing to others including design checks for the wall panels under lifting conditions (i.e. additional rebar required for lifting stresses).

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[KootK]

Link
Link

NZ and UK both have their own industry publications too.

I have this and highly recommend it it you can find it for a reasonable price: Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

This is excellent (and free). It's geared towards precast/prestressed but some of the theory and concerns are pertinent to tilt-up.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[msquared48]

JAE is correct.

Additionally, remember that some tilt-up walls have architectural reveals that can affect the structural depth of the wall you can use to design the reinforcing.

Mike McCann, PE, SE (WA)

 

[oengineer]

Is it worth it to purchase the Engineering Tilt-Up book:

http://www.tilt-up.org/resources/engineering_tiltup.php

?

 

[BadgerPE]

I would also suggest starting a discussion with a local tilt-up contractor. I learned a lot of what I know about tilt-up from the contractor I work with. Things like panel size, typical reinforcing, lifting design responsibility, etc. are all things that would be good to discuss with the contractor. Hopefully they have one on the project already and then it will be easy to get the needed information.

 

[spats]

oengineer... I suggest that you check out the Tilt-up Concrete Association website

http://www.tilt-up.org

for guidance. The ACI 551 committee document that you reference is way out of date. The current document is ACI 551.2R-15 "Design Guide for Tilt-Up Concrete Panels". The primary design basis for this document is Section 14.8 "Alternative design of slender walls" of the ACI 318-11 Code. ACI 551.2R-15 is the document I use to design tilt-up. There is also a variety of software available. Google it.

 

[hokie66]

All good advice. But it sounds like, for oengineer's building, this is just a precast wall leaning on a steel building. The wall, whether site cast or not, will probably be placed after the steel is erected.

 

[spats]

hokie... trying to understand the point you're making. The OP called it tilt-up (site cast). Precast or tilt-up makes no difference, except for fitting the panels on a truck if it's not site cast. It's still a slender element that needs to be designed for p-delta effects, whether it's load bearing or not. If not load-bearing, there are still p-delta effects from self weight,although the effects are fairly small. By the way, I am currently working on a project with a metal building and load-bearing tilt-up.

 

[hokie66]

I was just trying to make the point, apparently unsuccessfully, that sequence/methods of construction need to be considered in the design stage.

 

[oengineer]

Thank you all for your input.

@spats- The Engineering Tilt-Up book I referenced is from this website. I ask if it is worth purchasing because it's not cheap, but I will buy it if it is very useful for this type of design. The ACI 551 R-92(Reapproved 1997, 2003)TILT-UP CONCRETE STRUCTURES is what I found when I looked on Google. I will continue to look on Google for ACI 551.2R-15 "Design Guide for Tilt-Up Concrete Panels".

 

[spats]

oengineer... I'm not familiar with the Engineering Tilt-Up book, so I can't judge one way or another. It is available at the tilt-up.org website. it's $255 for non-members, and $185 for members, so it's definitely not cheap. The Hugh Brooks publication that KootK recommended above is 20 years old, unless there is a newer version than the Fourth Edition, so I would not recommend it.

The ACI 551.2R-15 publication is available from the ACI store through the link below for $108.50 non member, $66 member, and is highly recommended. I am a member of the ACI 551 Committee. The calculations are quite tedious if done by hand, so if you have more than a few different designs to perform, I would definitely recommend purchasing software. There are several excel-based programs out there that are not very expensive.

https://www.concrete.org/store/productdetail.aspx?ItemID=551215&Format=DOWNLOAD&Language=English

 

[Budding_SE]

I created a spreadsheet a while back to design tilt walls with openings.
Check out the code and you would be able to figure out what its doing.
I still havent finished the wall without any openings completely and it breaks occasionally but this should be a good start.

 

[KootK]

Thanks for sharing that Budding_SE, it very generous of you to do so. I have need of such a tool and, at the least, will find yours useful in the development/checking of my own.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

Thanks as well. I have a handful of sound panel walls we need to lift similar to a tilt-up wall and this will be helpful in double checking my hand calcs.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

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