Our resident expert, Cliff Billington is here to answer your burning questions about techniques and correct practices within the concrete industry.
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Cliff is here to help you with your construction conundrums, your precast problems and your building brain-teasers. 
Submit any questions you have, and we’ll do our utmost to get them answered as soon as possible!

Cliff,

Is it in a Code that you should not take friction into account?
I am tempted to use friction to resist wind or NHL forces in Crosswall construction.
Giles Atkinson

 

Giles,

I am not aware of any Code or Standard that says that you cannot take friction into account. However, the problem with doing so is that the actual coefficient of friction is itself very variable. Typically for example, the coefficient for concrete to concrete is about 0.8. However, this would be reduced by 20% in wet conditions.

For any other changes in the interface condition, further variations could apply. For any design, it is essential that assumptions can be relied on, with appropriate factors of safety, and not be subject to too many unknowns.

The most common way of transferring horizontal loads in precast cross wall construction is via proprietary systems such as wire rope loops, wall shoes etc.

  
 

 

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