RE: Tilt panels

[GB1000]

Hi, Apologies if this has been asked.

In relation australia tilt panel construction, I'm trying to find out what is the minimum reinforcement to use, there are a lot of companies which specify SL92 (292mm2) on a 150thk panel. however when I checked according to AS3600, the absolute minimum for 150thk wall is 375mm2 in the secondary direction. does anyone know anything different? Or do engineers just use a lower value out of risk?

 

[Agent666]

Not 100% familiar with Australian standards any more (from NZ), but whats your calculation governed by, min temp and shrinkage reinforcement? I don't believe you can reduce that. Pretty sure older versions of AS3600 had provisions that allowed reduction of min flexural reinforcement if you had 1/3 greater capacity than required and these companies may have been using these type of provisions to justify a lower degree of reinforcement in the secondary direction. There are also crack control reinforcement requirements which should also be assessed as often these have a min reinforcement at min spacing requirements.

T+S is all I'd provide in NZ unless there was bending in the secondary direction or restraint (if connected rigidly to a foundation or something where differential shrinkage might cause cracking), or if the panel required a higher level of reinforcement to resist shear. Though we don't see many companies using mesh, loose bars are preferred over here, so you get DH12-300 min most of the time as a practical minimum (376mm^2/m) which matches your value (great minds think alike...)...

 

[Retrograde]

You should get a copy of the Concrete Institute of Australia publication "Guide to Tilt-up Design and Construction".

"The requirement for minimum reinforcement to be provided to develop the modulus of rupture must be complied with"