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# Temperature for interlayer stiffness

## Temperature for interlayer stiffness

(OP)
Now that Saflex have their DG41 PVB which is supposed to compete with SGP, the question has become, what temperature can we justify for composite action calculations? DG41 has a shear modulus of 46MPA at 30degC, and 0.66MPA at 50degC. This is a ~100X drop, and effectively renders the interlayer structurally useless at 50C, and full composite action at 30C. ASTM E1300 talks about 50C for equivalence to its tables, but technically does not require it for first principles calculations.

- Can 30 degC be justified for wind load calculations of vertical glazing?

### RE: Temperature for interlayer stiffness

Very late to the party again,

Depending on local climate patterns, and where on the building your glazing in question is,

In my locale, heavy wind is almost always accompanied by rainstorms, and at night - id venture to say 1/50 yr winds, where the glass is sitting above 30C is highly unlikely.

Not too familiar with Georgia or Florida,

Your probably always safe on the north side of the building, where the sun never shines.

Hope I was of help

### RE: Temperature for interlayer stiffness

(OP)
NorthCivil - better late than never!

Yes, I have heard people using the justification that if you have 85mph winds that the solar heat gain is going to be relatively minimal because of the convective heat loss.

DG41 is awesome, but just has this annoying heat sensitivity.

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