Non Metal Materials in Steel Connections 2

[Bagman2524]

I believe there is a section in the AISC manual that prohibits non steel materials from being used in steel connections. Anyone know where in the AISC manual that is located? Thanks

All I know is P/A and Mc/I

 

[dik]

Don't know... I've often used a Fabreeka product to reduce thermal transfer. I suspect it depends on the materials.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[dauwerda]

I believe it is only addressed in the RCSC commentary, here are the applicable excerpts:

The presence of gaskets, insulation, or any compressible materials other than
the specified coatings within the grip will preclude the development and/
or retention of the installed pretensions in the bolts, when required. See the
Commentary to Section 1.1.

This Specification covers the design of bolted joints with collateral materials in
the grip that are made of steel. These provisions do not apply when materials
other than steel are included in the grip. These provisions are not applicable to
anchor rods.
Recently, other types of joints that contain low-modulus materials in the grip,
and most notably thermal break joints, have made an entrance in the market and
questions on their use, chiefly for components, such as cladding, awnings, and
roof posts, that are not part of a primary load-resisting system, have come forward.
Thermal break joints are not intended for primary load resisting systems.
Several research projects have been conducted (Peterman et al., 2017; Peterman
et al., 2020; Hamel and White, 2016) investigating the structural properties of
thermal break joints showing that the presence within the grip of compressible
gaskets, insulation, or other materials or coatings will preclude the development
and/or retention of the installation pretension in the bolts.
Peterman et al. show that low-modulus materials are permissible in snugtightened
joints with bolts subject to shear when long-term loads are limited
to 30% of the low-modulus materials’ ultimate load. Low-modulus materials
that showed acceptable behavior in that study had through-thickness modulus
of elasticity between 400 ksi and 800 ksi and through-thickness compressive
strength between 25 ksi and 65 ksi.
Additionally, with the presence of compressible materials in the grip, the snugtightening
operation will not generate a sufficient force in the bolt to deform
the shank so that the head and/or the nut adapt to the slope of the surfaces
under them. Therefore, only surfaces that are near-perpendicular to the bolt axis
should be used in thermal break joints.
Based on the results in the literature, the Engineer of Record should consider, as
a minimum, the following aspects of a thermal break joint:
• The stiffness and strength of the inserted layers and their influence on the
intended performance of the joint;
• The maximum bolt tension that the layers in the grip can withstand without
losing integrity or performance;
• The installation instructions to prevent overtightening of bolts;
• The effects of the thickness of the added plies on the stiffness and strength of
the bolting assembly and of the connection as a whole;
• The resistance to exposure of the added plies, when applicable;
• The type of forces that the joint is intended to transfer (e.g., shear, shear and
tension, compression, tension without fatigue);
• The long-term behavior of the inserted layers; and
• The electro-chemical interactions of the inserted layers with coatings on steel,
if applicable.

 

[Bagman2524]

Thanks dauwerda. RCSC section 3.1 is what I was looking for.

All I know is P/A and Mc/I

 

[dauwerda]

Happy I could help!