Pull-Out Strength of Screws in Screw Chases: Part 1

Abstract:

This paper presents test results and a proposed pull-out strength equation for tension-loaded screws installed in chases in extruded aluminum profiles. The screws are perpendicular to the extrusion's length. This connection is commonly used to resist outward wind load on glass in curtain walls and skylights. Two types of chase, each with 1/4 in. (6.35 mm) diameter 300 series stainless steel screws were used: a flat chase with AB tapping screws (1/4-14; 14 threads per 25.4 mm) and F tapping screws (1/4-20; 20 threads per 25.4 mm), and a longitudinally ribbed chase with UNC-thread machine screws (1/4-20). The extrusions included six cross-section shapes (three with flat chases and three with ribbed chases) and three alloy-tempers. Pull-out tests of 150 single screws were conducted. The Aluminum Design Manual [1] does not include pull-out strength equations for screws in chases; this research was intended to develop such equations. Pull-out strength increased with an increase in engaged length of screw threads with the chase. The shape and dimensions of the chase also affected the pull-out strength.

• Periodical: Key Engineering Materials (Volume 710)
• Pages: 115-120
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.710.115
• Online since: September 2016
• Authors: James C. LaBelle*, J. Randolph Kissell, Tanya A. Dolby
• Keywords: Pull-Out, Ribbed, Screw, Screw Chase, Tapping

References

[1] Aluminum Association, Aluminum Design Manual 2015, Arlington, VA, (2015).

[2] ASTM International, B557-10, Standard Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products.

DOI: 10.1520/b0557-94