lateral-torsional buckling on storefronts

Regulations have changed so there is a need to design for the lateral-torsional buckling on storefronts now.   

Section 8.4.B.3.a of the ‘Aluminum Windos and Doors, and Glazing’ specifications states the following:

The AAMA standard dealing with storefront design is ‘AAMA SFM-1-87:  Aluminum Storefront and Entrance Manual’.

Engineering Section 6.0 (shown below) directs us to the current Aluminum Association’s Aluminum Design Manual (2010):

The Aluminum Design Manual, section F.2 (shown below), indicates that when framing members are subject to lateral buckling, the nominal flexural strength must consider the un-braced length of the framing in question:

We want you to have this information to give you a better understanding of why we are designing open shaped verticals mullions to prevent lateral-torsional buckling.   This increases the stability and life of the storefront wall installation providing a higher level of client satisfaction to the end user.