The connection design should consider the possible limit states of pull-over, pull-out and tension failure of the connector. These potential limit states are addressed by AISI S100.

The flange bending, however, requires engineering judgment. The bending of the flange theoretically may be evaluated using yield line theory. In the absence of a rigorous yield line evaluation, designers can employ a method based on the cantilever beam analogy.

Method No. 1

This method has been used in the metal building industry for hanging loads off of a purlin flange. The allowable load determined by using the cantilever beam analogy (Fig. 1) assumes elastic behavior as follows:

M_n = S_xF_y = (bt² /6) F_y
M = P_n e
P_n = (bt² /6e) F_y
P = P_n/Ω

where e = distance from load application to the web centerline, b = 2e, F_y = yield stress, t = base steel thickness and Ω = 2.0 (AISI S100, Section A1.2)

However, one could assume the development of the plastic moment, thus using the plastic section modulus in lieu of the elastic modulus. Therefore, when using the plastic section modulus, S_x = bt²/4.

Fig. 1 — Using the cantilever beam analogy.

Method No. 2

The provisions of AISI S240, Section B3.2.5.2.2, Deflection Track Connection for C-Section Studs, are based on a cantilever beam analogy. Thus, one may consider using Eq. B3.2.5.2.-1 (Fig. 2) to determine the load capacity of the flange.

 

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