Title:
Behavior of
Cold Formed C Section Roof Purlins with Laterally Supported Tension Flange
: Experimental Study
Author: Abd El-Wahab El-Saadany
Collection: M.Sc. Structural
Abstract:
Designing
purl ins for roof systems attached to through-fastened panels has been a
subject well researched in the past. The AISI and AS/NZS specifications are
using a simplified approach to the design of these members where the fully
braced moment capacity of such members is multiplied by a reduction factor
(R-value) in cases of braced tension flange. This value represents the point in
between of the fully braced and fully unbraced member behavior. There was a big
difference between the two provisions in conditions of the R-value. The R-value
changes depending mainly on section depth in AISI. However, the AS/NZS
provisions depend on number of points that laterally braced for R-value
determination. Design of purlins that have laterally braced tension flanges as
laterally unsupported is very conservative. Since the Egyptian code had no
specifications for the design of such cases, the experimental investigation was
conducted in collaboration with Mancrew and Alex Steel to determine the R-value
and compare the results with the values of AISI and AS/NZS. The test setup was
as similar as possible to the previous R- value tests. Since AISI S 100 and
AS/NZS 4600 has limitations to the design equation, comparisons were done
between the test setup and the equation limitations. Based on the findings of
this test program, the R-value was closer to AS/NZS provisions. For C-purlins,
the R-value found to be 0.71 for depth d:S 6.5 in (165mm) and for 6.5in (165mm)
< d:S 8.5in (216mm) was 0.702. No significant change happened when deeper
section was used.
ليست هناك تعليقات:
إرسال تعليق