35th progress report
I. SCOPE OF THIS REPORT This report contains the complete evaluation of test results of the I-beam tests reported on in the 33rd and 34th Beam Reports. In considering the results of this evaluation, two factors should be kept in mind which adversely affect the accuracy of results: (l) These beams were designed primarily to serve as control specimens for future channel tests. Their usefulness in verifying the equivalent width approach is somewhat impaired by the fact that the compression flanges represent only a rather small part of the total cross-sectional area. Thus, a moderate change of equivalent width of the top flange will affect the properties of the entire cross-section (moment of inertia, section modulus, position of neutral axis) only to a very small degree, Since it is these properties which govern the quantities measured in the tests (strains, deflections, ultimate loads), the accuracy of determining equivalent widths is much smaller than the experimental measuring accuracy. (2) As pointed out on 2.2 of the 34th Report, the values of the yield points of different specimens cut from the same steel showed very considerable variations. Therefore, evaluations based on the yield point are adversely affected by this variation of mechanical properties. Despite these inevitable limitations the evaluation of the results of these tests is of considerable value. Previous investigations of the equivalent width were confined to the range of b/t from about 50 up to about 200. the present investigation covers the range from b/t = 14 to 56 and therefore fills in a gap in the low range. To be sure, exact values in this range are not as important as in the high range, since for such small bIt the reduction of the actual to the equivalent width is rather small and therefore the design moments of inertia and section moduli are not appreciably different from those computed for the full width.
Civil, Architectural and Environmental Engineering
American Iron and Steel Institute
Wei-Wen Yu Center for Cold-Formed Steel Structures
01 Mar 1944
Cornell University School of Civil Engineering, "Cornell University School of Civil Engineering Tests on light beams of cold-formed steel" (1944). CCFSS Library (1939 - present). 216.