Civil Engineering Study 97-3
This Third Progress Report summarizes the web crippling tests of 148 specimens and evaluates the test results along with an additional 114 web crippling tests which were reported in 1986 as part of a project on Design of Automotive Structural Components Using High-Strength Sheet Steels. The 148 web crippling tests conducted in this program are the part of the overall project on Strength of Flexural Members Using the Structural Grade 80 of ASTM A653 Steel (former ASTM A446 Grade E Steel). The objectives of the ongoing project are to study the strength and structural performance of flexural members as affected by using the high-strength, low-ductility Structural Grade 80 Steel and to develop appropriate design criteria based on the test programs. Four loading conditions, namely End-One-Flange (EOF), Interior-One-Flange (IOF), End-Two-Flange (ETF), and Interior-Two-Flange (lTF) conditions, were considered in the web crippling tests in this program and in those reported in 1986. The web crippling test program for this study included 136 single-rib and double-rib specimens having a hat-shaped section and sloped webs and 12 single-rib specimens having a hat-shaped section and vertical webs. The previous 114 specimens reported in 1986 had a single-rib hat-shaped section with vertical webs. For the specimens tested in this program, the yield strength of the steel ranged from 103.9 to 112.5 ksi, h/t ratio from 25.99 to 208.19, R/t ratio from 2.16 to 5.51, N/t ratio from 34.48 to 88.24, N/h ratio from 0.22 to 2.02, thickness of steel sheet ranged from 0.017 to 0.029 inches, and the angle between the plane of the web and the plane of bearing surface ranged from 59.5 to 90 degrees. All specimens were loaded to failure. Both the web crippling tests in this program and those reported in 1986 indicated that the tested ultimate loads for the four loading conditions were higher than the predicted loads using the AISI Specification, and modified kC1 and kC3 factors (1.691 for kC1 when Fy exceeds 91.5 ksi and 1.34 for kC3 when Fy exceeds 66.5 ksi), for the yield strength of the steels exceeding 80 ksi. The ratio of the tested ultimate load to the calculated load tends to increase with increase in the yield strength of the steels beyond 80 ksi. Therefore, it is conservative to use the kC1 and kC3 factors in Section 3.4 of the current AISI Specification for predicting web crippling strength of structural members with yield strength exceeding 80 ksi. It appears that the low ductility of the Structural Grade 80 steel does not reduce the web crippling strength of the members made of such steels. As a result, new modified kC1 and kC3 factors were developed based on the 262 web crippling tests which included the following parameters: the yield strength Fy ranged from 58.2 ksi to 165.1 ksi, h/t ratio from 25.99 to 208.19, R/t ratio from 1.496 to 5.696, N/t ratio from 22.70 to 88.24, N/h ratio from 0.17 to 2.02, thickness of steel sheets ranged from 0.017 in. to 0.088 in., and the angle between the plane of the web and the plane of bearing surface ranged from 59.5 to 90 degrees. Reasonable agreement was found between the tested ultimate loads and the predicted loads using the newly modified kC1 and kC3 factors. It is also recommended that in order to simplify designs, the current kC1 in Section 3.4 of the AISI Specification can be used for all the IOF, ITF, EOF, and ETF loading conditions, resulting in a simple but conservative solution.
Civil, Architectural and Environmental Engineering
Wei-Wen Yu Center for Cold-Formed Steel Structures
American Iron and Steel Institute
Cold-Formed Steel Series
Missouri University of Science and Technology
© 1997 Missouri University of Science and Technology, All rights reserved.
Report - Technical
Wu, Shaojie; Yu, Wei-wen; and LaBoube, Roger A., "Strength of flexural members using structural grade 80 of A653 steel (web crippling tests)" (1997). Center for Cold-Formed Steel Structures Library. Paper 173.