Experimental Study And Direct Strength Method Design Of 550MPa High Strength Cold-Formed Steel Continuous Hat Section Purlins

This paper introduces experimental study on bearing capacity behavior of 550MPa high strength cold-formed steel continuous hat section purlins. This experiment included 24 continuous hat section purlins whose section thickness were t=0.48mm,t=0.60mm,t=0.75mm,t=1.00mm;Single spans were l=1200～3000mm; Section forms were TOPSPAN 40 and TOPSPAN 61. Those purlins' bearing capacity behavior was tested. Because of the complexity of the sections, it is difficult to use the design rules in our current specification to calculate the load carrying capacity. So this paper firstly uses the finite strip method software CUFSM and the new design method in cold-formed steel field—Direct Strength Method to solve the specimens' load carrying capacity. The result shows that using Direct Strength Method to calculate the 550MPa high strength cold-formed steel continuous hat section purlins' load carrying capacity is reasonable. The differences between the calculated values and experimental values are allowed.Based on the experiment, the finite element program ANSYS 9.0 is applied to carry out the finite element nonlinear analysis of the specimens. The result of the finite element program, the result of the Direct Strength Method and the result of the experiment are much close to each other. The differences are allowable. These phenomena further prove the viewpoint of this paper and validate the reliability of this experiment.Moreover, this paper uses Direct Strength Method to further discuss the different section shapes and the different number of spans to find the related modified formulas.