Biaxial bending of cold-formed Z-beams

This paper reports the results of ten biaxial bending tests on unbraced, si mply supported, cold-formed steel Z-beams loaded at midspan in planes incli ned to the major principal plane. These results and those of six beams load ed in the major principal plane are compared with analytical predictions an d with simple design approximations. The tests show that the beam strengths decrease as the load inclination to the major principal plane increases, a nd that the strength is higher when the load inclination is toward the web than when it is toward the flange lip. Good agreement is demonstrated betwe en the test results and analytical predictions of the strengths. An extende d series of analytical predictions is used to develop simple interaction eq uations that can be used in the design of eccentrically loaded cold-formed Z-beams.