The Stability Of Purlin Supported By The Steel Sheet And Brace

The steel structure component, usually designed to large span, is easily to bucking, when bearing bending moment and axial force. And the properly layout of the brace can improve the stability and decrease the effect length factor. This paper report on the torsional restraints the steel sheet exerts on the purlin, together with the lateral spring support supplied by the brace. It include the following contents:First:the critical load of the singly symmetric I cross-section component supported by continuous lateral spring stiffness k, subjected to the pure bending moment and uniformly distributed load.Second: the connection of the purlin to the steel sheeting either through self-drilled nails or through specially designed splints. In both way,The steel sheets exert torsional restraints on purlins. This paper compares the performance of the two conncetion above and shows which connection is better in avoiding bucking, aslo it gives out the effective length factor of the purlin under this situation.Three:the threshold stiffness of the lateral brace to the singal span purlin. the stability analysis of the purlin when it is support by the torsion constraints and lateral brace.Four: if the free flange of a purlin is in compression due to negative moment, we consider the feluxral-torsional bucking model of the purlin into a compression member subject to a non-uniform axial force, with a continuous lateral support of stiffness k to see it's flexural bucking load, and compare the critical laod to the flexural-torsional bucking load we mention before.