Optimum Design of C Section of Cold Formed Thin Walled Beam subjected to Pure Bending Using Genetic Algorithm

Cold formed steel (CFS) has many advantages over other construction materials. CFS members are lightweight. They weigh up to 30-35% less than their wood counterparts.. This makes CFS members economical and the same time very easy to erect and install. They may be shaped (cold-bent) to nearly any open cross section. This allows for the use of optimization technique’s to find optimal shapes for the members’ cross sections. The research aims to show the genetic algorithm's ability in determining the optimum dimensions cold formed C section. To do so, the optimum design mathematical formulation was formulated by adding the manufacturing constraints that reflect the section folding operations in addition the geometrical and structural constraints. The research found that the genetic algorithm is effective tool in finding the best solution to this issue, as it showed its ability to deal with asymmetric section through reaching solutions conform to the basic principles of mechanics of material. The algorithm is adjustable, so that it can implement the design restrictions which are compatible with any codes or any manufacturing requirements imposed by modulation techniques.

Behavior of Slipped Bolted Steel Frames Consisting of Cold-Formed Steel Sections under Cyclic Loading

After passing through the allowable stresses stage Cold Formed Steel Frames fail under instability secure, these frames are designed to resist loads in the elastic stage [7]. Many efforts are being made to increase their performance by using special bolted or welded connections [13], such as rigid connections or plastic connections, stiffened and built-up sections [1] could be used to increase the sections resistance. In rigid connections [11], stiffeners are added to insure the flexural behavior of these connections [10] while the plastic deformation occurs at the Horizontal Boundary Element (beam) and far from the face of the column, such as stiffened bolted Apex connection. In plastic connections, the cold formed steel frame will produce high ductility performance through the nonlinear behavior by reaching the maximum bearing capacity of the bolts. Depending on this principle we should insure the elastic behavior of the boundary elements, and avoid local buckling by using high strength cold formed profiles and slipping bolted connections, the rotation of this slotted connection in certain angle after reaching the bearing capacity, will act as a plastic hinge that absorbs the extra stresses which will affect the steel frame due to the lateral loads such as Cyclic forces