Importance of Cold-Formed Steel in Seismic-Resistant Design of Structures
Cold Formed Steel is a product made by rolling steel or pressing steel in to semi-finished or finished goods at relatively low temperatures. Manufacturing of Cold Formed Steel (CFS) occurs at room temperature. In present scenario the use of CFS system is significantly increasing in countries where traditional structural solutions have always dominated the construction sector. This is mainly due to the developing and increasing technical, structural and economic competitiveness of such systems. The advantages with CFS are lightness of systems, high quality of end products, flexibility due to wide variety of shapes and section dimensions, short execution time due to dry constructions and minimization of environmental impacts due to the possibility to reuse the elements at the end of the life cycle. This paper presents the importance of CFS in various structural elements to mitigate the damage cost to these elements during earthquakes. These elements are investigated for seismic resistance in multi storey moment frames, factors like premature local buckling and low out of plain stiffeners known as the main structural deficiencies of CFS with thin walled elements hence in structures with CFS as the main load bearing components there is less energy dissipation due the above mention deficiencies. Therefore in order to improve the energy dissipation of CFS, an innovative CFS beam with curved flange was developed. The main aim of beam was to produce plastic moment due to large width thickness ratios of thin walled elements of CFS section; development of plastic moment was avoided. To overcome these limitations, the CFS elements were introduced with flange bends in C section leading to a curved flange section. Also modification like flange lips, introducing intermediate flange stiffeners and increasing the number of flange bends results in increase in moment resistance, ductility capacity and initial stiffness. Steel sheeted CFS using gypsum board claddings with different configuration on shear walls and partition walls on either or both sides resulted in increased of lateral stiffeners; shear strength and energy dissipation capacity. Use of MLC (Modular Light weight Cold Form beams) are designed to prevent early buckling phenomena that could affect the structural behaviour when thin sheets are used also provide high resistance to torsional flexural buckling.