ضريب طول موثر ستون هاي مقطع متغير در قاب هاي شيب دار تك دهانه ي آزاد در برابر حركت جانبي و با تكيه گاه هاي مفصلي

COEFFICIENT OF EFFECTIVE LENGTH OF TAPERED COLUMNS IN ONE-BAY GABLED FRAMES FOR STATE OF FREE TO SWAY WITH HINGED BASES

One of the most important design parameters of columns is their effective length in buckling. In the past , because of lack of analytical solntion for differential equation of deformation of a tape red column, determination of its effective length was don e by num erical methods which rcslllt in approx imate solut ions. In recent years , due to development of very powerful mathematical softwares, one can obtain analytical solution of equation of deformation and accurately find the coefficient of effective length. It will also facilitate to evalua te the values of errors of the past methods. The st ructure considered in this research is a one- bay gabled frame with tapered members tha t are solved for state of free to sway with hing ed bases. In this research by eqnating the external work 0 11 the structure with its internal flexural strain euorgy of buckling, and imposing th e boundary condit ions and compatibility conditions, an equation is found from which the critical load of th e structure and accordingly the coefficient of effective length of its columns is obtained. After a nalysis and obtain of precise graphs , that are more simple to use than graphs of AISC code of practice, the results are compared to the results of previous approximate methods .