Calculation of the weighting factors in Equation (17) obviously requires the knowledge ofmember forces. At this point in the procedure, member forces are not known; however, aswill be shown later (Equation (32)), forces are distributed among columns of equal diameterin proportion to their secant stiffness to maximum response, which simpli=es to the inverseof the column length. The weighting factor, Q, then reduces to the following equation, whichrepresents the column drift ratio: