NOVEL DESIGN ALGORITHMS FOR K-FACTOR CALCULATION AND BEAM-COLUMN SELECTION

Existing methods for calculating the LRFD design nomograph for an effective length K factor utilize iterative algorithms such as the method of bisection. This paper presents a novel algorithm that computes the K factor with no iterations. This algorithm computes an approximate K factor, which is often within 2% of the true nomograph value of K. The initial section selection method offered in the LRFD Manual is primarily a hand-calculation technique relying on the engineer's intuition for selection trial sections. A computer-based algorithm is developed herein for the initial beam-column section selection using the LRFD strength criteria (the beam-column interaction equation). An example problem presents typical preliminary member sizes for girders and beam-columns using these techniques. The computer program DFRAME, which uses these methods, is briefly described and is implemented in C++, an object-oriented language, using Digital Equipment and Sun workstations.