Practical design method for flexibly jointed frames with LRFD

To establish a practical design method for flexibly jointed frames as well as fully rigid frames based on the AISC-LRFD specification, a simplified method for the estimation of column design moments is proposed and its applicability is numerically discussed. In this paper, in order to convert a nonlinear connection stiffness into a linear one, the beam-line method is applied. Two connection stiffnesses are taken, one of which is a secant connection stiffness for first-order elastic analysis of frames, and the other is a tangent one for estimation of the column K-factor. The column end moments are estimated by using only BZ factor (P-Delta effect). Comparing the results with those obtained from the second-order elastic analysis for a flexibly jointed frame example, it can be shown that proposed simplified method gives reasonable values and will be useful for a practical frame design.