Simplified Computational Methods for the Second-Order Internal Force and Displacement of Semi-rigidly Connected Steel Frames

It is known that assuming connections to be either perfectly pinned or fixed joints for simplicity can cause considerable errors in frame analyses. The main objective of this paper is to present simplified hand computational methods for semi-rigidly connected steel frames, in which the second-order internal force and displacement are taken into consideration. The moment-enlarging method is used to analyze the internal force, which considers the influence of semi-rigid by multiplying the bending resistant stiffness of the beam and the modified stiffness factor together. D value method is also proposed for computing the displacement, which considers the influences of semi-rigid by the equivalent stiffness of the beam. One example is presented to indicate that the effect of semi-rigid connections must be considered fully in the computation of the semi-rigidly connected steel frames.