“Computational Civil Engineering - "Intersections" International Journal

“Computational Civil Engineering 2005”, International Symposium 207The beam-to-column connections considerate in the portal design arecorresponding as rigid by full welding, pinned by angles web cleats and as semirigidby top and seat angles or flush end plate. For demonstrative purposes, thestiffness for the semi-rigid connection is related to the beam stiffness as 4EI b /L b inwhich, I b is the beam moment of inertia and L b is the beam length.The moment diagrams for the three assumed beam connection types are presentedin Fig. 4.a., for the references model and in Fig. 4.b for the proposed program.127.5152.6 127.5152.6260.0260.052.2Kb =8Kc =887.193.6 113.8 93.6552.2Kb =8Kc =887.1113.8296.3296.331.7Kb = 4EIb/LbKc =871.531.679Kb = 4EIb/LbKc =871.530Kb = 0 Kc =296.3830296.330 30Kb = 0 Kc =a. b.8Figure 4.Bending moments in a portal (kNm).It can be seen that the bending moment for the members are very much influencedby the connection details.Practically, the beam-to column connections and the column-to-foundationsconnections have finite stiffness.An other example studied with the same program, consist in an elastic analysis of amulti-storey unbraced steel frame.The six storey frame with rigid joints has been proposed by Vogel (1985) ascalibration example for checking the accuracy of an ultimate strength analysis.Theframe has a total height of 22.5 meters and the width is 12 meters. No bracing isprovided to the frame. Frame elements are realized by European profiles, shown inFig.5. This frame was analysed for two types of beam-to-column connections.