ELSEVIER I. Conswct. Steel Res. Vol. 46, Nos. I-3, pp. 247-249, paper number 138, 1998 01998 Elsevier Science Ltd. All rights reserved Printed in Great Britain PII: s0143-974x(9@00125-9 0143-974X/98 $19.00 + 0.00 Modelling of Steel-Concrete Composite Joints N.E. Shanmugam, C.H. Yu, J.Y. Richard Liew and TH Teo Department of Civil Engineering, National University of Singapore, 10, Kent Ridge Crescent, Singapore 119260 Paper Number 138 Full paper on enclosed CD-ROM With the introduction of “ semi-rigidity” for joint design in frames, composite joints have become of particular interest. A small amount of reinforcement in the slab near the column may provide the joint with a remarkable degree of continuity. Therefore, a significant increase in stiffness and strength can be achieved by a very low additional cost. Recent research findings have provided more insight into the behaviour of composite joints, and analytical models for design of such joints have been proposed by several researchers (Anderson and Najafi, 1994; Xiao et al., 1996; Li et al., 1996; Wang, 1996). The object of this paper is to report the results from experimental studies (Teo et al., 1997) that have been carried out on composite connections in which effects of reinforcement ratio and concrete confinement at the junction of composite beam and composite column have been considered. Connection behaviour in respect of moment capacity, rotation capacity, rotational stiffness and ductility has been studied and the results are used to verify the existing analytical mod- els. Six specimens of steel-concrete composite joints were tested to failure and all specimens were of cruciform arrangement. Two 305 x 165 x UB54 sections of 1.6 m long and one 203 x 203 x UC46 section were connected to form the cruciform arrangement. The beams were connected to the column flanges by means of flush end plates and two rows of M20 Grade 8.8 bolts. The depth of the concrete slab was 120 mm and the width was taken as 1.5 m, seven times the column width. The slab reinforcement ratio in the case of SCCB 1, SCCB2, SCCB3 was chosen as 0.5%, 1.12% and 1.56%, respectively. Col- umns for these specimens were stiffened with transverse stiffeners at the level of the bottom beam flange. The number of shear connectors was also varied for the three specimens and full composite action was assumed to minimise longitudinal splitting and slippage between the concrete slab and steel beams. Two concentrated loads of the same magnitude were applied symmetrically at the free end of the cantilever at 1.5 m from the column flange and the 247