A steel-concrete composite solution for practical design of coupling beams

Coupled core wall (CCW) systems are attractive lateral systems for mid-to-high rise buildings where floor space is a premium. The types of reinforced concrete beams commonly used in these buildings pose major design as well as constructability challenges. This paper presents the design methodology and test results of a proposed steel-concrete composite beam that was developed with the intention of minimizing steel congestion over the clear span of the beam and the embedded regions while maintaining satisfactory strength, stiffness, and energy-dissipation characteristics. The proposed coupling beam consists of a vertical steel plate that is centrally located in the cross-section of a conventionally reinforced concrete coupling beam, and is embedded in the wall piers. To verify the design methodology, cyclic reversal testing of two half-scale subassemblies consisting of two wall piers connected by a coupling beam was conducted. This paper presents the measured strength, stiffness, energy dissipation, and rotation capacities of the proposed beam. It is shown that with proper detailing the proposed coupling beam performs well and represents a viable and practical alternative to the current practice.