Steel-Reinforced Concrete Coupling Beams. II: Modeling

Abstract

Using test results presented in previous studies, design and modeling recommendations for steel-reinforced concrete (SRC) coupling beams are provided for both code-based (prescriptive) design approaches and performance-based design approaches. Procedures for computing both nominal and expected (upper bound) moment and shear strengths are described. For embedment, a capacity design approach is recommended in which the provided embedment strength exceeds the expected beam strength. Two approaches are recommended for determination of effective stiffness, one based on using a rigid beam (for flexure and shear) along with an interface rotational spring, since test results from the literature indicate that the majority of the coupling-beam deformations were associated with interface slip/extension, and an alternative approach where the effective stiffness is based on the beam aspect ratio or beam length. Additional parameters are provided to define deformation capacity at significant strength loss (to complete the backbone relations) and to address cyclic degradation.