Christopher J. Motter

Steel-Reinforced Concrete Coupling Beams. II: Modeling

AbstractUsing 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 c...

Steel-Reinforced Concrete Coupling Beams. I: Testing

AbstractStructural steel-reinforced concrete (SRC) coupling beams are an alternative to conventional and diagonal rebar-reinforced concrete coupling beams. To address gaps in previous testing that was used to develop design recommendations, four large-scale, flexure-yielding, cantilever SRC coupling beams were embedded, without inclusion of auxiliary transfer bars and bearing plates, into reinforced concrete structural walls. Beams were tested by applying quasi-static, reversed-cyclic shear loading to the coupling beam, and moment and shear to the top of the wall to create cyclic tension and compression fields across the embedment region. The primary test variables were the structural steel section embedment length, beam span length (aspect ratio), quantities of wall boundary longitudinal and transverse reinforcement, and applied wall loading (moment, shear, and axial load). Favorable performance, characterized by minimal pinching and asymmetry in the load-deformation response and concentration of damage ...

Testing of 17 Identical Ductile Reinforced Concrete Beams with Various Loading Protocols and Boundary Conditions

A set of tests on 17 large-scale, nominally identical, beam specimens with variations in loading protocol, loading rate, and restraint to axial elongation are described. Three specimens were also repaired by epoxy injection following an initial damaging earthquake loading. This paper provides a detailed description of the test program, and the corresponding data are made available at Design-Safe (DOI: 10.17603/DS2SQ2K). While the primary goal of the test program was to improve the state of knowledge regarding the post-earthquake residual capacity of reinforced concrete plastic hinges in beams, the data are useful for modeling approaches that consider loading rate, plastic hinge elongation, cyclic degradation, and flexure–shear–axial interaction, in addition to investigating the effectiveness of post-earthquake repair techniques by epoxy injection of cracks.