NEW RESEARCH PRODUCT: RGA #06-19 Nonlinear Wind Design of Steel Reinforced Concrete (SRC) Coupling Beams: Design Recommendations
Abstract
Structures are typically designed to yield and sustain damage in a controlled manner during design- level earthquakes. While a similar approach has traditionally not been used for design-level windstorms, the recently-published ASCE/SEI Prestandard for Performance Based Wind Design (ASEC/SEI, 2019) describes design for modest nonlinear response of select structural members such as coupling beams. In this study, four steel reinforced concrete (SRC) coupling beams, with steel sections that embedded into a reinforced concrete wall, were tested quasi-statically under fully reversed cyclic wind demands with peak beam deformation of three times the yield rotation. The beams and walls were designed in accordance with seismic provisions in AISC 341-22 Section H5, and the walls were compliant with ACI 318-19 Section 18.10.6.5. The exception was the wall reinforcement for two of the four tests, in order to examine potential reductions to that prescribed. For one of these tests, the ratio of the strength of wall longitudinal reinforcement crossing the embedment length to that prescribed was 0.53. For the other of these tests, this value was 0.22 and the wall boundary transverse reinforcement at the embedment zone was also less than that prescribed. During each test, the wall was subjected to constant axial gravity load and fully reversed-cyclic lateral loading that was linearly proportional to the load in the test beam. The ratio of wall shear to beam shear was constant for the four tests, while the wall moment at the height of the coupling beam produced by the applied wall demands was the same for three tests and was larger by a factor of 2.0 for one of the tests with wall reinforcement compliant with AISC 341-22 Section H5.