| Connections between gravity framing (non-participating in resisting seismic forces) and the lateral force-resisting system need to he considered in building design. Studies of seismic behavior of the non-planar wall-to-beam joints are limited in literature. Furthermore, ACI 318 provisions with regard to seismic detailing of these joints are incomprehensive. The common practice is to provide a concealed column and/or a concealed beam where a gravity beam frames into the web of a structural wall. This research has a twofold objective. First, it is meant to assess the performance of these joints. Second, it will assess the impact of concealed columns on the overall performance of these joint. To accomplish these objectives, three half-scale reinforced concrete interior beam-wall joint specimens were tested under quasi-static cyclic loading. All test specimens had the same level of axial load, 0.2 Agƒ'c . The walls were designed to satisfy ACI 318 seismic provisions for structural walls loaded in the in-plane direction. The beams were designed as gravity members based on ACI 318-11 provisions. Test results show that failure in the form of punching or a combination of punching and flexure in the wall web is likely which could lead to a brittle behavior. Joint shear failure is unlikely. Due to the relative flexibility of the wall web and bar slip within the wall web, energy dissipation capacity is limited. Due to lack of anchorage within the wall web, slip cracks are likely to form at the beam-to-wall interface. The test results also indicate that the concealed column approximately doubled the plastic capacity of the specimens but did not appreciably affect the initial stiffness. Furthermore, the specimens with concealed columns exhibited a modest improvement in lateral strength and energy dissipation capacity. |
