NCEER-91-0018 | 2/28/1991 | 180 pages
TOC: The table of contents is provided.
Keywords: Shaking Table Tests, Lightly Reinforced Structures, Joint Confinement, Gravity Load Design, Beam Reinforcement, Reinforced Concrete Structures, Failure Mechanisms, Existing Buildings, Reinforcement Ratios, Column Lap Splices, and P Delta Effect.
Abstract: A 1/8 scale 3-story one-bay by three-bay office building was tested on the Cornell shake table. The structure was designed solely for gravity loads without regard to any kind of lateral loads. Reinforcement details were based on typical reinforced concrete frame structures constructed in the Central and Eastern United States since the early 1900's, and characterized by (a) lower reinforcement ratio in the columns, (b) discontinuous positive moment beam reinforcement at the columns, (c) little or no joint confinement, and (d) lap splices located immediately above the floor level. The model was tested using the time-compressed Taft 1952 S69E at different amplitudes. Auxiliary static loading and free-vibration tests were performed before and after each seismic test. Results indicate this type of building will experience very large deformations associated with a considerable stiffness degradation during a moderate earthquake. A significant P- effect was recorded due to the high flexibility of lightly reinforced concrete structures. It was found that reinforcement details are not enough to cause a complete failure mechanism. Lack of joint confinement was the primary source of damage. The location and details of the column lap splices did not cause a serious problem. Both experimental and analytical results indicated that the inclusion of the slab contributions to the beam flexural strength is a vital step in the assessment of the performance of lightly reinforced concrete structures during earthquakes.