Response of an Existing Two-Storey RC Frame Designed for Gravity Loads: In Situ Pushover Tests and Numerical Analyses

Abstract

The purpose of the research was to study the response of existing constructions, designed for gravity loads only in the South of Italy, more precisely in the Sicily Region. The building is an existing two-story reinforced concrete structure, built in the 80s. In order to design the test, numerical study on the structure has been conducted, using information reported on original design drawings or derived by in situ geometric and material investigation. A number of numerical models and pushover analyses of the structure have been carried out, in order to account for the uncertainties related to possible different responses. The numerical analyses aimed at estimating the capacity of the structure in terms of both force and displacement, the ductility reserve, and the most likely sequence of formation of plastic hinges. The pseudo-static cyclic test was designed to push and pull the building in one direction at increasing displacement levels, up to a drift of about 2%. At the end of the test, the infill panels were completely collapsed. Beams, columns, and joints showed plastic hinges and shear failures in different parts of the structure, with spread spalling of the concrete. Numerical and experimental results were found in fair agreement.

Effects of Reserve Capacity on Seismic Response of Concentrically Braced Frames by Considering Brace Failure

“…Christopher D. pointed out that the braced-gusset plate not only increased the flexural strength and stiffness of the structure, but also improved the collapse resistance of the structure [14]. Similarly, floor slabs not only contribute greatly to the initial stiffness of the structure [15] but also can provide asymmetric beam-to-column moment capacity until the crushing of concrete by 0.04 rad-story drift [16,17]. Even the theoretically pinned connections, such as beamcolumn connections employing a shear tab, double angle, and end-plate details, which are common in a gravity system, can develop roughly 15-20% of M p,beam on their own [14,18,19].…”