Seismic Performance Evaluation of Rehabilitated Reinforced Concrete Columns through Jacketing

Abstract

Rehabilitation techniques for seismically deficient reinforced concrete elements were developed more than 20 years ago. At that time, lateral-load response of rehabilitated elements was deemed satisfactory if significant strength degradation did not occur at a target displacement demand (typically large). Large economic losses in recent earthquakes have highlighted the importance of evaluating element response at other performance levels, such as those associated with smaller displacements. In order to accurately estimate the global response of rehabilitated reinforced concrete buildings, a thorough understanding on the response of individual rehabilitated components must be developed. ASCE/SEI Standard 41-06 – Seismic Rehabilitation of Existing Buildings, provides engineers with a much needed resource to incorporate performance-based concepts in seismic rehabilitation projects. Within ASCE/SEI 41-06, guidelines to develop backbone curves for modeling typical reinforced concrete elements, and acceptance criteria of these elements based on their calculated deformation are provided. The document, however, does not explicitly include information that can be used for elements that have been rehabilitated by methods such as jacketing. A need to examine the performance of these elements using a multi-level performance perspective is therefore warranted. In this paper, a comparison of the laboratory performance of jacketed reinforced concrete columns with modeling parameters in ASCE/SEI 41-06 is presented. This information is part of ongoing activities taking place within ACI Committee 369 – Seismic Repair and Rehabilitation, that focus on an evaluation of existing guidelines for the seismic rehabilitation of concrete buildings. Existing laboratory tests found in the literature are used to compare the plastic deformation capacity of jacketed reinforced concrete columns with the corresponding modeling parameters in ASCE 41-06. The three primary types of jacketing materials that have been used to date (concrete, steel, and fiber-reinforced polymers) are included in the study. Particular attention is paid on whether plastic drifts in jacketed columns compare favorably with modeling parameters in ASCE/SEI 41-06.