Seismic upgrade of a reinforced concrete building


Bayrak O., Binici B.

3rd International Conference on Earthquake Resistant Engineering Structures (ERES), Malaga, Spain, 01 September 2001, vol.9, pp.465-474 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 9
  • City: Malaga
  • Country: Spain
  • Page Numbers: pp.465-474
  • Middle East Technical University Affiliated: Yes

Abstract

This paper discusses results from an analytical investigation conducted to study the ductility demands imposed on reinforced concrete beams and columns of three-bay six-story reinforced concrete frames subjected to earthquake type loads. The ultimate goal of this study is to investigate and compare the behavior of Frame-NS, the ordinary moment resisting frame, and Frame-S, the special moment resisting frame designed to comply with the seismic design requirements of ACI 318-99[1], UBC-97[2], CAN A23.3-94[3] and NBC-95[4]. Determination of the critical locations in these frames and devising upgrade schemes that are consistent with the ductility demands on these locations constituted significant milestones in the seismic retrofit design. Although Frame-S displayed a higher level of ductility in comparison to Frame-NS, the pushover analyses results indicated that the most critical column hinges of Frame-S exploited their deformation capacities just prior to collapse. The most critical beam hinge, on the other hand, exploited 37% of its deformation capacity. More significantly, only 21% of the beam deformation capacities were exploited in the Frame-NS just prior to its collapse. The potential plastic hinge regions of the columns of Frame-S and Frame-NS were then wrapped using carbon fiber reinforced polymer fabrics impregnated with epoxy. Due to better confinement of the plastic hinge regions of the columns, their sectional deformation capacities increased considerably. Hence, the available deformation and energy absorption capacities of the beam hinges were mobilized to considerably higher levels (up to 48% in Frame-NS and up to 75% in Frame-S).