SEISMIC RETROFIT OF EXISTING REINFORCED-CONCRETE STRUCTURES USING ADVANCED COMPOSITE MATERIALS

Recent earthquakes have exposed the deficiencies in early seismic design and detailing of reinforced-concrete (RC) structures. Many investigators have dealt with the response of concrete frames and bridge bent systems subjected to earthquake motions. Until now, several strengthening strategies have been used to retrofit deficient structures especially the structures that were designed according to pre-1970s codes. A vulnerability analysis on most of these structures determines typical deficiencies in; 1) confinement of column lap splice regions, 2) anchorage of longitudinal column bars in the beams or footings, 3) confinement of column plastic hinge zones, and 4) shear capacity of columns and beam–column joints. This article is a part of a research program to provide effective seismic strengthening techniques for concrete frames and bridge bent systems. In this article, a brief overview of seismic retrofitting strategies including conventional steel and concrete jacketing as well as steel bonding is presented. In addition, an introduction to seismic retrofitting of RC structures with Fibre-Reinforced Polymers (FRP) is discussed. The modes of seismic failures, flexural and shear failures, and the objectives of seismic retrofitting are highlighted. Proper strengthening systems for the critical zones of the RC structures against the aforementioned failure modes are represented (e.g. confinement of plastic hinge zones and lap splice regions, prevention of the pullout of the column from the foundation or shaft and improvement of shear capacity of columns and beam-column joints). It has been proven that the FRP composite retrofitting technology is effective in seismic retrofitting of the RC structures and it outperforms most current conventional methods.

Keywords:

Fibre-Reinforced Polymers , Seismic Retrofit , Reinforced-Concrete Structures