Abstract:
The objective of this research work is to assess the seismic vulnerability of a retrofitted RC
frame. An analytical curve is developed for that purpose. The confinement behavior in RC
columns is explained in detail. The confinement mechanism in Fiber Reinforced Polymer (FRP)
confined concrete is discussed in particular. The critical areas in a frame are near joint regions of
columns which are critical in withstanding earthquake forces. Similar phenomena were observed
in the Kashmir (2005) earthquake (Ali, 2005). The provision of confinement to these critical
areas can improve the overall performance of the structure. The bar pullout mechanism is also
discussed, which is not taken care of while modeling the structures (Harajili, 2007.). The
provision of confinement also improves the bond strength of members. Different methods of
seismic vulnerability assessment along with their advantages and disadvantages are discussed.
An experimental program was carried to see the effect of CFRP confined concrete as compared
to un-confined concrete. Small scale specimen were tested using different layers of CFRP and
their results were used in analytical modeling of a typical deficient RC frame using an
appropriate analysis program. The results of experimental work done on a typical deficient RC
structure by Chaudat et. al, (2005) were available. Therefore, a simple analytical model of this
experimental work is developed to observe and compare the overall behavior of the deficient RC
structure with the FRP strengthened frame. An analytical tool based on finite element modeling
(Graham et. al., 2006) was used in this research work. The improved properties of four different
levels CFRP confined concrete were modeled in the software and the bar pullout effect was also
incorporated to see the effect of CFRP on seismic performance.
After the analysis, the results are used to derive seismic vulnerability curve for reference and
retrofitted frames for comparison. Seismic vulnerability curve is derived using seismic
vulnerability assessment framework proposed by Kyriakides (2007). The curves show
improvement in overall performance of the deficient RC structure after being retrofitted with
CFRP.
