Abstract:
The requirement of strengthening of reinforced concrete structures may emerge not only due to timed
degradation but also due to various reasons like construction faults, increased loads and changes in
utilization purpose etc. Rehabilitation of reinforced concrete structures using Carbon Fibre Reinforced
Polymer materials is recognized as a very effective retrofitting method. The current practice on
strengthening reinforced concrete columns with external CFRP jacketing is to provide full wrapping
all over the column with less care on the required strength increment As CFRP is a costly material,
providing partial wrapping may be a viable option for cost reduction rather than providing full
confinement. An experimental study was carried out with 17 specimens to study the partial
confinement effect. The test specimens consist of 6 plain concrete columns with 3 control specimens
and 3 fully confined columns. 11 reinforced concrete columns with 3 control specimens, 3 columns
with full confinement and 5 columns with partial confinement. Two wrapping patterns were used for
partially confined columns with 75mm and 50mm laminate width, keeping the volumetric ratio of
CFRP constant to study the effect of wrapping pattern and jacket location for strength and ductility
increment. The results of experimental study revealed that the load carrying capacity increment for
fully wrapped reinforced concrete columns were 100% while for plain concrete columns it was 47%
and for partially confined columns, the specimens with two 75mm wraps showed a capacity increment of 59% while specimens with three 50mm wraps showed an increment of 83%. It was observed that, by only changing the jacket location 15% ultimate load carrying capacity increment can be obtained. When ductility increment is considered it was observed that ductility increment is proportional to the strength increment.
