INTERFACE DEPENDENCY OF REINFORCED CONCRETE JACKETING FOR COLUMN STRENGTHENING

Abstract

This paper investigates the structural capacity enhancement of reinforced concrete column by concrete jacketing.
In view of investigating structural capacity and integrity of jacketed column, a total twelve retrofitted column
samples with different jacket thickness were experimentally tested. Samples are prepared with different types of
interface including no surface treatment, addition of bonding chemical, roughening of old surface, application
of welded ties, and changes in clear cover to investigate the influence of interface bonding between new and old
concrete. Analytical equations for jacketed columns are formulated as per elastic principle maintaining strain
compatibility at the interface in addition to concrete modeling using finite element method (FEM). Column
interaction diagrams as formed by analytical equations are compared and verified with existing Japanese code
and available FE software packages. Experimental investigation shows that failures occur relatively earlier
at the column interface than the core of the retrofitted column. Comparative study in terms of interaction
diagram shows that experimental result well agrees with the computed analytical result but deviates from the
FE analysis. Finally, an interface bonding reduction coefficient in the range of 0.65-0.88 is proposed for RC
jacketed column subjected to different types of interface.