Seismic performances of CFRP strengthened rubberized concrete columns : bidirectional shaking table test

Abstract

Rubberized concrete (RuC) columns exhibit greater ductility than conventional concrete columns, while their loading capacity could be significantly impaired with excessive rubber replacement. Carbon fiber reinforced polymer (CFRP) has proven effective in improving the loading capacity of RuC column, and many studies have been performed on this topic. However, shaking table tests on the seismic performance of CFRP strengthened RuC columns remain very limited. This paper conducted the first bidirectional shaking table test to investigate the seismic performance of RuC columns considering different CFRP wrapping schemes and peak ground accelerations (PGAs). Results showed that the stiffness degradation caused by rubber replacement could be compensated through CFRP wrapping, which not only enhanced the loading capacity of RuC column but maintained its deformability. The frequency reduction of RuC column was countervailed by over (Formula presented) through CFRP confinement. Owing to the synergistic actions from rubber contents and CFRP confinement under large excitation, the confined RuC column exhibited a favorable energy absorption ability with a maximum damping ratio of about 19 %. The fully-wrapped CFRP scheme was found more practical than the partially-wrapped one for strengthening RuC column to resist bidirectional earthquake ground motions. The drift ratio of RuC column was reduced by up to (Formula presented) via fully-wrapped CFRP, which helped prevent the RuC column from collapsing prematurely, while the increment in acceleration response was insignificant. Using CFRP for strengthening the RuC column is deemed practical and believed to facilitate the application of RuC material in civil engineering constructions.