Experimental study on seismic performance of reinforced concrete column retrofitted by asymmetric increased single lateral section

Abstract

In this article, a new retrofit method that the frame column is strengthened by asymmetric increased single lateral concrete section is proposed. The new added section could be ordinary reinforced concrete, bonded prestressed concrete, or unbonded prestressed concrete. The new added section could be connected with the column through anchor rebars, or prefabricated first, then be connected to the column through high strength bolts. The low cyclic reversed load experiment has been launched on understanding the seismic performance of one unretrofit specimen and six retrofitted specimens. The experiment has considered four main factors that is loading direction, material adopted on the new added section, different orders of unification of the retrofit column, and the process of prestress applying. Based on the experiment study, the characteristics including the failure mode, hysteresis loops behavior, bearing capacity, ductility, stiffness degradation, and energy dissipation ability are demonstrated. The bearing capacity calculation method of the retrofit column under compression–bending action is established. The calculation results and the experiment results show good agreement. Some suggestions for seismic design of the retrofit column are proposed. The experimental results show that the retrofitted column has good seismic performance and good retrofit effects. The research results could be references to the practical engineering design works.