Simulation of Tests on Cast-In and Postinstalled Column-to-Foundation Connections to Quantify the Effect of Cyclic Loading

Abstract

Additional columns are often used as a retrofitting solution for reinforced concrete structures, particularly in seismic regions. These columns require postinstalled starter bars that inhibit the detailing of the anchorage with hooks. Often, the anchorage length of straight starter bars cannot be accommodated in foundations, which are generally short. For this reason, reductions of the large anchorage length, which are required according to the design codes, are desirable. The aim of the study presented in this paper was to quantify the adverse effect of cyclic loading on the capacity of connections with reduced starter bar anchorage lengths. To this end, finite-element analysis employing bond elements was realistically carried out to simulate seismic tests on column-to-foundation connections. The analysis allowed the study of the effect of cyclic loading on global performance and local behavior in terms of tensile and bond stresses along the starter bar. An equation to take into account the effect of cyclic loading was developed, which is the prerequisite to use a new design methodology on the basis of concrete anchor design provisions for seismic design cases.