Application of yield devices of low invasivity for seismic upgrading of precast portal RC frames

This article presents a new upgrading technique to enhance the seismic response of portal RC frames made of precast RC members (PPRC). Low cost yield devices of C shape (C-devices) are incorporated in a non-invasive fashion around the beam-to-column joint regions in order to introduce additional sources or hysteretic energy dissipation which lead to significant reductions of lateral and residual displacements with reduced increments of base shear. A criterion for optimum calibration of device strength is defined, and an example of the application of the proposed upgraded technique is presented in terms of the study of an existing PPRC frame representative of an industrial building in its original and upgraded states. Nonlinear inelastic analyses (push over and seismic time-history) are conducted to assess seismic response. The beam-column connections of the PPRC frame under study are modelled as pinned connections, whereas the C-devices are modelled by equivalent inelastic springs. RC frame elements are modeled using fibre elements. Results indicate that the suggested upgrading technique offers an effective economic alternative to reduce damage and/or to avoid the seismic collapse of PPRC framed buildings.