Numerical Evaluation of the Steel Plate Energy Absorption Device (SPEAD) for Seismic Strengthening of RC Frame Structures

In this paper, a new strengthening technique is proposed: the Steel Plate Energy Absorption Device (SPEAD) system, which is intended to increase the flexural strength of beam and column members in RC frame structures. In this way, while permitting calibration of the strength increase in the beam to comply with the strength hierarchy criteria needed for a proper seismic behaviour it can provide additional energy absorption. A numerical evaluation of the SPEAD system is carried out by means of a refined 3D model built with an advanced nonlinear finite element program. The SPEAD system has been virtually applied (through finite element analyses) to an RC external beam-column joint, representative of typical existing RC buildings, and the numerical results are compared to those of a specimen that was not upgraded and subjected to the same experimental tests. The SPEAD upgraded model provided a strength increment of about 50% with also a strong reduction of bond-slip effects in the joint panel region. This latter, in turn, provided a beneficial increase of ductility. Based on the positive results from numerical simulations, a design method is also provided.