PSI - Issue 78

Angelo Masi et al. / Procedia Structural Integrity 78 (2026) 686–693

689

The SPEAD system was conceived to be applied to RC frames from the outside with reduced impact on the structure and using fewer materials, making it both environmentally and socially sustainable. The SPEAD device is applied through chemical anchors which allow it to be attached to the beam and column members within glued regions (Fig. 1). There is no connection between the SPEAD and the joint panel region to avoid additional shear stresses acting in that area. More details can be found in (Santarsiero et al., 2020; Ielpo et al. 2025).

Fig. 1. The SPEAD device.

2.2. Methodology In order to assess the effectiveness of the proposed device, a methodology consisting of four phases has been properly defined, including both experimental tests and numerical simulations, as follows: 1. Experimental tests on standalone devices (Fig. 2a); 2. Micro-modelling numerical simulations of RC portal frames retrofitted with SPEAD (Fig. 2b); 3. Experimental tests on RC portal frames retrofitted with SPEAD (Fig. 2c); 4. Macro-modelling numerical simulations of 3D existing RC prototypes retrofitted with SPEAD (Fig. 2d). More specifically, following numerical analyses based on simplified theoretical schemes to preliminary determine the main geometry dimensions of the SPEAD device, experimental tests have been set up on standalone devices under cyclic quasi-static loading (Phase 1). These tests are currently being carried out at the Laboratory of Structures of the University of Basilicata and are deeply described in Section 3. Experimental results from Phase 1 will be used in Phase 2 to calibrate numerical model of a one-bay, one-storey RC frame (portal) ideally extracted from the exterior frame of the 3D prototype used in Phase 4. To this purpose, refined micro-modelling approach using the ATENA 3D software (version 5.4.1) will be adopted to predict the structural response of the sub-assemblage and, in particular, to understand the progressive damage at the beam-column joints. Simultaneously, the same RC portal will be also experimentally investigated at full scale, comparing results obtained from the “as-built” configuration (Ventura et al., 2019) with those related to the “retrofitted” configuration (Phase 3). Finally, results from the previous phases will be used to reproduce the phenomenological response of the retrofitted hinges in terms of moment-rotation relationship within a non-linear lumped plasticity framework. Subsequently, numerical modelling using Opensees will be defined for a 3D prototype representative of pre-code RC buildings designed only for vertical (gravity) loads, and non-linear dynamic analyses will be performed to check the effectiveness of the proposed technique at global level under seismic actions and possible foundation settlements (Phase 4).