PSI - Issue 78

Maria Teresa De Risi et al. / Procedia Structural Integrity 78 (2026) 1151–1158 M.T. De Risi, C. Del Gaudio, G.M. Verderame / Structural Integrity Procedia 00 (2025) 000 – 000

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The number of reinforcing exterior strips have been designed to obtain a shear failure without or after column yielding, respectively, again based on Italian D.M. 2018 shear strength model for the case of steel cages, which prescribes a 50% reduction of yielding strength (f yw – herein assumed equal to f 0.2 ) to ensure that the exterior cage remains in the elastic range (see Eq. 1).

(1) In Eq. (1), t j and s are strips thickness and spacing, respectively, b and d represent the cross-section width and effective depth. As a result, 5 strips (with 250 mm spacing) have been used for column SL within the column shear span (L v ), and 15 strips (with 83 mm spacing) for SH specimen. 3. Test setup All columns have tested under quasi-static loading by means of the experimental setup shown in Fig. 4, which basically is a very simple cantilever scheme. The foundation block has been fixed at the strong floor, whereas a pseudo-static displacement history has been applied 140 cm far away from the top of the column foundation (i.e., the shear span, L v is equal to 1.40 m), thanks to a displacement control hydraulic actuator constrain at the top of the column. Three push/pull cycles for each target displacement were performed. Target displacement were defined as 0.25, 0.50, 0.75, 1, 2, 3, 4, and 5 times the expected yielding displacement (starting from the negative – pull – side). The applied displacement has been monitored by means of an external wire potentiometer located at a distance L v from the top of the foundation block, as in Fig. 4. Monitoring strain gauges have been also installed on the interior stirrups and longitudinal rebars of each specimen, and on the exterior steel strips (for retrofitted specimens) to record their strain demand. The Digital Image Correlation (DIC) technique has been also used for monitoring purposes, thanks to the employment of high-definition cameras located on both column sides of interest, where random patterns of points have been previously created.

Fig.4. Experimental setup adopted for columns (dimensions in cm).