PSI - Issue 11

S. Labò et al. / Procedia Structural Integrity 11 (2018) 185–193 Labò et al./ Structural Integrity Procedia 00 (2018) 000 – 000

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In this case, a maximum scale factor of 2 and upper and lower tolerance equal to 30% and 10% have been imposed. In Figure 5 the chosen combination is reported. The capacity curve resulting from the pushover analysis is reported in Figure 6. The seismic behaviour of the structure is significantly improved; in particular, the hinge distribution reports no damage in columns at the considered limit state but just the buckling of some diagrid diagonals at the ground floor.

Fig. 5 Sets of seven records considered in the nonlinear dynamic analyses (from: REXEL 2.2beta - Iervolino, Galasso, & Cosenza, 2010)

Fig. 6 Capacity curve of the retrofitted building: 1. controlled buckling of some diagrid diagonals at the ground floor, 2. yielding of the first diagonal, 3. buckling of all the ground floor diagonals, 4. yielding of some columns 5. First-floor diagonal buckling, 6. Column failure. Dotted line: LSLS displacement demand. The average results obtained from the 7-non-linear time history are plotted in terms of total roof displacement and interstory drift of the bare frame and of the retrofitted structure in Figure 7. As a result, a significant displacement reduction of the retrofitted structure is observed, which respects the target of 0.5% of interstory drift and guarantees the elastic behavior of the existing building, thus resolving the previously evaluated vulnerabilities.

Fig. 7. (left) Story displacement and (right) interstory drift of the retrofitted building in the LSLS displacement configuration.