PSI - Issue 44

Andrea Belleri et al. / Procedia Structural Integrity 44 (2023) 1006–1013 4 Andrea Belleri, Simone Labò, Maria Elena Cornelli, Martina Mazzucchetti / Structural Integrity Procedia 00 (2022) 000–000 of the existing building floor stiffness (Fig. 2b). The post-tension value to be applied to the coupling beam is derived by means of the iterative process reported below. The beam stress block extension ( a ) is evaluated as   0.1 ℎ  (2) The level arm between the post-tension load and the compression load acting on the concrete at the interface ( z ) is         (3) Then the first value of the post-tension to be applied to the coupling beam ( F p ) is derived as       (4) At this point, the iterative procedure starts by deriving the new extension of the stress block ( a ’ ) and the associated post-tension force ( F ’ p ) as        ∗    ; ′            (5) Where, f cd is the design cylinder compressive strength of the coupling beam concrete. 1009

b) c)

a)

Fig. 2. (a) double pin-supported walls internal actions; (b) beam to pin-wall interaction; (c) finite element modelling scheme.

Once the compressive post-tension force is derived, the rotation ( α ) of the beam ends with respect to the wall is derived as the sum of the rotation θ and β (Fig. 2b).          /  (6)