PSI - Issue 44

Fabrizio Comodini et al. / Procedia Structural Integrity 44 (2023) 1076–1083 Author name / Structural Integrity Procedia 00 (2022) 000–000

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b)

Fig. 7. Exoskeleton position a) facade SW ; facade NE

The exoskeletons are connected to the existing structures in correspondence with the floor slabs using new concept devices. Through iterative cycles of analysis, it was possible to calibrate the stiffness of the exoskeletons and the dimensions of the coupling device to achieve the expected seismic improvement objectives. In addition to the main intervention, other minor interventions will be carried out for the mitigation of local vulnerabilities and the construction of a new internal reinforced concrete wall in a transverse direction and positioned in the middle of the building. The new wall limits the deformability of the floors associated with the elongated shape of the structure. 4. Shear coupling device The connection system consists of two parts, one being integrated into the exoskeleton and the other being attached to the existing building; the two parts are interconnected by the shear connector. The shear connector is the steel element that transfers the seismic forces from the existing building to the exoskeleton. The part connected to the building consists of a steel beam on which contrast boxes are fixed into which it is inserted for one end of the shear connector. The contrast box is equipped with a vertical slotted hole through which the shear connector can slide in the vertical direction. The slotted hole allows vertical sliding between the two structures without generating excessive compression or traction in the building column. The shear connectors are formed by a steel profile with a full rectangular section with dimensions 100x50 mm and are positioned at center distance of the 800 mm. The other end of the shear connector is perfectly embedded in the steel beam of the exoskeleton. The shear connector is designed to have a yield strength equal to the maximum design shear force acting on it, once this limit is exceeded, the collapse mechanism of the connector is of the dowel action type with dissipative capacity The bending moment that is generated due to the distance between the exoskeleton and the existing structure is balanced by the pair of shear forces acting on the contrast elements placed at the end of the connector.

b)

a)

Fig. 8. Detail of exoskeleton coupling device a) 3D model axonometric view; b) side view design detail