Recent studies together with experimental evidences have pointed out criticisms and potentialities of steel concentric braced frames (CBF) in seismic areas. In particular, it has been observed that plastic mechanisms characterized by the yielding of diagonals while preventing the yielding/buckling of the beams and the columns and the failure of the connections, lead to good performances of CBFs in terms of ductility and energy dissipation. In the present paper a retrofit procedure for CBFs is developed, based upon principles of the Displacement Based Design (DBD). It consists essentially on: the prediction (from simple considerations over the strength hierarchy among elements: beams, columns, diagonals, gussets, …) of the displacement capacity of the CBF; the assessment if the displacement capacity of the structure is able to comply with the displacement demand under seismic action and therefore the prediction of a new dimensions for the some of the CBF’s elements in order to improve the overall seismic performance of the structure. The developed procedure is finally applied to some cases of study: the results are discussed in order to verify the ability of the proposed procedure to carry out suitable retrofitting interventions.
SEISMIC ASSESSMENT AND RETROFIT OF STEEL CBF
GRANDE, Ernesto;RASULO, Alessandro
2014-01-01
Abstract
Recent studies together with experimental evidences have pointed out criticisms and potentialities of steel concentric braced frames (CBF) in seismic areas. In particular, it has been observed that plastic mechanisms characterized by the yielding of diagonals while preventing the yielding/buckling of the beams and the columns and the failure of the connections, lead to good performances of CBFs in terms of ductility and energy dissipation. In the present paper a retrofit procedure for CBFs is developed, based upon principles of the Displacement Based Design (DBD). It consists essentially on: the prediction (from simple considerations over the strength hierarchy among elements: beams, columns, diagonals, gussets, …) of the displacement capacity of the CBF; the assessment if the displacement capacity of the structure is able to comply with the displacement demand under seismic action and therefore the prediction of a new dimensions for the some of the CBF’s elements in order to improve the overall seismic performance of the structure. The developed procedure is finally applied to some cases of study: the results are discussed in order to verify the ability of the proposed procedure to carry out suitable retrofitting interventions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
