A design procedure for dual eccentrically braced systems: Numerical investigation

The paper investigates the seismic response of dual braced structures constituted by eccentrically braced frames and moment resisting frames. The response of dual braced structures designed according to the procedure described in the companion paper is first examined with the aim of suggesting behaviour factors varying with the mechanical length of the links. A larger set of structures is then designed according to the proposed values of the behaviour factor to validate the expression adopted. The seismic response of these structures is obtained by incremental dynamic analyses with reference to deterministic and random values of strength of steel. To highlight the qualities of the response of these structures the results of the dynamic analyses are compared to those obtained from structures designed according to procedures suggested by codes. A comparison is also carried out with conventional eccentrically braced frames in which the degree of interaction between the eccentrically braced frames and the other parts of the structure is purposely held very low.

► This paper validates a design procedure for dual eccentrically braced structures
► The proposed behaviour factor depends on the plastic rotation capacity of links
► Significant limitation of the normalised link overstrength factor is not required
► The seismic damage of the links is fairly uniform in elevation
► The seismic response is better than that of dual structures designed by codes