## 1 Introduction  
Steel structures are largely selected for use in seismic areas [1, 2] since they can exhibit high levels of ductility and dissipation capacity [3]. Among the large variety of steel systems, eccentrically braced systems (EBFs) are one of the most ductile. EBFs are thought to concentrate the seismic damage mainly into the \"link\" element. This feature may allow for replacing the damaged links with new ones after seismic damage. Unfortunately, the yielding of links is associated with a permanent residual drift in the structure which can make impossible to replace the damaged links. To overcome such limitations, recent studies investigated the possibility of enforcing a re-centering capability in EBFs by simply adding some moment resisting frames (MRFs) in parallel to the EBFs, thus transforming the EBFs in a dual structural system (i.e., the combination of MRFs and EBFs) [4, 5]. [PERSON] and [PERSON] (2017) [6] present a review of the state of the art of the design of eccentrically braced frames, discussing the most significant studies in that field. Among them, [PERSON] et al. (2014) [7] highlighted that the upper bound value of the behavior factor for eccentrically braced frames in the Eurocode 8 is excessive (i.e., 6) and proposed the use of a lower value (i.e., 5). In 2017 [PERSON] et al. [8, 9] conducted a series of incremental dynamic analyses on MRF-EBF dual frames in order to estimate the behavior factor. They observed that the dual systems were not able to display the expected ductility. Therefore, they proposed a design procedure, aiming to enforce ductility. Recently, research on the implementations of removable links has been gaining attention with regard to both structural performance (optimal over-strength values) and cheaper rehabilitation. [PERSON] [10] studied the connections and local aspects of replaceable links. Experimental tests on replaceable shear links are also reviewed by [PERSON] et al. [11], covering recent experimental and numerical researches work performed in Canada and New Zealand, aimed to verify the replaceable link rotation capacity. [PERSON] et al. [12] performed numerical investigations investigating the procedure of link removal in both horizontal and vertical directions in multi-story dual MRF-EBF frames and made several proposals. The authors proposed the use of temporary tension-only rods to act as braces to ensure that the system is stable during the time of link cutting. Also, they found that removing the links from the top downward (least loaded towards most loaded) worked best for the lesser transfer of forces. In their plan, they propose to remove all links in one direction simultaneously in order to limit torsional effects. [PERSON] et al. [13; 14] investigated the recentering capability of dual frames of different configurations, one of which involved an MRF-EBF dual frame with links being removed after seismic events. The authors observed that the dual frames were able to restore themselves completely to their initial positions after being pushed until the target displacements were reached, once the links were cut, as shown below. Moreover, in 2016, [PERSON] et al. [15] also made numerical investigations into the dual MRF-EBF systems with link removal procedures (with a symmetric configuration, as above) but with different structural configurations (MRF + EBF + MRF or EBF + MRF + EBF) and also found that it was better for links to be removed from the least loaded towards the most. Within this framework, the main aim of the present work is to investigate the seismic behavior of dual structures made of MRFs and EBFs. In particular, short links are considered for the eccentrically braced frame, while the MRFs were designed to behave in an elastic range during the seismic events to guarantee redundancy and plastic distribution capacity once one or more links fail.