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The capacity of a structure can be assessed using inelastic analysis, requiring sophisticated numerical procedures such as pushover and incremental dynamic analyses. A simplified method for the evaluation of the seismic performance of steel moment resisting frames (MRFs) to be used in everyday practice has been recently proposed. This method evaluates the capacity of buildings employing an analytical trilinear model without resorting to any non−linear analysis. Despite the methodologies suggested by codes, the assessing procedure herein described is of easy application, also by hand calculation. Furthermore, it constitutes a suitable tool to check the capacity of the buildings designed with the new seismic code prescriptions. The proposed methodology has been set up through a large parametric analysis, carried out on 420frames designed according to three different approaches: the theory of plastic mechanism control (TPMC), ensuring the design of structures showing global collapse mechanism (GMRFs), the one based on the Eurocode 8 design requirements (SMRFs), and a simple design against horizontal loads (OMRFs) without specific seismic requirements. In this paper, some examples of the application of this simplified methodology are proposed with references to structures supposed to exhibit global, partial and soft storey mechanism.

The main aim of this work is to validate the application of a simplified performance-based method for assessing the seismic performance of steel buildings, focusing particularly on Moment Resisting Frames (MRFs) through nonlinear analyses. This simplified method defines the capacity curve of a structure through elastic and rigid-plastic analyses, calibrated by regression analyses conducted on 420 structures. To assess its accuracy, the method was compared with other analytical approaches, including incremental dynamic analyses (IDA) provided by existing codes. These analyses were performed on both real structures and simulated designs, considering recent and older codes. The comparison of capacity results derived from code-based approaches and IDA, aligned with the limit states outlined in current codes, showcased the high reliability of the proposed simplified assessment approach.

This paper validates a simplified approach for evaluating the seismic performance of concentrically braced frames (CBFs). The method, based on a performance-based design, defines a structure’s capacity curve through elastic and rigid plastic analyses. It is validated by comparing the results with those from 420 pushover analyses. Additionally, the method is applied to two case studies designed according to older code provisions, and its accuracy is verified through Incremental dynamic analyses (IDA). The results demonstrate that the simplified method is reliable and provides an accurate evaluation of the structure’s capacity compared to code-based tools.

The seismic events that occurred in the last decades have highlighted the importance of a correct design of the structures in seismic areas and the seismic inadequacy of a large part of the built heritage. Modern codes are still lacking in terms of prescriptions for the evaluation of the seismic performance of existing buildings. The present work proposes a simplified method for the evaluation of the demand in terms of plastic rotation for short links of steel Eccentrically Braced Frames (EBFs). A relationship for the evaluation of the demand, that exploits elastic analysis and rigid-plastic analysis extended to the second-order effects, is proposed. The calibration of this relationship was carried out on 420 EBFs equipped with short links designed according to three different approaches. The 420 frames have been also used to analyze the behavior in the plastic range of EBF type structures equipped with short links. The study also provides an extensive analysis on the influence of plastic redistribution capacity on the demand in terms of plastic rotations of links, corresponding to the achievement of the maximum bearing capacity. The obtained relation can be exploited as an assessment tool by comparing the demand with the link capacity. Moreover, from a performance-based design point of view, the same can be used for predicting the required ultimate plastic rotation as a function of the plastic redistribution capacity of the structure.

The force distribution proposed by codes, which in many cases is framed in the equivalent static force procedure, likely leads to design structures with non-uniform drift distribution in terms of inter-storey drift and ductility demands. This can lead to an unbalanced drift demand at certain storeys. This phenomenon may also amass cyclic damage to the dissipative elements at this very storey, therefore increasing the probability of premature failure for low-cycle fatigue. This work proposes a new force design distribution that accounts for higher mode effects and limits the displacement concentration at any storey thus improving the dissipative capacity of the whole structures. The main advantage of the proposed method stands in its formulation, which allows to spare any previous set up with structural analyses. The proposed force distribution has been applied to multi-degree-of-freedom systems to check its effectiveness, and the results have been compared with other proposals. In addition, in order to obtain a further validation of the proposed force distribution, the results obtained by using a genetic algorithm have been evaluated and compared. Additionally, the results provided in this work validate the proposed procedure to develop a more efficient lateral load pattern.

Parametric Finite Element (FE) simulations were performed to investigate the ultimate flexural of different configurations of friction steel beam-to-column joints equipped with FREEDAM (free from damage) dampers. The main aim of this study was to compare the effectiveness of friction dampers featuring either single or multiple slotted holes, examining how these variations influence the behavior of the joint and the devices under seismic loads. In particular, the ultimate behavior of the connection (i.e., when the device reaches its maximum stroke) was investigated to characterize the involvement of the bolts in shear, the bearing of the plates, and the yielding of the supporting components. The analysis of bolt stress states revealed significant differences influenced by the number of bolts and slots. The FE models were calibrated against the experimental results obtained within the FREEDAM RFCS Project. These insights contribute to the design and performance evaluation of steel beam-to-column joints with FREEDAM connections, in particular the detailing of the haunch slots, laying the groundwork for future research and applications.

This work aims to provide an effective structural solution, minimizing the discomfort during the works’ execution, for how to retrofit the Day-Hospital building of the National Cancer Institute “G. Pascale Foundation” in Naples. The structural vulnerability has been preliminarily evaluated for this scope, using linear static and dynamic analyses according to code provisions. The performance index in terms of peak ground acceleration (PGA), both for the life safety (SLV) limit state and the operational (SLO) limit state, has been evaluated. A seismic assessment has been performed by finite element (FE) analyses using the SAP2000 computer program, post-processor VIS15 and plugin SPF. Two main solutions have been proposed to improve the structural performance of the existing building. The first one is based on increasing the thickness of the existing reinforced concrete (RC) cores. The second solution is characterized by strengthening the RC cores using steel plates, steel strips and angles. A comparison of the proposed interventions is provided herein from the technological and financial standpoints.

The paper proposes a new methodology for the control of residual displacements in multi-storey steel structure frames. The work starts from the validation and extension of a mechanical model based on single degree of freedom systems, already proposed in previous work, following with analyses performed on a set of natural accelerograms. The same model is applied to multi-degree of freedom (MDOF) systems through an anlaytical design procedure. The procedure is used to dimension study cases composed of concentrically braced frames that are analysed through nonlinear dynamic analyses with earthquake records excerpted from the previous dataset. The results confirm the effectiveness and suitability of the proposed procedure for MDOF systems.

This work mainly aims to propose a new design procedure combining the benefits of the Performance-Based Plastic Design approach (PBPD) with a rigorous accounting of second-order effects. In fact, by exploiting the kinematic theorem of plastic collapse, second-order effects can be accounted for employing the concept of collapse mechanism equilibrium curve. The same tool constitutes the base of the Theory of Plastic Mechanism Control (TPMC) design approach. Besides, the paper reports a critical comparison between TPMC and PBPD, both having the scope to design structures exhibiting a collapse mechanism of global type. These two approaches are also compared with the refined PBPD where second-order effects are accounted for by the kinematic approach. Many steel moment resisting frames are designed according to PBPD, TPMC and refined PBPD and their performances have been compared on the bases of push-over analyses.

The capacity of a structure can be assessed using inelastic analyses, requiring sophisticated numerical procedures such as pushover and incremental dynamic analyses. A simplified method for the evaluation of the seismic performance of steel Concentrically Braced Frames (CBFs) to be used in everyday practice and the immediate aftermath of an earthquake has been recently proposed. This method evaluates the capacity of an existing building employing an analytical trilinear model without resorting to any non-linear analysis. The proposed methodology has been set up through a large parametric analysis, carried out on 420 frames designed according to three different approaches: the first one is the Theory of Plastic Mechanism Control (TPMC), ensuring the design of structures showing global collapse mechanisms (GCBFs), the second one is based on the Eurocode 8 design requirements (SCBFs), and the third is a non-seismic design, based on a non-seismic design (OCBFs). In this paper, some examples of the application of this simplified methodology are proposed with references to structures that are supposed to exhibit global, partial, and soft storey mechanisms.