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Non-structural elements play a crucial role in the overall seismic performance of buildings, as has been largely demonstrated in recent earthquakes that have stuck densely populated regions. Therefore, the development of performance-based seismic design and assessment methodologies for non-structural elements is becoming an important research topic within earthquake engineering. A crucial aspect in such methodologies is the accurate prediction of the seismic demands acting on non-structural elements in terms of consistent absolute acceleration and relative displacement floor response spectra for the most common types of structural seismic force resisting systems. Masonry-infilled reinforced concrete frames are one of the most common building typologies in high seismicity regions, such as the Mediterranean region. This study proposes a simplified procedure to estimate consistent absolute acceleration and relative displacement floor response spectra in masonry-infilled reinforced concrete frames based on an existing methodology to estimate consistent floor response spectra in bare reinforced concrete frames. Nine archetype masonry-infilled reinforced concrete buildings with different numbers of storeys and arranged with three masonry infill typologies were considered as case-study archetypes, and were used to validate the proposed methodology using nonlinear time history analyses. The proposed procedure can accurately estimate consistent absolute acceleration and relative displacement floor response spectra for masonry-infilled reinforced concrete buildings that respond both in the elastic and nonlinear ranges for all the non-structural period range. The estimates of floor response spectra given by the proposed procedure are fully consistent with the well-known pseudo-spectral relationship for the entire non-structural period range. [ABSTRACT FROM AUTHOR]

Addressing the seismic vulnerability of infrastructures is critical, especially for those built before the introduction of the current seismic regulations. One of the primary challenges lies in retrofitting these buildings without interrupting their functionality. In this context, the use of exoskeletons for seismic retrofitting represents an effective solution. This approach increases the seismic resistance and ensures the continuous operation of the building during retrofitting. This advantage is especially crucial for critical infrastructures, such as airports. Nevertheless, traditional seismic assessment methods based on pushover analyses might not accurately predict the seismic capacity of complex infrastructures dominated by local vibration modes. To bridge this gap, the study proposes refining the multimodal pushover analysis tailored for seismic vulnerability assessments of large infrastructures with exoskeletons characterized by low modal participation ratios. The Foggia Airport case study exemplifies these points and highlights the practical applications of the discussed advancements. The authors compared two force distributions for push-over analysis, addressing the fine-tuning of exoskeletons to maximize their seismic resistance. [ABSTRACT FROM AUTHOR]

The paper presents a study on the evaluation of seismic fragility of cylindrical ground-supported steel silos intended for storing solid material. Silos are a key facility in industrial processes. For example, cylindrical steel silos constitute the main structural component for several industrial activities, such as the ones aimed at the production of food and beverage, and seismic actions can cause high economic losses and long functionality interruptions. Thus, the main goal of this paper is to propose a numerical procedure aimed to assess the seismic fragility of different cylindrical steel silos, accounting for varying geometries and service conditions (i.e., filling level of granular-like material), and observing different failure modes. In detail, a set of smooth steel silos was selected, considering different geometrical configurations (i.e., varying from squattest to slenderest structures). Different service conditions were simulated, with the aim to observe the behaviour of empty and filled silos (30%, 60%, and 90% of filling degree with respect to the maximum capacity). For each configuration, a detailed numerical model was developed under proper boundary conditions, adequately simulating the shell structure, the solid material inside, and the interactions between them. After validating the numerical models against existing literature data, three different failure modes were identified and assessed, accounting for the most recurrent post-elastic buckling type (i.e., elephant foot) and considering the possible occurrence of the elastic ones (i.e., diamond or similar shape failures at the middle and top of the structures). Both static and dynamic analyses were performed to identify the most probable failure modes and evaluate the probability of exceeding each one. As the output of the proposed approach, the seismic performance of each silo under a specific limit state was provided in the form of fragility curves. The results highlight some novel aspects, starting from the role that service conditions assume in the silos seismic performance up to the possible differences in terms of failure modes for different silos geometrical structural configurations. [ABSTRACT FROM AUTHOR]

Even if precast pre-stressed hollow-core (PPHC) slabs are usually designed as simply supported elements, continuity with the supporting beam may exist when constructed together with a reinforced concrete topping and continuity reinforcing bars. During an earthquake (and possibly other lateral load), this continuity may result in bending moments being induced close to the supports as the buildings sway laterally. The response of precast floors to earthquake-induced demands has been addressed by past research. However, further investigation is required to improve understanding of several aspects of precast floor behaviour either revealed or emphasized by recent earthquakes in New Zealand. This paper proposes a mechanics-based modelling approach for the analysis of PPHC slab-to-beam seating connections. The model has been calibrated against existing test data to predict the failure of a PPHC slab under negative bending moments. The numerical outcomes allow comparison of the moment–drift response, principal tensile stresses, and crack progression during loading. The developed modelling approach will allow future studies to exhaustively investigate all aspects of precast floor behaviour by varying the properties and geometry of the PPHC seating connection. [ABSTRACT FROM AUTHOR]

Italian reinforced concrete precast industrial buildings featuring frictional beam-to-column connections suffered from severe losses following recent earthquakes. Despite the relevance of this topic, the current literature includes only few works investigating the seismic behaviour of these buildings, the influence of vertical records on their modelled dynamic response, as well as the sensitivity of their seismic fragility to the friction type implemented in-situ. The above considerations imparted momentum to this research. First, a sensitivity analysis was conducted considering both concrete-to-concrete and neoprene-to-concrete friction types, as well as the presence or absence of vertical records in the vulnerability analyses. Within a multiple-stripe analysis framework, a number of nonlinear dynamic analyses were carried out on two precast building models created in OpenSees and assumed to be located in three Italian cities subjected to different hazard levels. Fragility curves related to the limit states of Serviceability Preventing Damage and Life Safety were derived. Then, epistemic uncertainty in the friction type and the influence of vertical records on the fragility curve was treated by employing a logic tree framework, allowing for the derivation of weighted average fragility curves, one per city. While the latter are structure-specific and site-dependent, they may be considered as generic or typological fragility curves, for use by researchers or practitioners who are interested in carrying out a fragility analysis on a reinforced concrete precast industrial building but are not confident on the friction type implemented in-situ and the influence of vertical records for the site and structure at hand. [ABSTRACT FROM AUTHOR]

The seismic performance of suspended piping systems can significantly compromise the functionality of critical facilities due to the incorporation of inadequate seismic design based on prescriptive empirical regulations and guidelines. The performance-based seismic design (PBSD) of non-structural elements requires the evaluation of performance parameters, based on experimental data or numerical studies, for comparison with engineering demand parameters. Few research studies available in the literature provide the performance parameters required to enable PBSD of piping systems and more specifically of suspended piping restraint installations. This paper discusses the numerical modelling of suspended piping trapeze restraint installations based on component testing. Reliable numerical models capable of predicting the force–displacement (backbone) curves of suspended piping restraint installations are developed based on monotonic and cyclic test data of the components that make up these installations. The prediction capabilities of the numerical models are assessed against the results of monotonic benchmark sub-assembly tests reported in a previous study. The numerical models developed in this study can be used to extract performance parameters from the predicted force–displacement curves to be used within a probabilistic PBSD framework without the need to conduct additional testing. [ABSTRACT FROM AUTHOR]

This research work is related to the evaluations of some modelling assumptions of the stick-slip phase of the Friction Pendulum™ System (FPS) on the seismic response of base-isolated buildings. Although several theoretical and experimental research findings show the complexity of the FPS nonlinear behaviour, the current international seismic design codes allow the designer to model the FPS nonlinear response using simple bilinear constitutive relationship in order to reduce the computational effort for modelling and performing the analyses. Therefore, the problem that has to be faced by practitioners and researchers is related to the way of modelling the stick-slip phase and the corresponding friction phenomena with a simple bilinear constitutive model. This research work has been encouraged by some experimental evidence and performed for investigating, through a large parametric study, the influence that many modelling assumptions may have on the global and local responses of buildings. The study has been carried out without claiming to be innovative but for being a valuable tool in the design practice and, mainly, in modelling the nonlinear response of the FPS with the bilinear simplification allowed by design codes. [ABSTRACT FROM AUTHOR]