Spif |

UQ state-dependent framework for seismic fragility assessment of industrial components

Mon, 01 Sep 2025 00:00:00 +0000

Abstract

Recently, there has been increased interest in assessing the seismic fragility of industrial plants and process equipment. This is reflected in the growing number of studies, community-funded research projects and experimental campaigns on the matter. Nonetheless, the complexity of the problem and its inherent modelling, coupled with a general scarcity of available data on process equipment, has limited the development of risk assessment methods. In fact, these limitations have led to the creation of simplified and quick-to-run models. In this context, we propose an innovative framework for developing state-dependent fragility functions. This new methodology combines limited data with the power of metamodelling and statistical techniques, namely polynomial chaos expansions (PCE) and bootstrapping. Therefore, we validated the framework on a simplified and computationally efficient MDoF system endowed with Bouc–Wen hysteresis. Then, we tested it on a real nonstructural industrial process component. Specifically, we applied the state-dependent fragility framework to a critical vertical tank of a multicomponent full-scale 3D steel braced frame (BF). The seismic performance of the BF endowed with process components was captured by means of shake table campaign within the European SPIF project. Finally, we derived state-dependent fragility functions based on the combination of PCE and bootstrap at a greatly reduced computational cost.

Suggerimento

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State-dependent seismic fragility functions for bolted flange joints on special-risk industrial substructures

Sun, 28 Jul 2024 00:00:00 +0000

Abstract

Seismic vulnerability assessment of industrial plants and process equipment has gained attention lately. However, the complexity of the problem and its modelling, combined with a general scarcity of available data on industrial systems, contributed to limiting or developing risk assessment methods based on extremely simplified models. On these premises, a new methodology that combines limited data from finite element (FE) models with cutting-edge machine learning techniques is developed to generate state-dependent fragility functions for critical components mounted on archetypical industrial substructure modules. Specifically, referring to the classical forward uncertainty quantification scheme, a physics-informed FE model, calibrated on the results of a comprehensive shake table test campaign of a real-scale industrial braced-frame (BF) steel substructure, is considered. Time histories of seismic event sequences generated by a site-based ground motion model compose the input provided to the FE model. The uncertainty is then propagated through Monte Carlo analysis on inexpensive-to-run polynomial chaos expansion (PCE) metamodels set for each starting damage level condition measure. As a result, empirical state-dependent fragilities are evaluated, assuming the lognormal distribution.

Suggerimento

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State-dependent seismic fragility functions for vertical tanks installed on major hazard industrial substructure module

Mon, 01 Jul 2024 00:00:00 +0000

Abstract

Suggerimento

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Modelling of non-structural components of an industrial multi-storey frame for seismic risk assessment

Thu, 07 Sep 2023 00:00:00 +0000

Abstract

Seismic risk assessment of industrial facilities is complex due to the presence of different types of equipment. It represents a research issue that requires further investigation. To this end, some analytical approaches have been developed in the framework of performance-based earthquake engineering. Nonetheless, their accuracy in the case of complex critical facilities, such as nuclear and non-nuclear industrial plants, is still under investigation. Thus, the proposed study intends to research in depth, in a risk assessment framework, some critical aspects related to: (1) modelling of industrial facilities and their secondary equipment with different degrees of accuracy, also taking into account their dynamic interaction; (2) selection of seismic records for fragility analysis, due to the narrow distribution of frequency values for non-structural components; (3) effectiveness of performance-based earthquake engineering applied to this particular class of coupled structure-equipment for risk assessment. In this context, the proper selection of seismic records becomes relevant, and SCoRes, an innovative algorithm for accelerograms selection is worthy of investigation. On these premises, two different configurations of a primary industrial structure, i.e. a moment resisting frame and a braced frame, equipped with non-structural components and subjected to shake table test campaigns are selected as case studies. For the two configurations, a vulnerability assessment of two vertical tanks installed on the first floor was carried out. Along these lines, to establish the effectiveness of the proposed method for both the moment resisting frame and braced frame configurations, the mean annual frequency of exceedance of the bottom-wall strain of the above-mentioned tanks, both at the design basis and safe shutdown earthquake has been evaluated.

Suggerimento

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Seismic experimental analyses and surrogate models of multi-component systems in special-risk industrial facilities

Thu, 22 Dec 2022 00:00:00 +0000

Abstract

Nowadays, earthquakes are one of the most catastrophic natural events that have a significant human, socio-economic and environmental impact. Besides, based on both observations of damage following recent major/moderate seismic events and numerical/experimental studies, it clearly emerges that critical non-structural components (NSCs) that are ubiquitous to most industrial facilities are particularly and even disproportionately vulnerable to those events. Nonetheless and despite their great importance, seismic provisions for industrial facilities and their process equipment are still based on the classical load-and-resistance factor design (LRFD) approach; a performance-based earthquake engineering (PBEE) approach should, instead, be preferred. Along this vein, in recent years, much research has been devoted to setting computational fragility frameworks for special-risk industrial components and structures. However, within a PBEE perspective, studies have clearly remarked: i) a lack of definition of performance objectives for NSCs; ii) the need for fully comprehensive testing campaigns data on coupling effects between main structures and NSCs. In this respect, this doctorate thesis introduces a computational framework for an efficient and accurate seismic state-dependent fragility analysis; it is based on a combination of data acquired from an extensive experimental shake table test campaign on a full-scale prototype industrial steel frame structure and the most recent surrogate-based UQ forward analysis advancements. Specifically, the framework is applied to a real-world application consisting of seismic shake table tests of a representative industrial multistorey frame structure equipped with complex process components, carried out at the EUCENTRE facility in Italy, within the European SPIF project: Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities. The results of this experimental research campaign also aspire to improve the understanding of these complex systems and improve the knowledge of FE modelling techniques. The main goals aim to reduce the huge computational burden and to assess, as well, when the importance of coupling effects between NSCs and the main structure comes into play. Insights provided by innovative monitoring systems were then deployed to develop and validate numerical and analytical models. At the same time, the adoption of Der Kiureghian’s stochastic site-based ground motion model (GMM) was deemed necessary to severely excite the process equipment and supplement the scarcity of real records with a specific frequency content capable of enhancing coupling effects. Finally, to assess the seismic risk of NSCs of those special facilities, this thesis introduces state-dependent fragility curves that consider the accumulation of damage effects due to sequential seismic events. To this end, the computational burden was alleviated by adopting polynomial chaos expansion (PCE) surrogate models. More precisely, the dimensionality of a seismic input random vector has been reduced by performing the principal component analysis (PCA) on the experimental realizations. Successively, by bootstrapping on the experimental design, separate PCE coefficients have been determined, yielding a full response sample at each point. Eventually, empirical state-dependent fragility curves were derived.

Suggerimento

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Experimental performance of a multi-storey braced frame structure with non-structural industrial components subjected to synthetic ground motions

Thu, 05 May 2022 00:00:00 +0000

Abstract

The seismic risk assessment of industrial facilities mainly relies on historical data and the analysis and design of uncoupled secondary components. Accordingly, the dynamic interaction between primary structures and process equipment is overlooked. The SPIF project - Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities - was carried out to respond to this gap, within the European H2020 SERA framework. Its objective regarded the investigation of the seismic behaviour of an archetype industrial multi-storey steel moment resisting frame (MRF) structure equipped with non-structural components (NSCs) by means of shaking table tests. The goal of the proposed study was to extend the interaction analysis between a primary multi-storey braced frame (BF) steel structure and NSCs in a performance-based earthquake engineering (PBEE) perspective. Along this vein, to excite the vibration periods of the NSCs and thus enhance possible coupling with the primary structure, a synthetic site-based ground motion model (GMM) was employed. More precisely, the proposed research intended: (i) to severely excite the process equipment and supplement the scarcity of real records with a specific frequency content by means of a stochastic GMM; (ii) to quantify seismic-induced force and displacement demands of secondary components and their effects on the primary BF structure. The evaluation of the experimental data clearly shows buckling in the bracing system of the BF configuration and a strong interaction between vertical tanks and floor crossbeams of the BF. At the very least, the favourable performance of the archetype BF under strong seismic records is demonstrated.

Suggerimento

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Seismic performance of an industrial multi-storey frame structure with process equipment subjected to shake table testing

Wed, 01 Sep 2021 00:00:00 +0000

Abstract

Past earthquakes demonstrated the high vulnerability of industrial facilities equipped with complex process technologies leading to serious damage of process equipment and multiple and simultaneous release of hazardous substances. Nonetheless, current standards for seismic design of industrial facilities are considered inadequate to guarantee proper safety conditions against exceptional events entailing loss of containment and related consequences. On these premises, the SPIF project - Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities - was proposed within the framework of the European H2020 SERA funding scheme. In detail, the objective of the SPIF project is the investigation of the seismic behaviour of a representative industrial multi-storey frame structure equipped with complex process components by means of shaking table tests. Along this main vein and in a performance-based design perspective, the issues investigated in depth are the interaction between a primary moment resisting frame (MRF) steel structure and secondary process components that influence the performance of the whole system; and a proper check of floor spectra predictions. The evaluation of experimental data clearly shows a favourable performance of the MRF structure, some weaknesses of local details due to the interaction between floor crossbeams and process components and, finally, the overconservatism of current design standards w.r.t. floor spectra predictions.

Suggerimento

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Experimental investigation on the seismic performance of a multi-component system for major-hazard industrial facilities

Tue, 13 Jul 2021 00:00:00 +0000

Abstract

Past earthquakes demonstrated the high vulnerability of industrial facilities equipped with complex process technologies leading to serious damage of the process equipment and multiple and simultaneous release of hazardous substances in industrial facilities. Nevertheless, the design of industrial plants is inadequately described in recent codes and guidelines, as they do not consider the dynamic interaction between the structure and the installations and thus the effect of seismic response of the installations on the response of the structure and vice versa. The current code-based approach for the seismic design of industrial facilities is considered not enough for ensure proper safety conditions against exceptional event entailing loss of content and related consequences. Accordingly, SPIF project (Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities) was proposed within the framework of the European H2020 - SERA funding scheme (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The objective of the SPIF project is the investigation of the seismic behaviour of a representative industrial structure equipped with complex process technology by means of shaking table tests. The test structure is a three-story moment resisting steel frame with vertical and horizontal vessels and cabinets, arranged on the three levels and connected by pipes. The dynamic behaviour of the test structure and of its relative several installations is investigated. Furthermore, both process components and primary structure interactions are considered and analyzed. Several PGA-scaled artificial ground motions are applied to study the seismic response at different levels. After each test, dynamic identification measurements are carried out to characterize the system condition. The contribution presents the experimental setup of the investigated structure and installations, selected measurement data and describes the obtained damage. Furthermore, important findings for the definition of performance limits, the effectiveness of floor response spectra in industrial facilities will be presented and discussed.

Suggerimento

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Shake table testing for a multi-component prototype industrial plant: input and system modelling issues

Tue, 13 Jul 2021 00:00:00 +0000

Abstract

Recent destructive earthquakes in China (Sichuan, 2008 and Yushu, 2010), Japan (Tohoku, 2011) and Italy (Emilia, 2012) highlighted the social and the political consequences of seismic risk due especially to industrial facilities. More precisely, critical interactions between the supporting structure and process components reveal to be extremely vulnerable in a seismic scenario and capable to lead serious damage of process equipment and potential release of hazardous substances. This latter circumstance, underestimated by current codes, in addition to loss of production, pose a serious danger to humans and the surrounding environment. Based on these premises, the SPIF project - Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities - was proposed within the framework of the European H2020 - SERA funding scheme. In greater detail, the goal of the project is the investigation of both the seismic behavior and the dynamic interactions of a representative industrial substructure equipped with complex process technology by means of shaking table tests. A full-scale mock-up composed by two single-bay moment resisting frames with three floors equipped with tanks, flanges, pipes, cabinet etc. was built and tested using a unidirectional shaking table activated with several earthquake levels. More precisely, the salient features investigated by shaking table testing are: i) the interaction between a primary moment resisting frame steel structure and secondary process components that influence the performance of the whole system; ii) input and system modelling capable to faithfully reproduce the seismic response of SPIF tested structure. The comprehensive testing campaign demonstrated a clear dynamic interaction between the primary steel structure and secondary process units that emphasizes the need of further investigations and studies.

Suggerimento

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Bolted flange joints equipped with FBG sensors in industrial piping systems subjected to seismic loads

Sat, 26 Jun 2021 00:00:00 +0000

Abstract

The vulnerability of major-hazard industrial plants to natural hazards has been recognized as an emergent issue whose importance is underlined by the Sendai Framework, established immediately after the Tohoku earthquake of 2011, in Japan. Hence, seismic risk analysis is of paramount importance as testified by the intense research activity that characterized the last years. In this respect, structural health monitoring can represent a valuable tool able to strongly help the decision-making phase. Along this main vein, optical fibers (OFs) represent a class of sensors able to both monitor critical conditions, as leakage of hazardous material, and activate safety barriers, if any. More precisely, optical fibers represent an economic solution, whose characteristics appear particularly suitable for dangerous environments like major-hazard plants. However, investigations relevant to their use for seismic monitoring of chemical/petrochemical plants are rather limited, especially when subject to strong dynamic excitations. As a result, this paper deals with the analysis of optical fiber Bragg gratings (FBGs) applied to bolted flange joints (BFJ) under cyclic loadings. More precisely, two experimental programs, i.e., a cyclic test on a single BFJ and a series of shaking table tests on BFJs of a multicomponent system, demonstrated the effectiveness of the proposed monitoring systems in detecting hazardous conditions and, thus, their potential use in conjunction with safety barriers.

Suggerimento

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SPIF Processed Dataset

Fri, 01 Jan 2021 00:00:00 +0000

Abstract

Processed experimental dataset of the SPIF project (Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities), carried out within the European H2020 SERA Transnational Access programme at the EUCENTRE laboratories in Pavia, Italy. The dataset collects the processed measurements of the shake table test campaign on a full-scale, three-storey industrial steel frame structure, tested in moment resisting frame and braced frame configurations, equipped with vertical and horizontal tanks, a cabinet and piping networks with bolted flange joints. It includes input ground motions and the acceleration, displacement and strain responses of both the primary structure and the non-structural process components.

Suggerimento

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Seismic performance of multiple-component systems in special risk industrial facilities

Fri, 18 Sep 2020 00:00:00 +0000

Abstract

Past earthquakes demonstrated the high vulnerability of industrial facilities equipped with complex process technologies leading to serious damage of the process equipment and multiple and simultaneous release of hazardous substances in industrial facilities. Nevertheless, the design of industrial plants is inadequately described in recent codes and guidelines, as they do not consider the dynamic interaction between the structure and the installations and thus the effect of seismic response of the installations on the response of the structure and vice versa. The current code-based approach for the seismic design of industrial facilities is considered not enough for ensure proper safety conditions against exceptional event entailing loss of content and related consequences. Accordingly, SPIF project (Seismic Performance of MultiComponent Systems in Special Risk Industrial Facilities) was proposed within the framework of the European H2020 - SERA funding scheme (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The objective of the SPIF project is the investigation of the seismic behavior of a representative industrial structure equipped with complex process technology by means of shaking table tests. The test structure is a three-story moment resisting steel frame with vertical and horizontal vessels and cabinets, arranged on the three levels and connected by pipes. The dynamic behavior of the test structure and installations is investigated with and without base isolation. Furthermore, both firmly anchored and isolated components are taken into account to compare their dynamic behavior and interactions with each other. Artificial and synthetic ground motions are applied to study the seismic response at different PGA levels. After each test, dynamic identification measurements are carried out to characterize the system condition. The contribution presents the numerical simulations to calibrate the tests on the prototype, the experimental setup of the investigated structure and installations, selected measurement data and finally describes preliminary experimental results.

Suggerimento

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Ground motion model for seismic vulnerability assessment of prototype industrial plants

Sun, 19 Jul 2020 00:00:00 +0000

Abstract

Relationships between seismic action, system response and relevant damage levels in industrial plants require a solid background both in experimental data, due to the high level of nonlinearity and seismic input. Besides, risk and fragility analyses depend on the adoption of a huge number of seismic records usually not available in a site-specific analysis. In order to manage these issues and to gain knowledge on the definition of damage levels, limit states and performance for major-hazard industrial plant components, we present a possible approach for an experimental campaign based on a real prototype industrial steel structure. The investigation of the seismic behaviour of the reference structure will be carried out through shaking table tests. In particular, tests are focused on structural or process-related interactions that can lead to serious secondary damages as leakage in piping systems or connections with tanks and cabinets. The aforementioned test program has been possible thanks to the adoption of: (i) a number of artificial spectrum-compatible accelerograms; (ii) a ground motion model (GMM) able to generate a suite of synthetic time-histories records for specified site characteristic and earthquake scenarios. More precisely, GMM model parameters can be identified by matching the statistics of a target-recorded accelerogram to the ones of the model in terms of faulting mechanism, earthquake magnitude, source-to-site distance and site shear-wave velocity. As a result, the stochastic model, based both on these matched parameters and on filtered white-noise process, can generate the ensemble of synthetic ground motions capable of capturing the main features of real earthquake ground motions, including intensity, duration, spectral content and peak values. Moreover, the synthetic records are selected to target specific damages and limit states in industrial components. Finally, by means of the combination of artificial and synthetic accelerograms, a seismic vulnerability assessment of both the whole structure and relevant industrial components

Suggerimento

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A ground motion model for seismic vulnerability assessment of prototype industrial plants

Wed, 24 Jun 2020 00:00:00 +0000

Abstract

Relationships between seismic action, system response and relevant damage levels in industrial plants require a solid background both in experimental data, due to the high level of nonlinearity, and in knowledge of seismic input due to large uncertainty. Besides, risk and fragility analyses depend on the adoption of a huge number of seismic records usually not available in a site-specific analysis. In order to manage these issues and to gain knowledge on the definition of damage levels, limit states and performance for major-hazard industrial plant components, we present a possible approach and discuss results of an experimental campaign based on a real prototype industrial steel structure. The investigation of the seismic behaviour of the reference structure has been carried on through shaking table tests, focusing in particular on the structural or process-related interactions that can lead to serious secondary damages as leakage in piping systems or connections with tanks and cabinets. This has been possible thanks to the adoption of a ground motion model (GMM) able to generate a suite of synthetic time-histories records for specified site characteristic and earthquake scenarios. In fact, model parameters can be identified by matching the statistics of a target-recorded accelerogram to the ones of the model in terms of faulting mechanism, earthquake magnitude, source-to-site distance and site shear-wave velocity. Hence, the stochastic model, based both on these matched parameters and on filtered white-noise process, generates the ensemble of synthetic ground motions capable to capture the main features of real earthquake ground motions, including intensity, duration, spectral content and peak values. Finally, by means of the combination of a high-fidelity and a low-fidelity FE model as well as the stochastic input generated by a GMM, a seismic vulnerability assessment of both industrial components and the global structure can be carried out.

Suggerimento

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Investigation of the seismic behaviour of structural and non-structural components in industrial facilities by means of shaking table tests

Wed, 04 Mar 2020 00:00:00 +0000

Abstract

Industrial facilities consist of a primary load-carrying structure and of process components, such as vessels, tanks, piping and cabinets, that can be seriously damaged by earthquakes. Within the SPIF project (Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities), funded by the European H2020 SERA Transnational Access programme, a full-scale three-storey industrial steel frame equipped with vertical and horizontal vessels, a cabinet and connecting pipes was tested on the shaking table of the EUCENTRE laboratories in Pavia, Italy. This contribution presents the test structure, its installations and the measurement plan, with accelerations and relative displacements of the components and pipe sections recorded at increasing peak ground acceleration levels, with the aim of supporting design recommendations for the seismic performance of vessels, pipes and their connections.

Suggerimento

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SPIF - Prestazioni sismiche degli impianti industriali

Mon, 01 Jan 0001 00:00:00 +0000

Obiettivi del progetto

L’obiettivo del progetto (Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities) è lo studio olistico del comportamento sismico di impianti industriali dotati di tecnologie di processo complesse, tramite prove su tavola vibrante.

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