1,721,021 research outputs found
An energy-based design for seismic resistant structures with viscoelastic dampers
No full textThe present paper aims at studying the seismic response of structures equipped with viscoelastic dampers (VED). The performance of such a passive control system is here analyzed using the energy balance concept, which leads to an optimal design process. The methodology is based on an energy index (EDI) whose maximization permits determination of the optimal mechanical characteristics of VED. On the basis of a single degree of freedom model, it is shown that the maximum value of EDI corresponds to a simultaneous optimization of the significant kinematic and static response quantities, independently of the input. By using the proposed procedure, the optimal design of new and existing structures equipped with VED, inserted in traditional bracing systems, are here analyzed and discusse
A NOVEL MACHINE LEARNING BASED FRAMEWORK FOR THE SEISMIC RISK ASSESSMENT OF INDUSTRIAL PLANT
No full textIn last decades, Machine learning techniques (ML) have been extensively studied as a possible reliable family of regression methods. Recently ML, which originated in the field of computer science, has been widely investigated as an alternative and helpful method for solving engineering problems. The main feature of ML techniques is learning from a dataset, containing a certain amount of input/output fidelity data, in order to predict future output data related to a new set of input data in cost-effective computation time. With these premises, the application of this type of techniques to the civil engineering field, where a sufficient amount of data is available by means numerical and experimental simulations and from structural monitoring, seems interesting. Along this vein, the present paper aims to investigate the suitability of a novel ML based framework for the risk assessment of a Non Structural Component (NSC) of an industrial plant. The proposed method, which aims to solve some critical issues associated to the traditional risk assessment methodology, has the follow main advantages: (i) reduction of computational time by means an Artificial Neural Network (ANN) surrogate model; (ii) avoidance of prior assumptions on the distribution of fragility curves, sampling a large amount of data from the ANN surrogate model; (iii) avoidance of the record to record variability of the seismic input through a new record selection algorithm; (iv) integration of hazard and vulnerability analysis in the same framework. In this respect, a comprehensive sensitivity analysis of the ANN input parameters is performed (features selection), identifying the type and number of Intensity Measures (IMs) that represent the seismic input best related to the structural output, using Principal Component Analysis (PCA). Furthermore, a multiple stripe analysis is performed on a nonlinear finite element model (FEM) of the structure, deriving the set of data used to train and validate the ANN. Then, two different surrogate models in series are derived, investigating the architecture of the models (i.e. the number of hidden layers and parameters weight), to take into account both the dependence between the selected IMs and the relation between the IMs and the structural response. Different training and test subsets are used to derive the surrogate models, to find the best-performing structure. A sampling of the seismic input parameters of the ANN is obtained followed their probability distribution by means Metropolis-Hastings algorithm, to take in account the hazard of the site, and the risk assessment is directly carried out from the observed damage evaluated. The proposed framework, which represents an interesting alternative for seismic risk assessment, is finally applied to an industrial NSC
Performance-Based Earthquake Engineering Analysis of Short-Medium Span Steel-Concrete Composite Bridges
No full textIn this paper, the results of the performance-based earthquake engineering (PBEE) analysis, carried out to assess the seismic behaviour of short-medium span steel-concrete composite I-girder bridges, are presented and discussed. The selected case study is part of a group of bridges analysed within the SEQBRI project, funded in 2012 by the European Union, which deals with a systematic development of the PBEE analysis for short-medium span steel-concrete composite I-girder bridges. In this respect, fragility and damage analysis of the selected bridge are performed using a proper component-based numerical model along with wide experimental campaign. These outcomes are then integrated in the decision-making analysis, where the selected decision variable is the repair cost ratio of the bridge. The results show the good performances of short medium span steel-concrete composite bridges, both for minor and major damage scenarios
SI: Natech risk assessment of hazardous facilities
No full textIndustrial plants are prone to be highly damaged when subjected to strong earthquakes. This has been clearly demonstrated in the aftermath of strong seismic events, which may trigger technological accidents usually termed natural-technological (NaTech) events. One of the most famous examples is represented by the Fukushima disaster during the 2011 Tohoku Earthquake. Nevertheless, the effort in developing new design/assessment methodologies is becoming more and more important as clearly proven by the rapid increase of the scholarly contributions on this topic. In this respect, Performance Based Earthquake engineering, which has seen rapid growth in the field of civil structures, can still be considered rather new in the world of industrial facilities because of the neuralgic role of the consequence analysis, necessary to quantify the individual or societal risk. Moreover, the recent activity on the second generation of Eurocodes—and in particular on EN1998:4 dedicated to industrial equipment like silos, storage tanks, chimneys, towers, and masts—makes urgent the identification of the most recent contributions on the topic.
This Special Issue, titled Natech Risk Assessment of Hazardous Facilities, promoted by the Guest Editors, Fabrizio Paolacci, Christoph Butenweg and Dimitrios Vamvatsikos, aims to bring together the latest methodologies and techniques for a reliable assessment of NaTech risk and resilience of hazardous facilities. Contributions come from researchers and industry professionals, strongly involved in the activity of Working Group 13 that is working on seismic assessment, design and resilience of industrial facilities within the European Association of Earthquake Engineering. A total 10 papers have been accepted that cover many of the key topics related to NaTech events and consequences in industrial facilities. In particular: (1) hazard issues in NaTech risk assessment, (2) Advanced methodologies for earthquake-related NaTech risk assessment, (3) Seismic analysis of critical non-structural components, (4) Design of safety barriers to control seismic risk of hazardous plants, (5) Performance-based design/assessment of hazardous industrial facilities, (6) Resilience of industrial facilities and neighboring communities.
In the first paper, devoted to topic 1 and titled “The new seismic hazard model ESHM20 of Europe: Investigating the implications to the seismic design and risk assessment of major industrial facilities across Europe”, by Pitilakis K., Butenweg C., Riga E., Apostolaki S., Renault F., a large-scale study of the impact of the potential adoption of the 2020 European Seismic Hazard model (ESHM20) on the design of new industrial facilities as well as on the potential seismic risk of existing plants at European level with respect to the national seismic codes is presented. Based on the conducted illustrative studies, the consequences of a potential adoption of the revised Eurocode 8 and ESHM20 hazard maps are discussed and summarized in view of the harmonisation process in Europe.
The second paper titled “Risk‐targeted seismic design of the freeboard for steel storage tanks equipped with floating roofs” by Caprinozzi S., Žižmond J., Dolšek M., and developed within topic 2, proposes an original method for the quantification of the loss of containment due to seismically-induced liquid overtopping of tanks with floating roofs, which is addressed by introducing a risk-targeted freeboard seismic design. The proposed practice-oriented procedure can be applied to new or existing tanks for which the freeboard was designed based on the tank wall height or liquid height, respectively. It combines the conventional seismic risk equation, and the code-based equation for the maximum vertical liquid displacement at the tank wall corresponding to the seismic action. Parametric studies were conducted to obtain insights into the sensitivity of risk-targeted freeboards to the design input parameters. A design procedure was also used to develop risk-targeted freeboard maps for Slovenia.
Given the attention that the scientific community is paying on topic 3, its growth is accelerating. In the industrial field the role of ancillary elements is recognized to be of vital importance because even a simple (nonstructural) failure could result in severe consequences. In this respect the third paper titled: “Acceleration‐sensitive ancillary elements in industrial facilities: alternative seismic design approaches in the new Eurocode” by Kazantzi, A. K., Karaferis N. D., Melissianos V. E., Vamvatsikos D., undertakes a comparison study to investigate the seismic performance of ancillary elements in industrial facilities that are designed according to the regulations prescribed by the three design routes offered in the 2022 revised version of Eurocode 8. With respect to ancillary elements in the civil field, the design methodologies offered in Eurocode 8 – Part 4 (prEN 1998–4:2022) are less sensitive to uncertainty in the properties of the supporting structure and the ancillary elements and hence deliver design products that possess consistently safe seismic performance even in cases where a component finds its vibration period accidentally tuned to the period of the supporting structure.
Safety barriers is another critical aspect in designing new industrial facilities or mitigating the seismic vulnerability of existing ones. In this respect the fourth paper titled: “Seismic vibration mitigation of steel storage tanks by metafoundations endowed with linear and bistable columns” by Guner T. Bursi O.S., Broccardo M., a new mitigation strategy for seismic mitigation of typical storage tanks is proposed, where extreme loading conditions are considered by safe shutdown earthquakes. To protect the tank from strong earthquakes, finite locally-resonant multiple-degree-of freedom metafoundations were designed and developed; resonator parameters together with bistable columns were optimized by means of an improved time domain multiobjective optimization procedure. The performance of the optimized metafoundations was assessed by means of time history analyses and results were compared with a storage tank endowed with two rigid foundation solutions.
A group of four papers are devoted to topic 5. The fifth paper is titled “The Generalized E-DVA Method: A New Approach For Multi-modal Pushover Analysis Under Multi-component Earthquakes With Local Variables Maximization” by Lherminier O., Erlicher S., Huguet M., Civera, M., Ceravolo R., Barakat M.; it deals with a new pushover analysis approach for structures in hazardous plants subjected to seismic NaTech risk. The procedure applies a linear combination of modal load patterns, defined accordingly to the well-established Direct Vectorial Addition (DVA) method. With respect to other existing multi-modal pushover analysis techniques, elliptical response envelopes are employed to calculate the corresponding combination factors.
The sixth paper titled “Do soft soil layers reduce the seismic kinematic distress of onshore high-pressure gas pipelines?” by Makrakis N., Psarropoulos P.N., Sextos A., Tsompanakis Y., recognizes the importance of onshore high-pressure gas pipelines as critical infrastructure that usually cross seismic—prone regions and are vulnerable to permanent ground deformations due to active seismic faults. The study investigates the impact of soft soil layers on the seismic kinematic distress of onshore gas pipelines. An extensive parametric analysis is performed considering different faulting mechanisms and fault dip angles, as well as soil geometry and mechanical properties. The outcome of the paper is a set of design charts and tables for the preliminary seismic design of onshore high-pressure gas pipelines based on the prediction of pipeline deformations.
The seventh paper titled “Field reconnaissance on seismic performance and functionality of Turkish industrial facilities affected by the 2023 Kahramanmaras earthquake sequence” by Sagbas G., Sheikhi Garjan R, Sarikaya K., Deniz D., analyzes the effects the recent catastrophic earthquakes in southeast Turkiye, affecting 15 million-residents and a significant portion of its industrial community. The inspection results show that the earthquake sequence had a significant impact on industrial facilities, resulting in enormous economic losses and business disruptions lasting three months to two years. The most affected facilities were found to be those built before 2000, as well as precast reinforced concrete structures with pin-supported roofs. As a result, these types of facilities in earthquake-prone areas are strongly advised to be re-evaluated. Furthermore, various nonstructural building components, such as infills, claddings and equipment/machinery, were substantially damaged at the majority of the assessed sites, causing lengthy interruptions.
An interesting investigation on seismic performance of slender storage tanks is offered by Holtschoppen B., Knoedel P. in the eighth paper titled “Seismic response of slender storage tanks on tube feet or skirt support”. Slender storage tanks on tube feet or skirt support are essential components of industrial facilities and often contain large amounts of hazardous liquids. A procedure is suggested that lowers the overall stress resultants by calculating the hydrodynamic pressure and load components as a function of the geometrical characteristics of the tank. The general concept was developed for flat bottom tanks but can be transferred—with certain adjustments—to the considered slender storage tanks on tube feet or skirts. Its capability for design load reduction in comparison to the simplified calculation method is shown on an example case study.
Papers nine and ten are devoted to quantitative NaTech risk and resilience estimation. The paper titled “A probabilistic framework for the estimation of resilience in major-hazard industrial plants under seismic loading” by Kalemi B., Caputo A.C., Corritore C., Paolacci F., presents a probabilistic process flow-based framework for assessment of industrial plant resilience and economic losses in case of seismic events. Uncertainties are considered in the ability of plant equipment to withstand the disruption, and also in the recovery process including equipment recovery durations and recovery costs. Monte Carlo Simulation is used to account for the uncertainties of the model. A black carbon plant is used as a case study to show the applicability of the model. Results and capability of the proposed model shows that it can be a useful tool for decision makers, plant owners, insurance companies, emergency managers and plant designers in their decision-making process.
The last paper titled “Seismic Risk and Resilience Analysis of Industrial Facilities” by Tabandeh A., Sharma N., Gardoni P., proposes a formulation to model the functionality of interacting industrial facilities and infrastructure using a system of coupled differential equations, representing dynamic processes on interdependent networked systems. The equations are subject to uncertain initial conditions and have uncertain coefficients, capturing the effects of uncertainties in earthquake intensity measures, structural damage, and post-disaster recovery process. The paper presents a computationally tractable approach to quantify and propagate various sources of uncertainty through the formulated equations. The paper illustrates the proposed approach for the seismic resilience analysis of a hypothetical but realistic shipping company in the city of Memphis in Tennessee, United States. The example models the effects of dependent water and power infrastructure systems on the functionality disruption and recovery of networked industrial facilities subject to seismic hazards.
The Guest Editors of this special issue would like to express their sincere gratitude to all authors for their valuable contributions that will certainly represent a reference point for the risk and resilience evaluation of the process industries in the future. Finally, they want to express their appreciation to the Chief Editor Prof. Atilla Ansal for embracing and helping this special issue to come to fruition.
References
Caprinozzi S, Žižmond J. Dolšek M, Risk-targeted freeboard for steel storage tanks equipped with single deck floating roof. https://doi.org/10.1007/s10518-022-01564-z
Guner T, Bursi OS, Erlicher S, Seismic mitigation performance of periodic foundations for small modular reactors based on linear, nonlinear and bistable behavior. https://doi.org/10.1007/s10518-023-01692-0
Holtschoppen B, Knödel P, Seismic response of slender storage tanks on tube feet or skirt support. https://doi.org/10.1007/s10518-023-01704-z
Kalemi B, Corritore D, Caputo A, A probabilistic framework for the estimation of resilience in major-hazard industrial plants under seismic loading
Kazantzi N, Karaferis V, Melissianos, Vamvatsikos D, Acceleration-sensitive ancillary elements in industrial facilities: alternative seismic design approaches in the new Eurocode. https://doi.org/10.1007/s10518-023-01656-4
Lherminier O, Erlicher S, Huguet1 M, Civera M, Ceravolo R, Barakat M, The Generalized E-DVA Method: A New Approach For Multi-modal Pushover Analysis Under Multi-component Earthquakes With Local Variables Maximization. https://doi.org/10.1007/s10518-023-01790-z
Makrakis N, Psarropoulos PN, Sextos A, Tsompanakis Y, Do soft soil layers reduce the seismic kinematic distress of onshore high-pressure gas pipelines? https://doi.org/10.1007/s10518-023-01668-0
Pitilakis K, Butenweg C, Riga E, Apostolaki S, The new seismic hazard model ESHM20 of Europe: implications to the seismic design and risk assessment of major industrial facilities across Europe. https://doi.org/10.1007/s10518-023-01661-7
Sagbas G, Garjan RS, Sarikaya K, Deniz D, Field reconnaissance on seismic performance and functionality of Turkish industrial facilities affected by the 2023 Kahramanmaras earthquake sequence. https://doi.org/10.1007/s10518-023-01741-8
Tabandeh A, Sharma N, Gardoni P, Seismic Risk and Resilience Analysis of Industrial Facilities. https://doi.org/10.1007/s10518-023-01728-
Seismic response mitigation of chemical plant components by passive control techniques
No full textThis paper deals with the applicability of seismic passive control in major-hazard chemical installations.
The objective is to show numerically and experimentally the applicability of Passive Control Techniques
(PCT) in industrial plants. Consequently, the main components of a process plant are classified and
collected into a limited number of classes; for each class, the main damages caused by past earthquakes
are described and the most vulnerable components are identified. A synthesis of the effects of earthquakes
on the different typologies of process components is also presented and the most suitable
innovative seismic protection systems, in particular passive control techniques (PCT), are acknowledged.
Finally, the effectiveness of PCT in reducing the seismic response of process plant components is proved
by three representative case studies: a base isolated above-ground storage tank, a distillation column
connected by elastoplastic dampers to the adjacent service frame and an application of non-conventional
Tuned Mass Dampers to a support frame
Artificial Neural Network Technique for Seismic Fragility Analysis of a Storage Tank Supported by Multi-Storey Frame
No full textA Fragility function, which defines the conditional probability of exceeding a limit state given an intensity measure of the earthquake, is an essential ingredient of modern approaches like the performance-based earthquake engineering methodology. However, the generation of such curves generally entails a high computational effort to account for epistemic and aleatory uncertainties associated with structural analysis and seismic load. Moreover, a certain probability function, such as the log-normal distribution, is usually assumed in order to carry out the conditional probability of failure of a structure, without any prior information on the correct probability distribution. In this paper, an artificial neural network model is proposed to carry out fragility curves in order to avoid the aforementioned problems. In this respect, this paper investigates the following aspects: (i) implementation of an efficient algorithm to select proper seismic intensity measures as inputs for artificial neural network, (ii) derivation of surrogate models by using the artificial neural network techniques, (iii) computation of fragility curves by means Monte Carlo Simulations, and (iv) validation phase
Seismic risk assessment of liquid overtopping in a steel storage tank equipped with a single deck floating roof
No full textMajor earthquakes have demonstrated that Natech events can be triggered by liquid overtopping in liquid storage tanks equipped with floating roofs. Thus, research on the dynamic behaviour of steel storage tanks with floating roofs is still required. In this paper, the seismic risk against liquid overtopping in a real steel storage tank with a floating roof was analysed using a simplified model that was validated by a refined finite element model based on the arbitrary Lagrangian-Eulerian approach. The simplified model utilizes the Lagrangian of a floating roof-fluid system and is capable of providing a response history of the floating roof. It was demonstrated that it could predict the maximum vertical displacement very accurately, while some differences were observed in the response history of vertical displacement. The computational time for a single response history analysis based on the simplified model amounted to a few minutes, which is significantly less demanding compared to hours required for response history analysis in the case of the refined FE model. The simplified model is thus appropriate for the seismic fragility analysis considering the overtopping limit state. It is shown that the fragility curves are significantly affected by the liquid filling level. The risk for liquid overtopping is quite high in the case of a full tank. However, by considering the variation of filling level during the year, the overtopping risk was observed reduced by approximately 30%. Alternatively, the approximate fragility analysis for the liquid overtopping can be performed by utilizing the Eurocode formula for the vertical displacement of liquid. This approach is straightforward, but the formula does not account for the higher mode effects, which may result in overestimated seismic intensity causing overtopping, as discussed in the paper
Un approccio aleatorio per la valutazione di un indice in problemi di controllo passivo di sistemi a smorzamento lineare
No full textON THE USE OF ARTIFICIAL NEURAL NETWORK TECHNIQUE FOR SEISMIC FRAGILITY ANALYSIS OF A THREE-DIMENSIONAL INDUSTRIAL FRAME
No full textFragility function that defines the probability of exceedance of a damage state given a ground motion intensity (IM) is an essential ingredient of modern approaches to seismic engineering as the performance-based earthquake engineering methodology. Epistemic as well as aleatory uncertainties associated with seismic loads and structural behavior are usually taken into account to analytically develop such curves. However, structural analyses are time-consuming, requiring generally a high computational effort. Moreover, the conditional probability of failure is usually computed by regression analysis assuming predefined probability functions, like the log-normal distribution, without prior information on the real probability distribution. To overcome these problems, the artificial neural network (ANN) technique is used for the development of structural seismic fragility curves considering record-to-record variability and structural parameter uncertainties. In this respect, the following aspects are addressed in this paper: (a) implementation of an efficient algorithm to select IMs as inputs for ANN, selecting the most relevant ones; (b) derivation of surrogate models by using the ANN technique, c) computation of fragility curves with Monte Carlo Simulations method and verification of the validity. These methods enable the implicit treatment of uncertainty in either or both of ground motion intensity and structural properties without making any prior assumption about the probability function. This methodology is then applied to estimate the probability of failure of a nonstructural component (NSC), i.e., vertical tank, located on a typical three-dimensional industrial frame. First, an extensive sensitivity analysis on the ANN input parameters is performed (feature selection), identifying the type and number of seismic intensity measures (amplitude-based, frequency-based, and time-based IM). Then different surrogate models are derived investigating the number of hidden layers and parameters. A multiple stripe analysis is then performed on a nonlinear model of the structure, deriving the set of data for the ANN. Different training and test subsets are used to derive the surrogate model. Finally, a Monte Carlo simulation is performed to derive the fragility curves for the limit state considered. Finally, the risk assessment is obtained, evaluating the mean annual rate of failure of the NSC
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