Probabilistic seismic assessment of a high-rise URM building
TL;DR: In this paper, a detailed quantification of the uncertainties related to the mechanical properties of this construction material is conducted, and the influence of this variability on the seismic performance of a representative building model of the Eixample district in Barcelona, Spain, is analyzed.
Abstract: According to the Sendai Framework for Disaster Risk Reduction (2015–2030), disasters have demonstrated that the recovery, rehabilitation and reconstruction phase, which needs to be prepared ahead of a disaster, is a critical opportunity to “Build Back Better”, integrating disaster risk reduction into development measures. In this respect, a significant number of structures, that constitute several European urban nuclei, belong to old constructive typologies, which were designed and built without any consideration for the seismic hazard. One of the most used typologies exhibiting this shortcoming is unreinforced masonry (URM). Therefore, an important step towards increasing resilience of European cities is to deeply understand the seismic behavior of this frequent typology. In order to do so properly, detailed probabilistic nonlinear building models should be developed. However, including the uncertainties associated with this typology is challenging due to the heterogeneity of the different manufacturing techniques, executed under primitive industrial standards, and to the construction techniques, which are dependent on regional uses and criteria in a pre-code scenario. The object of this research is twofold. First, a detailed quantification of the uncertainties related to the mechanical properties of this construction material is conducted. Then, the influence of this variability on the seismic performance of a representative building model of the Eixample district in Barcelona, Spain, is analysed. This building typology represents 72% of the building stock in this district with an average age of 90 years, which means that the construction practice, at that time, was only regulated by early council guidelines that are considered pre-code rules. Specifically, the probabilistic approach is illustrated with a case study performed on an existing seven-story (high-rise) URM. A detailed numerical model of this structure has been developed and randomized taking into account the variability of the material properties. Accordingly, 1000 models were generated and analysed by considering as input different sets of material random variables. The compressive strength, Young modulus, shear modulus and shear strength are chosen and modelled to encompass the material uncertainties. The seismic response of each variant (i.e. selected set of mechanical properties) is obtained through a simplified non-linear static procedure aiming to compare and categorize the influence of the probabilistic input on the seismic performance of the building. Results are presented in terms of correlations between damage parameters and material properties. The analysis carried out shows that the variability in the material properties generates significant uncertainties in the seismic response of URM buildings, leading to over or underestimate expected damage when compared with results based on approaches that do not consider the probabilistic nature of the problem.
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16 citations
TL;DR: In this article , a review of the seismic resiliency studies performed in the recent decades, the frameworks for the quantification assessment of the community resilience are explained, and several case studies for community resilience and the application of different subsystems are reviewed and elaborated in this paper.
Abstract: Seismic resilience is a concept to evaluate the postearthquake functionality of structures that significantly play a critical role in postearthquake rescue and recovery. Indeed, the community is made up of more than just buildings; it is also made up of other subsystems such as hospital and school facilities as well as roads, drainage systems, sewer systems, and electrical power transmission networks. In recent years, the concept of community resilience as a tool for disaster risk management has attracted substantial attention from all parties, such as governments, designers, decision-makers, and stakeholders. Community resilience can be assessed more effectively by using a multi-disciplinary approach that takes into account the community’s uncertainties, as opposed to a single-criteria approach. The global community resilience model must be long-term validated and dependent on the most vulnerable and low-resilience portions of the community, according to a prior study. According to the review of the seismic resiliency studies performed in the recent decades, the frameworks for the quantification assessment of the community resilience are explained. Moreover, several case studies for community resilience and the application of different subsystems are reviewed and elaborated in this paper. Based on these resilience studies, the main challenges on the effectiveness of the resilience assessment are the availability and accessibility of the data, the financial resources, and the cooperation from all the parties.
6 citations
TL;DR: In this paper , the authors proposed a probabilistic methodology that can consider the uncertainty coming from various random variables to assess seismic resilience for high-rise buildings, where a 42-story composite steel frame-RC core tube building is used to show the proposed method.
Abstract: This paper presents a probabilistic methodology that can consider the uncertainty coming from various random variables to assess seismic resilience for high-rise buildings. A 42-story composite steel frame-RC core tube building is used to show the proposed method. Uncertainties associated with the input loads, annual discount rate, cost ratio, recovery time and unknown parameters (or coefficients) in the demand model for fragility analysis are taken into consideration. Firstly, the Bayesian updating rule is applied to determine the posterior distribution of unknown parameters in the demand model. Then, the epistemic uncertainty of unknown model parameters is considered according to the full probability theory, which is the main novelty of this study. Additionally, the record-to-record method is adopted to consider the uncertainty associated with input seismic ground motions. Furthermore, the Monte-Carlo simulation is used to generate samples of the annual discount rate, cost ratio and recovery time accounting for the impacts of their uncertainties on the structural functionality loss and seismic resilience. It can be concluded that the epistemic uncertainty associated with unknown parameters in the demand model has significant impacts on the fragility estimates and seismic resilience. This study provides an effective way to incorporate the uncertainty of various random variables into the seismic resilience assessment, which is helpful for the decision-makers to implement appropriate mitigation strategies . • A Bayesian-based method is presented to consider the epistemic uncertainty of unknown parameters for fragility analysis. • The Monte-Carlo simulation is used to consider uncertainties in the annual discount rate, cost ratio and recovery time. • This study offers a practical method for seismic resilience assessment of tall buildings with various uncertain parameters.
6 citations
TL;DR: In this article , the authors present integrated constructive solutions that combine both energy efficiency improvement and seismic strengthening, and evaluate one-shot, compatible, noninvasive, and complementary solutions applied to the façades of buildings with a minimum cost.
Abstract: The European building stock is an aging infrastructure, mainly built prior to building codes. Furthermore, 65% of these buildings are located in seismic regions, which need to be both energetic and seismically retrofitted to comply with performance targets. Given this, this manuscript presents integrated constructive solutions that combine both energy efficiency improvement and seismic strengthening. The goal and novelty is to design and to evaluate one-shot, compatible, noninvasive, and complementary solutions applied to the façades of buildings with a minimum cost. To do so, different constraints have been borne in mind: the urban environment, achievable seismic and energy performance targets, and reduced construction costs. The method was applied to an old Spanish neighbourhood constructed in the 1960s. Different retrofitting packages were proposed for an unreinforced masonry case study building. A sensitivity analysis was performed to assess the effects of each configuration. A benefit/cost ratio was proposed to comparatively assess and to rank the solutions. The results of the seismoenergetic performance assessment showed that improving the behaviour of walls leads to higher benefit ratios than improving the openings. However, this latter strategy generates much lower construction costs. Integrating seismic into energetic retrofitting solutions supposes negligible additional costs but can improve the seismic behaviour of buildings by up to 240%. The optimal solution was the addition of higher ratios of steel grids and intermediate profiles in openings while adding thermal insulation in walls and renovating the window frames with PVC and standard 4/6/4 double glazing.
2 citations
TL;DR: In this article , a critical review of integrated strategies combining seismic and energy refurbishment proposed in the literature is reported, including the feasibility of an integrated approach applied to heritage buildings, revealing that a fully efficient strategy for integrated retrofit has not still been proposed in literature and there are several open issues to be solved.
Abstract: The European building stock presents pertinent issues needing suitable strategies to be solved. In detail, this regards seismic safety and energy efficiency of buildings to ensure more liveable and safe cities, which represents an important goal for modern societies. Energy performance includes both comfort and saving, the latter required for a more responsible resource consumption within the building sector, having a considerable contribution to the total demand. Current strategies do not seem to be able to simultaneously solve such aspects satisfactorily, both for higher economic requirements and poor technical feasibility implied by separated and disharmonious interventions. Thus, a holistic perspective should be adopted to pursue such an ambitious objective, which has recently gained increasing attention among researchers. Current requirements are firstly highlighted to show the need for an integrated approach to building retrofit. Secondly, a critical review of integrated strategies combining seismic and energy refurbishment proposed in the literature is reported. Then, special issues are discussed, including the feasibility of an integrated approach applied to heritage buildings. This study revealed that a fully efficient strategy for integrated retrofit has not still been proposed in the literature and there are several open issues to be solved. However, current solutions may be further developed to improve them and the several options currently available demonstrated the increasing attention and importance of the topic. Finally, concluding remarks on this research topic have been drawn to promote future studies.
1 citations
References
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TL;DR: Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads as mentioned in this paper, which involves subjecting a structural model to one or more ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level.
Abstract: Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. It involves subjecting a structural model to one (or more) ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level. To establish a common frame of reference, the fundamental concepts are analysed, a unified terminology is proposed, suitable algorithms are presented, and properties of the IDA curve are looked into for both single-degree-of-freedom and multi-degree-of-freedom structures. In addition, summarization techniques for multi-record IDA studies and the association of the IDA study with the conventional static pushover analysis and the yield reduction R-factor are discussed. Finally, in the framework of performance-based earthquake engineering, the assessment of demand and capacity is viewed through the lens of an IDA study. Copyright © 2001 John Wiley & Sons, Ltd.
3,334 citations
Book•
29 Mar 1996
TL;DR: In this article, the authors focus on designing adequate displacement and ductility capacity into new bridges, with less significance placed on strength, where a strength hierarchy is established in a bridge to ensure that damage is controllable and occurs only where the designer intends.
Abstract: This book should be of interest to practicing bridge designers and researchers investigating the seismic design of bridges It is appropriate for graduate courses or upper level undergraduate courses in seismic design of bridges The approach relies heavily on the principles of capacity design, where a strength hierarchy is established in a bridge to ensure that damage is controllable and occurs only where the designer intends This approach, which is well established for seismic design of buildings, has been extended and modified to reflect the special demands and characteristics of bridges Particular emphasis is placed on designing adequate displacement and ductility capacity into new bridges, with less significance placed on strength The book is developed around two alternative design strategies: the traditional force-based approach where force levels are related to acceleration spectra, with checks to ensure adequate displacement capacity exists, and the newer displacement-based design approach, where displacements are the starting point in the design Introductory chapters discuss design philosophy and its impact on the performance of bridges in recent earthquakes, seismicity and soils effects, including liquefaction, in a form facilitating understanding by structural engineers, and the importance of rational consideration, from a seismic design viewpoint, of the various structural configuration possibilities in the conceptual design phase Extensive discussion of analysis is provided in Chapter 4, with emphasis on the importance of realistic modeling assumptions and appropriate choice of analytical tools Chapters 5 to 8 provide detailed information on the design of new bridges and the assessment and retrofit of existing bridges A separate chapter is devoted to design and retrofit using seismic isolation and dissipation devices Many design and analysis examples, some quite extensive in scope, are included Design aids in the form of charts and tables are also provided An index is provided
1,683 citations
TL;DR: In this article, the applicability of statistical inferences to seismic assessment procedures is discussed, and the application of statistical inference to seismic fragility functions is also discussed, using dynamic structural analysis.
Abstract: Estimation of fragility functions using dynamic structural analysis is an important step in a number of seismic assessment procedures. This paper discusses the applicability of statistical inferenc...
896 citations
TL;DR: In this paper, the idea of using inelastic demand spectra within the capacity spectrum method has been elaborated and is presented in an easy to use format, which represents the so-called N2 method formulated in the format of the Capacity Spectrum method.
Abstract: By means of a graphical procedure, the capacity spectrum method compares the capacity of a structure with the demands of earthquake ground motion on it. In the present version of the method, highly damped elastic spectra have been used to determine seismic demand. A more straightforward approach for the determination of seismic demand is based on the use of the inelastic strength and displacement spectra which can be obtained directly by time-history analyses of inelastic SDOF systems, or indirectly from elastic spectra. The advantages of the two approaches (i.e. the visual representation of the capacity spectrum method and the superior physical basis of inelastic demand spectra) can be combined. In this paper, the idea of using inelastic demand spectra within the capacity spectrum method has been elaborated and is presented in an easy to use format. The approach represents the so-called N2 method formulated in the format of the capacity spectrum method. By reversing the procedure, a direct displacement-based design can be performed. The application of the modified capacity spectrum method is illustrated by means of two examples. Copyright © 1999 John Wiley & Sons, Ltd.
774 citations
TL;DR: In this article, the authors developed both vulnerability and capacity curves with reference to an assumed typological classification system; moreover, their cross-validation is presented in the paper and the parameters of the two methods and the steps for their operative implementation are provided.
Abstract: The European Commission funded the RISK-UE project in 1999 with the aim of providing an advanced approach to earthquake risk scenarios for European towns and regions. In the framework of Risk-UE project, two methods were proposed, originally derived and calibrated by the authors, for the vulnerability assessment of current buildings and for the evaluation of earthquake risk scenarios: a macroseismic model, to be used with macroseismic intensity hazard maps, and a mechanical based model, to be applied when the hazard is provided in terms of peak ground accelerations and spectral values. The vulnerability of the buildings is defined by vulnerability curves, within the macroseismic method, and in terms of capacity curves, within the mechanical method. In this paper, the development of both vulnerability and capacity curves is presented with reference to an assumed typological classification system; moreover, their cross-validation is presented. The parameters of the two methods and the steps for their operative implementation are provided in the paper.
615 citations