FRAGILITY ASSESSMENT OF SLAB-COLUMN CONNECTIONS IN EXISTING NON-DUCTILE REINFORCED CONCRETE BUILDINGS

Fragility functions that estimate the probability of exceeding different levels of damage in slab-column connections of existing non-ductile reinforced concrete buildings subjected to earthquakes are presented. The proposed fragility functions are based on experimental data from 16 investigations conducted in the last 36 years that include a total of 82 specimens. Fragility functions corresponding to four damage states are presented as functions of the level of peak interstory drift imposed on the connection. For damage states involving punching shear failure and loss of vertical carrying capacity, the fragility functions are also a function of the vertical shear in the connection produced by gravity loads normalised by the nominal vertical shear strength in the absence of unbalanced moments. Two sources of uncertainty in the estimation of damage as a function of lateral deformation are studied and discussed. The first is the specimen-to-specimen variability of the drifts associated with a damage state, and the second the epistemic uncertainty arising from using small samples of experimental data and from interpreting the experimental results. For a given peak interstorey drift ratio, the proposed fragility curves permit the estimation of the probability of experiencing different levels of damage in slab-column connections.     

Numerical Simulation and Seismic Fragility Analysis of a Self-Centering Steel MRF with Web Friction Devices

This article presents the seismic fragility analysis of a self-centering steel moment-resisting frame (SC-MRF) with web friction devices. A detailed numerical model of the SC frame was developed using the Open System for Earthquake Engineering Simulation (OpenSees) and the elastoplastic responses of the SC-MRF were studied, including the strength degradation under cyclic loading, tendon rupture, beam buckling, bolt bearing and friction loss, etc. The proposed simulation approach is validated by comparing the simulated results with those in existing hybrid-simulation tests, quasi-static pushover test and low cyclic tests, where good agreement is observed. In addition to the well-established performance limit states (i.e., immediate occupancy, collapse prevention and global dynamic instability), two unique performance limit states (i.e., the recentering and repairable limit states) are defined for the SC-MRF. Finally, incremental dynamic analyses are conducted to evaluate the seismic fragilities regarding the five performance limit states.     

Historical Epistemology: On the Diversity and Change of Epistemic Values in Science

Historical Epistemology: On the Diversity and Change of Epistemic Values in Science. Historical epistemology involves the claim that the system of scientific knowledge is not determined by the observations but is also subject to epistemic requirements that may change in the historical process of doing research. As a result, the system of knowledge is path‐dependent in that its shape is contingent on epistemic choices made at certain historical points. I attempt to elaborate this approach by drawing attention to the double role of epistemic values. First, such values create relations of significance and thereby contribute to directing research into certain avenues. Second, they are also important in the process of confirmation in that they entail that certain forms of agreement with the facts are superior and preferable to other such forms. Some epistemic orientations and reorientations can be reconstructed as arising from an interaction with nature, but others are based on commitments to the kind of knowledge we appreciate. The epistemic authority of science is created in large measure by rules of the scientific community that express how to deal with knowledge claims.     

Allowing Traffic Over Mainshock-Damaged Bridges

A criterion is proposed for deciding whether, after a damaging mainshock, a bridge can still be open for either emergency or ordinary traffic. The criterion is based on the comparison between the collapse risk of the mainshock-damaged structure and the pre-mainshock risk of the intact structure. The approach requires fragilities for multiple damage states for the intact structure, and transition probabilities from these states to collapse for the damaged structure. The aftershock risk decreases with time, hence a decision for reopening might have to wait until the risk level goes down to an acceptable value. A realistic application demonstrates the approach.     

Development of Probabilistic Framework for Performance-Based Seismic Assessment of Structures Considering Residual Deformations

Recently, the importance of considering residual (permanent) deformations in the performance assessment of structures has been recognized. Advanced structural systems with re-centering properties as those based on unbonded post-tensioning tendons are capable of controlling or completely eliminating residual deformations. However, for more traditional systems, which count for the vast majority of buildings, residual deformations are currently considered an unavoidable result of structural inelastic response under severe seismic shaking.

In this article, a probabilistic framework for a performance-based seismic assessment of structures considering residual deformations is proposed. The development of a probabilistic formulation of a combined three-dimensional performance matrix, where maximum and residual deformations are combined to define the performance level corresponding to various damage states for a given seismic intensity levels, is first presented. Combined fragility curves expressing the probability of exceedence of performance levels defined by pairs of maximum-residual deformations are then derived using bivariate probability distributions. The significance of evaluating and accounting for residual deformations within a Performance-based Earthquake Engineering (PBEE) approach is further confirmed via numerical examples on the response of Single Degree of Freedom (SDOF) systems, with different hysteretic behavior, under a selected suite of earthquake records. Joined fragility curves corresponding to various performance levels, defined as a combination of maximum and residual response parameters, are derived while investigating the effects of hysteretic systems and strength ratios. It is observed that stiffness degrading Takeda systems result in lower residual deformations than elasto-plastic systems and show lower probability of exceeding a jointed maximum-residual performance level. For a chosen performance level, Takeda systems with higher strength ratios show better performance, particularly with lower intensity of excitations.     

FRAGILITY OF STANDARD INDUSTRIAL STRUCTURES BY A RESPONSE SURFACE BASED METHOD

National and international regulatory standards require industrial risk assessment, taking into account natural hazards including earthquakes, in the framework of Quantitative Risk Analysis (QRA). Seismic fragility analysis of industrial components may be carried out similarly as what has been done for buildings, even though some peculiar aspects require the development of specific tools. In the present paper a contribution to the definition of a rational procedure for seismic vulnerability assessment of standardised industrial constructions in a probabilistic framework is given. The method covers a range of components of the same structural type. Seismic reliability formulation for structures is used. Both seismic capacity and demand are considered probabilistic with the latter assessed by dynamic analyses. The application example refers to shell elephant foot buckling of unanchored sliding tanks. A regression-based method is applied to relate fragility curves to parameters varying in the domain of variables for structural design.     

THE EPISTEMIC AND MORAL ROLE OF TESTIMONY1

My aim in this article is to provide a critical‐productive appreciation of witness testimony that avoids the false and crooked dichotomies that pervade contemporary philosophy of history and historical theory. My specific, pragmatist approach combines the recent accounts of Hayden White about “witness literature” with the “generative‐performative” consideration of testimony by Martin Kusch. The purpose is to appreciate, in a non‐foundationalist way, the epistemic and moral role of testimony in the constitution of the representation of the recent past. To achieve this I examine the assumed epistemic and political privilege of the testimonies of survivors of state terrorism from the recent past, and I draw on insights of three of the most relevant survivor witnesses: Primo Levi, Victor Klemperer, and Pilar Calveiro. The essay tries to avoid both an epistemic and a moral posture based on something like “the privileged victim's perspective,” and instead approaches the specific analysis of production and circulation of witness discourse in terms of its contribution to the constitution of the past. That is, it recommends that one look at witness testimony not as an attempt to return to the past but as an action in the present. The result in so doing is to follow some recent results discussed in the new epistemology of witness testimony, which insist that: first, trust in testimony is an irreducible function of the acceptance of knowledge (this means that testimonies should not be treated as secondary sources of knowledge or as parasitical on experience and reason); and second, the production‐circulation of testimonies does not function only in the context of justification but is also legitimately constitutive of knowledge.     

Performance-based Seismic Risk Assessment of Urban Systems

ABSTRACT

Disaster risk mitigation has become a urgent global need. Similar to other natural hazards, earthquakes may cause significant damage on a large scale. In Europe and in other regions with dense urbanization, seismic events can heavily impact historical city centers due to the several structural fragilities. These centers are often part of the worldwide cultural heritage and their preservation is considered a strategic issue. Furthermore, earthquakes may have severe negative short-term economic effects on the impacted communities and adverse longer-term consequences for economic growth. For this reason, the development of an efficient approach for urban seismic risk assessment becomes essential. An original approach is proposed, based on performance concepts and multidisciplinary perspectives. The procedure is applied for validation to the city center of Concordia Sulla Secchia (Italy), damaged by the 2012 Pianura Padana Earthquake (PPE), comparing predicted damage scenarios with the actual post-seismic survey data.     

Parameterized Seismic Fragility Curves for Curved Multi-frame Concrete Box-Girder Bridges Using Bayesian Parameter Estimation

This paper addresses the application of a Bayesian parameter estimation method to a regional seismic risk assessment of curved concrete bridges. For this purpose, numerical models of case-study bridges are simulated to generate multiparameter demand models of components, consisting of various uncertainty parameters and an intensity measure (IM). The demand models are constructed using a Bayesian parameter estimation method and combined with limit states to derive the parameterized fragility curves. These fragility curves are used to develop bridge-specific and bridge-class fragility curves. Moreover, a stepwise removal process in the Bayesian parameter estimation is performed to identify significant parameters affecting component demands.     

Seismic Fragility Assessment of Lightly Reinforced Concrete Structural Walls

Development of fragility functions is a pertinent stage in seismic performance assessment of structures. A database of lightly Reinforced Concrete (RC) walls under simulated seismic loading is compiled from the literature to establish the drift-based seismic fragility functions. To classify the damage states experienced by RC walls, the Park-Ang Damage model is amended in this research. Then, the modified Bouc-Wen-Baber-Noori hysteresis model is implemented in ABAQUS to predict the hysteresis behavior of RC walls. Thereafter, the proposed hysteresis model is employed to develop the seismic fragility curves of low to mid-rise RC walls in Singapore using incremental dynamic analysis approach.     

Bayesian Spatial Filtering for Hedonic Models: An Application for the Real Estate Market

This article presents a Bayesian method based on spatial filtering to estimate hedonic models for dwelling prices with geographically varying coefficients. A Bayesian Adaptive Sampling algorithm for variable selection is used, which makes it possible to select the most appropriate filters for each hedonic coefficient. This approach explores the model space more systematically and takes into account the uncertainty associated with model estimation and selection processes. The methodology is illustrated with an application for the real estate market in the Spanish city of Zaragoza and with simulated data. In addition, an exhaustive comparison study with a set of alternatives strategies used in the literature is carried out. Our results show that the proposed Bayesian procedures are competitive in terms of prediction; more accurate results are obtained in the estimation of the regression coefficients of the model, and the multicollinearity problems associated with the estimation of the regression coefficients are solved.     

Seismic Fragility Evaluation of Lightly Reinforced Concrete Beam-Column Joints

Fragility functions play an essential role in evaluating the seismic vulnerability of structures. To establish the seismic fragility functions of lightly Reinforced Concrete (RC) beam-column joints, the Park-Ang Damage model has been amended to quantify the damage states and the modified Bouc-Wen-Baber-Noori model has been employed and implemented in ABAQUS to predict the structural hysteresis behavior. Following successful calibration of the numerical results of a RC test frame from literature, the proposed model has been utilized to assess the seismic fragility curves of low to mid-rise RC frames in Singapore for 30 scaled ground motions using incremental dynamic analysis approach.     

Seismic behavior of two Portuguese adobe buildings: part II —numerical modeling and fragility assessment

Considering the likely unfavorable behavior under seismic action of adobe construction, this article aims at providing a seismic fragility characterization of two adobe Portuguese traditional buildings, using numerical models calibrated over experimental results. The study of such two case-study buildings in the region of Aveiro contributes to the understanding of the seismic fragility of adobe construction in the region in general. The buildings were numerically modeled to estimate their structural behavior under seismic loading using adobe material properties that were calibrated based on the experimental results of a cyclic in-plane test of a full-scale double-Tshaped adobe wall. The method chosen to characterize adobe masonry and model its nonlinear behavior followed a total strain crack-based macro-modeling (TSCM) approach, whereas pushover analysis was carried out to reproduce the pseudo-static experimental test in order to enable a refined calibration of adobe masonry mechanical properties. Fragility functions were then derived, based on the above-mentioned numerical models, using nonlinear static analysis, bringing further insight on the seismic fragility of traditional Portuguese adobe construction.     

Rockfort Temple at Tiruchirapalli,India: Conservation of a Sacred Landscape

Sacred sites in India are subject to many development pressures. Unlike heritage monuments, cultural and historic landscapes have not been the focus of institutional protection and preservation efforts. Using Rockfort Temple complex at Tiruchirapalli, Tamil Nadu, as a case study, we propose that an integrated conservation approach be based upon restoring the natural and spatial archetypes that constitute the landscape vocabulary. A group of excavated and structural temples are located on a hill on the banks of the river Kaveri surrounded by a medieval fort that became the nucleus of urban growth over time. Overwhelming growth of commerce within the last half century has resulted in many problems such as traffic congestion, confusing circulation, and visual chaos, which in turn have led to the loss of sanctity. The structure of the pilgrim landscape constituted by circumambulatory paths, tanks and groves, shrines and temples can be clarified and made legible by minor design interventions such as restoring historic buildings, reviving the holy tanks, planting sacred trees, and building rest pavilions along the pilgrim path.     

Culture in global knowledge societies: knowledge cultures and epistemic cultures

Abstract

This paper explores the concepts of knowledge culture and epistemic culture against the background of contemporary transformations in global society. Studies of knowledge culture came to prominence in the 1970s, with the trend towards laboratory fieldwork and direct observation in the new sociology of science. If the focus in such early studies was on knowledge construction, the focus in an epistemic culture approach by contrast is on the construction of the machineries of knowledge construction, relocating culture in the micropractices of laboratories and other bounded habitats of knowledge practice. Not all places of knowledge, however, are bounded spaces, and there is a case to be made for including in the empirical agenda more distributed locations. This is done here by introducing the concept of 'macro-epistemics', to describe wider networks of knowledge generation such as what is often known as 'the global financial architecture'. The discussion concludes by moving out from macro-epistemic circuits to questions of the cultural environment of epistemic settings, and of the more general knowledge culture in which specific knowledge processes are embedded.     

Interpretive field geomorphology as cognitive,social, embodied and affective epistemic practice

This article examines the epistemic practices of interpretive field geomorphology—that is, the in-the-moment act of “seeing the landscape” geomorphologically. Drawing on the philosophical works of Wittgenstein and Merleau-Ponty, it aims to bring to light the complex, multi-dimensional, knowledge-producing process of field observation and interpretation. Methodologically the study is based on geomorphologists' accounts of their fieldwork, gathered through questionnaire and interviews. By paying attention to what geomorphologists say they are doing in the field, interpretive field geomorphology is articulated as a combined cognitive, social, embodied, and affective experience through which understanding is arrived at. The paper thus sheds light on one part of what Brierley et al. call “the dark art” of geomorphological interpretation, and draws out implications in terms of researcher positionality, researcher training, and offering an epistemic justification for field-based pedagogies.     

A Surface-Based Approach to Measuring Spatial Segregation

Quantitative indices of residential segregation have been with us for half a century, but suffer significant limitations. While useful for comparison among regions, summary indices fail to reveal spatial aspects of segregation. Such measures generally consider only the population mix within zones, not between them. Zone boundaries are treated as impenetrable barriers to interaction between population subgroups, so that measurement of segregation is constrained by the zoning system, which bears no necessary relation to interaction among population subgroups. A segregation measurement approach less constrained by the chosen zoning system, which enables visualization of segregation levels at the local scale and accounts for the spatial dimension of segregation, is required. We propose a kernel density estimation approach to model spatial aspects of segregation. This provides an explicitly geographical framework for modeling and visualizing local spatial segregation. The density estimation approach lends itself to development of an index of spatial segregation with the advantage of functional compatibility with the most widely used index of segregation (the dissimilarity index D ). We provide a short review of the literature on measuring segregation, briefly describe the kernel density estimation method, and illustrate how the method can be used for measuring segregation. Examples using a simulated landscape and two empirical cases in Washington, DC and Philadelphia, PA are presented.     

Age estimation of children from prehistoric Southeast Asia: are the dental formation methods used appropriate?

Inter-population differences in skeletal and dental growth and maturation are acknowledged frequently in the biological anthropological literature. These growth differences have implications for the reliability of standards for the estimation of age at death of archaeological subadults. The number of archaeological projects that are recovering human burials from non-European contexts, including Southeast Asia, and the increasing interest in subadult bioarchaeological studies provides the impetus for investigating this issue of ageing subadult individuals from these populations. This paper aims to address some of the problems of the representativeness of ageing standards for non-European children in bioarchaeology. This is achieved through a literature review of the issue of growth variability and age estimation, and a basic comparison of the commonly applied age estimation method based on North American children with a dental formation study of modern Thai children. Although these studies do not employ similar methods the Thai study is the only comparable data available and therefore serves as a starting point to address these issues. The results raise an important question for bioarchaeologists of the appropriateness of available ageing methods. In addition this paper emphasises the need for the use of appropriate methodologies in the collection and presentation of dental formation data.     

When Epistemic Communities Fail: Exploring the Mechanism of Policy Influence

Epistemic communities are an established concept in the study of international relations but can also explain policy change at the domestic level. This article asks why some epistemic communities manage to convince decision makers of their preferred policies while others do not. It suggests that the reason lies in the causal mechanism of epistemic communities' influence on decision makers, mediated by decision makers' demand for expert input. Most epistemic communities scholarship focuses on single case studies where the communities' influence on policy was strong and clear, leading to an overestimation of the groups' influence. To help correct this probable bias, this article compares a successful case of epistemic community influence (health technology assessment in Poland) with an unsuccessful example of the same policy (in the Czech Republic). The juxtaposition allows for unpacking of the necessary parts of the causal mechanism (emergence of an epistemic community, its activity, access to decision makers, and successful suasion) and separating them from the crucial scope condition. Decision makers' uncertainty about the policy issue at hand has traditionally been the key scope condition for epistemic communities but the successful Polish case demonstrates that epistemic communities can be influential even in highly certain areas of routine policymaking, leading to a reconceptualization of uncertainty as policymakers' demand for expert input. Demand can originate from various sources, but any change of it affects individual parts of the causal mechanism, leading to a success or failure of epistemic communities' policy enterprise.     

A SPATIO‐TEMPORAL KERNEL METHOD FOR MAPPING CHANGES IN PREHISTORIC LAND‐USE PATTERNS

Archaeologists are accustomed to considering both the spatial distributions of sites and the temporal distributions of dates as means of analysing the dynamics of prehistoric societies. However, spatial and temporal approaches have thus far remained largely separate, rather than being combined within a single, unified framework. A formal methodology is outlined that combines univariate kernel density estimation based on radiocarbon dates with bivariate kernel density estimation based on spatial site coordinates; the approach allows archaeologists to arrive at reconstructed land‐use distributions through time that not only correct for the problematic issue of site contemporaneity, but also reflect the continuous nature of the archaeological record. The model is implemented using as a data set a series of sites from the Mesolithic of Atlantic Iberia; the results demonstrate that it is capable of providing key insights into changing patterns of land use that are not apparent from either the temporal or the spatial perspective alone.