Use of Limit State Loss versus Intensity Models for Simplified Estimation of Expected Annual Loss

The expected annual monetary loss (EAL) is a powerful seismic performance indicator for a building as it quantifies repair and replacement costs considering a wide range of possible earthquake scenarios. Existing methods for the estimation of EAL are admirably rigorous but also represent a significant departure from current code assessment methods. By introducing simple loss vs. intensity relationships that are anchored to engineering limit states (set considering both structural and non-structural elements) it is shown that one can predict EAL values quickly, through a closed form expression that could be implemented easily in practice. The validity of the approach is demonstrated by comparing predictions of EAL with those obtained using refined EAL assessments, for a number of case study buildings. The limitations with the accuracy of the approach are discussed and the possibility of developing empirical loss vs. intensity relationships as part of future research is proposed.     

Effect of Topology Irregularities and Construction Quality on Life-Cycle Cost of Reinforced Concrete Buildings

Life-cycle cost (LCC) analysis entails consideration of building performance throughout the structures’ life. The impact and interaction of topology irregularities and construction quality (CQ) on LCC, however, are often ignored and require a more detailed evaluation. In this article, different levels and interaction of soft story (SS) and CQ are analytically modeled to quantify corresponding fragility curves and LCC (by considering hazard level, limit state cost, and probability of being in different damage states). The proposed method is illustrated with a three-, six-, and nine-story reinforced concrete building located in Vancouver (located in west coast of Canada).     

Fragility-Based Performance Evaluation of Asymmetric Single-Story Buildings in Near Field and Far Field Earthquakes

Previous studies have shown that both distribution and intensity of response parameters in asymmetric buildings are dependent on their stiffnesses and strength distributions. The locations of centers of strength and rigidity relative to the center of mass provide suitable metrics for strength and stiffness distributions. In general, the proper locations of these centers are a function of earthquake ground motion characteristics and the level of building's nonlinear responses. In this article, using nonlinear response evaluation of single-story building models with a wide range of uncoupled torsional to lateral frequencies subjected to near field and far field earthquake excitations the proper location of building centers is studied . Diaphragm rotation, interstory drift, hinge plastic rotation, and ductility demand are selected as damage measure parameters. To compare the performance of models in each limit state, fragility representation of responses is used. It is concluded that proper configuration of building centers in a torsionally stiff building fundamentally depends on the chosen demand parameter. The proper configuration of centers in a torsionally stiff building for a specific demand parameter can converge the probability and distribution of related damages to those in the symmetric building counterpart. When the critical demand parameter for a case is identified, its corresponding arrangements of centers for a suitable seismic behavior may also be recognized. By rearranging the configuration of centers based on the attained configuration, the adverse effects of asymmetry can be avoided.     

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.     

Sustainability of Highway Bridge Networks Under Seismic Hazard

In order to evaluate the seismic risk of transportation networks, it is necessary to develop a methodology that integrates the probabilities of occurrence of seismic events in a region, the vulnerability of the civil infrastructure, and the consequences of the seismic hazard to the society, environment, and economy. In this article, a framework for the time-variant seismic sustainability and risk assessment of highway bridge networks is presented. The sustainability of the network is quantified in terms of its social, environmental, and economic metrics. These include the expected downtime, expected energy waste and carbon dioxide emissions, and the expected loss. The methodology considers the probability of occurrence of a set of seismic scenarios that reflect the seismic activity of the region. The performance of network links is quantified based on individual bridge performance evaluated through fragility analyses. The sustainability and risk depend on the damage states of both the links and the bridges within the network following an earthquake scenario. The time-variation of the sustainability metrics and risk due to structural deterioration is identified. The approach is illustrated on a transportation network located in Alameda County, California.     

Numerical Fragility Analysis of Vertical-Pile-Supported Wharves in the Western United States

This study develops seismic fragility curves for vertical-pile-supported wharves commonly found in the western United States. Nonlinear time-history analyses of a two-dimensional numerical model under two ground motion suites are performed. The results show that the jumbo container cranes increase by 10.8% in the wharf deck drift. By using the experiment-based limit states, the proposed fragility curves demonstrate that, at a PGA of 0.50 g, the probabilities of exceeding slight, moderate, extensive, and complete limit states are approximately 23.0%, 7.0%, 4.0%, and 3.0%, respectively, while at a PGA of 1.00 g, the exceeding probabilities increase to 44.0%, 19.0%, 14.0%, and 11.0%, respectively.     

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.     

Identification of Suitable Limit States from Nonlinear Dynamic Analyses of Masonry Structures

Performance-based earthquake engineering, developed over the last decades for the design and assessment of other structures, can also be applied for masonry structures if the particularities of masonry are incorporated into the procedure. According to this methodology, structural performance can be assessed according to damage states which are identified through displacement/damage indicators. While various methods for the identification of limit states from the results of nonlinear static analyses exist, the identification of damage states from the results of nonlinear dynamic analyses is still uncertain. This article investigates a number of criteria allowing to identify the attainment of significant limit states from the results of time history analyses, in terms of appropriately identified response quantities. These criteria are applied to five building prototypes and their results are compared. A comparison with the limit states derived from nonlinear static analyses is also made.     

Language as an instrument of nationalism in Central Europe

This article presents a brief survey and analysis of the most intimate coupling of culture and national projects that occurred in Central Europe following the success of the Italian and German nation‐states established in this manner during the third quarter of the nineteenth century. Language is the very ‘stuff’ of culture as well as the instrument of communicating and reaffirming cultural difference vis‐à‐vis other cultures. As such, language became central to the processes of nation‐ and nation‐state‐building in Central Europe, leading to politicisation of language and also of linguistics and philology, which were expected to fortify the nations and their nation‐states than rather to lend themselves to objective research. It is proposed that this specific Central European interweaving of language and national projects may be better comprehended through the application of Einar Haugen's model of language standardisation and Miroslav Hroch's model of nation‐building. These two models in the Central European case seem to be closely corresponding to each other. The short catalogue of language elements used to produce national differentiation closes this contribution.     

The Politics of Development Metrics and Measurement: Impact Evaluations in Fairtrade‐certified Plantation Agriculture

This article presents an analysis of impact evaluations in the case of Fairtrade International in order to track the political effects of metrics and measurement procedures in development practice today. Metrics or ‘indicators’ have long been understood to have the effect of transforming the political visions of socioeconomic change that shape development interventions into seemingly non‐contentious, technical models. The common practice among development organizations of using such metrics as evidence of apolitical, technical development outcomes has wide‐ranging implications for the field of development and for development subjects. The article explores two specific implications by detailing impact evaluations on three Fairtrade‐certified cut‐flower plantations, which Fairtrade International contracted to inform a 2014 revision of its certification standards. The authors find, first, that debates over competing visions or definitions of development became concealed in technical debates over adequate metrics and measurements; and, second, that such debates over metrics and measurement consolidated the roles of experts and expert knowledge as mediators of what development can or should be. These findings enhance prior critiques of the supposed neutrality of development metrics by illustrating empirically how the processes of defining metrics and measurement conceal and circumscribe political debates over the meaning and making of development practice.     

Masonry Italian Code-Conforming Buildings. Part 2: Nonlinear Modelling and Time-History Analysis

ABSTRACT

The unreinforced masonry (URM) buildings designed to be conforming with the Italian building code, as illustrated in the companion paper, were analyzed by performing time-history analyses on models realized using an equivalent frame approach and by adopting two different constitutive laws. Both the effect of record-to-record variability and of epistemic and aleatory uncertainties in modelling were explored. The achieved results constitute the basis for the evaluation of the risk level implicit in Italian code-conforming buildings. Two main performance conditions are considered, namely usability-preventing damage and global collapse limit states.     

INSTANTANEOUS OPTIMAL CONTROL FOR SEISMIC ANALYSIS OF NON-LINEAR STRUCTURES

In this paper, an effective active control algorithm is developed for the vibration control of non-linear structural systems subjected to earthquake excitation. It is an attempt to include the non-linear characteristics of the structural behaviour throughout the entire analysis (design and validation), accounting for the eventual cumulative structural damage and energy dissipation. This is a very important factor since, in current design practice, structures are assumed to behave nonlinearly when subjected to strong ground motion. The proposed algorithm focusses on the instantaneous optimal control approach for the development of the control algorithm where the nonlinearities are brought into the analysis through a non-linear state vector and a non-linear open loop term. A performance index that is quadratic in the control force and in the non-linear states and is subjected to a non-linear constraint equation, is minimised at every time step. The effectiveness of the proposed non-linear instantaneous optimal control (NIOC) strategy is critically evaluated in comparison with currently available active control techniques. Numerical simulation results indicate that the proposed approach provides a significant reduction of the peak response quantities, such as maximum response deformation, maximum response acceleration, ductility of the system, associated with a reduced maximum control force.     

Displacement Ductility Limits for Pile Foundations in Cohesionless Soils

The displacement ductility limit for seismic design of concrete piles is determined for the range of cohesionless soils expected in practice. The curvature ductility capacity associated with specified performance limit states, namely, the “serviceability” and “damage-control” limits, is determined based on the current provisions for confining steel. An analytical model is applied to assess the displacement ductility factor at the specified curvature ductility level. The investigated parameters include the soil stiffness, pile diameter, longitudinal reinforcement ratio, axial force level, and pile above-ground height. A set of design displacement ductility factors is recommended and verified to ensure the satisfactory seismic performance.     

A Simplified Drift-Based Assessment Procedure for Regular Confined Masonry Buildings in Seismic Regions

This article presents a simplified procedure for assessing the seismic performance of existing low-to-medium rise confined masonry (CM) buildings, which are a typical construction type in Latin-America. The procedure consists of the estimation of the peak roof and first-story inelastic drift demand of CM buildings. The expected peak inelastic displacement demand is related to drift-based fragility curves, which express the probability of being or exceeding two key damage states in the masonry panels, developed from a relatively large experimental database. The proposed procedure could be very useful for obtaining rapid estimates of expected performance during future earthquake events and for assessing the seismic vulnerability of regular confined masonry structures.     

METHODOLOGY FOR THE PROBABILISTIC ASSESSMENT OF q FACTORS. A DAMAGE INDEX APPROACH

The objective of the present work is to present a methodology for the identification of relevant limit states, namely ultimate limit states leading to structural collapse, and for the assessment of design q factors (or force reduction factors) for reinforced concrete structures under seismic loading. It follows a probabilistic approach based on damage indices. The utilised nonlinear models, as well as the damage indices, which are those proposed by Miner and by Park and Ang, are.described. The methodology of analysis is presented emphasising its probabilistic characteristics. Some parametric studies are carried out, including the analysis of one regular plane frame reinforced concrete structure, designed for three different ductility classes (those proposed by Eurocode 8) and assuming different q factors in design. Results show how the chosen damage indices can be used as parameters to characterise the structural response and how the proposed methodology can be used to assess the design q factors. It is also shown that, for moderate seismic input, the three ductility classes are essentially equivalent in terms of maximum damage indices, but that for higher seismic levels the differences are evident, justifying the use of different q factors.     

The Baseline Stiffness Method for Damage Detection in Buildings Without Baseline Modal Parameters

A new method called the Baseline Stiffness Method (BSM), used to locate and quantify damage in buildings without baseline modal parameters (undamaged state), is presented. In order to determine this reference state, the BSM uses modal parameters from the damaged state of the building and the lateral stiffness matrix of the first story without damage. Afterwards, by means of an iterative process using singular value decomposition, location and severity of damage are obtained by comparing information about the damaged and non damaged states. Numerical and experimental examples are presented and discussed showing the advantages of the application of the proposed BSM.     

Making Democracy Legible? Voter Registration and the Permanent Electronic Electoral List in Benin

A core component of the infrastructural power of the modern state is the capacity to make its population ‘legible’, through the development of accurate registration and identification mechanisms. In discussing the relationship between democratization and state building, little attention has been paid to the electoral process as a technical process. Yet, the introduction of competitive elections presupposes the registration of voters and thus requires the development of the ‘legibility’ capacities of states. This is particularly evident in sub‐Saharan Africa, where democratizing states have been confronted with the weakness of their existing records and forced to develop new mechanisms for registering voters in a reliable manner. This article looks at the experience of the Liste Electorale Permanente Informatisée (the Permanent Electronic Electoral List) in Benin and discusses the potentialities and limits of voter registration as a state‐building tool.     

Privatization of Security,Arms Proliferation and the Process of State Collapse in Africa

Most so–called ‘collapsed states’ in Africa are extreme cases of the complex and contradictory processes of state–making and unmaking which are unfolding in the continent. Beneath the veneer of sovereignty, virtually all these nations started their independent existence in the 1960s as shell states. Since then, they have either followed the path of self–destruction (state collapse) or have sought to fill the shell with institutional content (state–making). Private military intervention is one of the key external factors undermining the state–building project. Whether in its traditional ‘soldier of fortune’ form, or in its current corporate cloak, the privatization of security injects an inflammatory element into the governance process in weak states. Since independence, the populations of Africa have been subjected to structural violence that has highlighted force and de–emphasized human security as the cornerstone of governance. Civil society reactions to this have become more pronounced since the end of the Cold War, and have led to negative reconfiguration in weak states that are least equipped to manage the new challenges. The privatization of security impedes efforts to fashion accountable governance, and entrenches the culture of violence. Private military companies, their partner arms brokers and local warlords are the principal actors in illegitimate resource appropriation — a major cause of ongoing asymmetric warfare in Africa — and the proliferation of weapons — an incendiary element in these wars.     

The transnational state and migration: Reach,flows and Policies

For long, state building has been addressed as the expression of an exclusive power over a portion of space and population. In recent years, the scholarship moved away from such a conception by regarding state building as an assemblage of multi-scalar public and private actors, beneath and beyond its territorial borders. This paper adds to this conversation by focusing on the way states transform as they engage with migration-induced transnational flows. This paper defines the transnational migration state as the set of policies, concepts and institutions designed to make the most of “profitable” migration-related flows (of people, money, ideas, etc.) while filtering out unwanted ones. Next to the national-level administrations in charge of the management of human, financial and immaterial flows, states seek to extend their reach by rescaling their engagement and relying on a range of private and civil society actors, including local authorities. This paper is a theoretical contribution to the debate on state reconfiguration in a world of globalised migration. It distinguishes and conceptualises two types of migration-related transnational migration states: emigration and immigration states tackling incoming and outgoing flows respectively.     

故宫灵沼轩残损分析及结构性能研究

故宫灵沼轩是我国最早建造的钢铁-砌体组合结构之一,目前损坏较为严重。为更好地保护和修缮该建筑,残损分析和结构性能研究是其修缮保护的科学基础。首先通过现场调研,对该建筑的残损状况进行分析,找出其显见的病害;然后通过精确测绘、材料检测及有限元模拟分析其结构性能,找出其隐在的病害;最后综合残损分析及结构性能分析结果,提出相应的保护措施建议。