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As one of the most important urban infrastructure systems, the road network plays a vital role in post-earthquake emergency response. Quantitative evaluation of the emergency response functionality of road network under earthquakes can provide decision support for emergency planning and future construction. In this paper, a novel network performance metric is proposed to consider both the special traffic demand in emergency response and the supply capability of road network. On this basis, an integrated probabilistic assessment framework for post-earthquake network emergency response functionality is presented, considering various uncertainties. In the framework, a penalty-based approach is proposed to consider the impact of partially degraded links on network functionality. At last, the proposed methodology is illustrated on the road network of Tangshan city, China, under different seismic scenarios. [ABSTRACT FROM AUTHOR]

Recent earthquakes have highlighted additional losses due to the lack of resilience of damaged structures. Environmental impact, as performance indicator, has also received increased attention within performance-based earthquake engineering. In this article, a combined probabilistic framework is proposed to assess seismic risk, sustainability, and resilience of a non-ductile reinforced concrete frame structure. The framework utilizes three-dimensional inelastic fiber-based numerical modeling approach to develop limit states associated with performance levels. The decision variables (i.e. repair cost, downtime, and equivalent carbon emissions) are quantified at both component level and system level and are compared considering seismic risk, sustainability, and resilience. In addition, the proposed approach considers uncertainties in the building performance and consequence functions of structural and non-structural components. Fast-track and slow-track schemes are utilized as a repair strategy and probabilistic resilience is quantified given the investigated time period. The proposed approach can aid the development of the next generation of performance-based engineering incorporating both resilience and sustainability. [ABSTRACT FROM AUTHOR]

How to incorporate near-fault directivity effect into the ground motion prediction equations (GMPEs) is an active research topic in recent years. Many studies demonstrated that the directivity could amplify the spectral accelerations (Sa) in a range close to the pulse period (Tp). This study intends to propose a new empirical narrowband model for including such effects. The ratio of the Sa from the original ground motions to the Sa from the residual ground motions is employed to quantify this amplification effects, under the assumption that the Sa from the residual ground motions are well predicted by the non-directivity-included GMPEs. Differing from previous models that suggested the amplified Sa arise in a smooth bell-shaped pattern, the proposed model assumes that the peak amplification occurs as a plateau in the intermediate range. This plateau, having a constant ordinate of about 3.31, starts and ends at the period of 0.75 and 1.09 times the Tp, respectively; while in the other ranges the amplification decreases away from the two sides of this plateau. To further simplify the proposed model, two additional controlling periods are derived to determine the period range with significant amplification effects. Then the proposed model is expressed in the form of a piecewise function comprising five line segments. Finally, it is concluded that the non-directivity-included GMPEs, when multiplying the proposed model, can reasonably approximate the Sa of the original ground motions in the statistical sense within the Tp-related range. [ABSTRACT FROM AUTHOR]

Summary: Ground motions with strong velocity pulses are of particular interest to structural earthquake engineers because they have the potential to impose extreme seismic demands on structures. Accurate classification of records is essential in several earthquake engineering fields where pulse‐like ground motions should be distinguished from nonpulse‐like records, such as probabilistic seismic hazard analysis and seismic risk assessment of structures. This study proposes an effective method to identify pulse‐like ground motions having single, multiple, or irregular pulses. To effectively characterize the intrinsic pulse‐like features, the concept of an energy‐based significant velocity half‐cycle, which is visually identifiable, is first presented. Ground motions are classified into 6 categories according to the number of significant half‐cycles in the velocity time series. The pulse energy ratio is used as an indicator for quantitative identification, and then the energy threshold values for each type of ground motions are determined. Comprehensive comparisons of the proposed approach with 4 benchmark identification methods are conducted, and the results indicate that the methodology presented in this study can more accurately and efficiently distinguish pulse‐like and nonpulse‐like ground motions. Also presented are some insights into the reasons why many pulse‐like ground motions are not detected successfully by each of the benchmark methods. [ABSTRACT FROM AUTHOR]

Many earthquakes have indicated that the mainshock-damaged structures may be more vulnerable to severe damage and collapse during the subsequent aftershocks. This manuscript presents a framework for the vulnerability assessment of structure under the mainshock-aftershock sequences. In this framework, the engineering demand parameter ( EDP ) which can more effectively characterized the additional damage of structure induced by aftershock, and the intensity measure ( IM ) having the higher correlation with the additional damage of structure are selected and used. The versatility of the proposed framework is demonstrated on a case-study reinforced concrete (RC) frame structure with 5 stories. The influences of aftershocks on the fragility of structure are studied for different limit states. The effects of aftershocks on the fragility of structure are more obvious for the case that mainshock fragility changes from 30% to 60%, and the maximum influence of aftershock can exceed 15%. The results in this study can be used to evaluate the vulnerability of structure under the seismic sequence in the pre-earthquake environment. [ABSTRACT FROM AUTHOR]

This manuscript investigates the constant damage inelastic displacement ratios for the mainshock–aftershock sequence-type ground motions. The inelastic displacement ratios are computed for three hysteretic models and two kinds of sequence-type ground motions, containing one or two aftershocks. The influences of aftershocks on the inelastic displacement ratios are quantitatively investigated with the scaled sequence-type ground motions. The results indicate that the dispersion of inelastic displacement ratio can be effectively reduced by aftershock when it is scaled with spectral acceleration to different relative intensities. Aftershock has more significant influences on the inelastic displacement ratio of Elastic-Perfectly-Plastic (EPP) system than that of degrading system. A simplified expression of constant damage inelastic displacement ratio is proposed for the sequence-type ground motions with strong aftershocks. [ABSTRACT FROM AUTHOR]

• A probabilistic framework to evaluate the seismic resilience of hospital buildings using Bayesian network is developed. • Simplified hospital building system and functionality indicators are defined. • Impact factor matrix is proposed to consider the interdependency of basic components and be as the input of BNs • One case study of a hypothetical hospital is given to illustrated the applicability of the proposed framework. Hospitals are indispensable to urban system, especially when an earthquake occurs. Once damaged, it is difficult for hospitals to maintain the continuity of emergency care operations for earthquake victims and ensure the safety of inpatients. A hospital can be regarded as a complex engineering system, whose physical performance relies on numerous sub-systems and components. The purpose of this paper is to propose a comprehensive framework to evaluate the seismic resilience of hospital buildings, considering the interdependencies on nonstructural components. In this study, critical departments and rooms in the hospital are selected as functional units and the Bayesian network method is used to reveal the interdependencies between departments, rooms, and internal components for the calculation of availabilities of departments and rooms. An impact factor is proposed to quantify the amplification effects of one component on the other component, which provides an interface to input the results of a series of upcoming experiments on multiple components. A case study of a hypothetic hospital is presented to demonstrate the applicability of the proposed framework. [ABSTRACT FROM AUTHOR]

The dynamic response of an elastic pounding oscillator subjected to harmonic excitation is investigated with dimensional analysis. To model the pounding process, a linear viscoelastic model is used to simulate the contact force. Through dimensional analysis, the peak structural response parameters of the pounding oscillator, including structural displacement, velocity, and penetration displacement, are characterized by a set of dimensionless terms (denoted by the Buckingham notation ). The reduced -set explicitly describes the interaction between the oscillator and the rigid barrier. Analytical solutions to dimensionless contact time, displacement, and velocity response are derived in this study and are further verified against the numerical simulation. The effect of pounding on the oscillator's response is illustrated using three well-divided spectral regions (i.e., amplified, deamplified, and unaffected regions), which are defined based on the dimensionless system frequency parameter . Parametric studies show that the penetration displacement for different levels of contact stiffness is insensitive to the dimensionless gap size but is affected significantly by changes in the coefficient of restitution . [ABSTRACT FROM AUTHOR]

The goal of this article is to select those real (or recorded) ground motions capable of exposing the low- and mid-rise reinforced concrete frame structures to an extreme limit state. By performing correlation analyses, two optimal intensity measures are first selected to represent the ground motion damage potential. Then based on each record's damage potential, four subsets of strong ground motions, referred to as the most unfavorable ground motions, are identified and preliminarily confirmed to be applicable to the low- and mid-rise RC frame structures. [ABSTRACT FROM AUTHOR]

In displacement-based seismic design, inelastic displacement ratio spectra (IDRS) are particularly useful for estimating the maximum lateral inelastic displacement demand of a nonlinear SDOF system from the maximum elastic displacement demand of its counterpart linear elastic SDOF system. In this study, the characteristics of IDRS for near-fault pulse-type ground motions are investigated based on a great number of earthquake ground motions. The influence of site conditions, ratio of peak ground velocity (PGV) to peak ground acceleration (PGA), the PGV, and the maximum incremental velocity (MIV) on IDRS are also evaluated. The results indicate that the effect of near-fault ground motions on IDRS are significant only at periods between 0.2 s - 1.5 s, where the amplification can approach 20%. The PGV/PGA ratio has the most significant influence on IDRS among the parameters considered. It is also found that site conditions only slightly affect the IDRS. [ABSTRACT FROM AUTHOR]

The paper presents a systematic review of the research advancements on the resilience of urban metro systems from the perspective of earthquake engineering. The review covers the concepts, indicators, and assessment methods of seismic resilience of urban metro systems. Four key aspects of seismic resilience of urban metro systems are reviewed, i.e., seismic damage analysis, post-earthquake functionality assessment, post-earthquake recovery assessment, and seismic resilience enhancement. The seismic damage mechanisms and seismic fragility of metro components are summarized, which are essential foundations for seismic resilience assessment. The post-earthquake functionality assessment methods of metro components and systems are then introduced, emphasizing the importance of reasonable quantification of functionality and consideration of functional interdependencies. Subsequently, examples of post-earthquake recovery of urban metro systems and post-earthquake recovery assessment methods are discussed, where the purpose of recovery assessment is to make decisions on recovery schedules to achieve more efficient post-earthquake recovery. The ultimate goal of seismic resilience assessment is to develop effective methods or strategies to ensure and enhance the functionality of urban metro systems, achieving an improvement in seismic resilience. This review summarizes the current state of research and the trends in development, providing directions for future studies on the quantitative seismic resilience analysis of urban metro systems. [ABSTRACT FROM AUTHOR]

Casualty prediction in a building during earthquakes benefits to implement the economic loss estimation in the performance-based earthquake engineering methodology. Although after-earthquake observations reveal that the evacuation has effects on the quantity of occupant casualties during earthquakes, few current studies consider occupant movements in the building in casualty prediction procedures. To bridge this knowledge gap, a numerical simulation method using refined cellular automata model is presented, which can describe various occupant dynamic behaviors and building dimensions. The simulation on the occupant evacuation is verified by a recorded evacuation process from a school classroom in real-life 2013 Ya’an earthquake in China. The occupant casualties in the building under earthquakes are evaluated by coupling the building collapse process simulation by finite element method, the occupant evacuation simulation, and the casualty occurrence criteria with time and space synchronization. A case study of casualty prediction in a building during an earthquake is provided to demonstrate the effect of occupant movements on casualty prediction. [ABSTRACT FROM AUTHOR]