Mohsen Ghafory-Ashtiany

Mohsen Ghafory-Ashtiany
International Institute of Earthquake Engineering and Seismology | iiees · Structure and Risk Management

PhD
Hazard, Vulnerability and Risk analysis. Urban Resilience System Modeling DRR project management Disaster Insurance

About

145
Publications
41,232
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Publications

Publications (145)
Article
Full-text available
This paper presents a comprehensive and integrated databank of the Iranian strong ground motions that occurred from 1973 to 2018. The databank consists of 7196 three-component acceleration records from 3180 earthquakes and 1157 stations in Iran. In this paper, the characteristics of this databank are presented in terms of event, station, and record...
Article
Full-text available
Owing to its geographical position within one of the most seismically active zones globally, Iran has experienced numerous historically impactful earthquakes. To finance a part of these losses and reconstruction expenses, earthquake insurance has been offered as a rider on fire insurance policies by Iranian insurers. This mechanism, if operated wel...
Data
In this study, strong ground motion record (SGMR) selection based on Eta (η) as a spectral shape indicator has been investigated as applied to steel braced frame structures. A probabilistic seismic hazard disaggregation analysis for the defi nition of the target Epsilon (ε) and the target Eta (η) values at different hazard levels is presented, taki...
Conference Paper
Prioritizing the seismic rehabilitation and recovery of different components of the power grids is essential to minimize physical damage, recovery time, economic losses, and affected population, as well as improve the performance and resilience of the power grids against possible future earthquakes. Based on the individual and network behavior of t...
Article
In this paper, a comprehensive and integrated structural health monitoring system, called the Integrated Bridge Health Monitoring Tool (IBHMT), is introduced. The IBHMT toolbox consists of three main steps: visual-based assessment, spectral-based assessment, and dynamic-based assessment (model updating). In this toolbox, the accuracy of the structu...
Preprint
Full-text available
This paper presents a comprehensive and integrated databank of the Iranian strong ground motions that occurred from 1973 to 2018. The databank consists of 7196 three-component acceleration records from 3180 earthquakes and 1157 stations in Iran. In this paper, the characteristics of the Iranian strong ground motion data are presented in terms of ev...
Article
Full-text available
Dhaka is one of the most populated cities in the world, which means that the occurrence of natural hazards will put the city in a critical situation. A seismic hazard analysis (SHA) is a prerequisite to reduce the risk of an earthquake event in Dhaka. This paper, focusing on the active faults of Bangladesh and the soil condition, represents the cal...
Preprint
Full-text available
This paper provides a new methodology for seismic performance evaluation and retrofitting of structures using the combination of fault tree and incremental dynamic analysis to cover some of the limitation of the existing methods. These limitations include the qualitative consideration of performance objectives, the consideration of uncertainties, a...
Article
Full-text available
One of the main components for developing regional seismic risk models is the fragility functions of common building types. Due to the differences between the national design codes, construction practices, and construction materials, it is necessary to develop specific fragility functions for the common building types which are constructed in each...
Article
Resilience analysis of power grids requires their performance assessment during threatening hazards. However, the diverse connections among various constituent components make studying power grids' network behavior complicated. This study aims to present a practical framework with appropriate computational speed and acceptable accuracy in estimatin...
Preprint
Full-text available
One of the main components for the development of regional seismic risk models is the fragility functions for common building types. Due to the differences between the national design codes, construction practices, and construction materials, it is necessary to develop specific fragility functions for the common building types which are constructed...
Article
After presenting a taxonomy of schools in part one and their modes of behavior during the Ezgeleh earthquake in November 2017, this paper quantifies the seismic resilience index of Iranian school buildings, including post-recovery and retrofitting processes. Six schools having different structural properties as being representative of the 3029 Iran...
Thesis
Full-text available
Damage in the post-tensioning system in pre-stressed bridges can result in costly repairs, replacement, lack of integrity, reducing the reliability and safety of the structure. Therefore, the health of these structural systems and their components must be preserved. Tension estimation of cables as axially one-dimensional tensioned members in differ...
Article
Vulnerability curves in seismic risk studies, represent the relation between mean damage or loss ratio and some earthquake intensity parameter(s). Mostly, these curves are developed based on observed damage ratios caused by actual events or analytic evaluation of seismic performance of different building typologies. Exclusively employing these mode...
Code
this is an under develope software for condition monitoring of external PT tendons. the sections for tensile force estimation is alredy finished. the damage detection part is under develop and it will be finished within time schedule
Article
Iran is one of the most earthquake-prone areas in the world and the resulting losses and casualties have had long-lasting effects on both its economy and citizens. As a vital structure in any community, schools are expected to maintain their initial functionality during a seismic event to guarantee the safety of students and act as an emergency cen...
Article
Full-text available
This paper outlines an optimisation model for land use planning which could be used by public officials and other stakeholders to prepare a risk-sensitive development plan fulfilling standard regulations of urban planning with an emphasis on earthquake protection. The presented model is based on a mixed integer quadratic programming method that pro...
Article
In this research, the active control of structures based on the critically damped condition was proposed for reducing displacements and drifts of structures under seismic loading. In this approach, the second-order dynamic equation is converted into a first-order dynamic equation and a first-order derivative operator with the same constants, which...
Chapter
Increasing number of power supply interruptions due to earthquakes leads to heavy direct and indirect economic losses and indicates the importance of resilience of electric power networks. The present study, focusing on the seismic resilience of the electricity transmission grid, is looking to develop a basic framework for calculating power grid pe...
Article
This study presents a new hybrid method to develop seismic fragility curves for horizontally-curved steel I-girder bridges using Artificial neural network and logistic regression methods. The approach for developing fragility curves based on the assumption that engineering demand parameters follow the lognormal distribution for calculating the prob...
Article
System identification methods (SIMs) are powerful tools for structural health monitoring. SIMs are used either for identification of modal parameters or for extraction of structural characteristic matrices. The current study aims to identify the real matrices of a structure using structural dynamics theory and stochastic subspace identification bas...
Article
This study presents a new hybrid method to develop seismic fragility curves for horizontally-curved steel I-girder bridges using Artificial neural network and logistic regression methods. The approach for developing fragility curves based on the assumption that engineering demand parameters follow the lognormal distribution for calculating the prob...
Article
This paper presents a simplified method for the evaluation of the tension in elastic cables and tendons based on the vibrational method. The accuracy and simplicity of this method are compared with other methods. The force transmitting members in different structures, including cable-stayed bridges, post-tensioned segmental bridges as axially one-d...
Conference Paper
Tendon tension loss is one of the most important damages of pre-stressed, cable-stayed, and suspension bridges. In this experimental study, a vibration-based method has been implemented for tension estimation of mono-strand externally tendon. The test has been done in the IIEES structural laboratory. In order to identify the natural frequency of th...
Conference Paper
Full-text available
Extended Abstract : Today, a wide range of tools and software are available for nonlinear dynamic analysis as a comprehensive method for estimation of seismic demand in highway bridges. Generally, nonlinear structural analysis methods based on the structural mechanic and mathematical methods are using in the estimation of the structural vulnerabili...
Conference Paper
Optimizing different aspects of a management program using the outcomes of a catastrophe model is an essential part of knowledge-based disaster management. Implementing this strategy, responsible authorities are able to effectively map out a master plan of actions for before, during and after the disaster. Focusing on seismic hazard in Iran and it...
Article
Schools should be considered as the most important structures in any society, in which children spend plenty of time. As a result, having a proper management of crucial engineering factors such as vulnerability and resilience of schools seems totally vital. The present study intends to deal with this issue in Iranian schools. As a case study, a hig...
Article
Abstract In this research the tail equivalent linearization method (TELM) has been extended to study structures with degrading materials. The responses of such structures to excitations are non-stationary, even if the excitations are stationary. Non-stationary behavior of the system cannot be considered by conventional TELM. Applying the convention...
Article
In this research the tail equivalent linearization method (TELM) has been extended to study structures with degrading materials. The responses of such structures to excitations are non-stationary, even if the excitations are stationary. Non-stationary behavior of the system cannot be considered by conventional TELM. Applying the conventional TELM,...
Article
Conditional spectra are a recent development in this field, which utilizes the advantages of spectral shape indicators, for example, epsilon and eta. The application of an eta indicator in conditional spectra calculations depends mainly on calculating the peak ground velocity epsilon, data about which are not readily available in the current litera...
Conference Paper
Increasing number of power supply interruptions due to earthquakes leads to heavy direct and indirect economic losses and indicates the importance of resilience of electric power networks. The present study, focusing on seismic resilience of the electricity transmission grid, is looking to develop a basic framework for calculating power grid perfor...
Article
Full-text available
In most seismic regions of the world, many unreinforced masonry buildings have been constructed for different uses, including schools. Statistical analyses showed that 90% of schools on the retrofitting list in Iran are unreinforced masonry buildings. The addition of shear walls is a frequently used retrofitting method in these buildings. However,...
Article
In this study, strong ground motion record (SGMR) selection based on Eta (η) as a spectral shape indicator has been investigated as applied to steel braced frame structures. A probabilistic seismic hazard disaggregation analysis for the definition of the target Epsilon (ε) and the target Eta (η) values at different hazard levels is presented, takin...
Article
Recent earthquakes have shown that Electrical Power Substations apparatuses are seismically vulnerable. This causes to disrupt the power supply in many cases, and therefore their seismic evaluation with high reliability is significantly important. Using fragility curves is a common practice for assessing seismic vulnerability. In general, fragility...
Article
Recent earthquakes have shown that Electrical Power Substations' equipment are seismically vulnerable, resulting in disruption of power supply in many cases, and therefore their seismic vulnerability evaluation is of great importance. Power transformers (PTR) are critical elements in a power substation, so their proper functioning during and after...
Conference Paper
Fragility curves are important elements in the loss estimation procedure since they are very useful instruments to evaluate seismic resilience index. This article tends to investigate the impact of retrotting on reducing the probability of structural failure as well as deriving resilience index in terms of fragility curves. Schools are essential f...
Conference Paper
This paper describes an overview on the observed vulnerabilities and damages to the Iran power supply systems due to the most common natural hazards, especially earthquake. Here as a case study, the behaviour of the electric power systems and typical failure modes during Manjil, Bam, Zarand and Kaki earthquakes with M>6 have been given. Each earthq...
Conference Paper
To increase the resilience of a system, reduction of recovery time and increasing the performance level of the system, or in other words, reduction of maximum probable loss to the system is required. So, in brief, the two main parameters affecting the amount of resiliency, are “recovery time” and “loss”. On one hand, different combinations of loss...
Article
This paper presents a new method for determining rocking ground motion considering the effects of both time delay and loss of coherency in spatially variable seismic ground motions. Acceleration, velocity, and displacement response spectra resulting from the rocking component are also derived. Next, new seismic intensity parameters are proposed to...
Poster
Full-text available
Mohsen Ghafory-Ashtiany, Mahban Arghavani. (2016). Quantification of Resilience in Earthquake Engineering. UNISDR Science and Technology Conference on the implementation of the Sendai Framework for Disaster Risk Reduction 2015-2030, 27-29 January 2016, Geneva International Conference Centre (GICC), Geneva, Switzerland
Chapter
The purpose of this chapter is to show the benefit of using the richness of Abrahamic religions toward developing an effective risk communication and education approach, especially among a religious community. The chapter approach is to present the guiding principle of disaster risk reduction (DRR); the views of Abrahamic religions and specially Is...
Article
Full-text available
Iran is one of the most earthquake-prone countries in the world. In recent earthquakes, the low quality of constructions has caused huge losses, both in human and economic terms. The high level of seismic hazard in combination with a high physical vulnerability of structures leads to a high earthquake risk of Iran, which has to be managed in some w...
Article
The present paper aims at evaluating damage and collapse behavior of low-rise buildings with unidirectional mass irregularities in plan (torsional buildings). In previous earthquake events, such buildings have been exposed to extensive damages and even total collapse in some cases. To investigate the performance and collapse behavior of such buildi...
Article
Rapid unmanaged growth of population and properties in metropolitan areas has increased the societal vulnerability to disasters. While the first step in disaster economic risk management is the quantification of economic losses, modeling unexpected events by equilibrium-oriented economic models which assume gradual and incremental changes over time...
Article
Full-text available
Iran is located in a highly seismic active region and building structures, therefore need to be designed and constructed to withstand major earthquakes. Structural mitigation measures are now seen as one key element to reduce economic as well as human losses for today and in the future. However, the costs and benefits of various options are difficu...
Article
This paper discusses the collapse behavior of low-rise plan-asymmetric buildings under bi-directional horizontal ground motions and utilizing strength and stiffness degrading nonlinear models. For this purpose, three-dimensional three-story and six-story reinforced concrete frame buildings with uni-directional mass eccentricities equal to 0% (symme...
Article
Full-text available
Many governments provide financial assistance for reconstruction of damaged housing units after a disaster in order to prevent vulnerable households from falling into poverty traps or entering low growth cycles. To lessen these risks and the overall financial burden on the public sector after extreme events, private insurance schemes provide one vi...
Article
The aim of “System Identification” is to determine modal and system properties of structural systems. This is while in “Damage Detection”, the identification of system characteristic matrices is as important as or even more important than the identification of frequency characteristics. Because of various constraints – i.e. difficulties in force ex...
Article
One of the main challenges in structural analysis is the reliable definition of structural loading; especially the loading pattern due to earthquake input acceleration at the base of the structure. During the past four decades, in spite of the fact that six components—three translational and three rotational—are needed to describe strong ground mot...
Article
As seismic waves pass through the foundations, the high frequency waves of the free-field motions will be filtered by foundations. To obtain these filtered motions named as foundation input motions (FIMs), the effects of the kinematic interaction between the foundation and surrounding medium due to the spatial variation of earthquake ground motion...
Article
Full-text available
Damage detection and estimation in structures using incomplete static responses are presented in this study. In the proposed approach, damage location and severity is determined by solving an optimization problem using a pattern search algorithm. Therefore, an objective function is formulated using incomplete static responses. Because of limitation...
Conference Paper
Natural disasters can cause huge human and economic losses, and subsequent operation efforts in disaster relief, recovery and reconstruction by the government, the private sector stakeholders as well as international donors can significantly drain their resources from other non-disaster related pre-planned investments. As a consequence, there is no...
Article
Full-text available
Problem: Strategic action plan-ning and scheduling (SAP) in the coordination of a disaster response team involves selecting and decom-posing an objective into sub-goals, grouping available units into coalitions and assigning them to the sub-goals, allocating units to tasks, and adjusting the de-cisions that have been made. The primary responsi-bili...
Conference Paper
Full-text available
In this paper Tail Equivalent Linearization Method (TELM) has been extended to cover independent bi-directional excitation that acts with different angle from the major axes of structure. The developed method has been applied on a 3D structure with a rigid diaphragm supported by four different columns with bi-axial Bouc-Wen non-linear behavior mode...
Conference Paper
Full-text available
In this paper Tail Equivalent Linearization Method has been expanded for 3D structures with biaxial Bouc-Wen material subjected to bi-directional excitation along the structural axes. Most computational part in TELM is to find the design point which is the solution of a constrained optimization problem. To do this it is required to calculate the re...
Article
In this paper, a crack identification approach is presented for detecting crack depth and location in beam-like structures. For this purpose, a new beam element with a single transverse edge crack, in arbitrary position of beam element with any depth, is developed. The development is based on a simplified model, where each crack is substituted by a...
Article
Full-text available
Tail equivalent linearization method is based on first order reliability method, which obtains an equivalent linear system for the considered nonlinear problem with equal tail probability related to a specified threshold and time. This method has been applied only to nonlinear non-degrading single- and multi-degrees of freedom shear beam two-dimens...
Article
Full-text available
SUMMARY It is expected that application of torsion provisions in typical seismic codes shows different levels of efficiency for torsionally stiff and flexible buildings. This paper studies difference in performances of a range of code designed torsionally stiff and flexible five-story building models. The models are classified in eight configuratio...
Article
Full-text available
In this study, a new method is proposed to provide the location and the extent of structural damage by using incomplete modal data and an evolutionary algorithm. The proposed method uses modal data to formulate objective function. This data is acquired by the modal analysis of damaged structure applying the finite element method. The particle swarm...
Article
Risk reduction as an outcome only takes place if results of risk estimation studies are used to develop action plans for risk-management and risk-reduction strategies. This paper describes an automated model that uses the output of existing earthquake loss estimation methodologies to support decision makers in evaluating a set of competing seismic...
Article
Considering the important role of Non-linear Time History Analysis (NLTHA) in the assessment of the seismic demand imposed to the engineering structures, and that the lack of appropriate strong ground motion recordings in some regions; has forced the earthquake engineers to select and modify a set of recordings from other available databases or use...
Article
The present paper aims at assessing the seismic collapse safety of three dimensional low-rise buildings with mass irregularities in plan. Nonlinear seismic behavior of three and six-story 3D reinforced concrete frame buildings with three bays in each direction having mass eccentricities in plan equal to 0% (regular), 10%, 20% and 30% were studied u...
Article
SUMMARYA methodology based on the progressive incremental dynamic analysis has been introduced in this paper to estimate the structural response and the corresponding annual probability of failure. The proposed methodology employs the genetic algorithm optimisation technique and an equivalent single‐degree‐of‐freedom system corresponding to the fir...
Article
Full-text available
In this paper, the seismic vulnerability of Mashhad city, as the second largest city in Iran, has been investigated using analytical fragility curves. Disaggregation analysis is first performed in order to identify the target epsilon at different hazard levels. The disaggregation results revealed different epsilon values at the first mode period of...
Article
In this paper a direct system identification method is presented for identification of general linear system physical parameters (structural mass, damping and stiffness matrices) using direct inverse solution of the equations of motion in the frequency domain. When the input and output (responses) measured data are noise free, the proposed method c...
Conference Paper
Full-text available
This paper presents that state-of-the art report on the characteristics of the rotational components and the common method for its estimation, as well as the need for for their consideration and their influences on the seismic loading of resistant structures against strong ground motions (SGMs) for reliable analysis and design. A new method for est...
Article
Full-text available
Incomplete sensed data in structures have made exact structural damage detection a serious challenge. In this paper, an effective method is presented for damage detection and estimation in structures based on incomplete modal data of a damaged structure via a pattern search algorithm. An objective function based on the condensed mass and stiffness...
Article
In this paper, a crack identification approach is presented for detecting crack depth and location in beam-like structures. For this purpose, a new beam element with a single transverse edge crack, in arbitrary position of beam element with any depth, is developed. The crack is not physically modeled within the element, but its effect on the local...
Article
The paper addresses the issue of research-ing into the engineering characteristics of rotational strong ground motion components and rotational effects in structural response. In this regard, at first, the acceleration response spectra of rotational components are estimated in terms of translational ones. Next, new methods in order to consider the...
Article
Full-text available
This paper presents novel approaches to structural damage detection and estimation using incomplete modal data and incomplete static response of a damaged structure. The proposed methods use modal data or static displacement to formulate objective functions. Damage location and severity in structural elements are determined using optimization of th...
Article
Full-text available
The influence of the indicator η on the collapse capacity of structural systems has been investigated in this paper. Eta has been introduced recently as an indicator of spectral shape which has strong influence on the structural nonlinear response. In this paper, a closed form formula has also been developed to predict the collapse capacity of stru...
Conference Paper
The aim of "System Identification" is to determine the modal and system properties of structural systems. Because of various constraints in practice only single excitation and partial measurement at selected degrees of freedom is possible. In this paper, to identify a structural system, dynamic load was applied only along one of the degrees of free...
Conference Paper
Full-text available
In recent decades, the agglomeration of population and investment had made the cities more and more vulnerable to natural and man-made disasters. Along with conventional risk reduction, alternatives like retrofitting vulnerable buildings, enforcing construction codes, supervising the construction process, and increasing the public awareness to eart...
Article
The damage that can occur to structures by way of deformation in bending under the excitation of random forces (referred to hereafter as ‘bending structures') is considered a local state due to the harm caused by cracks. Its effects on the behaviour of the structure are discussed as discontinuity phenomena. For the simulation of such discontinuitie...
Article
Full-text available
The sets of records developed for the SAC Steel Project are classified according to the level of seismic hazard and specific geographic region, and have been used extensively for structural response and seismic hazard analyses. This study presents a parametric analysis of these record data sets for generation of uniform hazard earthquake and near-f...