Abbas Moustafa
Minia University,Egypt, Civil Engineering, Faculty Member
- Dr. Abbas Moustafa is currently a Professor of Earthquake and Structural Engineering, Department of Civil Engineering... moreDr. Abbas Moustafa is currently a Professor of Earthquake and Structural Engineering, Department of Civil Engineering, Minia University, Egypt. He was the chairman of Department of Civil Engineering, Giza Institute of Engineering and Technology, Giza, Egypt during 2011-2012 and 2020-2021. He is also a Consultant Engineer and was the Head of Structural Group at Hamza Associates, Giza, Egypt during 2011-2014. Dr. Moustafa was a senior research associate at Vanderbilt University and a JSPS fellow at Kyoto and Nagasaki Universities. He has about 50 research papers published in international journals and conferences. He is the co-author of the book "Improving the Earthquake Resilience of Buildings" published by Springer in 2013, the editor of three books on Earthquake-Resistant Structures (2012), Geotechnical Earthquake Engineering (2012), and Earthquake Engineering (2015). He is also the Guest Editor for a Special Issue of Natural Science on "Earthquakes" published in 2012. He acts as editorial board member and reviewer for several regional and international journals. His research interest includes earthquake/wind/structural engineering, seismic design, nonlinear dynamics, random vibration, structural reliability, structural optimization, seismic codes, structural health monitoring and uncertainty modeling.edit
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It is evident that the response of linear structures under dynamic loads depends to two important dynamics parameters of structures, namely, the natural periods and structural damping. These parameters always characterize the oscillation... more
It is evident that the response of linear structures under dynamic loads depends to two important dynamics parameters of structures, namely, the natural periods and structural damping. These parameters always characterize the oscillation and the energy dissipation of buildings. In fact, the values of these parameters differ significantly, before, during and after an earthquake from values selected during the design phase. This phenomenon, among other, introduces uncertainty into the building simulation process, which remarkably influences the structural response and associated performance of the structure under dynamic loads. This paper develops a new methodology to estimate the maximum absolute response for linear structures with uncertain damping using the Artificial Neural Networks (ANN) and the Monte Carlo method. The proposed method is illustrated using the target design response spectra corresponding to the EC8 for linear structures exposed to seismic loads. The numerical resu...
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... This early estimation will enable the growers to decide if it is economic to continue the cultivation of the crop. It is well known that the yield of plants infected at an early stage of growth is almost nil (Kamal and Saydam, 1970).... more
... This early estimation will enable the growers to decide if it is economic to continue the cultivation of the crop. It is well known that the yield of plants infected at an early stage of growth is almost nil (Kamal and Saydam, 1970). ...
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ABSTRACT This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology... more
ABSTRACT This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology takes advantage of the response spectra and thus does not require explicit dynamic analysis of the actual structure. Uncertainties in the structural properties (e.g. member cross-sections, modulus of elasticity, member strengths, mass and damping) as well as in the seismic load (due to uncertainty associated with the earthquake load specification) are considered. The structural reliability is estimated by determining the failure probability or the reliability index associated with a performance function that defines safe and unsafe domains. The structural failure is estimated using a performance function that evaluates whether the maximum displacement has been exceeded. Numerical illustrations of reliability analysis of elastic and elastic-plastic single-story frame structures are presented first. The extension of the proposed method to elastic multi-degree-of-freedom uncertain structures is also studied and a solved example is provided.
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A hybrid qualitative-quantitative health assessment of structures using the bond graph theory is presented in this chapter. Bond graph (BG) is an energy-based graphical-modeling tool for physical dynamic systems, actuators, and sensors.... more
A hybrid qualitative-quantitative health assessment of structures using the bond graph theory is presented in this chapter. Bond graph (BG) is an energy-based graphical-modeling tool for physical dynamic systems, actuators, and sensors. BG provides domain-independent framework for modeling dynamic systems with interacting components from multiple domains. Discrete structures are modeled using one-to-one bond graph elements, while continuous structures are modeled using finite-mode bond graphs. BG facilitates the construction of temporal causal graph (TCG) that links the system response to the damaged component or faulty sensor. TCG provides qualitative damage isolation, which is not possible using most existing system identification techniques. This leads to rapid isolation of damage and significant reduction in computations. Quantitative identification of damage size is performed by analyzing the substructure containing the damaged component, using the nonlinear least-squares optim...
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Mobile mapping system is a close range photogrammetric system proved to be useful in many GIS applications. Whenever an area needs to be surveyed, a van equipped with all the necessary instruments and sensors travels into that area and... more
Mobile mapping system is a close range photogrammetric system proved to be useful in many GIS applications. Whenever an area needs to be surveyed, a van equipped with all the necessary instruments and sensors travels into that area and takes a series of ...
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ABSTRACT This paper develops a reliability-based computational methodology for modeling non-stationary random critical earthquake loads on structures using the site response spectra. The power spectral density function and the envelope... more
ABSTRACT This paper develops a reliability-based computational methodology for modeling non-stationary random critical earthquake loads on structures using the site response spectra. The power spectral density function and the envelope parameters of the ground acceleration are taken to be unknown and are computed such that the structural reliability index is minimized subjected to constraints reflecting known knowledge on the site seismicity. Specifically, bounds on the total energy, zero-crossing rate and entropy rate of the earthquake signal and positivity requirements are considered. These constraints are derived from the site response spectra. The formulation combines methods of structural reliability analysis, response surface fitting, FORM and nonlinear programming. Numerical illustrations on reliability-based critical earthquake inputs for elastic and inelastic frame structures are presented.
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Important and critical structures should be designed to resist transient extreme loads such as high velocity impacts and explosions. Blast-resistant design of structures includes architectural design and structural design against... more
Important and critical structures should be designed to resist transient extreme loads such as high velocity impacts and explosions. Blast-resistant design of structures includes architectural design and structural design against explosion forces. Blast loads could be internal due to explosion of gas pipes or external due to chemical bombs and car attacks. During the last few years, Egypt witnessed terrorist bombs and car attacks on important structures. These events caused large life losses and led to severe damage and collapse of several heritage and security buildings. In this paper, the response and damage of single-degree-of-freedom (SDOF) structures to blast loads are presented. The blast load is modeled as a time-variant function with positive and negative pressure zones. Firstly, the governing nonlinear differential equation of motion for SDOF of inelastic structures under blast load is provided. Subsequently, the solution of this equation is obtained using numerical integra...
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ABSTRACT Near-fault ground motion with directivity or fling effects is significantly influenced by the rupture mechanism and substantially different from ordinary records. This class of ground motion has large amplitude and long period,... more
ABSTRACT Near-fault ground motion with directivity or fling effects is significantly influenced by the rupture mechanism and substantially different from ordinary records. This class of ground motion has large amplitude and long period, exhibits unusual response spectra shapes, possesses high PGV/PGA and PGD/PGA ratios and is best characterized in the velocity and the displacement time-histories. Such ground motion is also characterized by its energy being contained in a single or very few pulses, thus capable of causing severe damage to the structures. This paper investigates the characteristics of near-fault pulse-like ground motions and their implications on the structural responses using new proposed measures, such as, the effective frequency range, the energy rate (in time and frequency domains) and the damage indices. The paper develops also simple mathematical expressions for modeling this class of ground motion and the associated structural responses, thus eliminating numerical integration of the equations of motion. An optimization technique is also developed by using energy concepts and damage indices for modeling this class of ground motion for inelastic structures at sites having limited earthquake data.
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ABSTRACT Multiple acceleration sequences of earthquake ground motions have been observed in many regions of the world. Such ground motions can cause large damage to the structures due to accumulation of inelastic deformation from the... more
ABSTRACT Multiple acceleration sequences of earthquake ground motions have been observed in many regions of the world. Such ground motions can cause large damage to the structures due to accumulation of inelastic deformation from the repeated sequences. The dynamic analysis of inelastic structures under repeated acceleration sequences generated from simulated and recorded accelerograms without sequences has been recently studied. However, the characteristics of recorded earthquake ground motions of multiple sequences have not been studied yet. This paper investigates the gross characteristics of earthquake records of multiple sequences from an engineering perspective. The definition of the effective number of acceleration sequences of the ground shaking is introduced. The implication of the acceleration sequences on the structural response and damage of inelastic structures is also studied. A set of sixty accelerograms is used to demonstrate the general properties of repeated acceleration sequences and to investigate the associated structural inelastic response.
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The response and damage assessment of engineering structures under near-field ground motions is currently of great interest. Near-field ground motion with directivity focusing or fling effects produces pulse-like ground motion that has... more
The response and damage assessment of engineering structures under near-field ground motions is currently of great interest. Near-field ground motion with directivity focusing or fling effects produces pulse-like ground motion that has characteristics different from those of ordinary records. ...
Research Interests: Civil Engineering, Geophysics, Computer Science, Structural Reliability, Stochastic processes, and 15 moreProbabilistic Logic, Damage Assessment, Models, Probabilistic Model Checking, Reliability, Reduction, Acceleration, Steady state, Model development, Ground Motion, Inelastic Response, Reliability Assessment, Structural Response, Near Field, and Probabilistic Model
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Pulse-like (also known as resonant, cycloidal pulses, or impulse-like) ground motion has been observed in near-field (also near-fault or near-source) records with directivity focusing or fling effects. This class of ground motion is... more
Pulse-like (also known as resonant, cycloidal pulses, or impulse-like) ground motion has been observed in near-field (also near-fault or near-source) records with directivity focusing or fling effects. This class of ground motion is significantly influenced by the rupture mechanism, substantially different from ordinary ground motion records, and can be characterized by the following features [1, 2, 3, 4, 5, 6, 7, 8, among others]: (1) long period and large amplitudes, (2) high peak ground velocity (PGV)/peak ground acceleration (PGA) and peak ground displacement (PGD)/PGA ratios, (3) unusual response spectra shapes, and (4) concentration of energy in one or very few pulses.
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In performance-based design, the structure is designed to behave linearly elastic without damage under a moderate frequent earthquake and to undergo repairable damage under a rare strong earthquake. Design earthquakes are specified in... more
In performance-based design, the structure is designed to behave linearly elastic without damage under a moderate frequent earthquake and to undergo repairable damage under a rare strong earthquake. Design earthquakes are specified in current seismic codes as single events. However, the structure may experience repeated accelerations in a short period of time. Ground accelerations of multiple sequences could result in more damage to the structure than a single ordinary event.
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The robust design of structures toward earthquake loads is the key for the mitigation of the structure damage against earthquake hazards. The structural engineer aims to design structures that are safe against possible future earthquakes... more
The robust design of structures toward earthquake loads is the key for the mitigation of the structure damage against earthquake hazards. The structural engineer aims to design structures that are safe against possible future earthquakes and economic at the same time. The selection of suitable design earthquake loads for structural design is the first step to achieve this goal. The use of accurate nonlinear model describing the inelastic behavior of the structure is the second step to achieve this goal. Earthquake loads can be specified for seismic design of structures using the response spectrum method, using recorded accelerograms, or using the random vibration theory. The method of the critical excitation has been developed in the literature for specifying mathematical earthquake loads on structures.
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Accumulated data and experiences are very important in the reliable seismic design of structures. However, it is also true that theoretical expectations and predictions are also of significance for the design of extremely important... more
Accumulated data and experiences are very important in the reliable seismic design of structures. However, it is also true that theoretical expectations and predictions are also of significance for the design of extremely important structures and facilities which are influential for the society and wide district. This was demonstrated in the past earthquakes which are very rare from the viewpoint of return period in the same area. The most devastating earthquake in Japan after the 1923 Great Kanto earthquake hit eastern Japan in the afternoon of March 11, 2011. The moment magnitude 9.0 earthquake is one of the five most powerful earthquakes in the world since modern recordkeeping began in 1900. It was made clear afterwards that the recording system for low-frequency and large-amplitude ground motions was not sufficient in Japan and the first preliminary Japan Meteorological Agency (JMA) magnitude was smaller than 8 (7.9 exactly). The JMA magnitude was updated immediately as 8.4. Records of earthquake ground motions outside Japan were then used to determine the exact moment magnitude of 9.0 (intermediate announcement was 8.8). The earthquake resulted from the thrust faulting near the subduction zone plate boundary between the Pacific and North America Plates.
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The accurate prediction of ground motions from possible future earthquakes is the first step toward the robust assessment and mitigation of structural damage against earthquake hazards. The modeling of critical or resonant ground motions... more
The accurate prediction of ground motions from possible future earthquakes is the first step toward the robust assessment and mitigation of structural damage against earthquake hazards. The modeling of critical or resonant ground motions has been developed by the present authors in several studies. These studies showed that the resonant ground motion has its energy in a narrow frequency range and produces larger damage in the structure compared to ordinary records. Resonant or pulse-like ground motion has been observed in near-field records with directivity focusing or fling effects. Such ground motion is influenced by the rupture mechanism and possesses the following characteristics: (1) large peak ground velocities and displacements, (2) concentration of energy in a single or a few pulses, and (3) unusual response spectra shapes. These features have been recently studied by these authors.
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The damage of structures induced by earthquake ground motions depends primarily on three parameters: (1) the characteristics of earthquake source properties and ground motions (magnitude, epicentral distance, duration, frequency content,... more
The damage of structures induced by earthquake ground motions depends primarily on three parameters: (1) the characteristics of earthquake source properties and ground motions (magnitude, epicentral distance, duration, frequency content, amplitude and local soil type), (2) the properties of the structure (natural frequencies, mode shapes, damping properties, material of construction, structural system and ductility capacity), and (3) how close the structure’s fundamental natural frequency to the dominant frequency of the ground motion. The 2011 off the Pacific coast of Tohoku earthquake has demonstrated these facts clearly. In general, the ground motion characteristics involve large inherent uncertainties and cannot be controlled while the structure’s properties have smaller variability and can be managed to some extent in general. For instance, the material and members of construction can be selected and the seismic-resistance of the structure can be improved to fairly high levels through member detailing for enhancement of ductility capacity.
Research Interests: Physics and Seismology
ABSTRACT Ground acceleration sequences separated by short time intervals have been observed at several parts of the world including Japan, Mexico, Turkey, Italy, and California. However, such ground motion data are not available in... more
ABSTRACT Ground acceleration sequences separated by short time intervals have been observed at several parts of the world including Japan, Mexico, Turkey, Italy, and California. However, such ground motion data are not available in catalogs for easy access to structural engineers. It should be emphasized that the 2011 off the Pacific coast of Tohoku earthquake had multiple sources and exhibited multiple sequences. Ground motion sequences can create significant damage in structures due to the accumulation of the inelastic deformation from the repeated sequences before any structural repair is possible. Additionally, the low-frequency content in secondary sequences may cause resonance in lower modes of the damaged structure leading to further damage to the structure (see Chap. 10). Accordingly, the verification of the structure adequacy to withstand multiple acceleration sequences without collapse is of essential concern in earthquake engineering, especially since current seismic codes do not account for their effects.
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ABSTRACT A gradient-based evolutionary optimization methodology is presented for finding the optimal design of both the added dampers and their supporting members to minimize an objective function of a linear multi-storey structure... more
ABSTRACT A gradient-based evolutionary optimization methodology is presented for finding the optimal design of both the added dampers and their supporting members to minimize an objective function of a linear multi-storey structure subjected to the critical ground acceleration. The objective function is taken as the sum of the stochastic interstorey drifts. A frequency-dependent viscoelastic damper and the supporting member are treated as a vibration control device. Due to the added stiffness by the supplemental viscoelastic damper, the variable critical excitation needs to be updated simultaneously within the evolutionary phase of the optimal damper placement. Two different models of the entire damper unit are investigated. The first model is a detailed model referred to as "the 3N model" where the relative displacement in each component (i.e., the spring and the dashpot) of the damper unit is defined. The second model is a simpler model referred to as "the N model" where the entire damper unit is converted into an equivalent frequency-dependent Kelvin-Voigt model. Numerical analyses for 3 and 10-storey building models are conducted to investigate the characters of the optimal design using these models and to examine the validity of the proposed technique.
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This paper develops a reliability-based computational methodology for modeling nonstationary random critical earthquake loads on structures using the site response spectra. The power spectral density function and the envelope parameters... more
This paper develops a reliability-based computational methodology for modeling nonstationary random critical earthquake loads on structures using the site response spectra. The power spectral density function and the envelope parameters of the ground acceleration are taken to be unknown and are computed such that the structural reliability index is minimized subjected to constraints reflecting known knowledge on the site seismicity. Specifically, bounds on the total energy, zero-crossing rate and entropy rate of the earthquake signal and positivity requirements are considered. These constraints are derived from the site response spectra. The formulation combines methods of structural reliability analysis, response surface fitting, FORM and nonlinear programming. Numerical illustrations on reliability-based critical earthquake inputs for elastic and inelastic frame structures are presented.
This special issue of Natural Science, entitled Earthquakes, tackles a wide range of research subjects related to earthquakes, including their nature, measures, causes of occurrence, characteristics, attenuation modeling, soil wave amplification, methods and tools of recording, analysis and predi...more
This special issue of Natural Science, entitled Earthquakes, tackles a wide range of research subjects related to earthquakes, including their nature, measures, causes of occurrence, characteristics, attenuation modeling, soil wave... more
This special issue of Natural Science, entitled Earthquakes, tackles a wide range of research subjects related to earthquakes, including their nature, measures, causes of occurrence, characteristics, attenuation modeling, soil wave amplification, methods and tools of recording, analysis and prediction, their effect on the built environment and methods of design, analysis, assessment, control and repair of engineering structures against seismic loads resulting from earthquakes. This special issue of Natural Science considers also other related subjects on explosions and volcanic phenomena and hyperbaric-Oxygen treatment due to crush injury resulting from earthquakes. The special issue contains fourteen research papers written by researchers and experts from several countries.
This paper develops a new framework for modeling design earthquake loads for inelastic structures. Limited information on strong ground motions is assumed to be only available at the given site. The design earthquake acceleration is... more
This paper develops a new framework for modeling design earthquake loads for inelastic structures. Limited information on strong ground motions is assumed to be only available at the given site. The design earthquake acceleration is expressed as a Fourier series, with unknown amplitude and phase angle, modulated by an envelope function. The design earthquake is estimated by solving an inverse dynamic problem, using nonlinear programming techniques, such that the structure performance is minimized. At the same time, the design earthquake is constrained to the available information on past recorded ground motions. New measures of the structure performance that are based on energy concepts and damage indices are introduced in this paper. Specifically, the structural performance is quantified in terms of Park and Ang damage indices. Damage indices imply that the structure is damaged by a combination of repeated stress reversals and high stress excursions. Furthermore, the use of damage ...
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This book deals with earthquake-resistant structures, such as, buildings, bridges and liquid storage tanks. It contains twenty chapters covering several interesting research topics written by researchers and experts in the field of... more
This book deals with earthquake-resistant structures, such as, buildings, bridges and liquid storage tanks. It contains twenty chapters covering several interesting research topics written by researchers and experts in the field of earthquake engineering. The book covers seismic-resistance design of masonry and reinforced concrete structures to be constructed as well as safety assessment, strengthening and rehabilitation of existing structures against earthquake loads. It also includes three chapters on electromagnetic sensing techniques for health assessment of structures, post earthquake assessment of steel buildings in fire environment and response of underground pipes to blast loads. The book provides the state-of-the-art on recent progress in earthquake-resistant structures. It should be useful to graduate students, researchers and practicing structural engineers.
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In this paper, an analytical pulse model for velocity pulses observed in near-field ground motions has been proposed for a systematic design and assessment of seismic protective systems. The proposed pulse model utilizes pulse period,... more
In this paper, an analytical pulse model for velocity pulses observed in near-field ground motions has been proposed for a systematic design and assessment of seismic protective systems. The proposed pulse model utilizes pulse period, decay factor, and shape parameters to model both buildup and decaying phases observed in recorded ground motions. It is demonstrated that the proposed model can successfully simulate observed ground motion pulses. Peak displacement, velocity, and acceleration of the analytical pulse model are directly correlated with peak ground motion parameters and the pulse period. The response spectra and displacement reduction factor using the pulse model correlate well with those using recorded ground motions for structural periods close to or longer than the pulse period, although there is lesser correlation for shorter structural periods because of exclusion of high frequency components in the pulse model. For a base-isolated building with 2.5 s natural period and equipped with supplemental viscous dampers, it is demonstrated that supplemental dampers are the most effective when the structural period is close to the pulse period. Displacement reduction using supplemental passive dampers is smaller when the pulse period is longer or shorter than the structural period, although the displacement demand is quite significant.
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The discusser states that the critical excitation paradigm relies on some of the earthquake parameters, such as, the maximum seismic magnitude expressed in terms of the energy or the peak ground acceleration (PGA). Firstly, it must be... more
The discusser states that the critical excitation paradigm relies on some of the earthquake parameters, such as, the maximum seismic magnitude expressed in terms of the energy or the peak ground acceleration (PGA). Firstly, it must be noted that earthquake ground motions ...
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This research develops a new and efficient hybrid qualitativequantitative system identification methodology for structures using the bond graph approach. Bond graphs provide a modeling framework that includes parametric models of both... more
This research develops a new and efficient hybrid qualitativequantitative system identification methodology for structures using the bond graph approach. Bond graphs provide a modeling framework that includes parametric models of both the physical system and the sensors. ...
Strong ground motion involves high uncertainties (eg time, location, magnitude, duration, frequency content, amplitude, etc.). Structural engineers are often concerned with the critical input or worst-case scenario that produces the... more
Strong ground motion involves high uncertainties (eg time, location, magnitude, duration, frequency content, amplitude, etc.). Structural engineers are often concerned with the critical input or worst-case scenario that produces the highest structural response. This talk deals with the ...
In Equations (5), (6), (7) and (9–11), the term wijt + (i – 1)T should be replaced with wij{t – (i – 1)T} and the term t + (i – 1)T with t – (i – 1)T. The envelope function shown in Figure 3 should be replaced with Figure 1 below for the... more
In Equations (5), (6), (7) and (9–11), the term wijt + (i – 1)T should be replaced with wij{t – (i – 1)T} and the term t + (i – 1)T with t – (i – 1)T. The envelope function shown in Figure 3 should be replaced with Figure 1 below for the two time periods 0 ⩽ t ⩽ T and T ⩽ t ⩽ 2T. Figure 1. The envelope function e(t) for the ground motion sequences
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The specification of earthquake loads as inputs to engineering structures is a crucial task in earthquake engineering. There are cases, however, where the site under consideration has limited or scarce seismic data, making this process a... more
The specification of earthquake loads as inputs to engineering structures is a crucial task in earthquake engineering. There are cases, however, where the site under consideration has limited or scarce seismic data, making this process a difficult task. Meanwhile, structural engineers are often concerned with the worst-case scenario that can happen to the structure during its service-life under possible future earthquakes. Repeated ground-motion sequences occurring after short intervals of time, resulting from mainshock-aftershock earthquakes, have been observed in many parts of the world. Such ground motion is capable of creating severe damage in the structure due to accumulation of inelastic deformations from multiple sequences before any structural repair is possible. This paper models ground motions of multiple sequences that produce the maximum damage in the structure. The ground acceleration is represented as Fourier series, with unknown amplitudes and phase angles, modulated ...
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The authors present an interesting application of digital image correlation techniques to the measurement of deformations in transparent media, and comment upon its accuracy in imagespace ie, in units of pixels. This valuable contribution... more
The authors present an interesting application of digital image correlation techniques to the measurement of deformations in transparent media, and comment upon its accuracy in imagespace ie, in units of pixels. This valuable contribution demonstrates that modern image analysis techniques are superior to conventional methods in which film photographs or x-rays are used to track target markers. With digitial image analysis, target markers need not be embedded in the soil, and many more measurement points can be established in ...
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The damping force exerted by a structure during an earthquake differs significantly from that specified in the design process. This introduces uncertainties in the design process of structures under earthquake loads. Accordingly, it is... more
The damping force exerted by a structure during an earthquake differs significantly from that specified in the design process. This introduces uncertainties in the design process of structures under earthquake loads. Accordingly, it is desirable to consider not only the effect of randomness of the seismic load but also the uncertainties in the structural parameters. This paper investigates the effect of uncertainties inherent in the damping ratio on the use of damping reduction factor (DRF) for the evaluation of high damping response spectra for linear structures with viscous damping. The DRFs are evaluated from both acceleration and displacement response spectra. Effects of period of vibration, level of damping ratio, soil class and uncertainties level of damping on the DRFs are evaluated and discussed. A numerical analysis implies that the maximum relative error estimated between the deterministic DRF and the DRF considering uncertainties in damping is about 14%. This implies that...