Seismic Engineering Research Papers - Academia.edu (original) (raw)

On Sunday, October 23rd, 2011, the Van province, in the Eastern Turkey, was
stricken by a magnitude Mw=7.1 earthquake. The maximum horizontal peak ground acceleration,
i.e. 0.182 g, was measured from the seismic station in Muradiye, at about 40 km
from the epicenter. SeveralMw > 5.7 strong motion aftershocks were recorded in November
2011. The exceptionally rich sequence of ground motionswas due to the dense seismotectonic
activity of the Eastern Turkey, where many active historical faults exist and newly generated
can also be found because of the ongoing continental collision between the Arabian and the
Eurasian Plates. The 2011 Van earthquake sequence caused 644 casualties, 1966 injuries
with 252 rescues; the total economic losses are estimated at around 1 billion US dollars. The
present paper deals with the seismological and structural damage assessment of two major
seismic events and aftershock sequences in Van region; special emphasis is on the findings of
the site investigations performed in the aftermath of the major seismic event. The performed
investigation has shown that there is substantial field evidence demonstrating that the losses
generated to the local social communitieswere caused by typical structural and non-structural
deficiencies that have been surveyed in the past in several moderate-to-major earthquakes
worldwide, especially in poor countries. Comprehensive numerical simulations were also
carried out to assess the characteristics of the strong motion records and their effects on
existing representative building type of structures in the earthquake-affected region. It was
found that the local building stock is highly vulnerable and requires urgent major structural
interventions for seismic strengthening. A cost-efficient retrofitting scheme is however not
straightforward. It should be a trade-off between two competing aspects: the use of innovative
materials and technologies on one hand, and the low-quality of the workmanships and lack of
adequate quality control during construction phase, which are available in the Van province,
on the other hand.

- by and +1
- •
- Earthquake Engineering, Seismic Engineering

Reinforced Concrete (R/C) buildings with masonry infills are amongst the most common structural systems in many countries with regions of high seismicity. The infill walls are usually considered as non-structural elements and, thus, are not taken into account in analytical models. However, numerous researches have shown that they can significantly affect the seismic response of the structures. Moreover, historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. The aim of the present study is to examine the role of masonry infills on the damage response of 3D R/C buildings with various structural systems subjected to seismic sequences. For the purposes of the above investigation a comprehensive assessment is conducted using 54 3-dimensional R/C buildings with different heights, structural systems and distribution of masonry infills. The buildings are analyzed by means of nonlinear time history analysis for 80 bidirectional seismic sequences. In order to account for the influence of the incident angle on the structural response, the two horizontal accelerograms of each ground motion are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The results revealed that the influence of the successive earthquake phenomenon on the structural damage is larger for the infilled buildings compared to the bare structures. Furthermore, when buildings with masonry infills are analyzed for seismic sequences, it is of great importance to account for the orientation of the seismic motion.

Mevcut yapıların deprem performans, risk ve güçlendirme analizlerinde, yanındaki yapı ile olan ilişkisini uygun modelleme teknikleri ile analiz aşamasının içine dâhil ederek, sonuçların ayrı ayrı analiz edilmiş binalara göre olan farklılıklarını incelemek önemli bir konu olarak ortaya çıkmaktadır. Bu çalışmada literatürdeki, komşu binaların birbirleri ile olan etkileşim modelleri, statik itme analizi ve doğrusal olmayan hesap yöntemleri, deprem ivme kayıtlarının bir veri tabanından alınması ve tasarım spektrumuna göre ölçeklenmesi, zaman tanım alanına göre hesap yöntemi, hareket denkleminin Newmark- yöntemi ile sayısal çözümü ve kırılganlık eğrileri ile bina performans seviyelerinin belirlenmesi konuları incelenmiştir. Bitişik (komşu) ve birbirine benzer binaların, deprem performanslarının birbirileri ile olan etkileşimli ve deprem yönüne göre değişen bir şekilde yapı blokları olarak ele alınıp, hasar görebilirlik-kırılganlık eğrileri yönünden değerlendirilmeleri incelenmiş ve binaların ayrı ayrı analiz edildikleri duruma göre daha farklı sonuçlar verdiği tespit edilmiştir.

This report presents the work I did as part of my graduation project. It consists of designing, studying and dimensioning the JW Marriott Tower in Casablanca Marina.
Being one of the largest cities in Africa, Casablanca plans to develop its international character by enriching its heritage of skyscrapers which are the symbol of power, energy and splendour of cities.
Having a unique architecture for the first time in Morocco, the tower presents enormous difficulties in terms of design and study since they work on the limits of current standards and regulations.
In this project I present initially a dossier about towers, their construction systems and their most used materials. Subsequently I explain the final design I have developed in accordance with the architectural plans and then I present the geotechnical context of the area and define the general hypothesis.
In the study and dimensioning phase, I study the structure in two approaches: a static approach and a dynamic approach. The static approach consists in studying the static behaviour of the tower vis-a-vis the permanent the exploitation loadings before dimensioning the structural elements outside the bracing system. In the dynamic approach I study the different horizontal and vibratory stresses, starting with the wind and then the seismic calculation.
After determining these stresses, I study the seismic design of the plates and shells as well as the foundations and the retaining walls and their stabilities and justifications in accordance to the ultimate, service and accidental states.

- by Mohamed FELLAH
- •
- Civil Engineering, Structural Engineering, Architecture, Structural Dynamics
- by fausto giovannardi
- •
- Civil Engineering, History, Social Sciences, Architecture

The seismic risk mitigation from the perspective of the old buildings stock is truly essential in Algerian urban areas, particularly those located in seismic prone regions, such as Annaba city, and which the old buildings present high levels of degradation associated with no seismic strengthening and/or rehabilitation concerns. In this sense, the present paper approaches the issue of the seismic vulnerability assessment of old masonry building stocks through the adaptation of a simplified methodology developed for a European context area similar to that of Annaba city, Algeria. Therefore, this method is used for the first level of seismic vulnerability assessment of the masonry buildings stock of the old city center of Annaba. This methodology is based on a vulnerability index that is suitable for the evaluation of damage and for the creation of large-scale loss scenarios. Over 380 buildings were evaluated in accordance with the referred methodology and the results obtained were then integrated into a Geographical Information System (GIS) tool. Such results can be used by the Annaba city council for supporting management decisions, based on a global view of the site under analysis, which led to more accurate and faster decisions for the risk mitigation strategies and rehabilitation plans.

The expected seismic losses of structures with Rotational Friction Dampers (RFDs) are assessed by the Endurance Time (ET) method considering the optimal frictional moment of the devices. A practical method is proposed to obtain the optimal frictional moment of the dampers in multi-story structures at multiple seismic hazard levels. The ET method is used as the analytical tool in this research due to its ability to reduce the number of required analyses and providing good estimations of structural responses at various hazard levels. In order to investigate the effectiveness of the dampers, the life cycle costs of a weak steel structure equipped with optimal RFDs are compared with a standard structure with optimal RFDs and without RFDs. To this end, a comprehensive performance evaluation is performed on the structures based on FEMA P-58 methodology. The ET method is also used as a tool to assess the structural responses in the framework of this methodology. The probability of collapse, fatalities, and expected damage costs are estimated utilizing a Monte Carlo procedure considering uncertainties. Also, a cost-benefit analysis is performed to determine the payback period of investment for the additional cost of the rotational friction damping systems.

The aim of this paper is to analyze the sensitivity of the base shear force to the randomness of the structure natural period and epicentral distance. To this end, several reinforced concrete buildings (6, 9 and 12 storey), with different floor plans: symmetric, monosymmetric, and unsymmetric are considered. These structures are erected at different epicentral distances. Initially, an expression liking the variation of the base shear force depending on the natural period of the structure and the epicentral distance is detailed. Then, this response is analyzed under the hypotheses that the both considered parameters (natural period and epicentral distance) are lognormal random variables, where the confidence interval of base shear force's statistics (mean, standard deviation) are analyzed under the change of the coefficient of variation "CV" of each parameter.

In May 2012, a series of medium-high intensity earthquakes struck a highly industrialized area of centralnorthern Italy and in particular the Emilia-Romagna region. As a consequence, there were 28 casualties, numerous injuries, and vast damage to thousands of civil structures, infrastructures and industrial facilities. After that, the
regional political authority, Regione Emilia-Romagna, spent billions of euro of state funding on reconstruction; as of 2018, almost EUR 1.9 billion was granted to business sector. In order to be able to fairly distribute financial aid to damaged productive facilities, a vast information system was created and data were stored in a database called SFINGE. Collected information regards losses, induced costs, reimbursements paid by the insurance companies, and money finally granted by the state. In this paper, we present the results of a study we conducted on the database; the requests for public funding were accessed and examined within a special scientific agreement between Regione Emilia-Romagna and RWTH Aachen University. Study results will be useful in predicting costs, economic losses and insurance refund for business activities damaged by seismic events. Public authorities can learn too, as the
paper presents a way of accounting consequences and granting refunds that proved to work effectively. Finally, reported data can be included within the existing theoretical framework of Performance Based Earthquake Engineering, significantly contributing to the definition of seismic performance assessment tools.

All of the investigations on the steel shear wall confirm its positive effect against lateral load such as wind and earthquake. This lateral load bearing system has many privileges like ductility, high energy damping capacity and... more

- by Behzad Bayat
- •
- Civil Engineering, Structural Engineering, Seismic Engineering, Ductility

This paper describes a seismic design procedure for rib-reinforced steel moment connections ba.c;ed on an equivalent strut model. It is shown from the results of finite-element analysis that the force transfer mechanism 10 the rib connections ts completely different from that predicted by the dac;sicnl beam theory and that a diagonal strip in the rib acts as a strut. By treating the rib as a strut, an equivalent strut model that could be used as the basis of a practical design procedure 1s proposed first A step-by-step design procedure i~ then recommended based on the proposed model.

- by AGS AO
- •
- Engineering, Steel Structure, Seismic Engineering, Steel Structures
- by Nicos Makris
- •
- Civil Engineering, Geology, Soil Science, Structural Engineering

This paper assesses the seismic performance of typical reinforced concrete (RC) existing framed
structures designed for gravity loads only. The sample two-storey structural system exhibits high
vulnerability, i.e. low lateral resistance and limited translation ductility; hence an effective strategy
scheme for seismic retrofitting was deemed necessary. Such a scheme comprises buckling restrained
braces (BRBs) placed along the perimeter frames of the multi-storey building. The adopted design
approach assumes that the global response of the inelastic framed structure is the sum of the elastic
frame (primary system) and the system comprising perimeter diagonal braces (secondary system); the
latter braces absorb and dissipate a large amount of hysteretic energy under earthquake ground
motions. Comprehensive nonlinear static (pushover) and dynamic (response history) analyses were
carried out for both the as-built and retrofitted structures to investigate the efficiency of the adopted
intervention strategy. A set of seven code-compliant natural earthquake records was selected and
employed to perform inelastic response history analyses at serviceability (operational and damageability
limit states, OLS and DLS) and ultimate limit states (life safety and collapse prevention limit
states, LSLS and CPLS). Both global and local lateral displacements are notably reduced after the seismic
retrofit of the existing system. In the as-built structure, the damage is primarily concentrated at the
second floor (storey mechanism); the computed interstorey drifts are 2.43% at CPLS and 1.92% at LSLS
for modal distribution of lateral forces. Conversely, for the retrofitted system, the estimated values of
interstorey drifts (d/h) are halved; the maximum d/h are 0.84% at CPLS (along the Y-direction) and 0.65%
at LSLS (yet along the Y-direction). The values of the global overstrength O vary between 2.14 and 2.54
for the retrofitted structure; similarly, the translation ductility mD-values range between 2.07 and 2.36.
The response factor (R- or q-factor) is on average equal to 5.0. It is also found that, for the braced frame,
under moderate-to-high magnitude earthquakes, the average period elongation is about 30%, while for
the existing building the elongation is negligible (lower than 5%). The inelastic response of the existing
structure is extremely limited. Conversely, BRBs are effective to enhance the ductility and energy
dissipation of the sample as-built structural system. Extensive nonlinear dynamic analyses showed that
more than 60% of input seismic energy is dissipated by the BRBs at ultimate limit states. The estimated
maximum axial ductility of the braces is about 10; the latter value of translation ductility is compliant
with BRBs available on the market. At DLS, the latter devices exhibit an elastic behaviour. It can thus be
concluded that, under moderate and high magnitude earthquakes, the damage is concentrated in the
added dampers and the response of the existing RC framed structure (bare frame) is chiefly elastic

At areas subjected to earthquake activity, strategic and vital underground structures should be designed to withstand both seismic and permanent loadings. This study aims to investigate the seismic interaction between tunnels and the surrounding granular dry soil. An advanced non-linear dynamic finite element model has been used to simulate such sophisticated problem, considering the full seismic interaction between tunnel, surrounding soil and bedrock motion. Extended Masing model is employed to simulate the nonlinearity and hysteresisty of the soil. Dynamic analysis is based on step-by-step integration schemes. Three artificial earthquake time-histories are used as control motions at the bedrock surface. Extensive comprehensive studies are carried out on a circular tunnel having diameters varying between 6 and 10 m, surrounded by homogenous sand layer of 30 m total thickness. The effect of sand layer relative density is examined using relative density range between 25% and 90%. Th...

- by Mohamed M Abdelmotaal
- •
- Geology, Structural Engineering, Geotechnical Engineering, Finite Element

Este Sol, su nombre 4 movimiento, es Naollin, este es nuestro Sol, en el que vivimos ahora. Y aquí está su señal, como cayó en el fuego el Sol, en el Fogón divino, allá en Teotihuacán. Igualmente fue este el Sol de nuestro príncipe, en Tula, o sea Quetzalcóatl. El quinto Sol, 4 movimiento su signo, se llama Sol de movimiento porque se mueve, sigue su camino. Y como andan diciendo los viejos, en él habrá movimientos de tierra, habrá hambre y con esto pereceremos. Leyenda de los Soles. Códice Chimalpopoca.

- by J. Carlos Delgado T.
- •
- Seismic Hazard, Seismic Retrofit, Seismic Engineering, Seismic

The slope stability evaluation using the generalized Hoek-Brown criterion and regarding the scale effect has been implemented in terms of the Chaarat gold project. Furthermore, the probabilistic assessment and sensitivity analysis are performed. Slope failure probabilities are determined, and the slope stability factors are obtained as functions of the slope height and angle. The slope stability estimation based on classified approach considering the scale effect, including GSI rating and probabilistic analysis is tested in rock slopes. Slope stability is mainly governed by variability of the Geological Strength Index related with the scale effect.

- by Igor fomenko
- •
- Slope Stability, Landslides, Seismic Engineering

The city of Ahmedabad of Gujarat in western India suffered severe damage during the 2001 M w 7.7 Bhuj earthquake, despite being ∼250 km away from the epicenter. Similar damage patterns were also reported during the 1819 Allah Bund earthquake (M w 7.8). To investigate the probable causes, we employed an integrated approach using multichannel analysis of surface waves (MASW), single and array mi-crotremor measurements, broadband earthquake data, and geotechnical investigations. Significant differences in site characteristics are observed in both the damaged and undamaged areas. The investigations revealed shear-wave velocity values in excess of 320 m=s and less than 220 m=s in the undamaged and damaged areas, respectively, in the top 6 m of the subsurface. The refusal (N 160) values are observed at 6–20 m and 20 m depth onward in the undamaged and damaged areas, respectively. The amplification factor in the damaged areas varies from 3.3 to 6.6 in the 1.5–2.0 Hz frequency range. On the other hand, the amplification factor in the undamaged areas varies from 1.0 to 3.0 in the 0.7–1.5 Hz frequency range. Nevertheless, the damages were mostly restricted to mid-to-high-rise buildings, located in the western side of the Sabarmati River, where the presence of a paleochannel is reported, and in some southeastern parts of the city, along lakes and ponds. The low-rise buildings on the eastern side of the river in the old city area remained almost intact. Our study confirms that local site effects together with the poor quality of construction contributed to the damages. Electronic Supplement: Table of shear-wave velocities, and figures of estimated shear-wave velocity and comparison of standard penetration test (SPT) N 160 model at the damaged and undamaged areas.

Seismic vulnerability assessment is of paramount importance for existing critical structures, e.g. health care centers and hospital buildings. Numerous surveys carried out in the aftermath of recent earthquakes have shown that the performance of hospitals is not impaired by the structural damage; functional breakdowns are instead major threats. Nonstructural components in buildings are rarely designed with the same care or with the same degree of scrutiny used for structural elements. In the present paper a checking/recording document is proposed, including the vulnerability of nonstructural elements and medical equipment; the overall seismic vulnerability is then estimated by a vulnerability index referred to both the functional and structural parts of the buildings. The simplified methodology, developed on the basis of studies carried out by Pan American Health Organization (PAHO) and World Health Organization (WHO), finally provides a safety index as function of all the parameters that characterize the seismic risk: vulnerability, hazard and exposition.

- by Fernando Rossi and +1
- •
- Earthquake Engineering, Seismic Engineering

Present paper attempts to summarize the theory of the non-linear force-displacement behavior of pile foundations, and the different non-linear t-z, q-z and p-y models suggested by various authors and design codes. The distant aim of the research is to investigate the influence of soil-structure interaction (SSI) on the seismic response of continuous girder bridges. As the first step, a numerical model is built in OpenSEES FEM software based on the idea of Beam on Non-Linear Winkler Foundation method. An overview and then a suggestion is made for the definition of the parameters needed for the t-z, q-z and p-y material models used in the applied software, considering the Eurocode 7 regulations. Cyclic pushover analysis is carried out to assess the significance of the different parameters of the soil on the cyclic behavior of pile foundations. The results are evaluated and compared.

- by RABBANI NAGRAL and +2
- •
- Composite Materials and Structures, Steel Structure, Structural Earthquake Engineering, Seismic Engineering

The structural design requirements of an offshore platform subjected wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under wave loading is presented, the structure is discretized using the finite element method, wave force is determined according to linearized Morison equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the one year return period wave and must be able to survive the 100 year return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.

- by Shehata E Abdel Raheem and +1
- •
- Engineering, Civil Engineering, Structural Engineering, Earthquake Engineering

Retaining wall is a structure used for supporting the soil mass laterally so that the soil can be retained at different levels on the two sides of it. Design of retaining wall needs the complete knowledge of Earth Pressure for both Active and Passive conditions. In the present work, an effort has been made to develop a formulation for critical wedge angle and thus seismic active pressure behind a vertical retaining wall supporting -backfill using pseudo-dynamic method. The effect of various parameters viz. time, shear and primary waves, time period of earthquake ground motion, angle of internal friction , angle of wall friction (δ), seismic acceleration co-efficients (kh , kv) are also taken into account to provide the variation of seismic active earth pressure.

A probabilistic seismic hazard assessment using an open source MATLAB software has been accomplished for Ermita, Manila. An Earthquake catalogue with earthquake events within latitudes 13° and 16° N, and the longitudes 119° and 123° E, and the active seismic sources were considered in this study. Active seismic sources that contributed to the hazard within the study area include 8 shallow crustal seismic source zones, the Manila Trench Plate in the west, the Philippine Fault Zone in the east and the East Luzon Trench in the northeastern part of Luzon. Other seismic sources are the Lubang Fault and the Casiguran Fault. Earthquake events were sorted to their corresponding seismic sources by their depth and location. The attenuation relationships used are Boore, et.al.(1997) for shallow crustal earthquakes, modified Youngs, et.al(1997) or Petersen, et. al. (2004) and Crouse (1991) for earthquakes developed from subduction zones. The peak ground acceleration (PGA) of the study was calculated and presented based on 2%, 5% and 10% probability of exceedance in 50 years (equivalent to 2500, 1000 and 500 years return period). The probability of exceedance of any given PGA was obtained and plotted to generate the hazard curve for the study area.

- by John Raymond Domasig
- •
- Seismic Hazard, Seismic Engineering, Seismic, Seismic analysis and design

Pojani N. (2003)
“Earthquake Engineering”, Toena Publisher, Tirana, 736 pages (in Albanian)

Frame bending moment diagrams for vertical and horizontal loading Portal's method Columns having floor beam on both sides i.e.inner columns have twice the stiffness compared to end columns. Storey shear is distributed accordingly among... more

- by Dr.Youssef Hamida
- •
- Seismic Engineering

جدران القص الخاصة لمقاومة الزلازل جدران القص • 1- لتشكيل مفصل بلاستيكي وعمل جدار في قسم تشتيت منطقة البلاستيك من الزلزال ، حيث يتم زيادة نقل الطاقة والتشوهات غير الخطية مع الحزم على الرغم من ارتفاع المقاومة ، وتحمل قوى القص القاعدية... more

- by Dr.Youssef Hamida
- •
- Seismic Engineering

 https://www.facebook.com/groups/1370910469592475/permalink/4852538538096300/
A bundled tube typically consists of a number of individual tubes interconnected to form a multicell tube, in which the frames in the lateral load direction resist the shears, while the flange frames carry most of the overturning moments.
يجب أن تقاوم الجمل الإنشائية structural systems المستخدمة في الأبنية العالية الأحمال الجانبية كما يجب أن توفر حلاً اقتصادياً بحيث تُستخدم المواد استخداماً فعالاً. فأكثر الجمل الإنشائية فعالية تلك التي تقاوم القوى الجانبية من دون زيادة تذكر في استهلاك المواد عن تلك اللازمة لمقاومة الأوزان الشاقولية، أي لا تنتج كلفة إضافية عن الزيادة في ارتفاع البناء. وبناء على هذا تصنف الجمل الإنشائية في الأبنية العالية
https://youtu.be/6EQpM2JcnVM

- by Dr.Youssef Hamida
- •
- Seismic Engineering

Understanding the parameters of PGA (peak ground acceleration) is very important for seismic hazard mitigation and environmental planning in Mandalay City, Myanmar. In this study, fifty SPTs (Standard Penetration Tests) measurement data were collected in Mandalay City, for calculating average shear velocity Vs 30 , which will be used in seismic microzonation mapping. The shear wave velocity Vs 30 of the top layer is Vs 30 ≤ 220 m/s. The ground motion characteristic was estimated by means of the predominant periods and linear magnification factors obtained using the multiple reflection analysis. The highest potential zone of seismic hazard mostly locates the north western marginal part of Mandalay city, in the proximal portion to the dextral Sagaing fault.

- by azrin ahmad
- •
- Structural Engineering, Seismic Hazard, Seismic Engineering

An overview of research on the development of the hybrid test method is presented. The maturity of the hybrid test method is mapped in order to provide context to individual research in the overall development of the test method. In the pseudo dynamic (PsD) test method, the equations of motion are solved using a time stepping numerical integration technique with the inertia and damping being numerically modelled whilst restoring force is physically measured over an extended timescale. Developments in continuous PsD testing led to the real-time hybrid test method and geographically distributed hybrid tests. A key aspect to the efficiency of hybrid testing is the substructuring technique where the critical structural subassemblies that are fundamental to the overall response of the structure are physically tested whilst the remainder of the structure whose response can be more easily predicted is numerically modelled. Much of the early research focused on developing the accuracy and efficiency of the test method, whereas more recently the method has matured to a level where the test method is applied purely as a dynamic testing technique. Developments in numerical integration methods, substructuring, experimental error reduction, delay compensation and speed of testing have led to a test method now in use as full-scale real-time dynamic testing method that is reliable, accurate, efficient and cost effective.

2.4.1 LU decomposition 2.4.2 QR decomposition 2.4.3 Schur decomposition 2.4.4 Spectrum decomposition 2.4.5 Submatrix decomposition 2.4.6 Singular value decomposition (SVD) 2.4.7 Eigenvalue decomposition 2.4.8 Cholesky decomposition 2.5 The matrix eigenvalue problem 2.6 Derivatives of matrices 2.6.1 Derivatives of a bilinear form 2.6.2 Derivatives of matrix traces 2.7 Perturbation 2.8 The least-squares method 2.9 Partial fraction expansion 2.10 Laplace transform and transfer function 2.11 Fourier series and Fourier transform 2.12 Variable separation method for partial differential equations 2.13 Poles and zeros of a polynomial function 2.14 State-space concept 2.15 Time series analysis 2.15.1 AR model 2.15.2 ARMA model 2.16 The z-transform Contents ix 13 Applications of modal analysis on real structures 13.1 Introduction 13.2 Modal analysis of a car chassis 13.3 Modal analysis of a lathe 13.4 Modal analysis of a shaper 13.5 Modal analysis of a combustion locomotive structure 13.6 Modal analysis of a power generator 13.7 Modal analysis of a flat flood gate 13.8 Modal analysis used for stability diagnosis 13.9 Modal analysis used for stump quality check 13.10 Modal analysis of ancient bronze bell 13.11 Modal analysis of bus roll cage structure for optimum rollover design Index x Contents This book provides a detailed treatment of the theory of analytical and experimental modal analysis with applications. It is intended for several uses. The materials can be selectively used for undergraduate and postgraduate courses. The book can be a reference text for practising engineers whose work involves modal analysis, and for researchers in other engineering and science disciplines who use modal analysis as a tool in their research. Though appearing to be specialized, modal analysis has been used in the last two to three decades in many engineering disciplines and technology fields to solve increasingly demanding structural dynamic problems. The path of modal analysis being incorporated into university teaching is paralleled with that taken by finite element analysis. Currently, the published literature in modal analysis is sparse without taking on board conference and journal papers. This is not conducive to users of this technology. Chapter 1 of this book begins with a brief introduction to the current status of modal analysis in engineering fields and the practical background which gave rise to modal analysis as an effective and an advancing technology. This is followed by a concise clarification of modal analysis and modal testing, and the theoretical framework for modal analysis. It is succeeded by an outline of applications of modal analysis in dealing with different types of engineering problems and practical challenges. This chapter closes on a summary note on the historical development of modal analysis. Chapter 2 reviews the mathematics tools used in the theory of modal analysis. In matrix theory, these include matrix inversion, linear simultaneous equations, eigenvalue problems, different decomposition of a real symmetrical matrix, matrix perturbation and the derivative of matrices. In addition, this chapter introduces poles and zeros of a polynomial function, Fourier series and transform, and the variable separation method for partial differential equations. These mathematics tools will be used in the following chapters of the book. Chapter 3 reviews the basic vibration theory which forms the basis of modal analysis theory. This chapter is an epitome of a textbook for mechanical vibrations or dynamics of machines. It intends to review relevant materials rather than to offer a comprehensive coverage of vibration theory. This is to facilitate a more thorough and smooth excursion in modal analysis theory. Chapters 4, 5 and 6 constitute the theoretical basis of modal analysis. In Chapter 4, modal analysis theory for an SDoF system is presented. It begins with the frequency response function (FRF) of an SDoF system, its concept and its different forms and various formats on which the FRF can be studied. This is followed by an in-depth disclosure of inherent properties of the FRF which will define modal analysis methods introduced in later chapters. The FRF of an SDoF system is mathematically simple and its physical interpretation unambiguous. However, when extended to an MDoF system, both the concept and definition of an FRF require more stringent deliberation. Chapter 5 deals with the modal analysis theory of an MDoF system without damping. It begins with the concept of normal modes of an MDoF system and its orthogonality properties. This is followed by the definition and description of the dynamic stiffness matrix and frequency response function matrix of an MDoF system. The physical interpretation of the FRFs is conferred and the different graphical presentation of FRFs is given. Next, the chapter establishes the relationship between the modal model of an MDoF system and its FRFs. This relationship forms the kernel of theoretical modal analysis and the foundation for developing experimental modal analysis methods. The asymptote properties of an SDoF FRF are extended in this chapter for the FRFs of an MDoF system. The chapter then continues to explore the orthogonality properties of an MDoF system from more contemporary viewpoints. The harmonic response analysis prepares the reader for a more advanced forced response of an MDoF system. The last section of the chapter provides a sound understanding of the anti-resonance and minimum properties of an FRF. This will lead to the latest progress of modal analysis on structural modification and optimization in later chapters. Chapter 6 is devoted to the modal analysis theory of an MDoF damped system. This is a natural extension of Chapter 5. In this approach, it is appropriate to begin with a proportional damping model which offers a special advantage of easy analysis. This is succeeded by an expansion of the theory of undamped FRFs into those for a damped MDoF system. Due to the existence of damping, the FRFs can be studied in the complex domain, allowing the study of their real and imaginary forms, Nyquist form and more. The force response of an MDoF damped system is analysed. The chapter ends on a note on complex vibration modes. Chapter 7, on the measurement of frequency response function data, provides a brief coverage of all aspects involved in conducting a successful frequency response function measurement. This includes preparation of the tested structure, general measurement set-up, selection of excitation forces and locations, selection of measurement locations, calibration of measurement set-up and acquisition of FRF data. This chapter closes at the assessment of FRF data during measurement and before the analysis of these data is to proceed. This is an important step to ensure accurate and sufficient FRF data, and a successful outcome of the analysis. The assessment includes the linearity, reciprocity and time-invariance check of the measured data, and the use of some characteristics of an FRF. Chapter 8 presents different modal analysis methods using measured FRF data. It begins with the identification of resonances from measured data. This is followed by the description of various modal analysis methods based on the SDoF assumption of MDoF assumption. This includes some latest modal analysis methods found in the literature and adopted by commercial modal analysis software. This full chapter coverage will provide a solid foundation for readers to conduct modal analysis on measured FRF data. Some of the figures are the outputs of a modal analysis software called ICATS. In addition to the methods based on FRF data, Chapter 9 provides a basic introduction xii Preface to modal analysis using free vibration or impulse responses of a structure -the time domain modal analysis. Chapter 10 deals with multi-input multi-output (MIMO) modal analysis. The estimation of accurate FRF data in the MIMO circumstance is discussed. A number of frequency and time domain modal analysis methods for the MIMO test are introduced. The volume of this book precludes the coverage of all the main applications of modal analysis. However, it would be useful to the reader to include some recent applications. Chapters 11, 12 and 13 serve this purpose. Chapter 11 discusses structural modification and its application to optimize the dynamic characteristics of a structure. This composes structural modification by changing the mass and stiffness properties and by changing physical properties such as cross-sectional changes of beam elements of a structure. This chapter embodies some late developments in structural modification and optimization. Chapter 12 introduces neural network, its applications in identifying dynamic characteristics of a system and in modal analysis. The use of the artificial neural network is taking a rapid pace in many engineering disciplines, including structural dynamics. This chapter can only serve as a brief introduction to this technique. Chapter 13 presents a number of practical applications of modal analysis. Many more can be found in the literature such as from the proceedings of the annual International Modal Analysis Conference. Materials presented here are selective for teaching and reference. Modal analysis draws strength from many sister disciplines in engineering. A book on modal analysis undoubtedly covers materials explored by numerous researchers and practical engineers. In this sense, the literature list at the end of each chapter can only be indicative. It is impossible for the authors to acknowledge all the individual contributions without which this book could not exist. We hope that this book will serve as a gateway for the reader to appreciate these contributions and to discover many more relevant readings in the modal analysis literature. Jimin He and Zhi-Fang Fu Overview of modal analysis 11

- by ᕧᖆᕬᘗᖱ ᒺᗋᖽᐸᓏ
- •
- Seismic Engineering

>> The telecommunication facilities by the basic law of telecommunication were added to the protection law against natural disasters as a scope of seismic design application on January 2007 since legal regulation had been reinforced in our country as in the circumstance that earthquakes are now frequently occurred in several areas over the world. This paper handles an establishing provision of concrete seismic design specification for applying to telecommunication facilities. For this purpose, this paper classified the parts of telecommunication facilities as being the correspondents to apply seismic design and analyzes the procedure of the design specification of building structure as the part of building construction law as a basic reference for seismic design application. And the method of introducing the foreign specification is presented. Thereon seismic design measures to be introduced into legal regulation are suggested for telecommunication service endurance against earthquake.

- by 상무 이
- •
- Seismic Engineering
- by Filippo Conti
- •
- Wind Engineering, Steel Structure, Seismic Engineering

The seismic vulnerability assessment of existing and
new lifelines, especially transportation systems, either highways or
railways, is becoming of paramount importance in resilient social
communities. The structural performance analysis of typical existing
bridges for high speed railway is however not an easy task to
accomplish. Additionally, the seismic assessment of such as-built
bridges tend to emphasize the high vulnerability of the structural
systems. In the present analytical work, the earthquake response
analysis of typical existing bridges for high speed railway was carried
out through linear and nonlinear dynamic analyses using refined
finite element three-dimensional lumped-plasticity models and
multiple component ground motions. The seismic vulnerability of
such bridges was assessed through local and global response
quantities. The retrofitting scheme adopted to augment the
earthquake performance of the sample bridge structures is the base
isolation system comprising either lead rubber bearings or steel
dampers. The present study investigates and compares the response
of such isolation devices. The outcomes of the numerical analyses
proved that the use of base isolation systems lowered significantly the
seismic demand, especially on the bridge piers and the foundation
systems. Hysteretic metallic devices were found more suitable for the
seismic isolation of railway bridges. Additionally, the need to comply
with the serviceability requirements is found to be more stringent for
the base isolation system in the design of retrofitting schemes for
railway bridges than the fulfillment of the ultimate limit state. Further
work is ongoing to account for the nonlinear modeling of the rail on
the global response of base isolated railway bridges under multiple
earthquake components.

This paper reviews the performance of reinforced concrete shear walls in buildings subject to seismic loading. The overall ductile structural response of buildings during earthquakes is an important characteristic that increases their overall ruggedness and robustness against significant damage or failure. This review discusses the seismic response of RC shear walls based upon established ductility principles and presents a case study example of a shear wall subject to beyond design seismic loading.

- by David J Hamilton
- •
- Seismic Engineering

La provincia Santiago de Cuba debido a su condiciones ingeniero geológicas, los distintos
procesos y fenómenos geológicos que en ella se manifiestan y sus vulnerabilidades, es
considerada como la de mayores potencialidades de manifestación de peligros y riesgos
geológicos en Cuba. Su análisis señala que existen insuficiencias en la gestión de riesgos,
pudiendo llegar a restringir el desarrollo económico y social del territorio.
Para mejorar la situación planteada se propone un procedimiento para la gestión de riesgos
geológicos en la provincia Santiago de Cuba basado en los principios de la gestión por procesos.
Su aplicación logra resultados importantes, entre ellos: múltiples mapas de peligro,
vulnerabilidad, riesgos geológicos y zonación ingeniero-geológica de multiamenazas; la
proposición de distintas acciones estratégicas según la situación estudiada, así como, un conjunto
de recomendaciones para la mejora continua de la gestión de riesgos geológicos en este territorio.
Finalmente la validación del procedimiento propuesto a través de un grupo de expertos en la
materia, confirma sus posibilidades de generalización a otros territorios del país.

Although hundreds of thousands of successful concrete and masonry buildings are annually constructed worldwide, there are large numbers of concrete and masonry structures that deteriorate, or become unsafe due to changes in loading, changes in use, or changes in configuration. Also the old structures designed for gravity loads are not able to withstand seismic forces and cause wide spread damages. Repair of these structures is often difficult, expensive, hazardous and disruptive to the operations of the building. The removal and transportation of large amount of concrete and masonry materials causes concentration of weight, dust, excessive noise and requires long period of time to gain strength before the building can be reopened for service.

- by LOKESH NAIK G T
- •
- Seismic Engineering

• The design of skyscrapers is usually governed by the lateral loads imposed on the structure.  As buildings have gotten taller and narrower, the structural engineer has been increasingly challenged to meet the imposed drift... more

- by Dr.Youssef Hamida
- •
- Seismic Engineering

В статье приводятся некоторые основные характеристики режима сейсмичности центральной и восточной частей Персидского залива и его побережья. Анализировались данные по количеству и пространственной позиции сейсмических событий, их энергетические характеристики (магнитуды) и глубины очаговых зон. Характер распределения во времени количества сейсмических событий обнаруживает квазипериодическую структуру с полупериодом порядка 5-6 лет. Следует отметить, что при увеличении или при существенном уменьшении количества землетрясений пространственное положение зон расположения их эпицентров остается неизменным. Положение гипоцентров рассматриваемых землетрясений охватывает широкий диапазон глубин - от мелкофокусных (2-10 км) до более глубоких (20-30 км). Отчетливо прослеживается общая тенденция к уменьшению за рассматриваемый период среднего уровня глубин очаговых зон, на фоне которого выделяются временные интервалы с относительно большим в среднем за год и относительно небольшим уровнем погружения гипоцентров. Выполненный анализ временных вариаций сейсмичности северо-восточной части бассейна Персидского залива показал высокую активность сейсмических процессов.

Propuesta para el análisis y diseño sísmico de edificios. Contiene mapas de amenaza sísmica para Bolivia, categorización de suelos y de construcciones, ductilidad, factor de comportamiento sísmico, espectros de diseño, análisis modal espectral tridimensional, combinación modal, efectos direccionales, diseño estructural sísmico y requisitos de detallado.

- by Rolando Grandi
- •
- Seismic Engineering

Bridge Engineering Handbook, Second Edition

- by Ricardo J Gómez
- •
- Bridge Engineering, Seismic Engineering

Lucrarea analizează eficiența metodelor neconvenționale de amortizare seismică, ca alternative la tehnologiile clasice de conformare seismică a structurilor. Lucrarea a fost prezentată în cadrul UT Cluj-Napoca, Facultatea de Construcții... more

- by Iulian F Popa
- •
- Earthquake Engineering, Seismic Engineering, Seismic Dampers

This standard prescribes procedures for the seismic analysis and design of liquid-containing concrete structures. These procedures address the "loading side" of seismic design and shall be used in accordance with ACI 350-01/ACI 350R-01,... more

- by Jhonny E. Mendoza
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- Seismic Engineering