bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mexico Earthquake of September 19, 1985—New Accelerograph Network for Mexico City
Authors: Espinosa-Aranda J. M. , Uribe A. , Frontana B. , Contreras O. , Ibarrola G.
Published: July 2003

As a result of the observed effects induced by the earthquakes of September 1985 in Mexico City's structures, the local government authorities increased their support for the installation of accelerographs in a network covering different zones of Mexico City. This paper presents the activities developed by the Centro de Instrumentación y Registro Sísmico (CIRES) concerned with: selection and procurement of suitable instruments, identification of the installation sites, and the installation of field stations. We also describe methods applied to the processing of seismic records and include a summarized catalog of accelerograms recorded to date.
Emergency Earthquake Damage and Usability Assessment of Buildings
Authors: Anagnostopoulos Stavros A. , Petrovski J. , Bouwkamp J. G.
Published: July 2003

An earthquake damage inspection form as well as criteria for assessing earthquake damage and usability of buildings under emergency conditions are presented. These criteria and the inspection form are key elements of the emergency inspection and have been based on recent experiences from damaging earthquakes in the Balkan region. They have been developed with a number of objectives in mind and notably the efficient use in the field and the reliable assessment of a builging's capacity. Since the emergency inspections of building damage will be a large scale operation, organizational aspects of this operation are discussed and specific recommendations are made.
Lifeline Response to the Tejon Ranch Earthquake
Authors: Schiff Anshel J.
Published: July 2003

The vulnerability of important high voltage switchyard equipment to low seismic input motions has again been demonstrated. Ten of sixteen 230 kV circuit breaker phases failed at the Edmonston Pumping Plant on the California Aqueduct. Failures were primarily porcelain members. The failures were due to both dynamic response of the members and to a lack of slack in conductors connecting adjacent equipment. The aqueduct was out of service for four days until power was partially restored. Repairing or replacing all damaged equipment is expected to take from 6 to 8 weeks. The importance and vulnerability of high voltage power equipment, the long time required to make repairs, and the difficulty in obtaining spare parts quickly emphasizes the need for cost effective measures to improve the seismic response of this type of equipment. While this earthquake did not substantiate the effectiveness of a base isolation system installed on one circuit breaker, it did illustrate the need for instrumentation to evaluate the performance of these systems. Leaks developed at two Smith-Blair mechanical couplings in one of two 192″ diameter aqueduct siphons near the pump plant. Whether this was due to ground deformations or inertial loads could not be determined.
Ground Acceleration near St. Michael's Church during the 1886 Charleston, SC, Earthquake
Authors: Elton David J. , Marciano Eugene A.
Published: July 2003

The historic and continuing seismicity in the southeastern U.S. indicate the seismic threat to the population. However, little is known about the engineering characteristics of eastern U.S. earthquakes because there are no strong motion recordings of them. In particular, the peak ground acceleration, needed for structural design, is not available except through correlations with western U.S. earthquakes or MMI data of unknown uncertainty. This paper estimates the peak ground acceleration experienced by St. Michael's Church during the 1886 Charleston, SC, event based on conventional and probabilistic structural analysis. The 1886 event, rated as MMI X and magnitude 7, is the only historic strong motion event greater than mb = 5 that affected Charleston. The analysis concluded that the peak ground acceleration for the 1886 event was 0.33g. The coefficient of variation of this acceleration was 24%, remarkably small when considering the uncertainty in the input parameters.
Considerations in the Epidemiology of Earthquake Injuries
Authors: Jones Nicholas P. , Krimgold Frederick , Noji Eric K. , Smith Gordon S.
Published: July 2003

In July, 1989, a workshop entitled “Earthquake Injury Epidemiology for Mitigation and Response” was held at The Johns Hopkins University in Baltimore, Maryland, U.S.A. The aim of the workshop was to gather a group of interested professionals, all directly or peripherally interested in the research, planning, mitigation, and response aspects associated with earthquake-induced injuries and deaths, to lay the foundations and begin to develop a research agenda for this emerging field. This was achieved by a combination of presentation of summary papers, discussions in small, multidisciplinary working groups, and plenary wrap-up and discussion sessions. The papers and transcriptions are available from the authors. The following paper presents a condensation and summary of the workshop, its discussions, and its important conclusions. References are cited where appropriate; much of the content reflects a condensation of the discussions.
Earthquake Hazard Estimation in Areas of Low Historical Seismicity: A Focus on the Northern Rio Grande Rift, Colorado and New Mexico
Authors: Glass Charles E.
Published: July 2003

Estimates of the probability of future earthquake activity are difficult to make in areas where historical seismicity may be low or absent, but where young fault scarps attest to recent or ongoing tectonism. Three non-Poisson models, a Weibull model, a Gaussian model and a lognormal model, are used to estimate the earthquake hazard for one such area, the northern Rio Grande Rift. This portion of the Rio Grande Rift displays numerous Holocene faults attesting to ongoing tectonism, but displays essentially no historical seismicity. The earthquake hazard for the Sangre de Cristo fault zone from Taos, New Mexico to Salida, Colorado calculated using these models is remarkably consistent (probability of at least one Mo = 7 earthquake in the next 50 years ∼ 2.5 × 10−3), with increased hazard for the Sangre de Cristo fault in north San Luis Valley (∼5.0×10−3) and near Taos (∼1.0×10−2) due to the long holding times along these segments.
Strengthening Buildings to a Life Safety Criterion
Authors: Englekirk R. E. , Sabol T. A.
Published: July 2003

This paper presents an approach to seismically strengthen buildings to a life-safety criterion. Existing buildings do not comply with most provisions of modern model building codes and, as a result, are often considered seismically deficient. Buildings identified as seismic hazards are often not rehabilitated because the cost of the rehabilitation proves uneconomical, but the buildings usually continue in use because there are no funds to replace the structure. Building occupants continue to be exposed to hazardous conditions until building owners are forced to rehabilitate or demolish the structure by legally mandated seismic rehabilitate programs. Attainment of economical strengthening schemes requires that one identify essential goals and approach the seismic rehabilitation problem from the perspective of trying to achieve these goals. If prevention of building collapse and preservation of life-safety are the objectives of seismic rehabilitation, acceptance of higher levels of building damage may be an acceptable tradeoff for a reduction in the seismic rehabilitation cost. Explicit consideration of the building's available ductility, existing stiffness, and permissible lateral displacement permit the introduction of strengthening systems that address the fundamental weaknesses in the existing building. This limits the expenditure of funds to that required to achieve the required level of life safety without having to spend money to unreasonably reduce damage levels.
Advantages and Limitations of Seismic Isolation
Authors: Stanton John , Roeder Charles
Published: July 2003

Under many circumstances, seismic isolation is an effective way of reducing the impact of earthquakes on structures. Dynamic forces in the structure itself are reduced at the expense of relatively large displacements in the isolators. These displacements can generally be predicted adequately by simple methods and accommodated without difficulty. However, some circumstances appear to exist where the isolator displacements might be significantly larger than conventional analysis would suggest, or where simplified methods of analysis may prove inadequate and fail to predict the response properly. The paper explores the limits of the applicability of equivalent linear analyses and the response to ground motions which might lead to large displacements isolation that can be achieved.
Empirical Methods for the Prediction of Response Spectra
Authors: Dunbar W. Scott , Charlwood Robin G.
Published: July 2003

Three empirical methods of estimating response spectra are reviewed. It is shown that these methods produce comparable results, provided that the comparisons are made in a consistent manner. Although the traditional method of scaling amplification factors by peak ground motions is fundamentally reasonable, there exist some significant discrepancies between scaled and other types of spectra. The basic reason for this is that the amplification factors commonly used in the engineering community are biased toward those of a large magnitude earthquake recorded on a soil site. The dependence of spectral shape on magnitude and site conditions can be accounted for by independent estimates of peak ground acceleration, velocity and displacement to scale an unbiased set of amplification factors derived for particular site conditions. Other methods of estimating spectra account for the dependence of spectral shape on magnitude and site conditions in a more direct manner. In order to reduce the discrepancies between scaled and other types of spectra, it is recommended that a new set of amplification factors be estimated using a suite of response spectra due to earthquakes whose magnitudes are evenly distributed in the range 5.0 ≤ M ≤ 7.5 and which have been recorded on sites having similar soil conditions.
Towards a Capacity-Design Assessment Procedure for Reinforced Concrete Frames
Authors: Priestley M. J. Nigel , Calvi G. Michele
Published: July 2003

A two-level seismic assessment procedure for reinforced concrete frame buildings is presented. The intent of the procedure is to determine the risk, in terms of annual probability of exceedance, associated with two limit states, namely a serviceability limit state and a survival, or ultimate, limit state. The serviceability limit state is determined by elastic response calculation, but the survival limit state analysis attempts to identify the strength and ductility of the critical collapse mechanism, and hence its probability of exceedance by comparison with reference spectra. The basis for identifying the critical collapse mechanism is a modified form of capacity design principles which allows local element failure provided overall structural integrity is not jeopardized.
Petroleum and Gas Facilities
Authors: Schiff Anshel J.
Published: July 2003

In the earthquake-affected area there are no natural-gas lines and a very limited number of petroleum-product lines. There is a petroleum line from Subic Bay to Clark Air Force Base; however, this line is some distance from the epicenter and was not damaged. Associated with the Port of San Fernando there are two lines used to unload petroleum products and transport them to nearby tank farms operated by several oil companies. Products are distributed by truck from the tank farms. There are no petroleum-processing facilities, such as refineries, in the area.
Transportation Facilities
Authors: Farrar Charles R. , Schiff Anshel J. , McLaughlin John
Published: July 2003

This chapter describes damage to the Port of San Fernando and the Baguio airport, and damage to the ground transportation system, primarily bridges.
Lifelines
Authors: Ballantyne Donald , Guerrero A. R. , O'Rourke Michael , Krinitzsky Ellis L.
Published: July 2003

This report presents findings of earthquake damage to lifeline facilities. Topics included are dams, water supply, sewage, power, communications, liquid fuels, and general transportation. Port facility structural and geotechnical aspects of the earthquake are discussed in Chapter 5—Industrial Facilities. Performance of bridges is discussed in Chapter 6—Bridges.
Seismic Code Decisions under Risk: The Wasatch Front Illustration
Authors: Taylor Craig E. , Reaveley Lawrence D. , Tillman Craig W. , Porush Allan R.
Published: July 2003

Regions of low-to-moderate seismicity but high catastrophic earthquake loss potential pose special issues with respect to seismic design codes as well as other significant policy decisions. These seismic design code decisions hinge on the amount of initial costs and on the size and certainty of benefits from increased design requirements. Since these decisions are made by government officials, these costs and benefits are distributed among various stakeholders in the community. This paper explains this perspective and clarifies earthquake risk methods needed to address these seismic design force level decisions in the Wasatch Front, Utah and, as a point of comparison, to the City of Los Angeles. These applications strengthen the case for a seismic zone 4 designation along the Wasatch Front but also raise issues about the roles of life-safety protection and certainty of benefits in seismic code decisions.
New Perspectives on Diffusion of Earthquake Knowledge
Authors: Michaels Sarah
Published: July 2003

This article contrasts different perspectives concerning the diffusion of earthquake knowledge among non-scientific audiences. The perspective that underlies much of current information dissemination efforts is a “producer-user” model. This model assumes a stable set of knowledge producers and an identifiable set of knowledge users. An alternative perspective is an “issue networks” model. This model assumes a more fluid set of actors and issues linked by common concerns about earthquake hazards. This latter model is suggested as a more accurate depiction of knowledge diffusion within the state and local earthquake policy arenas. This portrayal also leads to consideration of new strategies for disseminating seismological, earthquake engineering and related knowledge.
Sliding Isolation System for Bridges: Analytical Study
Authors: Kartoum Allaoua , Constantinou M. C. , Reinhorn A. M.
Published: July 2003

This paper reports on a parametric study of the response of bridges supported by an isolation system consisting of sliding Teflon bearings and displacement control devices. The isolated bridges are subjected to simulated earthquake motions which are compatible with CalTrans design spectra. The effects of isolation system properties, deck flexibility, pier flexibility, pier strength, distribution of isolation elements and earthquake type are investigated. Results are presented in a form that is useful in the design of sliding isolation systems for two-span continuous deck bridges. Comparisons with the response of conventionally built bridges demonstrate the significant benefits of seismic isolation. Finally, simplified code-type analysis procedures are presented and evaluated.
On Better Engineering Preparedness: Lessons from the 1988 Bihar Earthquake
Authors: Jain Sudhir K.
Published: July 2003

The rather moderate sized (magnitude 6.6) Bihar earthquake of August 21, 1988, demonstrated clearly that the Indian engineering profession is far from prepared for a larger earthquake. During the author's extensive travel within the areas affected by this earthquake, it became clear that the engineering community should immediately initiate serious and coordinated efforts to prepare for the possibility of a large earthquake in many parts of India or nearby countries. This paper discusses some such efforts and possible strategies. Suggested strategies for being better prepared include rationalization and implementation of the seismic codes, review of actual construction practices, seismic safety evaluation of critical facilities such as dams and refineries, training and preparation of field engineers for handling post-earthquake situations, and learning from earthquakes.
An Evaluation of Ductility and Detailing Requirements of Bearing Wall Buildings Using Data from the March 3, 1985, Chile Earthquake
Authors: Wallace John W. , Moehle Jack P.
Published: July 2003

The expected earthquake response of bearing wall buildings is investigated using data from the March 3, 1985 Chile earthquake. The study includes an examination of proportioning and detailing requirements for Chilean and U.S. bearing wall construction. Based on the requirements, minimum stiffnesses and strengths are characterized. Recorded ground motions in Vin~a del Mar, Chile and the western U.S. are analyzed and compared. Drifts and global displacement ductilities are estimated. Based on the findings related to drift and ductility, the need for concrete confinement at wall boundaries is investigated analytically. The analytical studies indicate that boundary confinement is not always necessary at wall boundaries. The performance of bearing wall buildings in the Chilean earthquake and the analytical studies conducted herein indicate that the form of construction used in Chile is a viable construction option in the United States.
The National Earthquake Hazards Reduction Program (NEHRP): Postearthquake Investigations
Authors: Hays Walter , Anderson William , Bufe Charles , Chung Riley , Cowan Brian , Heyman Barry , Lagorio Henry , Noji Eric , Whitcomb James , Wright Richard
Published: July 2003

The National Earthquake Hazards Reduction Reauthorization Act of November 16, 1990 required the NEHRP agencies to organize a program of postearthquake investigations that would take advantage of the opportunity to use worldwide damaging earthquakes as a scientific laboratory.
Viscoelastic Dampers as Energy Dissipation Devices for Seismic Applications
Authors: Chang K. C. , Soong T. T. , Lai M. L. , Nielsen E. J.
Published: July 2003

On the basis of extensive analytical and experimental investigations, some practical issues associated with the application of viscoelastic dampers to building structures for seismic performance enhancement are considered. It is first shown that the seismic response of a structure can be significantly improved with added dampers. Even at high temperatures, results show that a viscoelastically damped structure can still achieve a significant reduction of structural response as compared to the case with no dampers added. The development of a design procedure for viscoelastic dampers by taking into account the ambient temperature is addressed next, following a modal strain energy approach. Numerical simulation on equivalent structural damping and structural response confirms that the dynamic behavior of structures with added viscoelastic dampers can be satisfactorily predicted by conventional analytical tools. In addition, the design of structures with added viscoelastic dampers can be easily incorporated into a conventional design process.
A New Method for the Realistic Estimation of Seismic Ground Motion in Megacities: The Case of Rome
Authors: Fäh Donat , Iodice Claudio , Suhadolc Peter , Panza Guilano F.
Published: July 2003

A hybrid technique, based on mode summation and finite differences, is used to simulate the ground motion induced in the city of Rome by the January 13, 1915, Fucino (Italy) earthquake (ML=6.8). The technique allows us to take into consideration source, path, and local soil effects. The results of the numerical simulations are used for a comparison between the observed distribution of damage in Rome, and the computed peak ground acceleration, the maximum response of simple oscillators, and the so-called “total energy of ground motion”. The total energy of ground motion is in good agreement with the observed distribution of damage. From the computation of spectral ratios, it has been recognized that the presence of a near-surface layer of rigid material is not sufficient to classify a location as a “hard-rock site” when the rigid material has a sedimentary complex below it. This is because the underlying sedimentary complex causes amplifications due to resonances. Within sedimentary basins, incident energy in certain frequency bands can also be shifted from the vertical, into the radial component of motion. This phenomenon is very localized, both in frequency and space, and closely neighboring sites can be characterized by large differences in the seismic response.
Seismic Vulnerability Evaluation of Bridges in Memphis and Shelby County, Tennessee
Authors: Pezeshk S. , Chang T. S. , Yiak K. C. , Kung H. T.
Published: July 2003

The focus of this paper is to develop a screening procedure to obtain information and assess vulnerability of bridges located in the New Madrid seismic zone (NMSZ). This screening methodology includes structural elements, site, foundation, and importance of the bridge. An inventory of the river-crossing bridges in Memphis and Shelby County is made using the developed screening procedure; potentially hazardous bridges that require further detailed seismic evaluation and/or immediate seismic retrofitting are identified. The results of this study are important for future maintenance and improvement, earthquake loss estimates, seismic hazard/risk reduction, and earthquake preparedness/rescue plans for river-crossing bridges in the NMSZ.
Design Lessons in Residential Rehabilitation
Authors: Comerio Mary
Published: July 2003

In multi-family residential buildings, earthquake hazards mitigation and reconstruction are two sides of the same coin. The buildings are costly and difficult to retrofit and losses from the Loma Prieta earthquake make it clear that these buildings are significantly more costly and difficult to replace. Case studies of residential buildings which have been upgraded demonstrate that details and schedules are more important than the conceptual design. To achieve cost efficiency, traditional engineering design solutions must be adapted to the conditions found in existing buildings. Further, because construction is almost always done with tenants remaining in the building, cost efficiency must include social as well as technical design.
Divergent Issues in Rehabilitation of Existing Buildings
Authors: Jirsa James O.
Published: July 2003

A review of experience following recent damaging earthquakes shows that the reasons for repair and rehabilitation of damaged or inadequate structures varied greatly and often had little to do with structural issues. Cost of rehabilitation was found to be related not only to construction costs, but also to rents and leasable space, as well as to the costs associated with loss of revenue in case of damage during an earthquake which might curtail operations in the building. Design code requirements may impose restrictions that make it infeasible to rehabilitate some structures. Psychological and aesthetic issues dominated some projects. The purpose of this paper is to outline the divergent issues involved in the rehabilitation of a structure. The contrasts between the experience following Mexico City 1985 and Loma Prieta 1989 are striking.
Repair and Retrofit of Health Care Facilities
Authors: Poland Chris D.
Published: July 2003

While since 1973 the design and construction of new California Health Care Facilities have been regulated by special ordinances, pre-existing hospitals have remained largely non-compliant due to the prohibitive costs of upgrading. The special seismic design considerations that are needed for new and existing facilities, a program for assessing the projected performance of these facilities in terms of life-safety and ability to remain operational under various seismic conditions, as well as for developing effective, phased retrofit strategies to improve performance is discussed in this paper.
Seismic Ground Motion Hazard Assessment at a Site near a Segmented Subduction Zone: The Roseau Dam, Saint Lucia, West Indies
Authors: Aspinall W. P. , Shepherd J. B. , Woo G. , Wightman A. , Rowley K. C. , Lynch L. L. , Ambeh W. B.
Published: July 2003

The seismic hazard at the site of a new dam in Saint Lucia, West Indies, is evaluated probabilistically for engineering design purposes. The assessment takes advantage of recent high quality regional seismological data, reappraised older instrumental catalogues and current tectonic interpretations. Saint Lucia stands at a position in the Lesser Antilles island arc where two distinct, seismically active, subduction zones appear to converge at different depths. As a result, the seismic hazard is critically dependent on site position relative to the boundaries of these major source zones, which each exhibit different activity rates. The ground motion hazard at the damsite is computed using the probabilistic logic-tree program PRISK, which accepts weighted input parameter distributions and is also able to model complex source geometries such as those needed to realistically represent a subduction zone. At an exceedance probability of 2×10−3 per annum, the expected peak ground acceleration on rock at the site is 0.27g, and the expected peak ground velocity is 12.9 cm/sec. At an exceedance probability of 10−4 per annum, the expected peak ground acceleration on rock at the site is 0.51g, and the expected peak ground velocity is 29.1 cm/sec. The major contributor to the seismic hazard is a large magnitude earthquake occurring in the northern segment of the Lesser Antilles subduction zone. Sensitivity tests show that the results are stable in the face of rational variations in the seismicity parameters but the hazard values are dependent on the choice of attenuation relationship which, in the absence of local information, has to be adopted from other subduction zone areas. The PGA obtained in this study is markedly higher than the value suggested in current regional code recommendations.
Estimation of Surface Displacements Due to Earthquake Excitation of Saturated Sands
Authors: Glaser S. D.
Published: July 2003

This paper examines a variety of useful and important methods for estimation of liquefaction-induced ground displacement. The state-of-practice for estimating permanent ground displacements is empirical. Several methods are examined, and they all appear to have comparable predictive abilities. The recommended method takes into account geological, geotechnical, topographical, and seismological parameters. There have been a few recent attempts to construct constitutive models for post-liquefaction displacements, but at this time they are in formative stages and have not been rigorously proven.
Summary of Coastal Geologic Evidence for past Great Earthquakes at the Cascadia Subduction Zone
Authors: Atwater Brian F. , Nelson Alan R. , Clague John J. , Carver Gary A. , Yamaguchi David K. , Bobrowsky Peter T. , Bourgeois Joanne , Darienzo Mark E. , Grant Wendy C. , Hemphill-Haley Eileen , Kelsey Harvey M. , Jacoby Gordon C. , Nishenko Stuart P. , Palmer Stephen P. , Peterson Curt D. , Reinhart Mary Ann
Published: July 2003

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a few centuries to about one thousand years.
On the Use of Design Spectrum Compatible Time Histories
Authors: Naeim Farzad , Lew Marshall
Published: July 2003

To a designer of a nonlinear structure, there is nothing more attractive than a real or fictitious ground motion time history whose response spectrum matches the target design spectrum. Frequency-domain scaled, design spectrum compatible time histories (DSCTH) are widely used in analysis and design of special structures, particularly seismic-isolated buildings. Their use has been even mandated by some code provisions. At the first glance, it seems that DSCTH records furnish designers of earthquake resistant structures with a consistency and compatibility bridge between the two very different worlds of elastic and inelastic response. Closer examination, as presented in this paper, reveal however that there are significant potential problems associated with uncontrolled use of DSCTH records in seismic design. It is shown that the use of design spectrum compatible time histories can lead to exaggeration of displacement demand and energy input. This in turn can distort the expected performance of the structure when subjected to design earthquake ground motions.
CSMIP Strong-Motion Instrumentation and Records from the I10/215 Interchange Bridge near San Bernardino
Authors: Huang M. J. , Shakal A. F.
Published: July 2003

The 2540-foot long, multi-span, curved I10/215 interchange bridge near San Bernardino was extensively instrumented by the California Strong Motion Instrumentation Program (CSMIP) in cooperation with the California Department of Transportation (Caltrans). The locations of the sensors on this freeway interchange bridge were carefully planned to achieve specific instrumentation objectives. Significant sets of strong-motion records were obtained from this bridge during the magnitude 7.5 Landers and the magnitude 6.6 Big Bear earthquakes of June 28, 1992. The epicenters of these earthquakes were about 50 and 30 miles (80 and 48 km) from the bridge, respectively. The maximum ground acceleration at the bridge was about 0.10 g for both earthquakes. The relative motion of the deck across the hinges was recorded and is characterized by sharp spikes in the acceleration records with a peak value as high as 0.81 g during the Landers and 1.02 g during the Big Bear earthquake. Without the spikes the peak acceleration on the bridge would be about 0.40 g during the Landers and 0.30 g during the Big Bear earthquake. The Landers records show that the bridge structure had a period of about 1.7 seconds in the transverse direction and 1.0 second in the longitudinal direction. The maximum relative displacement between the deck and the footing of a 57-foot column was about 16 cm in the transverse direction and 5 cm in the longitudinal direction during the Landers earthquake. The maximum relative displacement across one of the hinges during the Landers earthquake was 1.2 cm in the transverse direction and 3.6 cm in the longitudinal direction.
Mortality and Morbidity Patterns Associated with the October 12, 1992, Egypt Earthquake
Authors: Malilay Josephine , Elias Ibrahim Fayez , Olson David , Sinks Thomas , Noji Eric
Published: July 2003

On October 12, 1992, the metropolitan area of Cairo, Egypt and surrounding villages in the Nile Valley sustained the effects of a moderate earthquake of magnitude MB 5.9 (MS 5.2). To identify mortality- or injury-prevention strategies for communities at risk, we investigated deaths and injuries that were associated with the event and modeled the time that patients spent in the hospital because of earthquake-related injuries. Populations in areas closest to the epicenter experienced increased death and injury rates (4.6 deaths per 100,000 and 80.6 injuries per 100,000) compared to those located further from the epicenter (0.8 deaths per 100,000 and 23.7 injuries per 100,000). The distribution of earthquake-related admissions in one hospital peaked within 36 hours after the earthquake. A general linear model predicted that older people were hospitalized longer than younger people and people with fractures to the trunk were hospitalized longer than those with injuries at other anatomical sites (p = 0.008). While recognizing that other characteristics are also important, we recommend that emergency managers consider proximity to the epicenter when planning response operations, and that health officials focus on ensuring appropriate medical care for older people and for people who have suffered severe injuries to the trunk.
Near-Source Ground Motion and its Effects on Flexible Buildings
Authors: Hall John F. , Heaton Thomas H. , Halling Marvin W. , Wald David J.
Published: July 2003

Occurrence of large earthquakes close to cities in California is inevitable. The resulting ground shaking will subject buildings in the near-source region to large, rapid displacement pulses which are not represented in design codes. The simulated Mw7.0 earthquake on a blind-thrust fault used in this study produces peak ground displacement and velocity of 200 cm and 180 cm/sec, respectively. Over an area of several hundred square kilometers in the near-source region, flexible frame and base-isolated buildings would experience severe nonlinear behavior including the possibility of collapse at some locations. The susceptibility of welded connections to fracture significantly increases the collapse potential of steel-frame buildings under strong ground motions of the type resulting from the Mw7.0 simulation. Because collapse of a building depends on many factors which are poorly understood, the results presented here regarding collapse should be interpreted carefully.
Seismic Test Methods for Architectural Glazing Systems
Authors: Behr Richard A. , Belarbi Abdeldjelil
Published: July 2003

An ongoing effort is being made at the University of Missouri-Rolla to develop standard laboratory test methods and codified design procedures for architectural glass under seismic loadings. Recent laboratory work has yielded some promising results regarding the development of an appropriate seismic test method for architectural glass, as well as identifying ultimate limit states that quantify the seismic performance and damage thresholds of various glass types. Specifically, a straightforward “crescendo-like” in-plane dynamic racking test, performed at a constant frequency, has been employed successfully. Two ultimate limit states for architectural glass have been defined: (1) a lower ultimate limit state corresponding to major glass crack pattern formation; and (2) an upper limit state corresponding to significant glass fallout. Early crescendo tests have yielded distinct and repeatable ultimate limit state data for various storefront glass types tested under dynamic racking motions. Crescendo tests will also be used to identify and quantify serviceability limit states for architectural glass and associated glazing components under dynamic loadings. These limit state data will support the development of rational design procedures for architectural glass under seismic loadings.
Pseudodynamic Capabilities of the ELSA Laboratory for Earthquake Testing of Large Structures
Authors: Donea J. , Magonette G. , Negro P. , Pegon P. , Pinto A. , Verzeletti G.
Published: July 2003

The paper describes the distinctive features of the pseudo-dynamic test method as implemented at the largest European reaction-wall facility. Both hardware and software aspects are considered. Particular attention is devoted to the digital control system and to the time integration algorithms. A test-restart procedure well suited for stiff/brittle structures and a coupled numerical-experimental substructuring technique allowing realistic earthquake testing of very large structures are included. Finally a prospective view of continuous pseudo-dynamic testing is introduced. Selected test results illustrate the advantages of the presented features.
Redefining Terms in the Field of Seismic Safety and Risk Mitigation
Authors: Sauter Franz F.
Published: July 2003

In recent publications, the need for common terminology in the field of seismic safety and risk mitigation has been brought up. Definitions for a wide range of terms in the field of seismic strengthening and upgrading of buildings has been suggested by several authors. Nevertheless, incongruities still persist and the meaning of such terms can have different connotations to the professionals, academicians and policy makers that make use of them. Some authors suggest that the seismic community should use terms in the same sense that words are used in ordinary communication. To pursue the goal of cleaning and standarizing our technical language, and in order to further focus the discussion on this matter, the author presents a critical review of the interpretation of the most common terms used in the earthquake engineering community. Based on dictionary definitions and the practical, common sense application of these terms, a summary of the proposed terminology is presented.
Evaluation of UBC-94 Provisions for Seismic Design of RC Structural Walls
Authors: Wallace John W.
Published: July 2003

New provisions for seismic design of reinforced concrete structural walls were incorporated into the 1994 version of the Uniform Building Code. The new provisions are based on the use of a displacement-based design methodology, which is a significant departure from prior codes. The format of the UBC-94 provisions offer significant advantages over previous design formats, with both simplified and detailed design approaches. As is the case with any significant code change, proper application of the new provisions requires a thorough understanding of the design methodology used to develop the provisions as well as its limitations. Given these needs, an overview of displacement-based and the UBC-1994 requirements is provided. The methods employed in UBC-94 to estimate the maximum displacement response are found to significantly underestimate maximum displacement; therefore, direct application of the provisions could lead to unconservative designs. Recommendations to address this shortcoming, as well as potential to improve the provisions in other areas are presented.
Damage Scenarios Simulation for Seismic Risk Assessment in Urban Zones
Authors: Barbat Alex H. , Moya Fabricio Yépez , Canas JoséA.
Published: July 2003

A methodology for simulating seismic damage of unreinforced masonry buildings for seismic risk assessment of urban areas is presented in this paper. The methodology is based on the Italian vulnerability index and on the results of a post-earthquake damage survey study whose main result was an observed vulnerability function. The Monte Carlo method was then used to simulate damage probability matrices, fragility curves and vulnerability functions, all of which are the basis of a seismic risk study. The simulation process required the generation of thousands of hypothetical buildings, the analysis of their seismic behaviour and probabilistic studies of the computed results. As an example, probable damage scenarios were developed for an urban zone of Barcelona.
Seismic Upgrading of Old Brick-Masonry Urban Houses: Tying of Walls with Steel Ties
Authors: Tomaz˘evic˘ Miha , Lutman Marjana , Weiss Polona
Published: July 2003

The influence of tying the walls with steel ties on the seismic behavior of existing brick-masonry houses has been investigated. Three models of simple two-story brick masonry houses with wooden floors, with or without wall ties, have been tested on a simple earthquake simulator. In addition, a model with identical structural configuration, but with r.c. slabs instead of wooden floors, has been tested for comparison. Whereas wooden floors with joists not anchored to the walls did not prevent separation and disintegration of the walls, rigid slabs and steel ties significantly improved seismic behavior. On the basis of test results, a simple method for designing the ties has been proposed.
Retrofit of Concrete Columns with Inadequate Lap Splices by the Use of Rectangular Steel Jackets
Authors: Aboutaha Riyad S. , Engelhardt Michael D. , Jirsa James O. , Kreger Michael E.
Published: July 2003

This paper describes an experimental research program on the use of rectangular steel jackets for seismic retrofit of non-ductile reinforced concrete frame columns. Eleven large scale columns were tested to examine the effectiveness of various types of steel jackets for improving the ductility and strength of columns with an inadequate lap splice in the longitudinal reinforcement. Response of the columns before and after being strengthened with steel jackets was examined. Several types of steel jackets were investigated, including rectangular solid steel jackets with and without adhesive anchor bolts. The test results indicate that a thin rectangular steel jacket combined with adhesive anchor bolts can be a highly effective retrofit measure for reinforced concrete columns with an inadequate lap splice. Design guidelines for the use of rectangular steel jackets as a seismic retrofit for non-ductile reinforced concrete columns are presented.
Expected Seismic Behavior of Older Steel Structures
Authors: Roeder Charles W. , Leon Roberto , Preece F. Robert
Published: July 2003

Older steel structures frequently require seismic rehabilitation, but the inelastic seismic behavior of these older structures is not well understood. A joint research study between the U. of Washington, U. of Minnesota, and Preece/Goudie and Associates examined this behavior. The study included experimental and analytical studies, and this paper is an overview of the research and the more important research results. It provides a concise summary of the rather extensive research program, and the research results are correlated to real structural behavior. This correlation includes evaluation and comparison with behavior observed during past earthquakes. The paper will help the reader understand the performance of the total structural system will provide valuable insight for engineers starting a repair or retrofit project, and it will isolate potential problem areas to be considered in rehabilitation projects.
Fiber Composites: An Economical Alternative for Retrofitting Earthquake-Damaged Precast-Concrete Walls
Authors: Ehsani Mohammad R. , Saadatmanesh Hamid
Published: July 2003

A new approach for seismic retrofitting of lightly-reinforced precast-concrete walls is presented. The technique involves epoxy bonding the reinforcing material (composite fabric) to the exterior surface of the wall. The flexible light-weight fabrics are extremely strong in tension and can significantly increase the flexural and shear capacity of the member. The thin composite fabrics cause little increase in the weight and thickness of the wall, causing little change to the inertial loads and eliminating the need for strengthening of the footings. Following the January 17, 1994 Northridge earthquake, this technique was applied to a tilt-up concrete building in southern California. The method proved to be the most cost-effective alternative to repair this damaged building in a very short time. More than 20,000 ft.2 of wall surface area were strengthened, making this project the largest reported application of this technique. This paper discusses some of the design considerations and the strengthening of the damaged building.
The Variability of PSV Response Spectra across a Dense Array Deployed during the Northridge Aftershock Sequence
Authors: Field Edward H. , Hough Susan E.
Published: July 2003

This study addresses the variability of pseudo-velocity response spectra across an array deployed on stiff soil in the San Fernando Valley during the Northridge (Mw 6.7) aftershock sequence. The separation between stations ranged from 0.5 to 5 km, and the aftershock magnitudes ranged from 2.3 to 4.0. We find that 95-percent of observed response spectra are within a factor of 1.9 to 2.6 of the network average. Statistically significant relative amplification factors were found for some of the sites, but the variability of observed response spectra is not significantly reduced by correcting for these effects. This implies that microzonation efforts on less than 5-km distance scales are not warranted at these types of sites. We also found a distance dependence for the response-spectral variability between neighboring sites. 95-percent are within a factor of ∼2.3 at 0.5 km, increasing to 95-percent within a factor of ∼4.2 at 5 km. No frequency dependence in these values could be resolved. Additional work is needed to examine the influence of other factors such as earthquake magnitude.
Prediction of Soil Effects on Seismic Motions: A Comparative Case Study
Authors: Bouckovalas George D.
Published: July 2003

Empirical predictions of soil effects on seismic ground shaking are related to 1-D seismic response analyses. The comparison focuses upon the peak ground acceleration ( amax) and velocity ( Vmax), the elastic acceleration response spectra (Sa) and the average horizontal Fourier amplitudes over a short and an intermediate period band (AHFA, AHFA*). Empirical predictions in terms of site geology are within the overall range of analytical predictions for amax and Vmax, but they do not depict the detailed effects of seismic motion and site characteristics. In addition, they agree to analytical predictions of Sa for relatively deep and flexible sites, but differ significantly for other sites. Empirical predictions in terms of the average shear wave velocity, agree well with analytical predictions for amax, Vmax, AHFA and AHFA* in the case of shallow and stiff sites subjected to weak seismic excitations, but they are relatively higher in the opposite case. Empirical predictions of Sa are generally within the range of analytical predictions, although empirically predicted peak amplification can not be related to resonance between the soil and the superstructure.
Evaluation of Recorded Earthquake Response of a Curved Highway Bridge
Authors: Desroches Reginald , Fenves Gregory L.
Published: July 2003

The Landers and Big Bear earthquakes on June 18, 1992, triggered a strong motion instrumentation network on a curved highway bridge. System identification of the processed acceleration records show the vibration period of the fundamental mode lengthened from 1.56 sec to 1.75 sec between the two earthquakes. A three-dimensional, calibrated model of the bridge is used to investigate the effect of modeling assumptions on the earthquake response of the structure. Linear models, commonly used in design, adequately bound the earthquake response of the bridge. However, the linear models do not provide an upper bound on the forces in all the columns. Longitudinal hinge restrainers have minimal effect on the earthquake response. The non-uniform input motion recorded at four support points has a moderate effect on the response when compared with the assumption of uniform free-field motion.
Stability Aspects of Elastomeric Isolators
Authors: Imbimbo Maura , Kelly James M.
Published: July 2003

The theoretical analysis for the buckling of isolators is well known and has generally been verified by experimental work, but there are some aspects of the analysis that have not been addressed in detail. This paper will study two examples, first the effect of end plate rotation on the buckling load and, secondly, the buckling of an isolator that is made up of two bearings, one on the top of the others. The effect of end plate rotation on the buckling load arises in situations where the stiffness of the superstructure is not high enough to ensure that the isolator is constrained against rotation at the top; this is often the case when retrofitting existing structures. The influence of the flexibility of the superstructure on the horizontal stiffness of the isolator and the reduction of the critical load due to this flexibility is evaluated in the paper. The results show a significant reduction of the critical load. The second analysis presented in the paper models the buckling of a composite isolator that is made up of two bearings, one on top of the other. Two approaches for evaluating the critical load of this composite isolator are discussed, and an approximate method is developed that provides results close to the complete solution.