bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversing Cyclic Elastic Demands on Structures during Earthquakes and Applications to Ductility Requirements
Authors: Perez Virgilio , Brady A. Gerald
Published: July 2003

The study of all earthquake-induced oscillator response peaks from selected records shows how these peaks decrease in amplitude with the number of cycles attaining them. These studies concentrate on the ratio between the peak amplitudes of response experienced throughout the duration of a given number of cycles and the maximum response. The ratio shows a trend that is fairly independent of the structure's period, the epicentral distance, and the earthquake magnitude. If during a very large earthquake a structure is forced into displacements beyond the elastic limit it must withstand them successfully with well-designed ductility. For long-period structures, these inelastic displacements, if assumed to result from idealized elasto-plastic behavior, are approximately equal to the elastic displacements under study. The trends shown here consequently indicate that the amplitudes of the elasto-plastic displacements still attained after two, four, or eight cycles, remain at levels that are appreciably high percentages of the maximum displacement.
Planning against Earthquakes in the United States and Japan
Authors: Arnold Christopher
Published: July 2003

Comprehensive earthquake disaster preparedness planning encompasses two distinct but related elements: emergency planning and hazard mitigation. A comparison of U.S. and Japanese earthquake disaster planning processes shows a major contrast in approach. The U.S. approach is based on legislation that loosely defines issues, but has no clear management structure. Japanese planning established a clear relationship between research, planning, and operations, and is strongly administered by central government which provides methodologies and assistance to lower governmental levels. However, neither the U.S. nor Japan procedures have yet been tested by a major event. The U.S. approach relies extensively on improvisation, and limited experience shows that this may be relatively effective: Japanese planning may be too fragile in relying too much on centralized management and communications.
Probabilistic Estimates of Maximum Seismic Horizontal Ground Acceleration on Rock in Alaska and the Adjacent Continental Shelf
Authors: Thenhaus Paul C. , Ziony Joseph I. , Diment William H. , Hopper Margaret G. , Perkins David M. , Hanson Stanley L. , Algermissen S. T.
Published: July 2003

Estimates of ground motion hazard from earthquakes in Alaska and the adjacent continental shelf indicate that, for all the exposure times considered, the predicted values of peak acceleration are highest in the Gulf of Alaska and near the major active strike-slip faults of southern Alaska. The evaluations assume a Poisson model of earthquake occurrence and are based on seismic source zones delineated from regional geologic considerations and the historical record of earthquakes. Calculated peak acceleration values for a return period of 100 years range as high as 0.4 g in the Gulf of Alaska sector between Kodiak and Kayak Islands, are about 0.2 g near Anchorage, and 0.1 g near Fairbanks. Values for most of the rest of the state are estimated to be less than .04 g; however, most of the southern Alaska industrial and population base lies within the 0.2 g contour. For a return period of 500 years, peak accelerations are estimated as high as 0.8 g for parts of southeastern Alaska near the Fairweather fault, 0.6 g or greater for part of the Gulf of Alaska, and are about 0.45 g and 0.2 g, respectively, for the Anchorage and Fairbanks areas. Values of acceleration for a return period of 2,500 years exceed 0.6 g for much of southern Alaska and are 0.8 g or greater near the Fairweather and central Denali faults; estimated values are 0.1 g or greater for nearly all of onshore Alaska and for the continental shelf areas of the Bering Sea, Norton and Kotzebue Sounds, southern Chukchi Sea and southeastern Beaufort Sea.
The Morgan Hill Earthquake of April 24, 1984—Strong-Motion Records
Authors: Brady A. Gerald , Shakal Anthony F.
Published: July 2003

Seventy-two strong-motion accelerograph stations, mostly from within the permanent networks of the U. S. Geological Survey and the California Division of Mines and Geology, were triggered during the Morgan Hill earthquake, April 24, 1984. Among the more interesting of the records are the large acceleration (1.29g) at Coyote Lake dam, the Gilroy array spanning the region between the San Andreas and Calaveras faults, the record from Hall's Valley (epicentral distance 4 km), and records from buildings, a bridge, and a dam within 20 km of the epicenter. Digitized data from 16 stations are available on tape.
The Morgan Hill Earthquake of April 24, 1984—Effects on United Technologies Corporation
Authors: Gates William E.
Published: July 2003

United Technologies Chemical Systems Division, a manufacturer of rocket engine propellants, was situated in close proximity to the Calaveras fault. Soil conditions and fault rupture mechanisms produced anomalously high ground motion at the site. The main plant complex insisted of more than 130 buildings, constructed within the past 25 years to building code standards that considered earthquakes.

Damage to buildings was not extensive and was limited to the structures founded in the valley on loose alluvial deposits. Most of the damage was associated with nonstructural building elements and equipment. Estimated repair costs exceeded $1.25 million. No lives were lost and only minor injuries were experienced. Important observations include: (1) soil amplification effects increased damage, and (2) that persons who had received blast response training responded far better than those who were not exposed to such training.
The Morgan Hill Earthquake of April 24, 1984—Performance of Residential Structures
Authors: Strykowski David
Published: July 2003

The Morgan Hill earthquake caused limited structural damage. Most of the damage was concentrated in the town of Morgan Hill, which has a population of approximately 19,000. According to the latest available data, there are 6,024 residences; of these, 834 are mobile homes. Less than one percent of the residential structures suffered major damage. Less than eight percent suffered minor damage. Damage to residential structures has been estimated by state officials to be $3,000,000.
The Morgan Hill Earthquake of April 24, 1984—Summary of Highway Bridge Damage
Authors: Land Richard , Munro James
Published: July 2003

Only one bridge of 39 investigated was observed to sustain major structural damage. The county bridge carrying East Dunne Avenue over Anderson Reservoir, Bridge No. 37C-166, was closed to traffic by a rock slide and suffered major damage.
Some Cost Considerations of the Seismic Strengthening of Pre-Code Buildings
Authors: Platt Christine M. , Shepherd Robin
Published: July 2003

Several earthquake ordinances have been enacted requiring owners of pre-1934 unreinforced masonry buildings either to upgrade their seismic strength or to demolish them. In this paper some of the factors which an owner must consider, including the relative costs of rehabilitation and reconstruction, are reviewed and specific examination of the after-tax returns for a hypothetical California building is made. It is shown that whereas there may be little direct income benefit gained from upgrading a particular building, tax shelter advantages may well provide sufficient financial inducement to justify a decision to upgrade rather than to demolish.
The Borah Peak, Idaho Earthquake of October 28, 1983—Societal Response
Authors: Nigg J. M.
Published: July 2003

This paper summarizes the societal impact of the October 28, 1983 earthquake on south-central Idaho. While local resources were sufficient to respond to immediate post-impact needs, the community of Mackay required substantial amounts of state and federal recovery funds for damage to residences, public buildings, roads, and life lines. Three types of post-impact problems were identified—interagency communication; media convergence; and public rumoring concerning dam collapse.
The Borah Peak, Idaho Earthquake of October 28, 1983—Structural Control of Groundwater Eruptions and Sediment Boil Formation in the Chilly Buttes Area
Authors: Waag C. J. , Lane T. G.
Published: July 2003

Groundwater eruptions attendant to the Borah Peak earthquake formed more than 40 sediment boils. The eruptions were strongly controlled by solution widened fractures in limestone underlying alluvium. The dominant fracture set oriented N15°-20°W is imprinted upon the thin alluvial cover which is a confining layer. The fractures and shear zones in the alluvium served as important conduits for the discharge of groundwater. Water and air expulsed from the underlying carbonate entered the alluvium under high pressure and entrained and fluidized the alluvium forming sediment eruptions. The pressure surge which caused the eruptions probably resulted from a porewater pressure increase caused by compression of the carbonate in the hanging wall as it dropped.
Assessing Seismic Response of Utah Gas Systems
Authors: McDonough Peter W. , Taylor Craig E.
Published: July 2003

The potential damage to lifelines from even moderate earthquakes can have significant and widespread effects on community well-being. Recently, under the sponsorship of the United States Geological Survey, researchers from California cooperated with a utility in Utah to analyze the seismic safety of natural gas facilities in Utah. They identified pipelines by system importance, size, and material, and then assessed the probability of structural damage to these components. These estimates, which reflect knowledge of Wasatch Front fault mechanisms, and an ability to model numerous seismic events by computer, are yielding significant knowledge of possible piping responses.

Project results included the number and location of possible pipeline breaks for various seismic events. This information was used to estimate gas loss and resultant system pressures. This, in turn, is currently being used to guide future system reinforcements, replacements, and installation of emergency system isolation valves. This project, involving the close interaction of both the utility and the research firm, is a good example of the type of practical research needed by industry.
The Design of Ductile Reinforced Concrete Structural Walls for Earthquake Resistance
Authors: Paulay Thomas
Published: July 2003

In the design of reinforced concrete multistorey buildings, in which lateral load resistance has been assigned to structural walls, the emphasis should be on a rational strategy in the positioning of walls and the establishment of a hierarchy in the development of strengths to ensure that in the event of a very large earthquake brittle failure will not occur. The preferred mode of energy dissipation should be flexure in a predictable region. Therefore failures due to diagonal tension or compression, crushing of concrete in compression, sliding along construction joints, instability of wall elements or reinforcing bars and breakdown of anchorages should be suppressed. These aims may be achieved with the application of a deterministic design philosophy and they necessitate special detailing and dimensioning of potentially plastic regions of walls. In several areas differences exist between code provisions and practices in the United States and New Zealand.
Performance Assessment of Steel Components
Authors: Krawinkler Helmut
Published: July 2003

This paper presents a methodology for the assessment of cumulative damage in structural steel components subjected to cyclic inelastic loading histories of the type experienced in earthquakes. The methodology is based on low-cycle fatigue concepts and the hypothesis of linear damage accumulation. It will be shown that seismic performance of a component depends on two structural performance parameters and on the number and amplitudes of all inelastic excursions and not only on the maximum excursion. Experimental and analytical procedures for obtaining the parameters needed for a performance assessment are suggested in the paper.
Performance Evaluation of Friction Damped Braced Steel Frames under Simulated Earthquake Loads
Authors: Filiatrault A. , Cherry S.
Published: July 2003

This paper presents the results obtained from tests of a new friction damping system, which has been proposed in order to improve the response of steel Moment Resisting Frames (MRF) and Braced Moment Resisting Frames (BMRF) during severe earthquakes. The system consists of a mechanism containing brake lining pads introduced at the intersection of frame cross-braces. Seismic tests of a three storey Friction Damped Braced Frame (FDBF) model were performed on an earthquake simulator table. The experimental results are compared with the findings of an inelastic time-history dynamic analysis. The results clearly indicate the superior performance of the FDBF compared to conventional building systems.
The Influence of National Attention on Long-Term Earthquake Preparedness Policy in Charleston, South Carolina
Authors: Gori P. L. , Greene M. R.
Published: July 2003

The Charleston, South Carolina, area offers a unique opportunity to study the implementation of policy for long-term earthquake preparedness at the local level. Our interviews of public officials and others documented the low state of preparedness in 1981 and an improved situation in 1986. Since 1981, increased national attention has been used by citizens of the Charleston area to overcome political, informational, social, organizational, and economic barriers that retard the implementation of policies to mitigate the damage caused by earthquakes.
Cladding Performance on a Full Scale Test Frame
Authors: Wang Marcy Li
Published: July 2003

The last phase of the recent U.S.-Japan Cooperative Research Program's full scale steel structure tests concerns the seismic performance of so called “nonstructural” or “extrinsic” elements. Both Japanese and U.S. elements were installed onto the full scale, moment resistant frame; static tests of the frame with cladding and internal elements took place during three weeks of July, 1984 at the Building Research Institute in Tsukuba, Japan. The U.S. side test focused on cladding, and the Japanese side oversaw testing of cladding common to Japanese practice, and internal partitions and ceilings common to both U.S. and Japanese practice. This paper describes findings of U.S. cladding performance tests with regard to values of seismic story drift designated in the Uniform Building Code, and observations of the behavior of Japanese elements.
Earthquake Hazard in the Eastern United States: Consequences of Alternative Seismic Source Zones
Authors: Thenhaus P. C. , Perkins D. M. , Algermissen S. T. , Hanson S. L.
Published: July 2003

The regional variability in expected ground motion associated with six different characterizations of seismic source zones for probabilistic ground motion assessment is examined for the eastern United States. Three of the seismic source zone models are based on types of geologic structure: (1) regions characterized by late-Precambrian faulting; (2) middle-to-late Paleozoic thrust tectonics; and (3) early-to-middle Mesozoic extensional features. Two other seismic source zone configurations considered are based on data related to vertical crustal movements, and the final source zone model investigated is that of Algermissen and others (1982). Maintaining the same maximum magnitude among all zones and for all source zone configurations, a comparison of results indicates a factor of 3 difference among source zone models for calculated acceleration levels in eastern Massachusetts, southeastern Maine, and the Cape Fear arch of eastern North Carolina; a factor of about 2 or greater difference for most other eastern seaboard areas; and a factor of 1.5 or less for much of the Appalachian region extending from New Brunswick to the Gulf Coast. Results show that certain source zone models based exclusively on speculative geologic hypotheses result in considerably lower ground-motion hazard than otherwise implied by accepting historical seismicity as a guide to future hazard. Significantly, variation in the seismic hazard estimates at probability levels of 1 in 500 due to uncertain earthquake causal structures or processes is considerably higher in the heavily populated northeast region than in the Charleston, South Carolina, area.
The Culprit in Mexico City—Amplification of Motions
Authors: Celebi M. , Prince J. , Dietel C. , Onate M. , Chavez G.
Published: July 2003

Mexico City has repeatedly suffered from the long-distance effects of the earthquakes that originate as far away as the subduction trenches near the Mexican Pacific Coast. The Michoacan, Mexico earthquake of 19 September 1985 was no exception and caused extensive damage to property and numerous loss of lives. The unique subsurface condition resulting from the historical lakebed has distinct resonant low frequencies around 0.5 Hz. The strong earthquake motions from long distances as well as the locally originating weak motions cause large amplifications at resonant low frequencies in the subsurface environment of Mexico City lakebed. In this paper, the resonant frequencies and associated amplification of motions in Mexico City are quantified in terms of spectral ratios using 19 September 1985 strong-motion data and weak motions recorded in January, 1986. These ratios confirm that the amplification of motions at resonant frequencies due to the subsurface conditions is indeed the culprit.
The Kalamata, Greece, Earthquake of September 13, 1986
Authors: Anagnostopolous S. A. , Rinaldis D. , Lekidis V. A. , Margaris V. N. , Theodulidis N. P.
Published: July 2003

This is a report on a recent earthquake that hit the Greek city of Kalamata on Sept. 13, 1986. The earthquake, although, moderately strong-reported magnitude Ms=6.2− caused heavy damage and killed 20 people. Strong-motion data are presented for the main event as well as from two recordings of the major aftershock. The records are interesting because they have been obtained at relatively small distances from the epicenter: approximately 9 km for the main event and 1 km for the major aftershock. Moreover, the soil profile at the recording site is known and is given here for complete documentation of the records. Very high spectral accelerations characterize the records and are partly responsible for the total or partial collapse of seven modern reinforced concrete buildings. A survey of damage is also presented with comments on its causes, in relation to the applicable seismic regulations and to local construction practices.
The San Salvador Earthquake of October 10, 1986—Geologic Aspects
Authors: Rymer Michael J.
Published: July 2003

The San Salvador earthquake struck an area of upper Cenozoic volcanic rocks, consisting of basaltic to silicic flows and tuffs. Tuff deposits constitute the upper 30 m of section below San Salvador; thinner sections are in the hills surrounding the city. Tuffs were important in landslide development during the earthquake and may have amplified ground motion. Faults mapped in the area strike east-west, northwest-southeast, and less distinctly, northeast-southwest and north-south. Ringlike structures formed by volcanic subsidence are also present in the area. No evidence was seen of surface faulting associated with the October 10 main shock or an earthquake on October 13 on a separate fault 7 km west-northwest of the main shock. Numerous cracks were seen in the epicentral areas of both earthquakes, but these are easily explained as secondary ground failures. Both of the earthquakes occurred on unmapped faults. The main shock caused several hundred landslides in an area of at least 200 km2. The most numerous landslides were soil slides and soil falls, which were especially common in stream banks and roadcuts. The earthquake also produced rock falls and slides, slumps, rapid soil flows, shattered ridge effects, and compaction. Landslides and related ground failures were triggered as much as 12 km from the epicenter and accounted for about 200 fatalities and at least 100 damaged homes.
The San Salvador Earthquake of October 10, 1986—History of Construction Practices in San Salvador
Authors: Lara Mauricio A.
Published: July 2003

Construction practice in San Salvador, as in the rest of El Salvador, had remained practically unchanged since the time of Spanish colonization up to around 1942. From then on, building practices from many other countries have been introduced, and they have exerted a major influence. The last four decades can be divided into five stages or periods induced by events such as earthquakes in El Salvador and neighboring countries, as well as the incorporation of foreign codes in lieu of a local one and the introduction of new techniques, such as soil mechanics and microseismic investigation. The incorporation of practices based on foreign codes contributed significantly to the improvement of construction practice but occasionally led to misinterpretations, e.g. in the evaluation of seismic actions. At present, a number of studies and records are available that can be used as a basis for the elaboration of an earthquake resistant design code.
The Whittier Narrows, California Earthquake of October 1, 1987—Buildings at Risk
Authors: Jones B. G. , Nicolaides C. N.
Published: July 2003

Current methods of risk assessment require determining the incidence of damage to the elements at risk in order to establish vulnerability. Recent disasters can provide extremely useful information for calibrating various parameters of damage rates. It is necessary to produce estimates of the elements at risk and apply the best information available concerning damage. This requires considering the total physical context in which the disaster occurred. We estimate population, number of buildings, building floor area, and building replacement cost for the Modified Mercalli Intensity VI, VII and VIII areas for the Whittier Narrows Earthquake and calculate incidence rates.
The Whittier Narrows, California Earthquake of October 1, 1987—Note on Peak Accelerations during the 1 and 4 October Earthquakes
Authors: Trifunac M. D.
Published: July 2003

Attenuation patterns of the recorded peak accelerations during two moderate earthquakes (ML = 5.9 and 5.3) in Los Angeles, California are described. It is shown that the recording of earthquake motions by dense arrays of accelerographs can yield a detailed and deterministic picture of the physical processes which are involved in shaping the observed variations of strong ground motion. For the two earthquakes the observed changes of peak amplitudes with respect to the azimuth and distance are slowly and continuously changing functions showing strong dependence of amplitudes on the radiation patterns of the two earthquakes and on the effects of wave propagation through irregular three-dimensional geology of the Los Angeles basin.
The Whittier Narrows, California Earthquake of October 1, 1987—Masonry Building Performance Survey
Authors: Hart G. C. , Kariotis J. , Noland J. L.
Published: July 2003

The observed earthquake response of unreinforced and reinforced masonry buildings during the October 1 and 4, 1987 Whittier Narrows Earthquakes was documented in a comprehensive building survey. This paper describes the extent of the survey, the type of data collected and a preliminary summary of some survey results.
The Whittier Narrows, California Earthquake of October 1, 1987—Performance of Tilt-up Buildings
Authors: Hamburger R. O. , McCormick D. L. , Hom S.
Published: July 2003

In the 1971 San Fernando earthquake the general performance of tilt-up structures was poor, and a number of collapses occurred. After this event substantial changes were made to seismic code provisions governing the design and construction of these buildings. The October 1, 1987 Whittier Narrows earthquake produced strong shaking (up to Modified Mercalli Intensity VIII) in an area containing thousands of tilt-up buildings of various ages. This recent earthquake thereby provided the first significant test of these new provisions.
The Whittier Narrows, California Earthquake of October 1, 1987—Damage to State Highway Bridges
Authors: Gates J. H. , Mellon S. , Klein G.
Published: July 2003

Damage to State highway bridges was confined primarily to one bridge at the Interstate 605 and 5 Interchange. Shear damage, classified as moderate, occurred to the columns of one bent. The bridge was shored up and opened to traffic in less than 22 hours. Minor damage also occured at bearings and other locations on sixteen other bridges. Evidence of movement was also noted on seven other bridges.
The Mexico Earthquake of September 19, 1985—Probability Distribution of Times between Characteristic Subduction Earthquakes
Authors: Jara J. M. , Rosenblueth E.
Published: July 2003

When earthquakes from a single source govern a structure's design, decisions are sensitive to the probability distribution of times between characteristic earthquakes and correlations between time elapsed and magnitude. Scarcity of data prevents a purely statistical study of these matters while absence of trustworthy theories prevents a purely analytical approach. Based on simulation using a physically founded mathematical model and on data from various parts of the world, we postulate a slip-predictable model and four candidate distributions with random parameters for the distribution of interoccurrence times in subduction zones: lognormal, gamma, inverse gaussian and Weibull. Probabilities are updated using data from three groups of subduction earthquakes. In all cases the lognormal distribution minimizes the disutility due to choosing a single model. The same distribution with fixed parameters gives almost equally good results.
The Mexico Earthquake of September 19, 1985—Estimation of Response Spectra in the Lake Bed Zone of the Valley of Mexico
Authors: Ordaz M. , Singh S. K. , Reinoso E. , Lermo J. , Espinosa J. M. , Domínguez T.
Published: July 2003

We estimate pseudo acceleration response spectra with 5% damping (Sa) for the great Michoacán earthquake at 22 lake bed sites (in addition to five sites where the event was well recorded) in the valley of Mexico. The method used consists of (a) estimation of Fourier acceleration amplitude spectra (FAS) at the sites via observed FAS at Ciudad Universitaria (CU) and compiled spectral ratios of these sites with respect to CU obtained from recorded earthquakes, (b) estimation of the duration of strong ground motion during the Michoacán earthquake at the sites, and (c) application of random vibration theory to predict Sa. A constant duration of 71 sec at all sites is found to be satisfactory. The main uncertainties in estimated Sa come from (a) possible nonlinear behaviour of the clay during the great earthquake (the spectral ratios used in the computation are mostly for moderate earthquakes, when the clay behaves linearly), and (b) variations in site's spectral ratios due to randomness and/or its dependence on earthquake characteristics which are presently unknown. Assuming that the nonlinear behaviour was neglegible and the spectral ratios estimated from one or few recordings are representative, we find (a) Sa ≥ 600 gals over a wide area of the lake bed zone, (b) Sa ≥ 1g at 14 out of the 27 sites, (c) regions of high Sa in the center of the city and east of CU, and (d) a good correlation between severe damage and regions with Sa ≥ 800 gals. Although in general our results agree with reported effects of the earthquake, because of the uncertainties mentioned above direct use of the computed response spectra for code or design purposes is discouraged.
The Mexico Earthquake of September 19, 1985—Behavior of Building Foundations in Mexico City
Authors: Mendoza M. J. , Auvinet G.
Published: July 2003

During the 1985 earthquake, a number of building foundations in the lacustrine soft soil area of Mexico City presented an inadequate performance. Previous high static contact stresses between the foundation and the supporting subsoil propitiated the appearance of plastic deformations of the soil under seismic cyclic stresses, which led to settlements and tilting of the buildings. Foundations of all kinds showed different degrees of vulnerability to the earthquake, but constructions on friction piles sustained the most severe damages. This can be attributed in some cases to non compliance with the accepted design criteria and current regulations. The main factor was however the pronounced dynamic magnification of seismic movements associated to the quasi coincidence between the natural period of some structures with moderate height on friction piles, and the long period of the subsoil motions, which led to large overturning moments and shear forces at the foundation level.
The Mexico Earthquake of September 19, 1985—Analysis of Building Response
Authors: Meli R. , Ávila J. A.
Published: July 2003

Response of simple structural models to the peculiar ground motions recorded in the lake-bed area of Mexico City was analyzed in order to explain the performance of typical buildings during the 1985 earthquake. Results for one-degree of freedom systems with different kinds of inelastic behavior show that when hysteresis loops remain stable under several cycles of large inelastic deformations, exceptionally large reductions in the structural response take place. Nevertheless, if the hysteresis loops show some degradation of strength for large displacements, the response increases sharply for the same critical periods. Results for multi-degree of freedom systems show large concentrations of ductility demands at lower stories. Static and dynamic analyses of linear and non-linear models of several typical mid-rise concrete buildings were also performed. The results agreed with reasonable accuracy with the observed behavior and with measurements of the response under low amplitude ambient vibrations.
The Mexico Earthquake of September 19, 1985—The Seismic Performance of Buildings with Weak First Storey
Authors: Ruiz S. E. , Diederich R.
Published: July 2003

During the Michoacan earthquake of Séptember 19, 1985, 8 percent of the damaged buildings in the Mexico City area were characterized by a first storey much weaker than the upper ones. Although it is recognized that these failures may have resulted from the combination of several features, in this paper it is intended to study the possible influence of the lateral strength discontinuity in the ductility demand at the first storey, and to try to understand the behaviour of this type of structures under the actions of the East-West component of the highest acceleration record obtained on soft soil in Mexico City during the mentioned earthquake. A parametric study for five and twelve-storey buildings with weak first storey is presented in this paper. The infill walls in the upper storeys were brittle in some cases and ductile in others. For certain cases, the results show the existence of a range of values of the ratio of seismic lateral resistance of the upper storeys to that of the lowest one for which ductility demands at the lowest story can be considerably higher than for other intervals. It is shown that the absorption capacity of ductile walls plays an important role in the displacement ductility demands of the first storey.
The Mexico Earthquake of September 19, 1985—Seismic Response of Asymmetrically Yielding Structures
Authors: Ruiz S. E. , Rosenblueth E. , Diederich R.
Published: July 2003

Some structures yield asymmetrically in the two opposite senses of a given direction. This can be due to structural configuration, asymmetry in loads, or tilting. As a consequence the capacity to resist earthquake motion can be much owing to a tendency to accumulate inelastic deformations in the weaker sense. The phenomenon is studied here for single-degree-of-freedom hysteretic bilinear systems subjected to simulated accelerograms of the E-W component of the motion registered in the Ministry of Communications and Transportation in Mexico City, during the September 19, 1985 earthquake. The evolutionary spectral power concept is used for this purpose. Approximate practical rules are deduced from results of this study which were included in the new Mexican seismic design code. The influence of motion duration is pointed out on this type of structures.
The Mexico Earthquake of September 19, 1985—Performance of Low-Rise Buildings in Mexico City
Authors: Miranda E. , Bertero V. V.
Published: July 2003

This paper summarizes the results of analytical studies conducted to understand the observed performance of low-rise buildings located in the soft-soil zone of Mexico City during the 1985 Michoacan earthquake. Two low-rise reinforced concrete moment resistant space frames were designed in accordance with the 1976 Code for the Federal District of Mexico. They were subjected to a series of static and time history dynamic analyses. The results indicate that the designed buildings have significantly larger lateral strengths than required by the Code and that these overstrengths were the main reason for the excellent performance of most of the low-rise buildings in Mexico City during the 1985 Michoacan earthquake.
The Mexico Earthquake of September 19, 1985—Statistics of Damage and of Retrofitting Techniques in Reinforced Concrete Buildings Affected by the 1985 Earthquake
Authors: Aguilar J. , Juárez H. , Ortega R. , Iglesias J.
Published: July 2003

The 1985 Mexico City earthquake caused very serious damage, especially in reinforced concrete buildings, making it necessary to repair and strengthen many structures. The authors had the opportunity to study 114 of these retrofitted buildings. The data base created with the collected information contains the description of the building, its damages and the retrofitting techniques used. The statistical analysis of this information makes it possible to identify the correlation among the structural and foundation types, the dominant failure modes, the causes of damage and the repair and strengthening techniques used in this group of buildings.
The Mexico Earthquake of September 19, 1985—Seismic Zoning of Mexico City after the 1985 Earthquake
Authors: Iglesias J.
Published: July 2003

Using a simplified method for the evaluation of the seismic capacity of medium rise concrete structures, it was possible to obtain the base shear coefficient corresponding to failure (resistance coefficient) for 162 buildings, and use it as an evaluation index. The resistance coefficients of the 90 evaluated structures that suffered severe damage were used to elaborate a map of intensities for the 1985 Mexico City earthquake. This map shows the strong interaction of neighboring zones of firm soil or rock that amplify the ground motion in the soft soil between them as much as 100%, this being the main reason for the high intensities observed in some districts of the city. Based on these results, a new seismic zoning was proposed for the chapter of the 1987 Mexico City Building Code.
Seismic Response of a Large-Span Roof Diaphragm
Authors: Celebi Mehmet , Bongiovanni Giovanni , Safak Erdal , Brady A. Gerald
Published: July 2003

Records obtained from the West Valley College Gymnasium in Saratoga, California during the 1984 Morgan Hill earthquake are used to study the dynamic behavior of the overall gymnasium as well as its flexible diaphragm. The ground-level motions recorded in the two orthogonal axes of the structure differ considerably in peak acceleration and amplify by approximately 1.5 times at the roof edges and by 4-5 times at the center of the diaphragm. The diaphragm responds with a frequency of approximately 4 Hz in both orthogonal axes.

A simple finite-element model is used to match the fundamental frequency of the diaphragm with that from the records. Using this model and the ground-level motions as input, the diaphragm center displacements are calculated by varying the structural damping. Best comparisons are obtained for 5% damping. These results are discussed in terms of the code provisions.
A Simplified Procedure for Constructing Probabilistic Response Spectra
Authors: Peng Ming-Hsing , Elghadamsi Fawzi E. , Mohraz Bijan
Published: July 2003

This paper provides a simplified procedure for computing the probabilistic maximum response of a linear single-degree-of-freedom system subjected to earthquake ground motion. The formulation uses the root-mean-square ( rms) response of the system and a probabilistic peak factor which is modified to account for the wide-band characteristics. The modification uses a set of damping-dependent coefficients obtained from correlating the peak factor with the ratio of the maximum response to the rms response from accelerograms recorded on alluvium and rock. The procedure incorporates the influence of soil condition and the strong motion duration as parameters in computing response spectra.
Inelastic Response of a Spectrum-Compatible Artificial Accelerogram
Authors: Barenberg Michael E.
Published: July 2003

The validity of evaluating the inelastic response of a structure subjected to an artificial accelerogram in lieu of a suite of eight recorded ground motions is determined by analyzing the inelastic response of single-degree-of-freedom oscillators over a range of frequencies from 1.0 to 10.0 Hz. A normalization procedure to minimize the dispersion in the ductility response of the oscillators subjected to the recorded ground motions is investigated. The artificial accelerogram is derived by superimposing closely spaced sine waves in order to match a target response spectrum. The results show that the artificial accelerogram is expected to produce the same amount of damage as the average of the recorded strong ground motions for structures with an initial frequency of less than 5.0 Hz and close to the average for the entire suite of ground motions for structures with frequencies greater then 5.0 Hz.
On Design of Eccentrically Braced Frames
Authors: Engelhardt Michael D. , Popov Egor P.
Published: July 2003

Seismic-resistant Eccentrically Braced Frames (EBFs) are becoming a widely used lateral resisting system for steel buildings, with even wider application anticipated as design requirements are put into building code format. This paper addresses a number of EBF design issues, which in the opinion of the authors are inadequately considered either in current practice or in the emerging code provisions. The overall design philosophy for EBFs is reviewed, with specific reference to the concept of “Capacity Design”. Application of capacity design principles assures that yielding will be restricted primarily to the ductile link elements, an important goal of EBF design. Further, through careful choice of frame geometry and link length at the preliminary stages, many potential design difficulties can be avoided. The paper also presents some important observations from experimental work currently underway on EBFs with long, flexural yielding links.
Demonstration of Torsional Coupling Caused by Closely Spaced Periods—1984 Morgan Hill Earthquake Response of the Santa Clara County Building
Authors: Lin B. C. , Papageorgiou A. S.
Published: July 2003

The parameters of the dominant modes of vibration of the steel-framed Santa Clara County Office Building in San Jose, California, are determined using “the modal minimization method” for structural identification. The optimal estimates of the model parameters are determined by minimizing a selected measure-of-fit between the responses of the structure and the model. Two types of models are used: (1) A planar linear model with classical damping and (2) A three dimensional linear model consisting of rigid floor decks, where each floor is allowed three degrees of freedom - two orthogonal translations plus a rotation. The Santa Clara County Office Building continued vibrating in a free vibration manner with very low damping, long after the intense part of ground motion had ended. The records of its torsional motion exhibit a strong beating effect which is explained by the strong coupling of torsional and translational modes of vibration. Such a strong coupling of modes of vibration is attributed to the proximity of the value of torsional stiffness to that of translational stiffnesses.
Toward a Philosophy for Seismic Retrofit: The Seattle Experience
Authors: Perbix T. W. , Burke P.
Published: July 2003

By examining seismic retrofit experience with three buildings in Seattle, important practical issues regarding the underlying economic, political, and social conflicts are explored. The philosophy of seismic retrofit and its resulting consequences for life safety, building usefulness both before and after seismic events, and the economic consequences of retrofit are examined in light of the professional and regulatory atmosphere. While a great deal of information is generated nationally in the field of seismic retrofit, its assimilation by the practising professional and regulatory official is incomplete and uncoordinated. The work proposes, therefore, a seismic retrofit design philosophy for discussion and possible use as a premise for development of codes. The proposed philosophy coordinates the economic, social, and life safety aspects of seismic retrofit in a way that meets the needs of designers and regulators who are currently forced to make social policy in their everyday design interactions.
Response Modification Factors for Earthquake Resistant Design of Short Period Buildings
Authors: Riddell Rafael , Hidalgo Pedro , Cruz E.
Published: July 2003

Most recent seismic codes include response modification factors in the definition of the equivalent lateral forces that are used for the design of earthquake resistant buildings. The response modification factors (R) are used to reduce the linear elastic design spectrum to account for the energy dissipation capacity of the structure. The evaluation of these response modification factors for various sets of earthquake records and ductility factors is presented herein. Special attention is given to the short period range where the reduction of linear elastic response spectra is smaller than the values for intermediate and long period structures. An idealized and simple variation of the response modification factor as a function of the period of vibration, suitable for seismic codes formulation, is also presented.
The Basics of Seismic Risk Analysis
Authors:   EERI Committee on Seismic Risk
Published: July 2003

Seismic risk analysis involves determining the adverse consequences that people and society might suffer as a result of future earthquakes, and estimating the probability of these consequences for some future time period. We review the methods used, and present a simple example for a hypothetical building in Los Angeles. The purpose of a seismic risk analysis is to make informed decisions about seismic safety, and this is illustrated with the Los Angeles example by presenting the implications of several options available for a property owner to accept, insure, or mitigate seismic risk.
Seismic Tests of Adobe Walls
Authors: Bariola J. , Sozen M. A.
Published: July 2003

The object of this investigation was to study the stability of adobe walls during earthquakes. Nine earthquake simulation tests were made to investigate the influence of the following variables: (1) type of ground motion, (2) slenderness (thickness/height ratio), (3) wall thickness. Dimensions of specimen ranged from: 0.2 × 1.2 × 1.4 m through 0.4 × 1.2 × 2.80 m. Six specimens were tested with a soft-soil ground motion and other five to stiff-soil ground motion. Behavior of all specimens was characterized by cracking at the base followed by rocking motion. Failure occurred by overturning (short specimens) or by upper-level cracking (tall specimens). An analytical model was successful in calculating the susceptibility of the walls to overturning. Experimental and analytical results indicated that failure depends primarily on ground motion acceleration level and wall slenderness.
Damage to Public Property in the Whittier Narrows Earthquake: Implications for Earthquake Insurance
Authors: French Steven P. , Rudholm Gary G.
Published: July 2003

The Whittier Narrows earthquake of October 1, 1987 caused significant damage in the Los Angeles urban area. This event provided an opportunity to observe the type and amount of damage sustained by public property and to investigate the funding mechanisms used to repair the damaged facilities. Repair of earthquake damage to public property, which includes public buildings and infrastructure lifelines, is largely funded by state and federal disaster relief payments. Records of the Federal Emergency Management Agency and California Office of Emergency Services were analyzed to determine the value of damage to different classes of infrastructure and public property. Nearly half of the total damage caused by this earthquake occurred to public buildings. The fact that public buildings comprise such a large proportion of the damage is important because these structures were eligible for private earthquake insurance. This factor should be considered in developing a national earthquake insurance program.
Evaluation and Use of Residual Strength in Seismic Safety Analysis of Embankments
Authors: Marcuson W. F. , Hynes M. E. , Franklin A. G.
Published: July 2003

A reevaluation of the performance of the Lower San Fernando Dam during the February 9, 1971 San Fernando earthquake was conducted to evaluate methods of determining the residual shear strengths of liquefied soils. The use of Standard Penetration Test (SPT) N-value correlations, as proposed by H. B. Seed and his colleagues at the University of California, and laboratory tests to obtain steady-state strength as proposed by Gonzalo Castro and his colleagues at GEI, Inc., are evaluated. A recommended approach for seismic safety analysis is presented. The approach, which is intended for use by practicing engineers and not for problems of a research nature, generally consists of the techniques developed by Seed and his colleagues and incorporates routine use of a field performance-based correlation between soil strength and SPT blow counts.
Evaluation of ATC Requirements for Soil-Structure Interaction Using Data from the 3 March 1985 Chile Earthquake
Authors: Wallace John W. , Moehle Jack P.
Published: July 2003

The effect of soil-structure interaction on building responses is investigated using data from the 3 March 1985 Chile earthquake. Four shear wall buildings located in Vin~a del Mar, Chile and subjected to strong, long duration, earthquake ground motions during the 3 March 1985 Chile earthquake are studied. Detailed analyses are conducted on one building using available information on soil properties, measured periods, and recorded ground motions. Based on the detailed study, ATC-3 procedures are used to incorporate soil-structure interaction effects for three additional buildings. The analyses indicate that soil-structure interaction is an important consideration for the stiff shear wall buildings located in Vin~a del Mar, Chile. Reductions in base shear of 10 to 47% were computed; however, roof drift ratios generally were unchanged. For spectra representing US design ground motions (ATC), reductions in base shear are not expected to be as pronounced and roof drift ratios are expected to increase moderately.
Soil-Structure Interaction in Buildings from Earthquake Records
Authors: Fenves Gregory L. , Serino Giorgio
Published: July 2003

An evaluation of the response of a fourteen story reinforced concrete building to the 1 October 1987 Whittier earthquake and 4 October 1987 aftershock shows significant effects of soil-structure interaction. A mathematical model of the building-foundation-soil system provides response quantities not directly available from the records. The model is calibrated using the dynamic properties of the building as determined from the processed strong motion records. Soil-structure interaction reduces the base shear force in the longitudinal direction of the building compared with the typical assumption in which interaction is neglected. The reduction in base shear for this building and earthquake is approximately represented by proposed building code provisions for soil-structure interaction.