bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mexico Earthquake of September 19, 1985—An Empirical Model to Predict Fourier Amplitude Spectra of Horizontal Ground Motion
Authors: Castro R. , Singh S. K. , Mena E.
Published: July 2003

We analyze Fourier acceleration amplitude spectra of 14 coastal earthquakes (5.6 ≤ Ms ≤ 8.1) recorded at a hill zone site in Ciudad Universitaria (CU), Mexico City (282 ≤ R ≤ 466 km, R= closest distance from CU to the rupture area). The observed smoothed spectra are fitted to the following model

log FS(T) = A(T) Ms + C(T) log(R) + B(T)

where FS is the maximum spectral value of either of the two horizontal components at period T. The coefficients A, C, and B are obtained for 18 periods (2.5 ≥ T≥ 0.2 sec). The observed spectra at CU are not reliable for most earthquakes beyond this period range. The predicted FS for the September 19, 1985, Michoacán earthquake (Ms = 8.1) is less than the observed FS for T ≥ 0.6 sec suggesting an anomalously large radiation towards Mexico City during the earthquake at these periods. This anomalous radiation is in agreement with the teleseismic evidence. FS at several sites in Mexico City (many on the lake bed zone) can be obtained from the predicted FS at CU and the known spectral ratios of these sites with respect to CU.
The Mexico Earthquake of September 19, 1985—General Soil Conditions and Clay Properties in the Valley of Mexico
Authors: Romo M. P. , Jaime A. , Reséndiz D.
Published: July 2003

We present and discuss the results of resonant column and cyclic triaxial tests on clay samples obtained from different sites within the Lake zone in the Valley of Mexico. Of particular interest are the nearly elastic behavior and low damping ratio even for shear strain amplitudes as high as 0.3 (%). A hyperbolic model reproduces adequately well the resulting shear modulus vs strain curves. Degradation of shear modulus caused by load repetition is negligible for strains lower than about 1 (%) but increases significantly for higher strains. A power-type expression fits well the modulus degradation vs number of cycles curves. Results from static triaxial tests indicate that for compression stress paths the induced pore water pressure is uniquely related to axial strains. Analyses of ground motions show that one dimensional wave propagation models may be used to predict free field seismic motions in most parts of the Lake zone.
The Mexico Earthquake of September 19, 1985—Deformability of Mexico City Hard Deposits under Cyclic Loading
Authors: Ovando-Shelley E. , Mendoza M. , Romo M. P.
Published: July 2003

Buildings founded on point bearing piles performed better than those founded on friction piles in Mexico City during the earthquakes of September 19 and 20, 1985. Nevertheless a few buildings supported on end bearing piles tilted considerably after the earthquakes. Friction piles have been preferred over end bearing piles in Mexico City because the latter type of foundation has drawbacks resulting from the apparent emersion of structures brought about by regional subsidence. Experimental research into the behavior of the soils that form the bearing strata for pile tips shows that stress path testing can be used to obtain a deformability parameter which allows for the calculation of permanent deformations induced by earthquake loading below end bearing piles. The tests indicate that the deformability of these soils under cyclic loading is rather low. The use of the deformability parameter is illustrated by means of an example which shows that the behavior predicted on the basis of stress path testing and a simplified deformation analysis is consistent with observed field performance.
The Mexico Earthquake of September 19, 1985—Earthquake Behavior of Soft Sites in Mexico City
Authors: Rukos E. A.
Published: July 2003

From the september 19, 1985 earthquake there are several acceleration records for the soft (lake bed) sites in Mexico City. One-dimensional propagation models of the incident seismic accelerations incorporate the wave propagation profiles at three of those sites. The undamped computed surface acceleration spectra compare well with the recorded ones for two sites. The other one does not produce adequate results, which is probably due to incomplete information on the shear wave velocities. Further investigation with the site impulse function indicates that the surface accelerations during the september 19, 1985 event had a frequency content determined, to a certain extent, by the natural periods of the site. Direct inspection of the recorded spectra for the september 19, 1985 earthquake at the studied sites shows that the relation between spectral periods corresponds to the closed form solution of an homogeneous layer with a fixed base. This relation may be different for other earthquakes recorded at these sites.
The Mexico Earthquake of September 19, 1985—Correlations between Dynamic and Static Properties of Mexico City Clay
Authors: Jaime A. , Romo M. P.
Published: July 2003

It is the purpose of this paper to present and discuss several empirical correlations between dynamic shear modulus and void ratio, and static shear modulus; shear wave velocity and electric cone point resistance. Also a discussion and a comparison is made of the results of field and laboratory measurements of Mexico City clay dynamic properties.
The Mexico Earthquake of September 19, 1985—Natural Period of Sites in the Valley of Mexico from Microtremor Measurements and Strong Motion Data
Authors: Lermo J. , Rodríguez M. , Singh S. K.
Published: July 2003

The period at which peak in the microtremor Fourier velocity spectra occurs in the transition and lake bed zones of the valley of Mexico is found to be the natural period of the site. These periods in the valley are compiled from the microtremor measurements carried out by Instituto de Ingeniería, UNAM and scientists from Japan (for a total of 181 sites). Using this data and the natural periods estimated from strong motion recordings (36 sites), an isoperiod contour map of the valley of Mexico is presented. This map may be useful in future design of important structures.
The Mexico Earthquake of September 19, 1985—Evaluation of the Seismic Capacity of Buildings in Mexico City
Authors: Noren~a F. , Castan~eda C. , Iglesias J.
Published: July 2003

As a consequence of the 1985 Mexico City earthquake, the authorities of the city have decided to evaluate the seismic capacity of the buildings without damage with the purpose of detecting those with the most vulnerability, in order to take the preventive actions necessary to improve the security of the citizens in future earthquakes. Based on the census of the structures of the city, the procedure of evaluation used considers three levels of increasing precision permitting a progressive selection of the buildings in bad condition. Work is now under process in the main districts of the city with good results.
The Mexico Earthquake of September 19, 1985—Analysis of the Seismic Performance of a Medium Rise, Waffle Flat Plate Building
Authors: Rodríguez M. , Díaz C.
Published: July 2003

This paper analyzes the seismic performance of a 15-story waffle-flat plate building affected by the September 19 Mexico earthquake. It also evaluates the adequacy of present analytical methods for predicting observed damage and response. In addition, it proposes a model to define the supplied slab seismic strength for nonlinear analysis. Results from this analysis correlate reasonably well with the observed seismic behavior of the building. Particularly, distribution of computed maximum rotational ductility demands on slabs agree well with observed maximum slab damage in the building.
The Mexico Earthquake of September 19, 1985—Response and Design Spectra Obtained from Earthquake-Damaged Buildings
Authors: Gómez A. , Ortega R. , Guerrero J. J. , González E. , Paniagua J. P. , Iglesias J.
Published: July 2003

The resistant shear force of 13 buildings severely damaged by the 1985 Mexico City earthquake was determined by static and dynamic analyses. The results of the static analysis suggest the advisability of increasing the shear base coefficient of the 1987 Mexico City building code RDF87 from 0.4 to 0.6 in the high seismicity zones of the area. The results of the dynamic analysis show that in order to obtain the same safety level, the maximum ordinate of the design spectrum should be larger than the base shear coefficient used with the static method, leading to a 0.8 maximum ordinate for Mexico City. When the resistant shear force is plotted as a function of the natural period of each building, the response spectrum obtained is very similar to the inelastic spectrum derived from the accelerograms, considering 5% critical damping, a ductility factor of 4 and degradation in resistance from 5% to 10%. Based on these results, new design spectra are proposed for use in the high seismicity zones in Mexico City.
The Mexico Earthquake of September 19, 1985—Case Studies of Seismic Strengthening for Two Buildings in Mexico City
Authors: Foutch D. A. , Hjelmstad K. D. , Calderón E. Del Valle , Gutiérrez E. Figueroa , Downs R. E.
Published: July 2003

The earthquake that shook Mexico City on 19 September 1985, destroyed several hundred buildings and took thousands of lives. Two buildings located in the most highly damaged part of the city experienced strong shaking, but suffered only slight damage. These reinforced concrete frame buildings had been retrofit with steel bracing systems and infill reinforced concrete walls prior to the earthquake. Forced vibration tests, analytical studies and geotechnical investigations for each building have been conducted. The results indicate that the steel bracing systems strengthened the buildings and stiffened them, moving their natural periods away from the 2.0-second predominant ground period in that part of the city. Implications for the design of strengthening systems have been determined.
The Mexico Earthquake of September 19, 1985—Behavior of Heavy Cladding Components
Authors: Goodno B. , Craig J. , Zeevaert-Wolff A.
Published: July 2003

A combined field study of building cladding performance during the 1985 Mexico earthquake and supporting analytical and experimental studies of cladding systems, typical of those used in Mexico City, are described. Results reported are from an on-going research effort which is broken down into three phases: (I) Nonstructural damage survey and evaluation for selected buildings in Mexico City; (II) Laboratory testing of cladding connections representative of Mexican practice; and (III) Analytical evaluation of a case study building for cladding-structure interaction effects. This study of the behavior of architectural cladding systems in the Mexico Earthquake is complementary to earlier work involving laboratory testing and analytical studies of cladding connection designs typical of U.S. practice. The data gathering, laboratory experimental, and analytical phases were designed to provide a balanced and coordinated attack on the problem of nonstructural performance in earthquakes and to extraction of as much useful information as possible for the benefit of both Mexico and the United States.
The Mexico Earthquake of September 19, 1985—Design Spectra for Mexico's Federal District
Authors: Rosenblueth E. , Ordaz Mario , Sánchez-Sesma F. J. , Singh S. K.
Published: July 2003

We describe the methods used to obtain seismic design spectra adopted for different zones of Mexico's Federal District in 1987 Building Code. Paper exposes the two approaches followed in the study, deterministic and probabilistic. The assumptions adopted are presented and justified. Several aspects that require detailed scrutiny are pointed out.
Past and Possible Future Earthquakes of Significance to the San Diego Region
Authors: Anderson John G. , Rockwell Thomas K. , Agnew Duncan Carr
Published: July 2003

The potential for earthquakes that may significantly affect the San Diego, California, region is examined from the viewpoint of geology, seismic history, and strong ground motion. We have compiled the best available data on slip rates and recurrence times for all major faults in southern California and northern Baja California, identified possible fault segments that might rupture in single earthquakes and obtained repeat times for these events which are consistent with (or at least not contradicted by) trenching studies. The most important faults for San Diego's seismic hazard are the Rose Canyon fault, the Elsinore fault, and faults immediately offshore (Coronado Banks, San Diego trough). There have not been any major earthquakes on any of these nearby faults in historical time, but the geological evidence is clear that such events will eventually occur.

San Diego is located on the western flank of the Peninsular Range batholith, and there is weak evidence that attenuation in this batholith might be lower than average for California. We combine the geological data with an attenuation model to obtain an estimate for the occurrence rate of various levels of peak ground acceleration in downtown San Diego from events with moment magnitude greater than about 6. We find that peak accelerations of 10% g to 20% g are expected about once every 100 years. There are considerable uncertainties in this estimate, but nevertheless, strong ground shaking from a magnitude 6.0 or greater earthquake near the populated area would not be a scientific surprise.
Generating Seismic Design Power Spectral Density Functions
Authors: Christian John T.
Published: July 2003

The most widely used way to describe earthquake motions for purposes of design is the response spectrum, but it is often difficult to apply a response spectrum when dealing with multiple degrees of freedom or with complex representations of structural behavior. The power spectral density function, which is a more fundamental description of the frequency content of ground motion, has found increasing use and is essential in the most popular methods of developing artificial earthquake time histories. Although in theory the response spectrum and the power spectral density are closely related, in practice it has proven difficult to compute one from the other. Two integration schemes described in the literature have been implemented in an interactive micro-computer program SPEED and are found to give substantially identical results. When they are used to find a power spectral density function that corresponds to a standard design response spectrum, the results do not converge at frequencies above 10 Hz. Possible explanations for this lie in the shape of the prescribed standard response spectra, the methodology used to generate them, and the lack of statistical variation at high frequencies. When power spectral density functions are calculated for response spectra determined from a statistical evaluation of strong motion across the full range of frequencies, the calculations converge rapidly.
Some Statistical Aspects of Earthquake Occurrence in Iraq
Authors: Fahmi Khalid J. , Al Abbasi Jamal N.
Published: July 2003

Owing to Iraq's unique geographic location (29-38.5 N;39-49 E) the eastern and northeastern parts of the country are directly influenced by the seismic activity of the Tauros-Zagros tectonic zones. An earthquake data file containing nearly 550 entries covering the period 1905-1984 is compiled and an analysis of completeness is performed using Stepp's (1973) model. It is observed that the file is complete for 4.8 Ms and greater over the whole 80-year sample of data while during the past 25 years this threshold drops to about 4.1 Ms. The “completed” data file is then employed in re-evaluating the magnitude-frequency formula for the country. To further investigate the problem of earthquake occurrence a simple statistical treatment is applied to a “constant-b” seismicity model whereby an increase in the frequency of occurrence of approximately 35% is identified in the latter half of the seismic history of the country.
Slotted Bolted Connections in Aseismic Design for Concentrically Braced Connections
Authors: FitzGerald T. F. , Anagnos Thalia , Goodson Mary , Zsutty Theodore
Published: July 2003

The use of concentrically braced steel frames to satisfy lateral force requirements is a common design practice in regions of strong seismicity. They provide a very efficient means of fulfilling the dual objectives of earthquake resistant design, that is, damage control and collapse prevention. While tensile yielding and inelastic buckling of bracing elements provide the basic energy absorbing mechanism, there are inherent problems with member behavior under multiple cycles of inelastic deformations. Inelastic energy dissapation, however, may also be provided by friction resistance in slotted bolted connections, thus eliminating the need for inelastic member buckling. Limited laboratory tests indicate that this concept may be a viable alternative for use as a lateral force resisting system for both new construction and the seismic upgrading of existing structures.
Predicted Ductility Demands for Steel Moment Resisting Frames
Authors: Roeder Charles W. , Carpenter James E. , Taniguchi Hidetake
Published: July 2003

Recent changes to the United States seismic design provisions permit the use of weak column-strong beam steel moment resisting frames. This design concept has not been used in the past, because it results in plastic hinges in the columns during moderate or extreme earthquakes. This paper shows the results of inelastic dynamic response calculations on a weak column frame and a comparable strong column system. The results show that the ductility demand is much greater for the weak column strong beam framing system with some acceleration records. The required ductility is then compared for the different structural systems and both are compared to the results of experiments. The comparison suggests that the weak column system may not be able to develop the required ductility. The results of this paper should help define the viability and limits in applicability of the weak column system.
Seismic Testing of Eccentrically Braced Dual Steel Systems
Authors: Whittaker Andrew S. , Uang Chia-Ming , Bertero Vitelmo V.
Published: July 2003

Two six-story eccentrically braced dual steel systems (EBDSs) were tested as part of the U.S.-Japan Cooperative Earthquake Research Program. The first, a full-scale structure ( prototype) was pseudo-dynamically tested in the Large Size Structures Laboratory of the Building Research Institute in Tsukuba, Japan. The second, a similitude scaled replica of the first, was tested on the earthquake simulator at the University of California at Berkeley. The prototype was designed for the minimum earthquake forces specified by the 1981 Japanese Aseismic Code and satisfied the current earthquake-resistant design regulations in the U.S.A. (1985 UBC, 1984 ATC 3-06 and 1986 SEAOC). The performance of the EBDS (both prototype and model) was outstanding in terms of its elastic strength and stiffnesses during minor earthquake shaking and its ability to absorb and dissipate energy, without strength and stiffness degradation, during severe earthquake shaking. Substantial overstrengths of both EBDSs with respect to their nominal yielding strengths were observed during severe earthquake shaking. However, the response modification factors currently adopted by the ATC and SEAOC significantly overestimated the experimental values in both instances.
Seismic Velocities and Attenuation from Borehole Measurements near the Parkfield Prediction Zone, Central California
Authors: Gibbs James F. , Roth Edward F.
Published: July 2003

Shear (S)- and compressional (P)- wave velocities were measured to a depth of 195 m in a borehole near the San Andreas fault where a recurrence of a moderate Parkfield earthquake is predicted. S-wave velocities determined from orthogonal directions of the S-wave source show velocity differences of approximately 20 percent. An average shear-wave Q of 4 was determined in relatively unconsolidated sands and gravels of the Paso Robles Formation in the depth interval 57.5-102.5 m.
Magnitude and Distance Scaling of Response Spectral Shapes for Rock Sites with Applications to North American Tectonic Environment
Authors: Silva Walter J. , Green Robert K.
Published: July 2003

Response spectral shapes (Sa/a) computed from the BLWN (Band Limited White Noise) ground motion model combined with RVT (Random Vibration Theory) compare favorably with shapes computed from WNA (Western North American) earthquakes recorded at rock sites. The comparisons are made at close distances and for moment magnitudes 4 1/2, approximately 5, 6, and 6 1/2. Predicted spectral shapes for the ENA (Eastern North America) show reasonably good agreement with empirical results at frequencies of 1 and 10 Hz and with other random process models at frequencies of 0.5, 1, 2, 5, 10, and 20 Hz. Magnitude dependence of Sa/a is predicted to be significant for periods greater than 0.2 seconds in WNA and for periods greater than 0.1 seconds in ENA and increases with increasing period. Distance scaling appears to be significant only in WNA and at distances exceeding 50 km.
Vibration Characteristics and Earthquake Forces in a Fifteen Story Building—An Abridgement of an Original Paper by Edward C. Robison, 1950
Authors: Blume John A. , Rinne John E.
Published: July 2003

This paper is an abridgement of a classical mathematical solution of twelve of fifteen translational modes of vibration of a fifteen story building. This work was done just prior to the advent of the digital computer, by Edward C. Robison (C) in the period 1948-1950. He used seven place logarithms! The solution is in terms of lateral forces in each of twelve modes at each of fifteen floors coming out of admissible solutions for eigenvalues from the characteristic equation. These forces, when “normalized” by a constant multiplying factor for each mode, add algebraically to the weight of each floor, and in the over-all to the weight of the building—a principle illustrated by Robison's work and by Figure 9 of the Joint Committee's report (a) for which figure Milton Ludwig (D) was responsible, independently, about the same time.
Inducing the Private Purchase of Earthquake Insurance through the Involvement of the Insurance and Mortgage Finance Industries: An Overview of Potential Problems
Authors: Brown James M.
Published: July 2003

Private procurement of earthquake insurance is often advocated as a preferred means to mitigate the economic consequences of severe earthquake damage. For recognized reasons, a large majority of residential property owners have demonstrated a marked reluctance to purchase earthquake insurance. Suggestions that the property damage/casualty insurance industry and/or the mortgage finance industry act as catalysts to stimulate widespread private acquisition of earthquake insurance protection have not been embraced by either industry for a number of understandable reasons. Nonetheless, interest in, and the potential for, such intervention remains strong, and many current obstacles might prove surmountable. One such obstacle is the risk of antitrust violations arising in the course of the interactions which might be necessary if either or both referenced industries actively engaged in creating a widespread demand for earthquake insurance. Legal counselling by antitrust specialists could permit such a risk to be largely avoided and substantially diminished.
Present State of Seismic Design and Analysis Regulations in Chile
Authors: Cruz Ernesto F.
Published: July 2003

A summary of the different provisions existing in Chile is given. The codes related to earthquake engineering practice are divided into two major groups: the first defining the loads and actions, and the other dealing with materials behavior, resistance, and detailing requirements. The overall characteristics of these codes are discussed. Special emphasis is given to the seismic design code provisions that define the level of earthquake action to expect, depending on building characteristics and site soil conditions. No seismic risk map is included in the code. Two different analysis procedures are allowed: an equivalent lateral forces procedure where torsion is considered through an amplification of the static torsion in the building; and the standard response spectrum analysis method with a three degree of freedom per story model of the building. The maximum responses of the different modes are combined using a special combination rule. Additional restrictions are imposed to torsional effects, and to overall building deformations. Finally, the basic ideas being discussed in the revision that is actually being done to the code are presented.
Dynamic Site Periods in Charleston, SC
Authors: Elton David J. , Martin James R.
Published: July 2003

The 1985 experience in Mexico City has again demonstrated that building damage from earthquakes is related to the ground conditions beneath the building. When the natural period of the building matches the natural site period, resonance can occur, resulting in large building deformations and severe damage. Mapping dynamic site periods for a city, and governing building construction accordingly can greatly reduce the threat of damage from earthquakes. Using dynamic soil property data and a one-dimensional linear elastic computer program, a dynamic site period map for Charleston, SC, is developed and presented. Comparison of the building damage distribution for the 1886 earthquake with the distribution of dynamic site periods shows the important role of dynamic site period. An approximate method of estimating the linear site period is given.
Comparisons among Earthquake Codes
Authors: Luft RenéW.
Published: July 2003

This review paper compares ANSI, NEHRP, SEAOC, and UBC. A few essential differences among these documents are as follows: (a) The NEHRP document gives force levels corresponding to a strength-based or limit states design, while the other three documents give force levels that correspond to working or service stress design; (b) the importance factor is used as a multiplier of base shear level in all documents except NEHRP, which treats building importance by a seismic hazard exposure group; (c) NEHRP and UBC-1988 contain detailing requirements for all common construction materials and all seismic zones, while UBC-1985 contains detailing requirements for zones of high seismicity but only limited requirements for zones of moderate seismicity; (d) P-delta analysis is specified by NEHRP for all buildings that must be analyzed, by SEAOC for buildings that exceed drift limits, by UBC-1988 for all buildings except those in Zones 3 and 4 meeting drift limits, and is not specified by ANSI.
A Wedging System for Downhole Accelerometers
Authors: Youd T. Leslie , Tang Y. K. , Stepp J. Carl , Holzer Thomas L. , Jackson Garrett O.
Published: July 2003

A wedging system for coupling downhole accelerometers into cased boreholes has been developed and deployed at an EPRI/USGS instrument array located in the Cholame Valley near Parkfield, California. The wedging system allows downhole accelerometers to be set and retrieved by hand. With this system accelerometers can be readily retrieved from cased holes for inspection, maintenance, or redeployment.
Shear Wall Resistance of Lightgage Steel Stud Wall Systems
Authors: Adham S. A. , Avanessian V. , Hart G. C. , Anderson R. W. , Elmlinger J. , Gregory J.
Published: July 2003

Experimental investigations were conducted to evaluate the lateral load-deflection characteristics of lightgage steel stud/gypsum wallboard panel combinations subjected to lateral cyclic loads. In all, six 8′ × 8′ specimens were tested. A reasonable one-to-one correspondence between the strap area increase and the increase in the contribution from the strap to the overall loadcarrying capacity of the panel at intermediate and high drift ratios was observed. The panel lateral stiffness for a given stabilized cycle degraded by about 7% to 15% as compared with the lateral stiffness of the corresponding virgin cycle. Lateral stiffness degradation increased as the drift ratios became larger. The energy dissipation ability of the panels in the stabilized cycle was about 60% of the virgin cycle. An average value of equivalent viscous damping for all the cycles based on panel hysteretic behavior was about 12%.
Recent Trends in Ground Motion and Spectral Response Relations for North America
Authors: Atkinson Gail M. , Boore David M.
Published: July 2003

Recent ground motion relations which predict pga, pgv and psrv for rock sites in ENA are based on a stochastic model whose parameters are indicated by seismological studies of earthquake source and attenuation processes. The validity of the model is verified by application to WNA. The choice of model parameters is validated by comparison of model predictions with ground motion data for ENA. For any magnitude, near-source ENA ground motions are enriched in high frequencies relative to WNA motions. This causes eastern pga values, and psrv values for frequencies greater than 10 Hz, to be greater than their western counterparts. For psrv at frequencies less than 10 Hz, median near-source ground motions in ENA are roughly comparable to those in WNA. Eastern ground motion characteristics have important implications for seismic hazard. High frequency structures in many parts of ENA face a hazard comparable to that in many active areas of California, whereas the hazard for low-frequency structures on rock sites in ENA is relatively modest.
Seismic Safety through Public Incentives: The Palo Alto Seismic Hazard Identification Program
Authors: Beatley Timothy , Berke Philip
Published: July 2003

The City of Palo Alto, California, located in the mid-Peninsula area south of San Francisco, has taken a unique approach to the problem of retrofitting existing seismically vulnerable buildings. Specifically, Palo Alto has adopted a Seismic Hazard Identification Program which mandates the preparation and filing of seismic engineering reports and relies on the creation of incentives for voluntary retrofitting. The findings of this article are based upon an extensive set of personal interviews conducted in September, 1988, as well as an examination of city ordinances, staff reports, council minutes and other relevant documents. The article first describes the history of seismic policy in Palo Alto leading to the adoption of the seismic identification program. It then goes on to describe in detail the specifics of the Palo Alto program; its key provisions and requirements. Finally, an extensive discussion is provided of the factors which influenced the adoption of the program, and its final form and content.
Perspectives on the International Decade for Natural Disaster Reduction
Authors: Hays Walter W.
Published: July 2003

Disaster preparedness and disaster mitigation are the goals of nations throughout the world during the 1990's. The United States will lead this cooperative effort and marshall its national resources to reduce the disaster potential of earthquakes, floods, windstorms, landslides, volcanic eruptions, tsunamis, and wildfires. These natural hazards cause annual losses of approximately $10 billion in the United States and many times that throughout the world. The type and severity of the hazard varies from State-to-State in the United States. All States are at risk from flooding from sources such as precipitation, snowmelt, thunderstorms, and, along the coast, the storm surges generated in hurricanes. No State is free from the potential impacts of ground shaking induced by earthquakes, although the frequency of damaging earthquakes is much greater in Alaska and California than in the remainder of the Nation. Landslides also occur in all the States and Territories. The Western States are potentially vulnerable from wildfires and volcanic eruptions. Damaging tsunamis in the past have struck Hawaii, Alaska, Washington, Oregon, California, Puerto Rico, and the Virgin Islands. The goal of the Decade is to keep such occurrences in the future from being disasters.
Seismic Vulnerability Evaluation of Existing Buildings
Authors: Aktan Ahmet Emin , Ho I-Kang
Published: July 2003

A study of building seismic vulnerability evaluation methods in the U.S. and Japan lead to a constructive critique of the FEMA-178. Research is formulated to extend FEMA-178 so that types of construction which have not yet experienced damaging earthquakes may be reliably evaluated. An element-level analytical model accurately simulating the critical response and failure mechanisms of the soil-foundation-structure in its current state emerges as a key. Developing such a model may prove difficult in case a facility has unusual and/or irregular attributes as well as damage and/or deterioration. Researchers efforts to construct and experimentally identify a 3D analytical model of a 27-story RC flat-plate building with closed thin-walled core systems are described. Forced-excitation modal testing is explored and is shown to be a reliable tool. It is exemplified that structural identification as well as other nondestructive evaluation tools may become essential for reliably evaluating seismic vulnerability of construction which have not yet revealed all of their “weak-links”.
Evaluation of the Effects of the 1985 Michoacan Earthquake on the Water Systems in Metropolitan Mexico City
Authors: Ayala A. Gustavo , O'Rourke Michael J. , Escobar J. Alberto
Published: July 2003

During the Michoacan earthquake of September 19, 1985, the water supply and distribution systems of Metropolitan Mexico City were severely damaged. This paper investigates the type of damage, taking into consideration the characteristics of the earthquake and the peculiar soil and topographic conditions of the valley where the city is situated. It describes the water systems in the metropolitan area, the main features of the subsoil conditions and the engineering aspects of the earthquake, highlighting their relationship to lifeline earthquake engineering. The investigation concentrates on the damage statistics for the buried segmented pipelines in the water systems. It observes and explains the relatively low damage to lifelines in the epicentral region by analyzing and comparing ground motion characteristics there and in Mexico City. Finally, based on the analysis of this information, some recommendations are given to reduce the seismic vulnerability of the water systems in the metropolitan area.
Estimating Size Distributions of Building Areas for Natural Hazards Assessments
Authors: Jones Barclay G. , Lewis Blane D.
Published: July 2003

It is very helpful to be able to estimate the number of buildings in floor area size categories for various purposes in risk assessment, vulnerability reduction, emergency response, recovery and reconstruction planning. We compile a frequency distribution by floor area from a data set for 900,000 buildings using complete enumerations of buildings from several urban areas. Three models are fit to the data: the lognormal distribution and two regression models based on the negative exponential. A regression model estimating the percentage of buildings larger than a given size provides the best fit and is a useful technique for making predictions. Since estimates produced by regression techniques have known error distributions, the results will only be approximate. For places for which the building stock has considerably different characteristics from the data set, the parameters of the model will have to be recalculated. An actual example of an application of the model is presented.
Correlation between Static and Dynamic Response of Model Masonry Structures
Authors: Paulson T. J. , Abrams D. P.
Published: July 2003

The paper presents correlations between response of the same structural system subjected to either dynamic shaking or static lateral forces. Two one-quarter scale test structures were constructed with identical designs and were tested in the laboratory using two different methods. The first structure was subjected to simulated earthquake motions on a shaking table while the second structure was forced to displace through the same history at static rates using computer controlled servohydraulic actuators.

Characteristics of dynamic lateral force distributions are examined first and followed by a description of techniques used for the static loading experiment. Correlations are made between observed response of the statically and dynamically tested twin structures to suggest differences in strength, stiffness and energy dissipation that may arise with each test method.
The Influence of the Coastal Plain Sedimentary Wedge on Strong Ground Motions from the 1886 Charleston, South Carolina, Earthquake
Authors: Chapman M. C. , Bollinger G. A. , Sibol M. S. , Stephenson D. E.
Published: July 2003

The effect of Atlantic Coastal Plain sediments on ground motion from the 1886 Charleston, South Carolina, earthquake was studied using linear regression analysis and ground motion modeling. Statistical tests applied to 264 Modified Mercalli intensity reports at epicentral distances less than 400 km showed that intensities within the Lower Coastal Plain (near the coast) averaged from 0.5 to 1.0 units less than intensities within other areas over comparable distances. Simulated ground acceleration time histories were generated along two profiles: one trending northeast from the epicenter along the coast and another trending northwest toward the Fall Line. The modeling results (which assume linear behavior) indicate that the thick coastal sediments attenuate high frequency motions (>3-10 Hz), while amplifying lower frequency motions. In contrast, locations on thinner sediments to the northwest experience amplification of high frequency motions. The overall effect is that peak acceleration decays more slowly with distance in the thinning sediments to the northwest of the epicenter than in the thick sediments along the coast.
Competing against Time: Report of the Governor's Board of Inquiry on the 1989 Loma Prieta Earthquake
Authors: Housner George W. , Thiel Charles C.
Published: July 2003

A Board of Inquiry was appointed by the Governor of California to investigate the 1989 Loma Prieta Earthquake. The formation of the Board was prompted by earthquake damage to bridges and freeway structures and the desire to know not only what happened, but how to prevent such destruction in future earthquakes. The Board made fifty-two specific findings and eight recommendations. They identified three essential challenges that must be addressed by the citizens of California, if they expect a future adequately safe from earthquakes: 1) ensure that earthquake risks posed by new construction are acceptable; 2) identify and correct unacceptable seismic safety conditions in existing structures, and; 3) develop and implement actions that foster the rapid, effective, and economic response to and recovery from damaging earthquakes The Loma Prieta earthquake should be considered a clear and powerful warning to the people of California. Although progress has been made during the past two decades in reducing earthquake risks, much more could have been done, and awaits doing. More aggressive efforts to mitigate the consequences of future, certain earthquakes are needed if their disastrous potential is to be minimized and one of the most fundamental of responsibilities of government is to be fulfilled—to provide for the public safety. The Governor signed an Executive Order implementing the principal recommendations of the Board that may prove to be the most significant step to improve seismic safety within the State taken in the last several decades. It establishes the policy that all state owned and operated structures are to be seismically safe and that important structures are to maintain their function after earthquakes.
The 1983 Liege Earthquake: Damage Distribution and Site Effects
Authors: Jongmans D. , Campillo M.
Published: July 2003

On November 8, 1983, a moderate magnitude (Ml=4.9) earthquake struck Liege (Belgium). A damage study has shown that site effects at different scales have played an important role in amplifying ground motion. On a large scale, the damage distribution has been determined by the presence of a large Carboniferous syncline beneath the city as shown by 2D numerical modeling. On a small scale, the main damage concentrations can be correlated with local superficial deposits which have amplified ground motions in the frequency range of buildings. A geophysical survey was carried out to measure the shear wave velocity of the different formations. Site response computations were made at numerous sites in order to estimate the possible amplification and to compare the results with the damage. It was shown that the spectral amplifications computed in the dominant frequency range of the buildings are consistent with the damage data. In very affected areas, 1D amplifications of 4 to 6 were obtained and in some cases 2D effects may have occurred.

The Liege earthquake, taking place in the intraplate region of Northwestern Europe, presents a significant interest to other similar areas as the eastern United States.
Evaluation of Indirect Economic Effects Caused by the 1983 Nihonkai-chubu, Japan, Earthquake
Authors: Kawashima Kazuhiko , Kanoh Takashi
Published: July 2003

Effects of an earthquake are not necessarily restricted to damage of structures, but extend much further. This paper presents a method for estimating indirect economical effects caused by an earthquake. Loss of production may be caused by a decrease of products due to damage of production, damage of transportation facilities, and damage of materials and goods. Effect of investment for restoration is also considered. Based on direct loss associated with production loss, a secondary “ripple” effect was estimated through an inter-industry relation analysis (input-output analysis). The procedure was applied to the Nihonkai-chubu, Japan, Earthquake of 1983. Estimated gross products at the damaged region agreed fairly well with those actually observed after the earthquake.
Evaluating Alternative National Earthquake Insurance Programs
Authors: Mittler Elliott
Published: July 2003

In April, 1990, two bills to create a national earthquake insurance program were introduced in the United States Congress. The content and scope of these bills are analyzed and compared, taking into account the results of over twenty five years of investigations concerning what role the federal government should have in a national program. Both bills are still under review by committee. Progress is being made toward adoption of a national program. A critical determinant will be if Congress can first determine and then agree to an acceptable link between insurance and mitigation.
Damage at Sürgü Dam during May 5, 1986, Malatya, Turkey, Earthquake
Authors: Ozkan Y. , Erdik M. , Yilmaz C. , Bakir S.
Published: July 2003

On May 5, 1986, an earthquake of magnitude about 6 struck South Anatolia, creating widespread damage at rural structures and causing extensive longitudinal cracks at the crest of Sürgü Dam. In this paper general information about the earthquake is given and the results of block-mass and circular arch types of pseudo-static slope stability analyses are presented. It has been concluded that the critical acceleration levels obtained from the analyses are under the expected acceleration levels at the dam's body during the earthquake. Probabilistic findings based upon seismicity observed in the last century indicate that substantially higher level of ground shaking may occur at the dam site. Such occurrences are considered to cause hazardous damage to the dam.
Analysis and Testing of the FBA-11 Force Accelerometer
Authors: Rihn W. J. , Miller W. F. , Crouse C. B. , Holbrook E. L. , Hushmand B.
Published: July 2003

The FBA-11 is a feedback-controlled accelerometer widely used to measure and record accelerations arising from earthquakes. It has found application both for structural response and for ground motion studies. The design intent of the FBA-11 was to provide electronic control of the natural frequency, damping, and output voltage. Included in this paper are (1) a circuit analysis yielding the complete closed-loop transfer function, and (2) the corroborative test results from shake table evaluations. The transfer function can be used to correct recorded accelerations for instrument response.
Empirical Spatial Coherency Functions for Application to Soil-Structure Interaction Analyses
Authors: Abrahamson N. A. , Schneider J. F. , Stepp J. C.
Published: July 2003

The spatial coherency of strong ground motion from fifteen earthquakes recorded by the Lotung LSST strong motion array is analyzed. The earthquakes range in magnitude from 3.7 to 7.8 and in epicentral distance from 5 to 80 km. In all, a total of 533 station pairs are used with station separations ranging from 6 to 85 meters. Empirical coherency functions for the horizontal component S-waves appropriate for use in engineering analyses are derived from these data. The derived coherency functions are applicable to all frequencies and to separation distances up to 100 m. For these short station separations, the coherency decreases much faster with increasing frequency than with increasing station separation. The computed coherencies indicate that at high frequencies (>10 Hz) over 25 percent of the power of the ground motion is random for station separations greater than 30 m.
The Victoria Accelerogram for the 1980 Mexicali Valley Earthquake
Authors: Anderson John G. , Brune James N.
Published: July 2003

Most of the remarkable digital strong motion accelerogram from the June 9, 1980 Mexicali Valley earthquake (Mw = 6.4) has been recovered by careful analysis. Peak horizontal accelerations (.98g, .87g) and duration were similar to the values for the recent Superstition Hills earthquake. The vertical accelerogram clipped the 1g instrument several times. The records provide an important example of near fault accelerations from a second earthquake in the deep sediments of the Imperial Mexicali Valley (the other being the records from the 1979 Imperial Valley earthquake). The 1980 accelerograms are important because they were not affected by foundation filtering, as were the records for the Imperial Valley 1940 earthquake, and because they illustrate the damaging near-source, intermediate frequency velocity pulse associated with passage of the rupture front.
Foam Rubber Modeling of the El Centro Terminal Substation Building
Authors: Brune James N. , Anooshehpoor Abdolrasool
Published: July 2003

Results from a layered foam rubber model of soil and the structure (3-D) of the El Centro Terminal Substation building, site of the well known recording of the 1940 El Centro earthquake, indicate that the response of the foundation for frequencies above 4 Hz is as much as a factor of 3 lower than the free-field response amplitude. To validate the modeling technique with sample structure, we use the formulation for calculating theoretical responses of Wong and Luco (1977). Two-dimensional computer model results by Shannon and Wilson, Inc. and Agbabian Associates (1980), gave a response amplitude in the building about a factor of 2 lower than the response amplitude of the free-field for frequencies above 1.5 Hz. Foam rubber modeling shows that at higher frequencies most of the reduction in response is due to the energy being scattered by the shape of the rigid foundation rather than its inertial mass. Under the assumption that most of the energy was vertically incident SH, the free-field peak acceleration during the May 18, 1940 El Centro earthquake was about 50% higher than recorded on the 1940 accelerogram. The transfer function is very similar in shape to the weighting function used by Munguia and Brune (1984), to match synthetic accelerograms with the 1940 El Centro earthquake, suggesting that much of the relative deficit in high frequency energy was a result of soil-structure interaction rather than a source effect.