bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstruction after Earthquakes: Sustainability and Development
Authors: Kreimer Alcira
Published: July 2003

This paper identifies key sustainability issues arising in earthquake-related projects financed by The World Bank. First, Bank-financed reconstruction activities are briefly described within the background of the Bank's objectives in development. Second, the connections between human activities and development decisions on the one hand and seismic risk and vulnerability on the other are discussed. The multiple nature of earthquake-related losses are identified, including economic (direct and indirect), time-related and institutional losses. Third, resource mobilization efforts following disasters are discussed, including issues related to local and international aid. Fourth, the inclusion of measures geared to preventing losses in Bank-financed reconstruction efforts are explored within the overall context of preserving sustainability and reducing vulnerability. The paper offers the conclusion that the losses from vulnerable development amount to a significant burden to member countries governments, institutions, and populations.
Directional Site Resonances Observed from the 1 October 1987 Whittier Narrows, California, Earthquake and the 4 October Aftershock
Authors: Vidale John E. , Bonamassa Ornella , Houston Heidi
Published: July 2003

We present evidence that sites often resonate preferentially in a particular compass direction. The 1 October 1987 mainshock and 4 October 1987 aftershock in the Whittier Narrows, California, sequence had very different focal mechanisms. Nevertheless, at 8 of 11 strong-motion stations for which digitized records of both events are available, the direction of strongest shaking in the two events was much more similar than would be expected from their different mechanisms. The coincidence of the polarizations from the two events was greatest at frequencies with peaks in the amplitude spectra, suggesting that site amplification and directional resonances are linked. Knowledge of directional site resonances may aid in predicting the directions of damaging earthquake motions.
Isolating Building Contents from Earthquake Induced Floor Motions
Authors: Yaghoubian Jack
Published: July 2003

A simple and effective system has been developed and is in use to isolate and substantially reduce both earthquake induced large accelerations and displacements simultaneously. The base isolation system protects building contents susceptible to damage by earthquake induced motions. The single isolation unit has been extensively tested during shaketable test programs. The isolation system operates at about critical damping and can accommodate a large variety of random dynamic motions generated by earthquakes. The system is flexible and can be customized for different configurations and specific functional performances.
Ground-Motion Attenuation Equations for Earthquakes on the Cascadia Subduction Zone
Authors: Crouse C. B.
Published: July 2003

An extensive ground-motion data base was compiled for earthquakes occurring in subduction zones considered representative of the Cascadia subduction zone in the Pacific Northwest. The attenuation characteristics of horizontal peak ground accelerations (PGA) and 5 percent damped pseudovelocity (PSV) were studied for various subsets of the total data base. These data suggested that the PGA tend to saturate at small source-to-site distances and large magnitudes. When unprocessed data were added to the data base, the attenuation of PGA with distance was found to be greater than the attenuation observed for the processed data only, a result which was attributed to the selection of only the stronger motion records for processing. The results of the data analysis were used to establish the proper form of regression equations for estimating PGA and PSV at firm-soil sites in the Pacific Northwest. A total of 697 PGA components and 235 PSV components were selected for the regressions. The resulting equation for estimating PGA in gals was

ln (PGA) = 6.36 + 1.76M − 2.73 ln (R + 1.58 exp (0.608M) + 0.00916h, σ=0.773

where M is moment magnitude, R is center-of-energy-release distance in km, h is focal depth in km, and σ is the standard error of ln (PGA). Although σ was relatively large, the residuals from the regressions appeared to decrease with increasing M and R. The results of the PSV regressions showed that the M coefficient and the coefficient of the f(R, M) attenuation term generally increased with period, which is consistent with regression results reported by others. The regression equations were reasonably accurate in predicting the response spectra of accelerograms recorded at Olympia and Seattle, Washington during the 1949 and 1965 Puget Sound earthquakes, but overestimated the spectra of the weaker motions recorded at Tacoma and Portland during the latter event. The median response spectra predicted by these equations for a Washington Coastal Ranges site were similar to the spectra computed by Heaton and Hartzell based on their simulations of ground motions from hypothetical giant earthquakes (M = 9.0 and 9.5) in the Pacific Northwest.
Seismic Evaluation of Modular Office Furniture System
Authors: Filiatrault A.
Published: July 2003

This paper presents the results of a preliminary experimental investigation into the seismic behaviour of a free standing modular office furniture system. The experimental study consisted in visually observing the behaviour of a full scale typical furniture unit under uniaxial (horizontal) components of various earthquake ground motions. Two different orientations of the unit relative to the direction of the earthquake excitation were considered. The results of the study showed excellent behaviour of the unit. No permanent structural damage and only minor non-structural damage (mainly books falling off a shelf) was observed. The shifting, rocking and vertical movements of the unit were very small. The unit remained always stable against the possibility of overturning.
Seismic Testing of Steel Plate Energy Dissipation Devices
Authors: Whittaker Andrew S. , Bertero Vitelmo V. , Thompson Christopher L. , Alonso L. Javier
Published: July 2003

In a research program, co-sponsored by Bechtel Power Corporation and CounterQuake Corporation, the seismic performance of steel plate added damping and stiffness (ADAS) elements was investigated through a series of sub-assemblage experiments and by the earthquake simulator testing of a three story ductile moment resisting space frame (DMRSF) upgraded with ADAS elements. The sub-assemblage testing of the ADAS elements demonstrated their stable hysteresis for a large number of yielding cycles. The addition of the ADAS system (ADAS elements and chevron braces) to the DMRSF limited the frame's response to acceptable levels during severe earthquake simulation. The research program clearly demonstrated that ADAS elements can be used to effectively upgrade moment resisting frames (MRFs) and concentrically braced frames (CBFs) to achieve a moderately stiff building with extremely good energy dissipation characteristics. The implications of the research results for the design and upgrade of buildings using ADAS elements, and potential uses for ADAS elements, are presented in the latter part of the paper.
Buildings
Authors: Cole Eugene E. , Phipps Maryann T.
Published: July 2003

Damage to buildings was surprisingly light considering the severity of the April 22 event.

Most buildings near the epicentral region are either light steel frame farming structures or small wood frame commercial and residential structures. Although some of these buildings were observed to have suffered partial or total collapse, the great majority of them were only lightly damaged.
A National Assessment of Local Earthquake Mitigation: Implications for Planning and Public Policy
Authors: Berke Philip R. , Beatley Timothy
Published: July 2003

This paper presents conclusions and their implications for planning and public policy from a comprehensive study of local seismic hazard mitigation programs throughout the United States. Data from the study were obtained from a mail survey and three case communities. A key study conclusion is that while earthquake mitigation activity is higher among California communities than in communities of other states, it is considerably lower than for other types of hazards. Other key conclusions are that local officials can undertake a variety of activities to effectively advance planning for earthquakes, and that the more effective activities occurred through an interactive learning process where creative compromises among differing community perspectives were more likely. These conclusions imply that while there is a substantial need to better integrate earthquake mitigation into development and land use decision making, local government efforts to advance mitigation programs have a substantial potential for success. They also imply that achieving effective local response requires substantial changes in current practices of federal, state and local governments.
The Effectiveness of Fault Zone Regulations in California
Authors: Reitherman Robert
Published: July 2003

In 1990 a study was completed for the California Division of Mines and Geology on the effectiveness of California's fault zone regulations (the Alquist-Priolo Special Studies Zones Act and associated policies and activities). The Act, passed in 1972, instituted the following elements of a statewide mandatory approach to dealing with the hazard of surface fault rupture: state mapping of fault zones (Special Study Zones) where active faults are suspected; local government imposition of the requirement of a geologic study on new building projects within these Zones (with some single family dwellings and low-occupancy structures exempt); review procedures for the studies submitted by an applicant's geologist; prohibition of the siting of projects on active faults; notification of real estate purchasers that a property is located within a Zone. This paper presents the results of that evaluation and comments more broadly on applying the Alquist-Priolo model to other regions and to other geologic hazards.
Impacts of the Los Angeles Retrofit Ordinance on Residential Buildings
Authors: Comerio Mary C.
Published: July 2003

The Los Angeles Earthquake Hazards Reduction Ordinance, enacted in 1981 required owners of all unreinforced masonry (URM) buildings to comply with retroactive seismic standards. Among the 8100 URM buildings are approximately 1600 residential buildings with 46,000 housing units. As of March 1991, 55% are complete, 13% are in progress, 12% have been demolished and 20% have not complied. Data kept by the city shows the average cost per unit to be about $6000, and the average rent increase for tenants to be $67 per month, a 14-26% increase over pre-retrofit rents. Less than one-third of the owners completing the retrofit have applied for rent increases. Only 6% of the completed buildings have received financing assistance from the city. Two-thirds of the residential building owners appear to be finding the financing to complete the retrofit without assistance from the city but the remaining one-third of the units are at risk because owners are unable or unwilling to undertake the required work. Tenants who were forced to leave demolished or vacated units had difficulty finding replacement housing at affordable rents, and all tenants in downtown neighborhoods have been impacted by increasing rents and lost units. The Los Angeles experience is important for other cities attempting to establish ordinances and prepare policy for assisting building owners and tenants.
Sliding Isolation System for Bridges: Experimental Study
Authors: Constantinou M. C. , Kartoum Allaoua , Reinhorn A. M. , Bradford Paul
Published: July 2003

A seismic isolation system for bridges has been tested on a shake table. The system consisted of Teflon disc bridge bearings and displacement control devices. These devices provided restoring force for re-centering the bridge during earthquake excitation, additional energy dissipation capacity and rigidity for service loading. The tests were carried out with a 51-kip model which was subjected to strong recorded earthquake motions with a wide range of frequency content and to simulated motions compatible with CalTrans 0.6g design spectra. In all tests the isolated deck responded with peak acceleration less than the peak table acceleration and peak bearing displacement less than the peak table displacement. Results from an analytical model show very good agreement with experimental results.
Nonlinear Seismic Response of Soft-First-Story Buildings Subjected to Narrow-Band Accelerograms
Authors: Esteva Luis
Published: July 2003

The nonlinear dynamic response of shear systems representative of buildings with excess stiffness and strength at all stories above the first one is studied. Variables covered were number of stories, fundamental period, along-height form of variation of story stiffness, ratio of post-yield to initial stiffness, in addition to the variable of primary interest: the factor r, expressing the ratio of the average value of the safety factor for lateral shear at the upper stories to that at the bottom story. The lateral strength at the latter was taken as equal to the nominal value of the corresponding story shear computed by conventional modal dynamic analysis for the design spectrum specified by Mexico City seismic design regulations of 1987 for a seismic behavior (ductility) reduction coefficient of 4.0. The excitation was in some cases the EW component of the accelerogram recorded at the parking lot of the Ministry of Communications and Transport in the same city during the destructive earthquake of September 19, 1985, and in some other cases an ensemble of artificial accelerograms with similar statistical properties. It is concluded that the nonlinear seismic response of shear buildings whose upper stories have lateral strengths and stiffnesses which correspond to safety factors larger than those applied to the first story is very sensitive to the relation between the average of the over-strength factors at the upper stories and that at the first one, as well as to the ratio of post-yield to initial stiffnesses. The nature and magnitude of the influence of r on the maximum ductility demands at the first story depend on the low-strain fundamental natural period of the system. The ductility demands computed for elastoplastic systems may in some cases be extremely large. Accounting for P-delta effects leads to an enhancement of the sensitivity of the response with respect to r.
Application of System Reliability Theory in the Seismic Analysis of Structures
Authors: Tung Albert T. Y. , Kiremidjian Anne S.
Published: July 2003

This paper presents a system reliability based analysis method for evaluating the seismic safety/reliability of structures. The seismic analysis procedure developed represents a practical approach in quantifying the risk of structural failure due to seismic hazard. The procedure developed is for framed structures consisting of discrete-state elements. The probabilistic modeling of the seismic load utilizes the hazard curve of the region and the dynamic amplification factor spectrum matching the local geologic condition. The loadings in the structural components are obtained based on a quasi-dynamic analysis and the identification and computation of the component and system failure probabilities are implemented in the software package FAILSF. For illustrative purposes, an elevated liquid storage vessel was used for the application of the seismic analysis procedure.
Microzoning the Likelihood of Strong Spectral Amplification of Earthquake Motions Using MMI Surveys and Surface Geology
Authors: Bodle Thomas
Published: July 2003

A statistically based microzonation tool for delineating zones within a region most susceptible to strong spectral amplification of earthquake accelerations in the 2 to 4 Hertz range is introduced using detailed Modified Mercalli Intensity (MMI) surveys and surface geology. A rationale for the research method is discussed using four arguments: the Fourier spectral analysis of earthquake ground motions and the spectral response method; an empirical versus a theoretical justification, low cost, and a consideration for previous research into the topic specific to the area of the case study chosen.
Air Permeability in a Seismically Loaded Shear Wall
Authors: Girrens Steven P. , Farrar Charles R.
Published: July 2003

We performed an experimental study to measure the air leakage from a seismically damaged concrete shear wall. In this study, we used static load-cycle testing to simulate earthquake loading and made permeability measurements by pressurizing one side of the shear wall above atmospheric conditions and recording the transient-pressure decay. The air permeability measurements made on the shear wall before loading fell within the range of values published in the literature for concrete permeability. As long as the structure exhibited linear load-displacement response, no variation in the air permeability was detected. Experimental results indicate that the air permeability in the shear wall increased by a factor of 40 after the wall had been damaged (cracked).
Residential Water Heater Damage and Fires following the Loma Prieta and Big Bear Lake Earthquakes
Authors: Levenson Leo M.
Published: July 2003

To obtain data on the extent of earthquake damage to residential water heaters, and the effectiveness of prevailing water heater restraint methods, we surveyed 299 randomly-selected people who lived in the City of Santa Cruz, California, at the time of the 1989 Loma Prieta Earthquake. We also reviewed the rate of water-heater linked fires in the Big Bear Lake area following the 1992 Big Bear Earthquake. In Santa Cruz, 13% of the respondents' water heaters suffered damage from the earthquake, most commonly water leaks costing under $50 to repair. Two percent of the water heaters suffered gas leaks. No water heater related fires were reported in our sample or in the City of Santa Cruz following the earthquake. Repair costs for solar water heater systems averaged over $600 per damaged system. The sample revealed no quantifiable reduction in earthquake damage associated with reported prior water heater strapping with plumbers tape. In the Big Bear Lake area, 11 out of 13 structural fires were attributed to water heater gas leaks. Water heater-related fires occurred at a rate of roughly 6 per 1,000 structures. Further studies are needed to compare the effectiveness of different water heater restraint methods, and to identify factors that contribute to ignition in water heater related fires.
The Benefits of a Seismic Retrofit Program for Commercial Unreinforced Masonry Structures: Salt Lake County, Utah
Authors: Emmi Philip C. , Horton Carl A.
Published: July 2003

This paper assesses the benefits of a seismic retrofit program for commercial unreinforced masonry structures (CURMs) in Salt Lake County, Utah. A comparative risk assessment embedded in a geographic information systems is the method used. A policy evaluation time horizon of twenty years is set. Future rates of demolition and rehabilitation, with and without a retrofit policy, are assumed. Damage functions for ordinary and retrofitted URMs are used to assess losses having a 10 percent chance of being exceeded over a 50-year exposure period. With a retrofit program, expected losses are reduced by 57 percent or more than a quarter billion dollars when compared to the no-policy scenario. Expected injuries and fatalities are reduced by more than 80 percent. These are minimal benefits expected from enforcement of the seismic provisions of the Uniform Code of Building Conservation.
Public Property Damage and Emergency Response Costs: Comparing the Loma Prieta and Whittier Narrows Earthquakes
Authors: French Steven P.
Published: July 2003

This research project investigated the damage to public property caused by the 1989 Loma Prieta earthquake. The claims filed by state and local governments, special districts and non-profit organizations under FEMA's disaster assistance program were analyzed to better understand the pattern of damage caused by the earthquake. These claims accounted for nearly $600 million. Emergency response costs (debris removal, emergency services and safety services) accounted for more than 40 percent of total claims. Public buildings comprised another 40 percent, while all types of infrastructure systems accounted for only about 13 percent of the total. While the proportion of damages attributable to public buildings was similar to that experienced in the smaller Whittier Narrows earthquake, the proportion attributable to emergency response activities was much larger for the Loma Prieta event. This research suggests that emergency response costs are proportionately larger for more severe earthquakes, especially in the hardest hit areas.
Pilot Studies of Seismic Hazard and Risk in North Sulawesi Province, Indonesia
Authors: Thenhaus Paul C. , Hanson Stanley L. , Effendi Ismet , Kertapati Engkon K. , Algermissen S. T.
Published: July 2003

Earthquake ground motions in North Sulawesi on soft soil that have a 90 percent probability of not being exceeded in 50 years are estimated to be 0.63 g (63 percent of the acceleration of gravity) at Palu, 0.31 g at Gorontalo, and 0.27 g at Manado. Estimated ground motions for rock conditions for the same probability level and exposure time are 56 percent of those for soft soil. The hazard estimates are obtained from seismic sources that model the earthquake potential to a depth of 100 km beneath northern and central Sulawesi and include the Palu fault zone of western Sulawesi, the North Sulawesi subduction zone, and the southern most segment of the Sangihe subduction zone beneath the Molucca Sea. An attenuation relation based on Japanese strong-motion data and considered appropriate for subduction environments of the western Pacific was used in determination of ground motions.

Field investigations following the 18 April 1990 North Sulawesi earthquake (Ms 7.3) established the Modified Mercalli intensity (MMI) distribution throughout Kodya Gorontalo (the mayorial province of Gorontalo). The total number of masonry houses (permanent and semipermanent dwellings) within the MMI V isoseismal was approximated from housing counts obtained from a sampling of 19 villages. From the post-earthquake damage investigation and from comparisons to masonry construction in the United States, a vulnerability curve was constructed for masonry housing in Gorontalo. Assuming an average value for a house of $1,053, total economic loss to masonry housing from the 18 April 1990 earthquake is estimated to be $1,198,578, a loss equivalent to the destruction of 9.6 percent of the masonry dwelling stock of Gorontalo. Simulation of the earthquake history for the past 31 years within 300 km of Gorontalo indicates an average annual loss to masonry housing of $358,609, or $30 on a per house basis. Catastrophe potential (a worst-case loss) for masonry housing in Gorontalo that has a 90 percent probability of not being exceeded in 250 years is estimated to be $3,083,525, a loss equivalent to the destruction of 25 percent of the masonry dwelling stock of Gorontalo.
An Evaluation of Two-Level Seismic Design Procedure
Authors: Uang Chia-Ming
Published: July 2003

The two-level design philosophy is recognized by modern seismic codes. When this philosophy is implemented in the code, the intensities of the two design earthquakes, the structural performance criteria, explicit versus implicit design approach, and the effectiveness to achieve the performance criteria vary considerably from one code to the other. For the ultimate limit state, the UBC was compared with seismic codes of Canada, Japan, and Eurocode. It was found that a trend to deviate from the UBC approach of using a single seismic force reduction factor (i.e., Rw) is apparent. Instead, an approach using a compound force reduction factor which considers the contribution of structural ductility and structural overstrength is preferred. For the serviceability limit state, a comparison of the level of design earthquakes and performance criteria of the UBC, Tri-Services Manual, and the Japanese code indicates that the UBC produces the most flexible structure, and that UBC does not control structural damage. It is suggested that the UBC adopts an explicit serviceability design procedure.
Treatment of Parameter Uncertainty and Variability for a Single Seismic Hazard Map
Authors: Bender Bernice K. , Perkins David M.
Published: July 2003

The inputs to probabilistic seismic hazard studies (seismic source zones, earthquake rates, attenuation functions, etc.) are uncertain, being based on subjective judgments and interpretations of limited data. In the face of this uncertainty, we consider (a) how one might “reasonably” determine the ground-motion levels to show on a single probabilistic seismic hazard map, and (b) the extent to which uncertainty in the calculated levels can be meaningfully represented on such a map. If the “best guess” estimates of the earthquake rate, the Gutenberg-Richter b-value and the maximum magnitude for a single source zone are regarded as uncorrelated and the uncertainty in each parameter can be regarded as symmetric about the estimated value, then the probabilistic ground-motion levels calculated using these best estimates represent both most likely values and also approximate mean values.
Viscoelastic Mechanical Damping Devices Tested at Real Earthquake Displacements
Authors: Bergman David M. , Hanson Robert D.
Published: July 2003

Experimental steady-state hysteretic characteristics of ten direct shear seismic damping devices (DSSDs) are presented. The devices were tested over a range of frequencies and displacements chosen as representative of building responses during moderate to severe level earthquakes. Three different damping materials, produced by 3M Corporation and Lord Corporation, were used in the devices. Excitation frequency, strain amplitude, damping material initial temperature, temperature change over the test duration, cyclic energy dissipation, and damping material moduli (including complex shear, storage and loss moduli) are reported for all tests performed. The influence of frequency, displacement amplitude, temperature, and cumulative energy absorption on the damping material mechanical properties and hysteretic stability are examined. Methods by which material moduli can be used to design damping devices for specified spring stiffness and equivalent viscous damping are presented. Limitations of the hysteresis model, test results, and design methodology are discussed.
Inelastic Response of R/C Structures with Viscoelastic Braces
Authors: Lobo R. F. , Bracci J. M. , Shen K. L. , Reinhorn A. M. , Soong T. T.
Published: July 2003

The addition of viscoelastic braces in structures for vibration reduction has been proposed and implemented in the past decade in metal scaled models of full-scale structures. Viscoelastic braces can provide energy dissipation, while the structure remains elastic. In reinforced concrete structures, the seismic response is usually inelastic, which is often accompanied by permanent deformations and damage. The addition of viscoelastic dampers can dissipate energy at the early stages of cracking of the concrete elements and reduce the development of damage. With proper selection of dampers, this damage can be substantially reduced or even eliminated. However the addition of viscoelastic dampers may stiffen the structure unnecessarily producing increased inertial forces and base shears when subjected to seismic motion. The quantification of the influence of viscous damping and elastic stiffness properties of dampers during the inelastic response of reinforced concrete structures is the subject of this investigation. Models for analysis of inelastic response with damage indexing for reinforced concrete structures that include viscoelastic braces are developed and calibrated using experimental data produced by shaking table tests. These models are then used to determine the variation of expected damage in the presence of damping and quantify the hysteretic energy dissipation along with the damping energy.
Passive Control of Building Response Using Energy Dissipating Cladding Connections
Authors: Pinelli Jean-Paul , Craig James I. , Goodno Barry J. , Hsu Cheng-Chieh
Published: July 2003

Ductile cladding connections take advantage of the cladding-structure interaction during an earthquake to dissipate energy. An experimental test program studied the behavior of the different components of a connection system. Analytical models of the connection were incorporated into a 2D model of a six story building with cladding. Time histories of the energy demand and supply to the building, both with and without cladding, trace the response of the structure to earthquake excitations. Results show that properly designed energy dissipative connector elements can be responsible for the total hysteretic energy dissipated in the structural system. A design criterion for the connection that is formulated in terms of energy provides the optimal balance of stiffness and strength to be added to the structure by the dissipators. It results in maximum energy dissipation in the connectors, no plastification in the structural members, and reduced structural response. This approach could be applicable to both new and retrofitted buildings.
Monte-Carlo Simulation of the Theoretical Site Response Variability at Turkey Flat, California, Given the Uncertainty in the Geotechnically Derived Input Parameters
Authors: Field Edward H. , Jacob Klaus H.
Published: July 2003

In the weak-motion phase of the Turkey Flat blind-prediction effort, it was found that given a particular physical model of each sediment site, various theoretical techniques give similar estimates of the site response. However, it remained to be determined how uncertainties in the physical model parameters influence the theoretical predictions. We have studied this question by propagating the physical parameter uncertainties into the theoretical site-response predictions using monte-carlo simulations. The input-parameter uncertainties were estimated directly from the results of several independent geotechnical studies performed at Turkey Flat. While the computed results generally agree with empirical site-response estimates (average spectral ratios of earthquake recordings), we found that the uncertainties lead to a high degree of variability in the theoretical predictions. Most of this variability comes from poor constraints on the shear-wave velocity and thickness of a thin (∼2m) surface layer, and on the attenuation of the sediments. Our results suggest that in site-response studies which rely exclusively on geotechnically based theoretical predictions, it will be important that the variability resulting from input-parameter uncertainties is recognized and accounted for.
Seismic Design of Buildings in China
Authors: Shiping Hu
Published: July 2003

This paper gives the reader a general perspective on the subject of seismic design of buildings in China and may be of special interest to those who may do building design in that country. In the introduction, the main characteristics of Chinese earthquakes, some major earthquake disasters in the past, and a brief history of seismic design in China are related. The paper goes on to relate some new features of the recently promulgated seismic code which include a new design spectrum, how to identify liquefiable soil, the three levels of seismic protection, and the two-phase design. The paper also presents the seismic design of multistory brick and reinforced concrete buildings which differs somewhat from that of other countries, and three examples of actual design.
New Directions in Structural Seismic Designs
Authors: Popov Egor P. , Yang Tzong-Shuoh , Grigorian Carl E.
Published: July 2003

The code stipulated seismic force requirements for buildings from the historical point of view are described first. This is followed by examples of the emerging criteria of inelastic seismic spectra for displacement ductility, and number of yield reversals as a function of building period and strength. Novel spatial representations of seismic input energy and hysteresis energy, interpreted as damage energy, are given next. The available structural resistance countering the imposed seismic demand is illustrated by the ductile behavior of steel moment resisting frames (MRFs) and eccentrically braced frames (EBFs). A discussion of a practical and versatile frictional energy dissipating connection is given at the end.
Seismic Strengthening with Minimum Occupant Disruption Using Performance Based Seismic Design Criteria
Authors: Hart Gary C. , Elhassan Rami M.
Published: July 2003

A performance based design criteria for seismic rehabilitation requires considerable communication with building owners to develop a mutual understanding of the design constraints and the product that is delivered. This communication becomes even more complex when the goal is to minimize the occupant disruption. This paper presents a discussion of two seismic rehabilitation projects in Southern California where minimizing occupant disruption was essential and where the seismic design was a performance based design. One building was a midrise concrete-frame building housing computer facilities and executive personnel. The other building was an unreinforced masonry residence for business and movie professionals. In both situations base isolation was the best design solution.
Jackson Brewery: Upgrading an Historic Unreinforced Brick Building
Authors: Siegel Henry I. , Fowler Lawrence W.
Published: July 2003

The Jackson Brewery, a five story unreinforced brick building and an historic landmark, was seismically upgraded to meet the requirements of the 1990 San Francisco Building Code. Portions of the building had been damaged during the 1989 Loma Prieta earthquake. Repair work and seismic upgrading had to meet the standards of the city's Landmarks Board. Various seismic schemes were evaluated. An eccentric brace scheme was selected. This solution had the least impact on the building's facades and did not significantly increase the mass of the building. Structural details are exposed and some details, such as collector angles, underwent significant re-design to lower cost and integrate with the architectural design of the building.
High Seismic Economic Risk Buildings: Recognizing a Potential Problem
Authors: Wong Kit M.
Published: July 2003

The objective of this paper is to present an overview of buildings in California that may pose a high earthquake economic risk, beyond the issue of life safety. To help recognize this potential problem, four prototypes of high economic risk buildings were developed based on the damage statistics of public buildings from the Loma Prieta Earthquake and the building code history of the western United States. These prototypes are illustrated herein. The greatest sources of economic loss due to earthquakes appear to be historic buildings built before 1937 and concrete multi-story buildings built before 1961. The potential loss from these building types raises a number of significant implications for other regions of the United States.
A Basis for Evaluation of Seismic Hazard and Design Criteria for Saudi Arabia
Authors: Al-Haddad M. , Siddiqi G. H. , Al-Zaid R. , Arafah A. , Necioglu A. , Turkelli N.
Published: July 2003

This paper presents the fundamental issues and policy decisions that formed the basis of the hazard and design aspects of a comprehensive research project conducted for development of the preliminary seismic design criteria for the Kingdom of Saudi Arabia. The study represents the first regionally consistent and systematic collection and critical treatment of the limited historical and instrumental data on earthquakes and seismotectonics of the region, and development of seismic design criteria. The development of the seismic design criteria followed somewhat conservative course, rather than a strict scientific approach, in estimation of the seismic hazard. One of the significant outcome of the study was the preparation of an upto-date and refined earthquake catalog of the region. The catalog contains both, the historical data available in Arabian and English literature, and the data recorded by international and local seismic monitoring agencies. The data were critically treated and superimposed upon the available tectonic information of the Arabian peninsula to obtain a preliminary seismotectonic map of the region. The results of the probabilistic seismic hazard assessment indicate that the highest relative predicted ground-motion occurs near the northwestern border neighboring the Gulf of Aqaba and also near the southwestern border, neighboring Yemen. Based on iso-acceleration map for 10% probability of being exceeded in 50 years, for the seismic design purposes the Kingdom was delineated into four seismic zones. Following UBC format the seismic zones are assigned numbers 0, 1, 2A and 2B. Widely used codes, SEAOC and UBC were selected as the model for development of seismic design recommendations. Selection of the structural system is based on structural performance category which is determined by seismic zone number and the intended occupancy category. Rw-factors for different types of structural system were assigned lower values in consonance with the design and construction practices prevalent in the country. The significance of this study is in its implementation of a global scheme in development of seismic design criteria of a region beset with limited seismic data.
Seismic Response of Adjacent Buildings with Similar or Different Dynamic Characteristics
Authors: Athanassiadou Christina J. , Penelis George G. , Kappos Andreas J.
Published: July 2003

The seismic response of adjacent buildings in series, having similar or different dynamic characteristics, is studied using SDOF systems subjected to a base motion. The phase difference (due to travelling seismic waves) in the starting times of excitation of adjacent structures is taken into account, as well as the changes on response quantities due to pounding. A parametric study is carried out to investigate the influence of the main parameters of the problem. The analysis indicated an increased response of the end structures, as well as of the most rigid structures in the series. The critical problem of the required width of seismic joint to minimise the effect of pounding was studied and found to lie well below that recommended by some modern seismic codes.
Seismic Ductility Demands Predicted by Alternate Models of Building Frames
Authors: Diaz Orlando , Mendoza Enrique , Esteva Luis
Published: July 2003

Peak values of story ductility demands produced by earthquakes on several models of multistory rigid frames are evaluated by means of step-by-step nonlinear dynamic analysis of structural response to simulated ground motion time histories. The models studied include the basic rigid frame model with nonlinear behavior concentrated at plastic hinges eventually forming at the ends of beams and columns, as well as two approximations, the conventional shear-beam system and a shear-frame system constituted by ordinary reinforced concrete columns and infinitely stiff and strong beams. Two families of models were studied, including seven-story and fourteen-story systems, respectively. The contributions of soil-structure interaction, stiffness-degradation and P-delta effects were analyzed. The equivalent shear-beam model produced results clearly different from those of its rigid frame counterpart: while peak values of story ductility demands vary gradually along the height of rigid frames, they concentrate at the bottom story of shear-beam systems, where they are significantly greater than for the corresponding rigid frame. The responses of both, shear-beam and shear-frame systems, displayed a more pronounced sensitivity to variations in the lateral strengths of structural members than that observed in rigid frames.
P-Δ Effects on Single-Degree-of-Freedom Structures in Earthquakes
Authors: MacRae Gregory A.
Published: July 2003

A vertical force, P, moving through a lateral displacement, Δ, causes extra “ P-Δ” forces on a structure that are not accounted for in analyses based on the undeformed structural geometry. If the effect of these P-Δ forces are large, then displacements during an earthquake may be greater than those when the P-Δ effect is not considered and the likelihood of overturning increases. This paper discusses previous studies to understand the problem of P-Δ. The likely change in response of bilinear oscillators is found from knowledge of the behaviour of simple single degree of freedom bilinear oscillators and the effect of P-Δ on a hysteresis loop. Using the “hysteresis centre curve” (HCC) concept, recommendations are made for the design of single degree of freedom structures with general shape hysteresis curves considering the P-Δ effect.
Narrow Plywood Shear Panels
Authors: Schmid Ben L. , Nielsen Richard J. , Linderman Robert R.
Published: July 2003

The Uniform Building Code allows plywood sheathed narrow shear panels having a height-to-width ratio of 3.5-to-one (UBC Table 25-I) to be used as lateral force resisting elements. Previous laboratory testing has concentrated on panels having a height-to-width ratio of one-to-one. This paper presents some results from the testing of plywood shear panels with a height-to-width ratio of two-to-one. Three panels were tested; each was configured to model a different construction scenario. The panels were subjected to fully reversed cyclic pseudo-static loads. Comparison of the results from the three panels indicate that the tie-down anchors must be installed with careful attention to bolt tightening sequence and torque in order to better resist lateral displacements in an earthquake. Vertical dead loads were found to reduce uplift of the panel which, in turn, reduces lateral displacements resulting from panel rotation. Decreased shear values for plywood shear walls subjected to cyclic loading and additional decreased shear values for walls with a height-to-width ratio of two-to-one are recommended.
Estimates of Site-Dependent Response Spectra for Design (Methodology and Justification)
Authors: Borcherdt Roger D.
Published: July 2003

Recent borehole-geotechnical data and strong-motion measurements constitute a new empirical basis to account for local geological conditions in earthquake-resistant design and site-dependent, building-code provisions. They provide new unambiguous definitions of site classes and rigorous empirical estimates of site-dependent amplification factors in terms of mean shear-wave velocity. A simple four-step methodology for estimating site-dependent response spectra is specified herein. Alternative techniques and commentary are presented for each step to facilitate application of the methodology for different purposes. Justification for the methodology is provided in terms of definitions for the new site classes and derivations of simple empirical equations for amplification as a function of mean shear-wave velocity and input ground-motion level. These new results provide a rigorous framework for improving estimates of site-dependent response spectra for design, site-dependent building-code provisions, and predictive maps of strong ground shaking for purposes of earthquake hazard mitigation.
Low-Rise Shear Wall Ultimate Drift Limits
Authors: Duffey T. A. , Farrar C. R. , Goldman A.
Published: July 2003

Drift limits for low aspect ratio reinforced concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Based on the geometry of structures designed for protective purposes and concerns regarding their response during seismic loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which loading is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information.

The statistical nature of the data is also investigated. For example, at ultimate load the median drift limit is 0.72 percent, and it increases to 1.84 percent when the load drops to 50 percent of its ultimate value. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of these statistics to estimate probability of failure for a shear wall structure is illustrated. Finally, a brief comparison of drift limit results with existing seismic design code requirements is presented.
Wide Beam-Column Connections under Earthquake-Type Loading
Authors: Gentry T. Russell , Wight James K.
Published: July 2003

Wide beam-column connections, whose beams are wider than their supporting columns, are often found in one-way concrete joist systems and in other buildings where floor-to-ceiling heights are restricted. Research into the seismic behavior of these connections stems from the recommendation by ACI-ASCE Committee 352 (Monolithic Connections in R/C Framed Structures) that these connections be evaluated for use in high seismic zones. Four exterior 3/4-scale specimens, including transverse beam with reinforcement, were tested at the University of Michigan Structural Engineering Laboratory. The effects of joint shear stress level, fraction of beam longitudinal reinforcement anchored in the column core, and beam-width to column-width ratios (bw/bc) were explored as part of this research. The experiments show that wide beam-column connections can be used in high seismic zones if they are detailed correctly. If they are not detailed correctly, the exterior connections will be incapable of transferring the plastic hinge bending moments to the column because the transverse beam cracks in torsion. To prevent this cracking of the transverse beam, limits on the torque applied to the transverse beam are proposed.
Inelastic Deformation of One-Story Asymmetric-Plan Systems Subjected to Strong Earthquake Ground Motions
Authors: Ozaki Masakazu , Azuhata Tatsuya , Takahashi Toru , Shaomei M.
Published: July 2003

Inelastic response of one-story building systems with eccentricity is investigated based on linear static and nonlinear dynamic analyses using asymmetric-plan systems simultaneously subjected to strong earthquake ground motions in the x- and y-directions. Inelastic story drift ratios in the x- and y-directions are evaluated considering shear and torsional strength capacity and the corresponding shear force and torsional moment acting in each direction of asymmetric-plan system. Response analysis of one-story systems with one-axis plan asymmetry and varying parameters such as uncoupled lateral vibration period, torsion-to-lateral frequency ratio, rigidity and strength eccentricities, and shear and torsional strength capacity ratio is carried out and compared with those of corresponding one-story symmetric systems. In addition, inelastic response of one-story building systems with two-axes eccentricity including a L-shape asymmetric-plan system is also investigated.
Earthquake-Resisting System Selection Statistics for Reinforced Concrete Buildings
Authors: Eberhard M. O. , Meigs B. E.
Published: July 2003

To document current practice in selecting earthquake-resisting systems for reinforced concrete buildings, a survey was sent to consulting firms located in the United States, Canada, Chile, Colombia, Mexico and Peru. The respondents documented the earthquake-resisting systems for 4700 cast-in-place buildings that they had designed during the last five years. In addition, the respondents listed the factors that most affect the selection of earthquake-resisting systems. This paper presents a statistical summary of the responses and compares the responses collected from three U.S. geographical regions (Northern California, Pacific Northwest and Southern California) and among the six surveyed countries.