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Strong-Motion Instrumentation of Buildings
Consortium of Organizations for
Strong-Motion
Observation Systems

COSMOS

1301 South 46th Street
Richmond, California 94804
July, 2002

Technical Editors
J. Carl Stepp
Robert L. Nigbor
C. Allin Cornell
Roger D. Borcherdt
Kent Ferre
William T. Holmes
Mel Lund
William U. Savage

General Editor
Claire M. Johnson

Invited Workshop
on
Strong-Motion Instrumentation of Buildings

held at

Marriott Courtyard Hotel, Emeryville, CA

November 14, 15, 2001

Sponsors
The U. S. National Science Foundation
The U. S. Geological Survey

4.3 Summary and Recommendations

J. C. Stepp
COSMOS
W. U. Savage
U.S. Geological Survey
R. L. Nigbor
University of Southern California
C. A. Cornell
Stanford University

Introduction
Currently 207 buildings have reasonably extensive strong-motion instrumentation as part of the California Strong-Motion Instrumentation Program (CSMIP) and the U.S. Geological Survey's (USGS) National Strong-Motion Program (NSMP) [Shakal et al., these Proceedings; Celebi, these Proceedings]. Approximately 500 additional buildings located in Los Angeles County have minimal instrumentation, as specified by the Uniform Building Code guideline [Savage, 1997]. In addition a few private sector companies have instrumented some of their buildings for emergency response and recovery operations following damaging earthquakes [Otey, 1997]. To date, the total number of buildings with adequate strong-motion measurement instrumentation amounts to less than 3% of the estimated 10,000 needed for all measurement purposes, including emergency response and recovery following a damaging earthquake [Stepp, Ed., 1997].

The Advanced National Seismic System (ANSS), which was authorized by the Congress in 1999, takes a step toward meeting the need for documenting strong-motion response measurements of buildings. The legislation authorized 3000 three-channel instruments for placement in structures of all types (including buildings) and an additional 3000 three-channel instruments for measurement of strong-ground motion in urban areas throughout the United States [USGS, 1998]. The level of the ANSS authorization for strong-motion instrumentation of all structures falls far short of the estimated need for measurements in buildings alone. Nevertheless, the authorization presents a major opportunity to significantly advance strong-motion measurements. At the same time it presents a significant challenge for the community of earthquake professionals, requiring consideration of tradeoffs and development of implementation strategies with the highest likelihood for improving earthquake engineering practice and advancing earthquake safety. Implementation strategies must include the following:

balance national and regional allocation of resources;
develop criteria and guidelines for selecting specific buildings in order to obtain recordings in representative building types and for specific measurement objectives;
stimulate advancements in instrumentation technologies;
identify actions to strengthen coordination between the ANSS and building owners aimed at expanding private participation;
consider the needs for building health monitoring for emergency response and recovery; and
include plans and resources for data archiving and dissemination.

This Workshop focused primarily on strong-motion instrumentation of buildings as the priority need for the portion of ANSS resources allocated for strong-motion instrumentation of structures. Emphasis was placed on identification of knowledge gaps with respect to the types of buildings, the types of response measurements, and the national and regional allocation of resources that together are likely to have the highest payback for advancing earthquake safety practice. Consideration was also given to opportunities for advancing monitoring technologies and to stimulating participation by building owners in strong-motion instrumentation of buildings. The Workshop findings are intended to serve as the basis for development of strategies, criteria, and guidelines for optimally implementing the strong-motion element of the ANSS. This summary of findings and recommendations of the Workshop has been prepared from audio recordings made during the plenary discussions and from illustrations and written materials prepared by the four Breakout Group Recorders.

Summary of Findings
Building Types and Measurement Priorities
Predictive modeling is at the heart of earthquake engineering. It is central to everything earthquake engineers do, from post-earthquake investigations to retrofitting, evaluating, and designing structures, and to performance-based design. The guiding objective of instrumentation for structural response measurements should be to gain understanding of the behavior of representative structure types in order to improve general predictive models with the following goals in mind:

* challenging, verifying or calibrating models;

* calibrating design and retrofit rules (codes); and

* calibrating post-earthquake evaluation rules.

Structural response recordings needed to meet this objective and advance earthquake engineering practice should determine measurement objectives for the population of structures, as well as for individual structures, the number of instruments required in each building type, and the types of instruments to be installed. Together with consideration of the probability of obtaining recordings in a reasonable time (discussed in Borcherdt et al., these Proceedings), these objectives form the basis for establishing criteria and developing guidelines for selecting structures for strong-motion instrumentation.

The guidelines should require that specific measurement objectives be established for any and all structures selected for strong motion instrumentation in the context of filling information gaps and to improve earthquake safety. This should be done prior to instrumentation design and procurement.
The most important measurement objectives are considered to fall into the following categories:

* improving modeling of elastic response

* improving modeling of nonlinear response

* evaluation of interstory drift

* evaluation of torsional deformation

* evaluation of diaphragm deformation

* evaluation of soil-structure interaction

Criteria for instrumentation of specific structures must address how many instruments are required to reasonably assure that a specific monitoring objective will be met. In order to adequately measure response. Workshop consensus was that a minimum of 20-50 recording channels are needed for detailed response definition in a building. For example, in order to be reasonably certain that sufficient recordings for the determination of interstory drift will be obtained, placement of instruments on about one third of a building's floors is required. Assuming an average of 30 recording channels per building and three components for each instrument installation location, the currently authorized capital expenditure would permit instrumentation of 300 buildings. The currently authorized ANSS capital funding for 3000 three-component instruments for measuring response of structures is clearly inadequate to meet the need, even assuming all of the instruments were placed in buildings. Tradeoffs must be accepted in the development of guidelines and criteria for implementation of the system.
As an initial tradeoff, it is recommended that instrumentation of buildings should be given high priority. Other structures, such as bridges, other lifeline structures, dams and other critical facility structures, typically have independent requirements for strong-motion measurements. Other tradeoffs, discussed in more detail later in this Summary, include real-time monitoring of buildings for structural health assessment and emergency response and recovery. The tradeoffs within the building inventory should take into consideration priority building types (considering current inventory, current construction and future trends), priority response measurement needs, and the likelihood of obtaining useful measurements in a reasonable time. It is recommended that the tradeoffs should emphasize instrumentation of fewer buildings, with a scope of instrumentation to reasonably ensure that established measurement objectives will be met.
The types of instruments selected for a particular building depend on the building type and on the established measurement objective. For example, displacement response measurements are needed for determining interstory drift. Strain measurements may be required to determine the deformation of tilt-up wall connections. Other types of response measurements, such as connection rotation or soil-structure interaction, may require additional types of sensors or measurement strategies. Other objectives may require still other types of measurements, types of instruments, instrument configurations, or numbers of instruments. It is strongly recommended that the building-specific objectives be defined first, then the instrumentation designed. Both should be done prior to instrument procurement.
Criteria for selecting specific buildings for instrumentation should be based on the considerations discussed in the preceding paragraphs. Specifically, selection criteria should be based on the following:

the number and value of the building types rather than on a simple sampling of the distribution of buildings of a given type in a region;
occupancy (office, hotel, hospital, etc.);
representative retrofitted building types;
foundation conditions; and
potential for contributing to the objectives established for ANSS building instrumentation program.

Development of ANSS building selection guidelines should take the CSMIP [Shakal, et al., these Proceedings] guidelines as a starting point. The ANSS Regional Committees should contribute to development of the guidelines, and the guidelines should have a long timeframe from a national perspective.
All buildings selected for installation of strong-motion instruments should have a reference strong motion station as defined by COSMOS [2001]. The reference stations should be part of the additional 3000 urban strong-motion stations authorized as part of the ANSS capital expenditure for strong-motion instruments. This critical need emphasizes the importance of coordinated planning and selection of sites for urban strong-motion stations. The objective should be to optimize the location of strong-motion instruments installed for the purpose of obtaining data for development of ShakeMaps that support response and recovery following damaging earthquakes, for example, with the need for building reference stations.
Resource allocation for instrumentation of buildings in different regions of the nation should consider the probability of obtaining recordings, but also needs to address different building types, construction types, and any regional variations in code strength and ductility requirements. Recordings of the response of some of model building types-different construction types, different levels of strength and ductility-in regions with lower seismicity should also be obtained if such model building types are sufficiently important and are not available in high seismic hazard areas. Because one model can span many building variations, however, the major consideration should be the probability of obtaining recordings that advance general understanding of the performance of building types that comprise national building inventory.
Data collection, maintenance, archiving and dissemination must be considered necessary elements of the building instrumentation program. The scope of data collection must include:

*metadata such as relevant information about the building and the site;

*building response recordings; and

*the damage state of the building associated with all recordings.

Real-time recovery of strong-motion recordings to assess building damage immediately following a large earthquake is an important safety objective, with potentially important economic payback for the building owner. This important use of strong-motion recordings was recognized in the planning for the ANSS, which included consideration of instrumentation to support damage assessments for emergency response and recovery [USGS, 1998]. Different points of view were expressed about the scope of instrumentation needed in a building to meet this monitoring objective. There was agreement, however, that instrumentation of a significantly large number of buildings would be necessary to effectively meet this monitoring objective. The required number of strong-motion instruments would greatly exceed the current ANSS capital authorization for instrumentation of buildings. Nevertheless, real-time and near real-time recovery of building response recordings is considered to be a need that should be given continued attention in future ANSS planning. One option would be to give building owners incentives in the form of assurance of early resumption of building occupancy following a damaging earthquake. Finally, as discussed later on in this Summary, continued attention should be given to developing innovative instrumentation and monitoring technologies. Goals for such development are to reduce the cost of strong-motion instrumentation of buildings and to improve the quality or timeliness of recorded data.

Guidelines for Establishing National Priorities
Although the ANSS is a national program, considerations for establishing national priorities should take account that part of its mandate is to acquire useful measurements in a reasonable time frame. Considerations for selecting building types and for measurement priorities discussed in the preceding section generally apply throughout the nation, as any building response recordings obtained in one region will in general be transferable to other regions. This warrants allocating resources and instrumenting those buildings where the probability of obtaining data is higher. The approach should also give appropriate consideration to the need for response measurements in specific regional model building types, different construction types, and different levels of strength and ductility regions of low seismicity and hazard.

Recognizing that the ANSS is a national program, trade-off is required for a balanced national allocation of funding for instrumentation of buildings. Because the ANSS is a national program, the long-term program goal recommendsit is recommended that 30% of the authorized 3000 strong-motion instruments allocated to structures in the ANSS Plan be distributed equally among the ANSS regions (with the exception of the Hawaii Region as will be discussed later). This portion of the allocation will insure that each region has a minimum number of instrumented buildings. The allocation should be primarily for the purpose of obtaining response measurements of unique regional building types. The remaining 70% of the capital budget for instrumentation of buildings should be apportioned to ANSS regions based on relative regional seismic hazard/risk criteria. This implies that of the 300 thirty-channel building installations, about 13 should be installed as a minimum in each ANSS region, with the remaining allocated using the AEL-AELR index described by Borcherdt et al. (these Proceedings)

Guidelines for Establishing Regional Priorities
Guidelines for establishing priorities for allocating resources within regions must should accommodate the guidance described by Borcherdt et al. (these Proceedings), as well as such locally causative relevant factors as earthquake magnitude, local foundation conditions, local variation of seismic hazard within a region, and local distribution of losses expected in an urban area at risk. These additional considerations, together with the local and regional distributions of expected losses as calculated using HAZUS, provide a quantitative basis for assigning regional priorities and development of criteria and guidelines for selecting specific buildings. As discussed earlier in this Summary, Workshop consensus was that HAZUS results should be used to establish regional priorities based on the distribution of regional loss for maximum considered earthquakes in a region. The distribution of loss within regions for these events can be used to define areas and types of buildings most likely to be damaged. The percent of the total loss for each building type multiplied by the number of buildings allocated to the region based on the national priority appropriation provides a quantitative basis for allocation of resources for instrumentation of each building type. Borcherdt, et al. [1997] suggested a similar procedure, based on ground motion estimates for a repeat of the 18 April 1906 San Francisco earthquake, as a means of developing estimates for instrumentation of the built inventory in the San Francisco Bay Area. The results should then be reviewed and interpreted by regional committees as a guide for selecting specific building types and locations and, with other locally causative factors, for establishing a ranking of priority installations. As discussed by Borcherdt et al. (these Proceedings), specific building types for consideration-especially in high seismic hazard areas such as Anchorage-should include the following:

*steel moment-resisting frame (10-20 stories);

*steel braced frame (10-20 stories);

*reinforced CMU (5-14 stories);

*ductile concrete moment-resisting frame (10-20 stories);

*concrete shear wall (10-15 stories);

*timber building (shear wall) (5-stories) and

*special general buildings (large, complicated framing system).

Criteria and guidelines for selecting specific buildings should be integrated with guidelines and criteria for selecting free-field sites for strong-motion instrument installation in urban areas. The ANSS authorization allocates 50% of the capital expenditure for strong-motion instruments for installation in structures and 50% for installation in the free field for ground-motion monitoring. As recommended by Borcherdt et al. (these Proceedings), this allocation should be viewed as a long-term commitment for the ANSS rather than as a yearly requirement for allocation of resources by region and within regions. The ANSS management and each ANSS region should have the flexibility to plan and prioritize resources considering the most urgent instrumentation needs identified by its Regional Committee as long as the 50%-50% authorized target is met in the long term for the program. Priority needs are expected to vary from region to region. In addition, each region should have the option to use a portion of their ANSS funds for mobile instrumentation to conduct structural response studies as necessary, for example, to measure basic dynamic characteristics of given classes of buildings during ambient conditions or during frequently occurring small earthquakes. Such data are lacking outside of California and are potentially important for determining whether certain code provisions, which are based largely on California data, are applicable to buildings in lower seismic hazard regions that may have different properties and may experience different ground motion characteristics. To ensure that building measurement data needs are met, at least half of the members of each Advisory Committee in an ANSS region should be earthquake (structural and geotechnical) engineers.

Opportunities for Use of New Technologies
One important need is to optimize the costs of instrumentation by taking advantage of advances in instrument technologies. With regard to current technology needs for strong-motion accelerometers, Workshop discussions developed the following recommendations:

* +/-4g full-scale is sufficient for both reference stations and building response accelerometers

* > 4g should be considered for special measurements (e.g., impact/pounding, special buildings, equipment)

* < 4g may be sufficient for downhole measurements where justified

*200 SPS is considered minimum for buildings in order to meet the need for higher mode information

*When high accelerations are anticipated, sample rate and frequency response must be appropriately increased 16-bit resolution (sensors+recorder) is considered minimum for building response monitoring; higher resolution would be better

As is also the case with current technologies, new technologies for building monitoring requires a clear understanding of how the data are to be used in order to determine the appropriate building monitoring system technologies or monitoring configuration. As discussed earlier, the instrumentation for obtaining real-time response measurements for assessment of damage states of buildings following strong earthquake shaking is also a priority. The value of such measurements is sufficiently high to warrant continued investment in developing effective monitoring technologies that are cost-effective enough to be attractive to individual building owners; therefore, real-time monitoring of some buildings or of some channels in selected buildings should be considered as part of the ANSS. For example, although earthquake engineers consider measurement of interstory drift to be of primary importance, currently these measurements are not accurately obtained with standard building instrumentation deployment. In the short-term, such measurements could be obtained by placing accelerometers or velocity sensors on adjacent floors. In the long-term, research is needed to develop new technologies for direct measurement of interstory drift. In addition, direct measurement of base rotation is considered to be of primary importance for understanding of soil-structure interaction. Instrumentation technologies for these measurements are currently available and should be installed in selected buildings.
Replacing cable connections of a building monitoring system with wireless technology may provide more flexibility as well as reduce costs and should be considered where possible and practical. Currently, however, wireless technologies do not have the distance range to completely replace cabled connections. Continued evolution of this technology is needed before wireless completely replaces cabling. Other monitoring technologies together with their potential importance for the short-term (current ANSS planning) and the long-term and are summarized in Table 1.

Requirements for instrumentation of buildings for short-term assessments of damage states, coupled with adequately broad real-time data acquisition to support emergency response and recovery would require funding significantly larger than is currently authorized for strong-motion instrumentation. This important need should, however, be given continued long-term attention. In particular, the possibility of developing more effective and lower cost instrumentation technologies should be given ongoing attention as part of the ANSS Program. This effort should target new technologies that can reduce the costs of instrumentation and monitoring while ensuring that the required data are obtained. Importantly, cooperative projects for instrument development should be developed in conjunction with NSF's developing George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES).

Considerations for Encouraging Private Participation
Private sector building owners assume that their buildings are properly designed and constructed. Accordingly, they are interested in strong-motion monitoring only as it related to protecting their investment and continued operation in the event of an earthquake. To engage private section participation, building monitoring must be presented in the context of operational decision-making. In the event of an earthquake, the primary focus of a building owner/operator is determining when a building may resume operation and is safe for occupancy. A direct correlation must be drawn between data collected and the health and integrity of the structure.

To encourage private sector organizations to participate in building monitoring systems depends on two natural allies: the owners and the structural engineers. Owners who have previously instrumented structures and have used response results in decision-making are excellent advocates in promoting monitoring systems. Second, experienced structural engineers can advise building owners and point to their own practical experiences with successful uses of building response measurements. These organizations/owners and practitioners are considered the best resources for any effort aimed at expanding private participation in strong-motion instrumentation of buildings.

Another important perspective that emerged from Workshop discussions is the knowledge gap that exists between private sector users of strong-motion data, as well asand the providers of strong-motion data who are trying to meet their needs. Strong-motion monitoring has traditionally focused on providing building response measurements for dynamic modeling purposes. The products that are delivered by the providers respond specifically to the needs of this user group. In order to encourage building owners to invest in strong-motion monitoring, products that the owners can actually use must be provided.

Demonstration projects, with co-funding or CRADA relationships, are seen as a way of expanding private sector participation and getting new organizations involved in building instrumentation projects. To bridge the education gap between owners and strong-motion data providers, guidelines focused on the practical application of strong-motion data should be prepared that specifically target building owners. The ANSS should consider providing technical support for private owner participation in building monitoring by serving as recorder and distributor of any data collected. The building owner's needs for the data may be as limited as providing data obtained from free-field station that can be incorporated into ShakeMap. If instrumentation of a building meets the national and regional priorities of ANSS and the owner agrees to the use of the data for the public good, then the project would clearly contribute to ANSS goals. There is a range of possible building owner relationships with the ANSS that would have to be developed on a case-by-case basis. Building owner/operators engaged on any level in getting and applying earthquake data become advocates for the overall ANSS program.

Recommendations
Building Types and Measurement Priorities

The authorized ANSS capital budget for strong-motion instrumentation of structures should focus on instrumentation of buildings. This recommendation addresses the critical gaps in knowledge about building performance that can be filled only when response information becomes available. This recommendation targets buildings because other sources of funding are generally available for instrumentation of dams, bridges, and other lifeline and/or critical structures.
A guiding objective for ANSS instrumentation of buildings should be to obtain response measurements to advance understanding of the response behavior of representative building types in order to improve general predictive models by calibrating and/or modifying models, calibrating design rules (codes), and calibrating post-earthquake evaluation of design rules. To validate the integrity of these recordings in order to perform these calibrations, strategies must be developed to allocate and site instruments so that any building monitoring system response measurements obtained are representative of the general population of building types. In addition, these recordings should serve the guiding basis for establishing objectives for instrumentation of specific buildings.
The most important measurement objectives considered are as follows: modeling of elastic and inelastic response, determination of interstory drift, determination of the torsional deformation, determination of diaphragm deformation, and determination of soil-structure interaction. Program level guidelines for capturing building responses that satisfy these objectives should be developed and implemented.
Specific measurements objectives should be defined in every building slated for strong-motion instrumentation. This should be done before instrumentation design and procurement.
Criteria for selecting buildings within regions should include:

* the number and value of the building types rather than a simple sampling of buildings of a given type in a region;

* occupancy (office, hotel, hospital, etc.);

* representative retrofitted building types

* foundation conditions;

* model building types and construction practices;

* the need for measurements on equipment within buildings; and

* the potential for contributing to the objectives established for the ANSS building instrumentation program.

A strong-motion reference station should be associated with every instrumented building.
Data collection, processing, maintenance, archiving, and dissemination must be key, necessary elements of the ANSS building instrumentation program. The scope of this effort must include the following:

* metadata, such as relevant information about the building and site;

* building response recordings; and

* information about the damage state of the building associated with all recordings.

Real-time recovery of strong motion recordings for the purpose of assessing building damage immediately following a large earthquake is an important safety objective, with potentially important economic payback. Meaningful implementation of this measurement objective would require instrumentation of a significantly large number of buildings, well beyond the currently authorized ANSS budget for instrumentation of structures. Nevertheless, the real-time recovery of building response to recordings considered critical and should be given continued attention in future planning. Consideration should be given to revising the Uniform Building Code to include implementation of building health monitoring. Other options for consideration include giving incentives (in the form of assurance of early resumption of building occupancy following a damaging earthquake) to building owners who install building monitoring systems.

National Priorities

Allocating resources for instrumentation of buildings in different regions of the nation should give high weight to the probability of obtaining recordings. It also must address different model building types, construction types, and any regional variations in code strength and ductility requirements. Sufficiently important model buildings types located in regions with low seismic hazard may be instrumented if such model building types are not located in highly seismic regions. Major consideration should be given, however, to the probability of obtaining recordings to be used to calibrate and advance current computer structural models, as well as improve earthquake engineers' understanding of performance of building types within the building inventory.
As a long-term, national program goal, allocation of resources should be based on allocating 30% of the total authorized resources evenly among ANSS regions, with the remaining 70% determined by a formula that combines annualized earthquake loss and a percentage of annualized earthquake loss ratio by state, as described by Borcherdt et al. (these Proceedings). Region 7: Hawaii is an exception because of its combined moderate seismic hazard and relatively smaller building inventory relative to other regions. Table 2 is a proposed national allocation of resources tabulated for each ANSS region. Future allocation of resources for instrumentation of buildings in Puerto Rico as part of the National ANSS Program also should be based on application of this formulation.

Regional Priorities

Guidelines for establishing criteria for identifying specific buildings within ANSS regions should be a high priority. The guidelines should accommodate Recommendations 1 through 8, as well as local building and seismic hazard factors. Significant weight should be given to local seismic hazard and to local annualized expected earthquake loss and annualized loss ratio for urbanized areas within ANSS regions. Additional local factors to be addressed include a) types of buildings (see Borcherdt et al., these Proceedings); b) expected maximum ground motion intensityseverity; and c) foundation geology and soil conditions.
Criteria and guidelines for selecting buildings for instrumentation within a region should be closely coordinated with criteria and guidelines for establishing free-field strong-motion reference stations in urban areas. To the extent practicable, every instrumented building should have a strong-motion reference station.
Each ANSS region should have the flexibility to allocate resources for strong-motion instrumentation of buildings and free-field strong motion stations annually, recognizing that the long-term national objective of the strong-motion element of the ANSS is to achieve approximately a 50%-50% allocation of strong-motion instruments in buildings and in urban free-field locations.

Use of New Technologies

Recommended current specifications for strong-motion accelerometers are as follows:
Consider using other types of sensors or monitoring strategies when appropriate to accomplish specific building instrumentation objectives.
Real-time monitoring of buildings or some channels in selected buildings should be part of the ANSS building instrumentation program. The ANSS program should actively seek to establish agreements with NEES and local governments for joint support of such efforts.
The ANSS should allocate a reasonable portion of its total resources for strong-motion installation and monitoring to actively advancing instrument and monitoring technologies with the objective of improving measurements and reducing cost.

Engaging Private Participation

The ANSS should develop strategies to ensure private participation in the ANSS strong-motion element. This effort should engage local jurisdictions responsible for emergency response and recovery following damaging earthquakes, individual building owners, practicing earthquake engineers, and code groups and code implementation officials. The strategies should define how the ANSS serves these constituencies. Demonstration projects involving the various constituencies should be pursued.

References
Borcherdt, R. D., A. Frankel, W. B. Joyner, and J. Bouabid (1997). Vision 2005 for earthquake strong ground-motion measurement in the United States. In: Proc., Vision 2005: An Action Plan for Strong Motion Programs to Mitigate Earthquake Losses in Urbanized Areas, J. C. Stepp, Ed., National Science Foundation. Borcherdt et al. (2001). National and regional priorities for allocation of strong-motion instrumentation in buildings, these Proceedings, pg 152.

Celebi, M. (2001). Current practice and guidelines for USGS instrumentation of building, including federal buildings, these Proceedings, pg. 23.

COSMOS (2001). Guidelines for installation of advanced national seismic system strong-motion reference stations.

COSMOS Publication No. CP-2001/02, Richmond, Calif., http://www.cosmos-eq.org/Guideline_PDF.pdf.

Nishenko, S. (2001). National perspectives on seismic risk, these Proceedings, pg. 139.

Otey, D. (1997). Kaiser Permanente Northern California strong motion instrumentation program, In: Proc., Vision 2005: An Action Plan for Strong Motion Programs to Mitigate Earthquake Losses in Urbanized Areas, J. C. Stepp, Ed., National Science Foundation.

Savage, W. U. (1997). Strong-motion programs mandated by code and regulation, In: Proc., Vision 2005: An Action Plan for Strong Motion Programs to Mitigate Earthquake Losses in Urbanized Areas, J. C. Stepp, Ed., National Science Foundation.

Shakal, A. F. et al. (2001). Strategies and criteria for the selection of buildings for instrumentation, these Proceedings, pg. 5

Stepp, J. C., Ed. (1997). Proc., Vision 2005: An Action Plan for Strong Motion Programs to Mitigate Earthquake Losses in Urbanized Areas, J. C. Stepp, Ed., National Science Foundation.

U.S. Geological Survey (1998). An assessment of seismic monitoring in the United States: Requirements for an Advanced National Seismic System, USGS Circular 1188.

Table 1. Applicable technologies for building monitoring.

Table 2. National priorities for allocation of building instrumentation resources to ANSS regions. The number of buildings with 30 channels each is based on three thousand, 3-channel accelergraphs as requested by the ANSS proposal [Borcherdt et al., these Proceedings].