In October 2002, PEER awarded the Applied Technology Council (ATC) a contract to investigate the seismic response of short period buildings (ATC-55-1). The ATC-55-1 project is being conducted in support of a larger ATC project (ATC-55), “Evaluation and Improvement of Inelastic Analysis Procedures”, which is funded by the Federal Emergency Management Agency. The objectives of the larger ATC-55 project, which is being conducted in several phases over a two-to-three year period, are:

1. the development of practical recommendations for improved prediction of inelastic structural response of buildings to earthquakes (i.e., guidance for improved application of inelastic analysis procedures) and
2. the identification of important issues for future research

Phase I of the ATC-55 Project, completed in December 2001, focused on the assembly and refinement of important issues relating to the improvement of inelastic seismic analysis procedures. Activities included:

1. the formulation of an initial Work Plan
2. the solicitation of input from researchers and practicing engineers
3. the development of study models of typical buildings to stimulate discussion, facilitate analytical studies, and provide example applications
4. the identification and description of key issues requiring analytical study in Phase 2; and
5. the development of a Phase 2 Work Plan. These activities and related findings are documented in detail in the ATC-55 Project Phase I Report, which was completed in October 2001

Phase II of the ATC-55 Project consists of analytical studies to explore selected key issues, the generation of written discussions on important topics, and the formulation of focus groups to provide input and feedback on the concepts being developed on the project. Phase II also includes Focus Group meetings and the assembly and review of guidelines for the improved practical implementation of the procedures, including a draft camera-ready copy of the guidelines. One of the issues to be addressed in the Focus Groups is the seismic response of short-period buildings. This issue is being addressed under the subject ATC-55-1 Project. The investigation will be conducted in consultation with the ATC-55 Focus Group on Short-Period Buildings and the results from this investigation will be incorporated in the final report being prepared under the ATC-55 project, “Guidelines for Improved Practical Implementation of Inelastic Seismic Analysis Procedures”.

Issues to be addressed for Short-Period buildings include:

Input Motions At issue are processes that cause ground motions at the base level of structures to deviate from free-field motions, including embedment and base slab averaging effects. Engineering models are needed to estimate these effects within the framework of the ATC-55 Guidelines.

Foundation Damping There is a need to review available models for the damping attributable to foundation-soil interaction, including radiation damping and hysteretic soil damping.

The project will provide guidelines for the incorporation of soil-foundation-structure interaction effects into nonlinear static procedures for performance-based design. Accordingly, the work is in direct support of PEER’s mission.

1. Review documents containing relevant background information for the ATC-55 project (to be provided by the ATC-55 Project Director) and consult with appropriate project personnel to gain additional familiarity with the technical scope of the project and its objectives
2. Review available literature related to technical issues such as kinematic soil-structure interaction, foundation damping, and ground motion incoherence Consult as needed with experts in those technical fields
3. Participate as needed in ATC-55 Project Management Committee (PMC) meetings
4. Participate in research program on Issue 3, Non-Uniform Input Motions, by
   • attending meetings with the member of the PMC who leads the Focus Group on Short-Period Buildings and
   • provide suites of appropriately incoherent input motions for use in the research work.
5. Prepare draft written report chapter documenting the outcomes of the above work for presentation to an ATC-55 Focus Group for Short Period Buildings. After suitable review, it is intended that this chapter would be part of the ATC-55 project report
6. Participate in Focus Group meeting to solicit input and attempt to reach consensus on technical issues raised in the draft report chapter.
7. Working with Focus Group Leader, the ATC-55 Project Director, and other PMC members, prepare the final draft of the report chapter originally drafted in (5). This report chapter is the project deliverable

The final report on this effort is to be completed by April 2003.

question skipped

Testing of SFSI is being performed within PEER by Kutter and Martin, which is leading to more sophisticated models for soil-foundation interaction springs. This work is complementary to the current work. The PI is unaware of other current projects outside of PEER that are supportive of this work.

question skipped

Results of project will be incorporated into the ATC55 document, and hence will likely see use in industry.

Draft report December 2002, final report April 2003

Final project report for inclusion in ATC 55 document