Project Title/ID Number Damage Assessment of Building Nonstructural Components —5242002
Start/End Dates 10/1/02—9/30/03
Project Leader Eduardo Miranda (Stanford/Faculty)
Team Members Shahram Taghavi (Stanford/Grad Student)
Project goals and objectives

The objective of this study is to develop information and procedures to estimate the seismic performance of nonstructural components. This involves

  1. the estimation of Engineering Demand Parameters (EDP) that are relevant to nonstructural components, which usually involve additional information to that required to estimate the performance of structural components;
  2. the development of fragility functions that enable the estimation of the probability of being in different damage states as a function of EDPs;
  3. the development of loss functions that permit the estimation of economic losses as a function of the damage state.

This project is being conducted in connection with the seven-story reinforced concrete building PEER testbed structure. Loss estimation associated to structural components is being conducted in another project (Project # 1182002).

Role of this project in supporting PEER’s vision

The PEER mission is to develop and disseminate technologies to support performance-based earthquake engineering. In particular, one of PEER’s goals is to providing quantitative tools for characterizing and managing seismic losses. This project contributes to the estimation of the performance of nonstructural components which are the largest contributors to economic losses resulting from earthquakes.

Methodology employed

The methodology being employed to estimate the seismic performance of nonstructural components is based on PEER framework equation. This project is developing some of the information that will enable the PEER methodology to be applied to nonstructural components. In particular, work is needed in the following areas:

  1. Identification and classification of nonstructural components. Information of which nonstructural components are commonly installed in buildings is needed. They need to be classified according to their function in the building, according to the EDP that they are most sensible to, according to the impact to functionality of the building, according to their cost contribution to the total structure, etc.
  2. Development of fragility curves in order to be able to predict the probability of being in a certain damage state. Damage states and engineering demand parameters change from one nonstructural component to another.
Development of loss functions that permit the estimation of the economic losses or downtimes associated with the damage to nonstructural components.
Brief description of past year’s accomplishments and more detail on expected Year 6 accomplishments
Using architectural drawings of the tested structure, in year five a database of nonstructural components installed in the building was developed. Components were classified according to the taxonomy developed during year 4. The approximate cost of practically all components has been identified and major components to cost have been identified.

Figure 1. Cost distribution of nonstructural components in the Van Nuys testbed (in 1966 dollars)
Larger View

Fragility functions for gypsum board partitions on metal studs have been developed. These functions have been developed for three damage states associated with particular repair/replacement actions. Loss functions associated with these repair/replacement actions have also been developed.

In year six we are concentrating our efforts in two areas. The first area is the collection of EDP-DM pairs from 19 CSMIP-instrumented buildings that were shaken during the 1994 Northridge earthquake. The peak acceleration demand in instrumented floors need to be identified for each building, and acceleration in non-instrumented floors need to be estimated. Similarly, drift demands need to be estimated for each building in each direction using system identification techniques. Then damage observed in nonstructural components and the floor level in which they were observed need to be identified and classified. This is a slow and tedious process, but these pairs will provide very valuable information of the performance of many types of nonstructural components that have been subjected to different levels of structural motion. This information can be directly used to develop fragility functions.

The second area is the development of simplified methods to estimate peak floor acceleration demands and floor spectra ordinates in building subjected to earthquakes. The method has been compared to results from some analytical models and we have started to compare the results of our method to motions obtained in instrumented structures. Preliminary results look very promising. This method will permit the estimation of the acceleration demands on buildings that were not instrumented but where reports of damage after an earthquake are available.

Other similar work being conducted within and outside PEER and how this project differs

Within PEER:

  1. Building loss assessment: PI Eduardo Miranda, Stanford University, Project No. 1182002. Loss assessment with emphasis on structural components.
  2. Building loss assessment: UC Berkeley case study; PI Mary Comerio, UC Berkeley, Project No. 1192001. Project associated with another testbed structure with emphasis on building contents.
  3. Performance Characteristics of Building Contents: PI Nicos Makris, UC Berkeley, Project No. 5302002. Experimental project of performance of building contents.

Outside PEER: One project being conducted at USC related to nonstructural components in hospitals.

Our project is more focused on developing fragility curves of specific nonstructural components installed in commercial buildings and complements other projects in PEER that develop these functions for structural elements and contents. It also develops cost functions for different nonstructural components.

Plans for Year 7 if this project is expected to be continued

During year seven we plan to start using the information that was collected as part of the ATC-38 project on the performance of buildings that were close to recording stations. We will extract information on the performance of nonstructural components in commercial buildings with emphasis to acceleration-sensitive components. We will then estimate acceleration demands in each story in each of these buildings to get motion-performance pairs, which will then be used to generate fragility functions.

Describe any instances where you are aware that your results have been used in industry

Fragility functions developed in this project are starting to be used by structural engineering consultants to identify various levels of damage that are expected in interior partitions of buildings as a function of interstory drift.

Expected milestones
  • Motion-damage pairs from instrumented buildings – July 2003
  • Fragility functions for selected components – September 2003
  • Simplified method to estimate acceleration demands – September 2003

Fragility functions for selected components, Simplified method to estimate acceleration demands.