The goal of this project is to develop and calibrate tools for assessing reinforced concrete column seismic performance, including data and models for both seismically conforming (ductile) and non-conforming (brittle) columns.

PEER's mission is to "develop, validate and disseminate performance-based seismic-design technologies." This mission has many facets, but one important step is to relate deformation demands placed on structural members with the likelihood of reaching particular levels of damage. For example, at a particular level of deformation, what is the likelihood that the reinforcing bars in a column will have buckled? This project provides the data and tools necessary to construct this link for reinforced concrete columns, one of the most vulnerable and critical structural components of building and bridges.

1. Continue to expand the scope of existing PEER column database, which was developed in years 1-5. This database will provide the basis with which to evaluate seismic design and assessment tools. The online database can be accessed at http://ce.washington.edu/~peera1.
2. Develop and apply performance models to relate numerical data from simulation models to damage states that represent column performance in the PEER PBEE methodology. In particular, we will select, calibrate, exercise and validate OpenSees models for columns in collaboration with Professors Fenves, Fillippou and Deierlein.
3. Investigate whether and how accounting for the effects of cumulative deformation will improve the accuracy of estimates of column damage.
   Implement these models as part of the I-880 bridge testbed. The column performance models will incorporate uncertainties and inaccuracies in column behavior and be able to track the effects of these factors through the analysis.

DATABASE
The size and scope of the database have been expanded during the past year. Most importantly, the online database not only provides test properties and digital, force-deflection histories, it also now provides the peak level of column deformation preceding the observation of each level of damage. The database is available at http://ce.washington.edu/~peera1.

PROGRESSION OF DAMAGE
A series of non-dimensional measures of column deformation (drift ratio, displacement ductility, plastic rotation, nominal compressive strain and nominal tensile strain) have been evaluated to determine the suitability for predicting the onset of spalling and bar buckling.

• k is equal to 50 for rectangular-reinforced concrete columns and 150 for spiral-reinforced columns
• L: length of column to point of inflection
• P/Agf'c : axial-load ratio
• : transverse reinforcement ratio
•  fytrans : yield strength of the transverse reinforcement
•  f'c : concrete compressive cylinder strength

For each model, fragility curves have been developed, such as the one shown in Figure 1.

During Year 6, damage models will be developed for the OPENSEES simulation models. The potential of accounting for deformation history will also be investigated.

This work does not duplicate research performed by others, but it does depend on extensive interaction with other PEER researchers.

Once the models have been calibrated for columns, it will be necessary to integrate the damage estimates into analyses of more complex structures. In such structures, it will be necessary to distinguish between model inaccuracy and inherent variability, in order to large numbers of columns (to what extent are individual assessments of individual columns independent of assessments of other columns in the same structure?)

Fragility curves were provided to CALTRANS.

• June 2003 - PEER report that describes current models based on overall deformation.
• June 2004 - PEER report that describes OPENSEES damage models and their accuracy.

Prediction models and accuracy statistics for development of damage in reinforced concrete columns.