JOINT CONFERENCE PROCEEDINGS 7th International Conference on Urban Earthquake Engineering (7CUEE) & 5th International Conference on Earthquake Engineering (5ICEE) March 3-5, 2010, Tokyo Institute of Technology, Tokyo, Japan A STEEL DATABASE FOR COMPONENT DETERIORATION OF TUBULAR HOLLOW SQUARE STEEL COLUMNS UNDER V ARYING AXIAL LOAD FOR COLLAPSE ASSESSMENT OF STEEL STRUCTURES UNDER EARTHQUAKES Dimitrios G. Lignos 1) , Helmut Krawinkler 2) 1) JSPS Post Doctoral Fellow, Disaster Prevention Research Institute (DPRI), Kyoto University, Japan 2) Professor Emeritus, Dept. of Civil Engineering, Stanford University, Stanford, CA, USA d.lignos@kt2.ecs.kyoto-u.ac.jp, Krawinkler@stanford.edu Abstract: Collapse assessment of structural systems under earthquake excitations requires analytical models that are capable to simulate deterioration of structural components. Reliability of analytical predictions to collapse depends on available experimental data that serve for validation and improvement of component deterioration models. This paper summarizes the development of a database that includes more than 120 tubular hollow square steel columns subjected to combined axial load and cyclic moments. The database serves for deterioration modeling of tubular steel columns. Based on extensive calibration of the simulated hysteretic response using a deterioration model with available digitized moment rotation data, relationships are proposed that associate analytical model parameters with criteria that control deterioration of tubular hollow square steel columns. The relationships are developed based on multivariate regression analysis. It is shown that the pre and post capping rotation and cyclic deterioration of tubular hollow square steel columns strongly depend on the axial load and the depth to thickness ratio of the column section. 1. INTRODUCTION Recent earthquakes around the world (Northridge 1994, Kobe, 1995, Taiwan, 1999, China, 2009) demonstrated that structural systems may collapse when they are subjected to extreme seismic events. In order to assess the collapse potential of structural systems under earthquakes within a confidence level, state-of-the art analytical models that are able to simulate important component deterioration modes should be used together with advanced numerical analysis tools. Reliability of analytical simulations based on these models is based on extensive calibration of the deterioration model parameters with available experimental data from steel and reinforced concrete component tests. This experimental data needs to be available in a consistent format, and most important, the digitized load deformation (deduced moment rotation) diagrams should also be provided. Hence the development of component databases is necessary for calibration and improvement of available deterioration models and statistical assessment of their parameters. So far, few databases are available that provide partial information on steel and reinforced concrete (RC) component hysteresis, setup and configurations (SAC, 1998, http://www.sacsteel.org/connections/ , Berry et al. 2004, Panagiotakos and Fardis, 2001, Fardis and Biskinis, 2003). Hajjar (2000) and Tort and Hajjar (2004) developed a database of rectangular concrete – filled steel tubes (CFT) for performance – based design and evaluation of distributed and concentrated plasticity analytical models for cyclic analysis of CFT columns (Hajjar et al. 1997, 1998). Recently, Lignos and Krawinkler (2007, 2009) developed a database of more than 300 steel beams. This database provides complete information on metadata, results and fully digitized load - deformation (deduced moment - rotation) data and serves for modeling of component deterioration of steel beams with different connection types. This database can be also used for modeling of component deterioration of steel columns, but with caution due to limited experimental data that is available. The steel beam database is available through George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) central repository(https://central.nees.org/?action=DisplayExperime ntMain&projid=84&expid=1590 ). This paper summarizes the development of a steel database for modeling of component deterioration of tubular hollow square steel columns under varying axial load and cyclic or monotonic bending moments. Based on the available information from this database and a recently developed deterioration model, relationships are proposed that associate deterioration model parameters with geometric and material properties of the tubular hollow square steel columns. 2. COMPONENT DETERIORATION Many analytical models that simulate component deterioration in strength and stiffness are available in the