Analysis of UCSAnalysis of UCSby OpenSeesby OpenSees

GSR Tae-Hyung Lee PI Khalid M. Mosalam

May 23rd, 2002 Meeting at RFS

ObjectivesObjectives

• Conduct and verify a 2-D nonlinear time history analysis of UCS using OpenSees

• Develop floor responses to be utilized for the UCB and UCI shake table tests of the building contents

• Assess the importance of the different sources of uncertanties on the structural response

• Extend investigation to 3-D modeling including multi-directional ground motion

Current StatusCurrent Status

• 2-D structural model completed for the UCS building

• Time history results (as absolute and relative floor displacements and accelerations and mid-points of all floors) are available for two levels of seismic hazard (50% and 10% in 50 years)

• Similar results will be available for the third level of seismic hazard (2% in 50 years) by the end of July.

Future TasksFuture Tasks

1) Verification:

A similar shear wall building where response data are available will be analyzed using the same modeling approach in OpenSees

An example is the 9 story Robert A. Millikan Library Building at Caltech [McVerry 1979]

Future Tasks Future Tasks (Cont.)(Cont.)

2) Assess Importance of Uncertainties:The following five sources will be considereda) Spectral accelerationb) Massc) Dampingd) Force-deformation characteristics of the different

elements, e.g. in terms of moment-curvature relations

e) Soil/foundation properties

Future Tasks Future Tasks (Cont.)(Cont.)

2) Assess Importance of Uncertainties (Cont.):

The objective is to conduct similar study to that of (Porter et al. 2002, Earthquake Spectra) with focus on structural response parameters (rather than costs) and their sensitivity to modeling issues and input intensities.

The importance of uncertainties will be assessed by developing a “tornado diagram” using the idea of “swing” estimation.

Future Tasks Future Tasks (Cont.)(Cont.)

A methodology has been developed using SFEM to generate probabilistic moment-curvature or interaction diagrams of RC elements [Lee and Mosalam, 2002, Computers and Structures]

Future Tasks Future Tasks (Cont.)(Cont.)

Several verification studies were conducted

Future Tasks Future Tasks (Cont.)(Cont.)

Some results of interaction diagrams

Future Tasks Future Tasks (Cont.)(Cont.)

3) Extension to 3-D:

Modeling structural elements in longitudinal as well as transverse direction.

Subject the building to simultaneous components of the ground motions.

Investigate variations of floor response parameters within the floor space.