Validated Models of Passive Resistance of Homogeneous Backfills


Featuring Ertugrul Taciroglu, Ph.D.
Department of Civil & Environmental Engineering
The Henry Samueli School of Engineering and Applied Science, UCLA

Location:  Engineering Tower, Room 331
Free and open to the public

Recent advances in performance-based seismic assessment and design of bridges calls for the development of computationally efficient high-fidelity models for nonlinear transient dynamic analyses. A significant component of such models is that of the nonlinear lateral force-deflection of bridge abutment-embankment systems.  To this end, we performed extensive parametric studies using a previously validated limit-equilibrium model, with the aim to obtain a simple closed-form relationship for lateral response of abutment backwalls with uniform backfill. The resulting hyperbolic force-deformation (HFD) backbone curve has explicit dependency on the physical properties of the abutment system, including the backwall height. All input parameters to the HFD equation are measurable via standard geotechnical laboratory tests; and the HFD formulas are demonstrated to be valid for a broad variety of backfill materials. As opposed to limit-equilibrium models that produce only discrete data points on the backbone curve, the HFD equation can easily be implemented in a structural analysis package as a nonlinear spring that accounts for the bridge abutment-backfill interaction. Published measurements from several small-scale laboratory and full-scale field tests along with LSH simulations are used for validating the model.

About the Speaker:

Ertugrul Taciroglu earned a B.S. degree in 1993 from Istanbul Technical University, and M.S. and Ph.D. degrees from the University of Illinois at Urbana-Champaign (UIUC) in 1995, and 1998, respectively. After a stint at the Center for Simulation of Advanced Rockets (UIUC) as a postdoctoral research associate, he joined the Civil and Environmental Engineering Department at UCLA in 2001. His research activities span the disciplines of theoretical and applied mechanics, and structural and geotechnical earthquake engineering. He is currently conducting projects on topology optimization of smart material systems, soil-structure interaction in deep and shallow foundation systems, wave propagation in continuous media, inverse problems—with various applications in system identification, structural health monitoring as well as surveillance—and simulation of structural response under extreme loadings such as explosions, and ballistic impact.. Taciroglu is the 2006 recipient of a U.S. National Science Foundation Faculty Early Career Development (CAREER) award. He serves in various technical committees of the American Society of Civil Engineers (ASCE), and is an associate editor of the Journal of Structural Engineering.