9416463 Cheng This project investigates damage and collapse behavior of MissionGothic Undercrossing and Bull-Creek Canyon Channel bridges. Damaged structures on site were studied and field observations extensively with eminent engineers in California were exchanged. The tasks include: (1) failure criteria and nonlinear finite element analysis, (2) structural modeling and response analysis, (3) effect of interacting ground motions, (4) results synthesis, and (4) recommendations on bridge code improvements. Analysis includes formulation of nonlinear finite elements and the effect of interacting ground motion on structural response. Analytical results will verify field observations and enhance current practice in design and retrofit of bridges in the US. This is a Northridge Earthquake project. ***
