Substructural Identification for Damage Detection in Uncertain Environments
Structural health monitoring promises to provide owners and engineers with tools to determine the condition of existing structures and make sound decisions for future investments. Though many algorithms have been developed to detect damage in a structure, further exploration is required in identifying damage-related behavior in field structures subject to large behavioral changes due to uncertain loading conditions and varying environmental conditions. This research aims to use substructuring techniques to identify damage in a divide-and-conquer manner. Such an approach will advance long-term monitoring deployments, which up to now have been able to detect the presence of damage, but not always the location. The experimental program involves sensor deployments on campus bridges in uncontrolled in situ conditions, and on small prototype structures tested and damaged under controlled laboratory conditions. |
Monitoring Staged Concrete Bridge Deck Pours Adjacent to Live Traffic
The need to minimize the impact of bridge deck repairs on traffic operations has led to the use of staged construction, where part of the existing bridge deck is left operational such that traffic can be maintained while the remaining part of the bridge deck is repaired or replaced. For new decks or full-depth replacement of existing ones, the presence of live load on one side of the bridge while concrete is cast on the other side not only generates vibrations on the curing concrete, but also relative vertical movement between the longitudinal joint and the adjacent bridge girder on the side being constructed. The objectives of this research are to evaluate the performance of various longitudinal joint designs applicable to bridge decks constructed in stages and to develop recommendations for the design and construction of staged concrete bridge decks and overlays. |
Progressive Collapse Simulation using Absolute Nodal Coordinate Formulation
Structural collapse is the disproportionate failure of a structural system precipitated by a localized extreme damage event. Obtaining experimental data for structural collapse is difficult and costly, and therefore much effort in recent years has focused on developing computational tools to model structural collapse in lieu of full-scale tests. Collapse is characterized by finite strains, large displacements (i.e., nonlinear geometry), and contact of many elements, for which traditional finite element formulations were not originally intended. The Absolute Nodal Coordinate Formulation (ANCF) is proposed to address these concerns. ANCF is specifically formulated to handle large displacements and rotations, and has been successfully used for multibody dynamic simulations of mechanical systems. Continued research has focused on the adoption of ANCF under the constraints of civil structural systems and materials, particularly reinforced concrete. |