The collision of overheight
vehicles and objects with bridge girders is a not uncommon occurrence that
requires timely inspection and engineering assessment to determine if repair or
replacement is required. When girders of
prestressed concrete bridges are impacted, this assessment is particularly
challenging due to the potential for internal damage that is not readily
detected by conventional visual inspection.
Furthermore, when girders are damaged during the construction of the
bridge, subjectivity in the assessment may lead to disputes with liable parties
that can lead to litigation and delay construction.
The primary objective of this research
project was to produce a physics-based approach to support the assessment of
prestressed concrete girders impacted by overheight vehicles. The research leverages high-fidelity finite
element (FE) modeling with advanced constitutive and contact models, while
building on verified techniques for collision simulations. A key innovation is
the development of a Collision Analysis Engine (CAE), an automated script
library that generates detailed 3D models of bridge superstructures from basic
parameters, incorporating elements like girders, decks, diaphragms,
reinforcement, and elastomeric bearings.
Additionally, the research introduces the first high-fidelity finite
element model of a dump truck with raised bed to permit simulation of the most
common vehicle involved in overheight collisions. A case study involving impact damage to
girders of a prestressed concrete bridge under construction is used to validate
the plausibility of the model.
Developed model of dump body and assembled model of dump truck with raised bed.
Furthermore, insight into differences in failure mechanisms and
vulnerabilities of girders during construction are produced through simulations
and the effect of the presence and type of intermediate diaphragm on girder
resistance to impact damage is explored, resulting in guidance for inspection
of prestressed concrete girders when impacted prior to the construction of the
deck.
The research advances the state of knowledge by providing the first comprehensive
parametric studies of raised bed dump truck collisions with prestressed
concrete girder bridges, revealing critical insight into the effects of bridge
characteristics and truck velocity, angle of raised bed, impact location, and
vertical underclearance violation on the resulting damage and producing
empirical model to predict impact force characteristics.
Lastly, a framework for risk-based,
simplified prediction of damage severity based on iso-damage curves is
formulated and demonstrated using a detailed model of a representative
superstructure.
