Electronic Thesis/Dissertation
"Current Topics on Bridge Engineering" Open Access
Nowadays, engineers are challenged to provide economic solutions that could be implemented within minimum schedules. Also, higher security levels are in need.One of the most time consuming tasks in a bridge project is the construction of the superstructure. Precast full-depth concrete deck panels used with prestressed concrete girders could improve the time schedule for this task. A connection system using 1-1/4" diameter steel double-headed studs is proposed to provide composite behavior to the deck/girder system. Six specimens were tested under direct tension to test the capacity of the connectors to provide their full strength in order to achieve the composite behavior. Results showed that the connection provides the adequate capacity if additional reinforcement is placed next to the connectors. Non-linear finite element simulations were also performed to analyze the failing mechanism and to validate the results.Used to estimate long-term deflection, the "Precast Concrete Institute multiplier method" has not been updated since 1977. A parametric investigation was performed to develop refined multipliers for prestressed concrete girders considering different concrete strengths, two different codes and different time stages for the girders placement. A time-step method that considers the advances in concrete such as creep, shrinkage and relaxation formulations was used to estimate deflection at different stages and for comparison with the original multipliers method.Terrorist attacks and openness of bridges increased the need to evaluate their vulnerability to events such as impact and to include their effects into the design. Analytical and experimental investigation was conducted to study the vulnerability of bridge girders under impact loads. A displacement-based procedure was modified to predict the velocity of a mass that will cause a specific damage level in a reinforced concrete element. Moment-curvature relations that consider strain rate effects and nonlinear load deformation relations were developed. A single degree of freedom system was used to develop nonlinear shock spectra that correlate the peak dynamic impact force with the peak force of an equivalent static linear system. Nine reinforced concrete beams were tested under lateral impact for different damage levels. To estimate the impact velocities a Monte Carlo simulation was also performed.
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Mesia_gwu_0075A_10291.pdf | 2018-01-16 | Open Access |
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