Spring
2004
Dynamic Analysis and Experimental Verification of Bridge Vibration
Md. Sorowar-E-Morshed
The
main objective of this work is to study the dynamic behavior of two- and
three-dimensional bridges under moving vehicular loads. The two-dimensional
straight bridges are studied both by numerical analysis and experimental
verification, while the three-dimensional curved bridges are only studied
numerically. A
bridge model is developed at the Structural Mechanics and Strength of Materials
laboratory of UAP. The experimental works use an aluminum bridge deck about
10-ft long. A laboratory arrangement consisting of vehicular loading with
different wheels, superimposed load and vehicular velocity and a computerized
data acquisition system are also developed for this study. The data collected
for simply supported and three-span continuous bridge includes the deflection at
particular reference points. The experimental and numerical results show
reasonable agreement, with the experimental values being within 0.60 to 1.33
times the numerical values. But the vehicular velocities generated in the
laboratory are found to be inadequate to cause significant dynamic effect on the
bridges, and the deflections obtained for various velocities are not
significantly different.
The work on three-dimensional RCC bridges concentrates on numerical studies to investigate some important deflection and force parameters for two-span straight bridge, arch bridges, horizontally curved bridge and three-dimensional curved bridge. The HS20 loading is used for the dynamic analyses, which are performed for vehicular velocities of 44 ft/sec and 88 ft/sec. The
impact factors obtained from this study are within the limits specified by
AASHTO for the absolute maximum deflections and forces but far exceed the AASHTO
specified values for maxima in the reverse directions. This can be crucial for
the structural design of the bridges made of RCC in particular, whose behavior
under tension and compression are entirely different. |