| Bridge piers are often subjected to lateral loading that is not neglectible when compared to vertical loads. Such loading conditions may include wind, water and earthquakes. In order to develop a time domain analysis for the nonlinear dynamic response of piers and their foundations the computer program Florida-Pier was modified. Florida-Pier is a nonlinear finite-element program, developed at the University of Florida, designed for analyzing bridge pier structures composed of pier columns and cap supported on a pile cap and piles with nonlinear soil. The program was developed in conjunction with the Florida Department of Transportation (FDOT) structures division. The piers and the piles are modeled as nonlinear 3D beam discrete elements. These elements use the true material stress-strain curves (steel and concrete) to develop its behavior and stiffness modeling. Nonlinear dynamic capability was added to these elements by adding to the stress-strain curves the ability to represent loading, unloading and reloading behavior, typical of dynamic loading. In addition, a mass matrix for this element was also implemented. The mass matrix for the piles cap was also developed. The cap is modeled as linear shell elements. The stiffness matrix for this type of element is considered to remain unchanged during the dynamic analysis. A nonlinear model was also added for the soil. The p-y springs generated by the program now have the capability of loading, unloading and reloading, just like the steel and concrete. Such models can then be applied to dynamic analysis of reinforced concrete structures subjected to seismic, impulsive, or wind loads. In addition, being the current state-of-practice, modal analysis was also implemented. Seismic load can now be applied to the linear structure considering the nonlinear behavior of the foundation. A description of the analysis used to model the nonlinear dynamic behavior of bridge piers, as well as the implemented nonlinear material behavior, is presented in this dissertation. |
