Advancing the seismic design of reinforced concrete bridge columns

Recent earthquakes near highly populated cities have reminded the world and engineers about the destructive capabilities of an earthquake event. This is especially true in the design of reinforced concrete bridge columns that need to survive an event to maintain life safety and provide operational capacity along major lifelines to provide immediate assistance to the regions affected. The research presented within this document examines the current state of practice and looks for ways to improve the design methodologies prior to an event that highlights unforeseen consequences. This is accomplished through a series of analytical and experimental studies that include: (1) the development of a new simplified method for the lateral load response of columns continuously supported on drilled shafts; (2) the behavior of concrete and soil when subjected to frozen conditions; and (3) the impacts of current methodologies for the establishment of transverse confinement reinforcement on the seismic response of reinforced concrete bridge columns. A new approach is discussed within that defines an equivalent cantilever supported by a flexible base using a set of three springs for the establishing the lateral load response of columns continuously supported on drilled shafts in non-cohesive soils. This is an extension of the work presented in Appendix A in order to provide a consistent approach for both cohesive and non-cohesive soils that may be encountered near a bridge site. The effective height of the system was defined as the distance from column tip to the point of maximum moment to identify a critical design location for the establishment of transverse confinement reinforcement. The new method was found to adequately capture the response when