Factors that influence end zone cracking in pre-tensioned prestressed concrete bridge beams - A finite element analysis
Abstract
The basic problem studied as part of this master's thesis work consists of two main parts. The first part investigates the incidence of cracking in end regions and potential methods and means to help mitigate the incidence of cracking through changes in prestress force and eccentricity. Previous experimental testing revealed that cracking in the regions may come from a number of different causes, some of which may be more studied and better understood than the others. Under loading, failures in end regions of prestressed concrete beams generally occur due to combinations of shear and bond failure. Interaction with flexural cracking is also observed. Historically the interpretation of these failures has been confused. Based on the past experience, a number of variables used in the design and study of prestressed concrete beams may affect the end regions of beams when the prestressing is initially applied as well as during the loading of the beams. The second part uses finite elements analysis (FEA) to examine results from experimental testing programs, and uses FEA to help develop rational design methods to help prevent shear failures in the end regions of precast/prestressed beams. Beams developed through experimental testing programs described in John Jacob (1998) thesis work from the University of Oklahoma, Norman, and Amol Ganpatye (2006) thesis work from the Oklahoma State University, Stillwater, are selected to be analyzed with FEA. Commercially available software FEA package called ANSYS 17.0 contains suitable finite elements or block elements that are used to analyze stresses in the concrete after applying prestressing forces at the ends of the prestressed concrete beams that mimic the transfer of prestressing forces into the concrete. FEA model is used to observe the behavior in the end regions of beams by comparing and contrasting changes in the potential flexural, shear and bond stresses in the beam as the number of variables is modified. This research paper describes the methods and means to help mitigate cracking and addresses potential gaps or limitations in the existing knowledge and current design practices, and provides the results of the linear elastic static finite elements analysis. It is believed that this work will provide summary of the current state-of-the-art and point direction for future studies and research.
Collections
- OSU Theses [15752]