Research On The Static Behavior Of Segmental Precast Concrete Piers

For the sake of the alleviation of growing traffics and consequent congestion, the viaduct can be considered as an effective solution. Segmental Precast Concrete Pier, characterized by rapid construction and less intervention on existing traffic system, attracts extensive attention domestically and globally. In comparison to integrated structures, there exist a few uncertainties in terms of the connections between precast segments, which limit the application of this sort of structure in construction work. Therefore, theoretical researches and experiments regarding to Segmental Precast Concrete Pier are of significant importance. This thesis describes the static experiment of two different Segmental Precast Concrete Piers and their numerical simulations. The following refers to the working process and conclusions.1. As the outputs of the static experiment of Segmental Precast Concrete Piers, horizontal load-displacement curve on the top of the pier and relevant stresses were obtained, together with the exhaustive record of the failure of samples. Simplified mechanical model and bidirectional flexural procedure based on plane cross-section assumption were implemented to analyze the results. Theoretically, the failure of the pier starts from the flexural cracks at the bottom of the pier, where represents a weak surface on the tensile zone of a plain concrete. The failure mechanism reveals a crush on the compressive zone of the concrete, and simultaneously a rigid body motion occurs on the compressive edge at the bottom of the pier.2. The finite element analysis software "ABAQUS" was used to simulate the Segmental Precast Concrete Pier and a comparison between the numerical and the experimental results was made. Consequently, the stress state of the glued material was at the elastic phase along the whole process. The crack located on the joint was proven to be the sequence of the crack on the plain concrete. Less contribution was found on the reinforcements, which was designed to be resistant against global cracking load and to be beneficial on ultimate bearing capacity.3. A simplified theoretical analysis was made on the behavior of the pier under loading. A discussion on the formation of plastic hinges at the bottom compressive zone was undertaken. MATLAb coding was implemented in order to simulate the flexural behavior of the model.4. The effect of the vertical load magnitude on the mechanical behavior of the Segmental Precast Concrete Pier was studied. It can be demonstrated from the numerical results that, the cracking load and the ultimate bearing capacity ascend as the result of vertical load increase. While it comes to a certain extent, a failure, which is characterized by compressive, flexural and shear components, occurs. This results in a complex failure other than a simple bending failure.5. Based on the foregoing conclusions, three improvement measures were proposed in order to optimize the mechanical behavior of the Segmental Precast Concrete Pier:(1) extent the reinforcement into the shear key;(2) increase the height of the shear key;(3) arrange the shear keys along the perimeter of the segments. It was proven by the finite element analysis that, all these three scenarios can increase the global cracking load and ultimate bearing capacity in a good manner, as well as the ductility of the structure.6. A preliminary discussion on the computational method about the sectional bending capacity of Segmental Precast Concrete Pier was undertaken.