Behavior of Curved Post-Tensioned Concrete Structures

Principal Investigators: Oguzhan Bayrak and Trevor Hrynyk
Research Assistants: Jongkwon Choi and Clint Woods

4 men in hardhats in front of curved concrete structure

Research aimed toward understanding the underlying mechanics and behavior of curved post-tensioned concrete structures subject to prestressing loads is somewhat limited in the literature. Previous research focused on radial stress development has been analytical and, to the research team’s knowledge, there is no experimental research on this topic currently available in the public domain. As a result, this research study is aimed at producing unique experimental data to gain important insights into the effect of localized tensile stresses and concrete delamination behavior in curved post-tensioned structures.

Large-scale specimens with quarter circle geometries were constructed without through-thickness reinforcement and tested under monotonically increasing circumferentially-applied prestressing forces. The curved post-tensioned concrete specimens were extensively-instrumented to capture abrupt delamination crack formation. As concrete delamination failures are directly dependent on the tensile strength of concrete, a battery of concrete tension tests (e.g., modulus of rupture, split tensile test, and direct tensile test), compression tests and modulus of elasticity tests were conducted to characterize the material properties.  

Test results are currently being analyzed to gain insights into the delamination failure experienced by the test specimens. Early analyses of the data indicate that the delamination failure does not scale well and that there is an apparent size effect that governs the delamination behavior. The data gathered is currently being used to gain additional insights into the radial stress distribution, the stress concentration around the ducts, prestress loss over the lengths of the tendons, and the reasons behind the apparent size effect observed in the tests.

3 men looking at computers while concrete testing happens inside warehouse 
3 men looking at cracked curved concrete structure 
4 views of a machine compressing concrete