Master of Engineering Science
Civil and Environmental Engineering
Nehdi, Moncef L.
Reinforced Concrete Pipe (RCP) is widely used in storm and wastewater management owing to its resiliency and reliability. The century old Three-Edge Bearing Test (TEBT) is currently used to classify RCP strength. The test relies on the skill and experience of the operator for capturing the occurrence of a 0.3-mm-wide crack using a leaf-gauge, which induces subjectivity and error. Studies have also indicated the TEBT crack bears little structural significance.
This thesis aims at improving the TEBT by replacing the arbitrary crack-width with rational capacity-driven criteria. A wide range of full-scale RCP were instrumented and subjected to the modified TEBT to obtain load vs. deflection curves. Two rational criteria were developed to replace the arbitrary crack-width measurement, vastly improving the reliability of the TEBT. Parametric analysis was conducted on finite-element models (FEMs) to investigate the effect of RCP reinforcement area, yield strength, cover, and positioning on the proposed criteria.
Summary for Lay Audience
Reinforced-concrete pipe (RCP) is generally made with precast concrete and reinforced with one, two, or three layers of cages manufactured from steel wire. RCPs are buried underground and generally serve as wastewater sewers or stormwater drains. When buried, RCP must possess adequate mechanical strength to resist the weight of soil and any structures which may be built above. To ensure an that RCP can withstand the design loads, a specimen is tested by crushing it along its length and recording the load required to cause a 0.3-mm-wide crack to appear. This test is known as the Three-Edge Bearing Test (TEBT). The TEBT requires a human operator to determine when the specified crack occurs, which can lead to inaccuracies due to the operator calling the crack too early or too late. Furthermore, the 0.3-mm crack width was randomly selected and does not indicate a definite structural capacity.
To solve this problem, the present thesis investigates whether pipe strength can be classified based on load-deflection behaviour instead. Load-deflection is a plot of how much a given pipe specimen deflects (or deforms) as the applied load increases. The TEBT was carried out on full-scale RCP specimens instrumented with sensors, which measured the change in diameter during loading. Based on these results, modified TEBT criteria are suggested to replace the existing crack-measurement requirement. The suggested criteria should allow the industry to classify pipe based on rational scientific principles rather than error-prone crack measurements. To investigate the effect of reinforcement on the modified criteria, numerical models were created using computers to simulate RCP undergoing the TEBT. These simulations also provided some insight into how certain reinforcement variables can affect the overall load-deflection behaviour of RCP, providing benefit to the field of RCP design.
Younis, Abdul-Aziz, "Experimental and Numerical Study on Three-Edge Bearing Test for Reinforced Concrete Pipe" (2020). Electronic Thesis and Dissertation Repository. 7146.