Behaviour and Design of Reinforced Concrete Pipes

Abstract

The overall objectives of this thesis are to determine if Indirect and Direct Design methods currently used for reinforced concrete pipe are able to accurately predict the capacity of the pipe, to identify discrepancies between the two methods, and to provide potential modifications to the methods to reduce inconsistencies. As part of this investigation, two 0.6 m pipes (nominal strength classes 100-D and a 140-D) and two 1.2 m pipes (a 65-D with Wall B and a 65-D with Wall C) were tested under single wheel pair loading at burial depths of 1.2, 0.6 and 0.3 m. The test pipes did not crack at the applied service load of 110 kN and did not pass the crack width limit until between 2.5 and 4 times the service load. A 0.6 m 100-D pipe was also tested under simulated deep burial and it was found that the calculated test D-Load is 1.9 times greater than the designated D-Load of the test pipe. It was found that both methods were conservative and that the Direct Design method should be modified to more closely align with the Indirect Design. An investigation of the Direct Design parameters found that by considering thick ring theory and the Modified Compression Field Theory with two layers of reinforcement, the required amount of steel from Direct Design could be made to align very closely with the Indirect Design. An additional test was completed to further assess the Direct Design method on a 0.6 m 140-D pipe to measure the pressure around the circumference of the pipe and compare this measured pressure to the commonly used pressure distribution for Direct Design. The results show that at the minimum cover (0.3 m) the test pressure is higher than predicted at the crown, lower than predicted at the invert, and nearly zero at the shoulder, springline, and haunch, which is inconsistent with most of the predicted results at these locations.