Buckling and ovaling of pipe-line
Jirsa, James O.
Master of Science
In this investigation buckling failure of pipes and the influence of ovaling on the flexural behavior of pipe lines stressed beyond the elastic limit were studied. A total of six pipes were tested. Each pipe was loaded to produce a constant moment over the mid-length of the specimen. Experimental moment-curvature relationships into the plastic region of behavior were obtained. Theoretical ovaling values were computed, using a strain energy procedure, and were compared with experimental results. Empirical equations, relating the bending strength at buckling failure to the physical properties of the pipe were presented. The following conclusions were made: 1. An approach suggested by Ades satisfactorily predicted the moment-curvature and ovalization-curvature relationships for bare pipes under monotonic loading. 2. Diameter to thickness ratio controlled curvature at buckling failure. Pipes with lower D/t ratios were able to withstand greater curvature before the compression surface buckled. 3. The concrete coating had little effect on the buckling and ovaling characteristics of the pipes at the simulated field joint. 4. Empirical equations were developed which satisfactorily represented buckling behavior in the range of D/t ratios tested.