Analysis on Pre-Stressed Friction Loss in Bending Channel under Contact Pressure Non-Uniform Distribution Hypothesis

Abstract

The pre-stressed friction loss formula in bending channel recommended by Bridge Rules was based on the uniform distribution hypothesis of contact pressure. From some conflicts in application of the formula, the non-uniform distribution law of the contact pressure was revealed. On the basis of elastic contact analysis, two types of non-uniform distribution hypothesis were proposed, including cosine and second-degree parabola distribution. Then the contact positive pressure expressions were derived respectively and the frictional resistance was calculated to compare with the calculated value under the uniform distribution. The results indicate that the friction resistance under any non-uniform distribution of positive pressure is less than under the uniform distribution. So the uniform distribution assumption of contact pressure does not cause Bridge Specifications formula underestimate friction loss. It is necessary to do further research on the applicability of Coulomb’s law under the contact conditions in the curved channel.

Research on Prestressed Loss in Curving Hole of Prestressed Concrete Structure Caused by Frictional Resistance

“…5, we can conclude that prestressed loss in practice is different from prestressed loss in current norms. Literature [4] has researched several contact stress distributions in curving hole, and the prestress loss in uniform distribution of contact stress is large than other distribution. However, prestressed loss in current norms is smaller than prestressed loss in practice.…”

“…3 Contact stress in curving hole From the stress in A and B in fig.4and fig.5, we can conclude that prestressed loss in practice is different from prestressed loss in current norms. Literature[4] has researched several contact stress distributions in curving hole, and the prestress loss in uniform distribution of contact stress is large than other distribution. However, prestressed loss in current norms is smaller than prestressed loss in practice.In fact, each strand is not bonded together and the contact status is shown in fig.4a; Without original status, parts of strands contact with bellows, and others sit over it after stretching, see Fig.4b.…”