Prestressed Concrete Pipe Beams

Abstract

In the design of sewerage systems, the engineer is constantly faced with the problem of conducting sewerage from one point to another in the most economical manner. The most direct way for this to be done is to construct a sewer at a uniform slope in a straight line between both points in question. Crossing rivers, streams, peat bogs, swamps, and valleys is a continuing problem. The means of getting from one side of these obstacles to the other is usually accomplished by a grade-line sewer under the obstacle, by an inverted siphon ' (or pressure sewer) beneath the obstacle, or by spanning the sewer line over the obstacle. The main disadvantage of crossing under a river or stream with a grade-line sewer is almost invariably the deep cuts which are required on either side, with the resulting additional costs of excavation, etc. The main disadvantage of crossing under a river or stream by an inverted siphon is the complexity of construction. In addition, if the expected sewage flow in the early years differs considerably from the