What Does Short-Term Bending Stress Mean?
Short term bending stress is measured as the pressure on a pipe that will cause the pipe to break when the pressure is raised from zero to a certain limit. In trenchless technology, pipes are installed without trenching by using methods such as directional drilling and microtunneling. Pipe materials used are high density polyethylene (HDPE, polyvinyl chloride (PVC), reinforced concrete, glass reinforced plastic (GRP) etc. All these materials are subject to bending stress during the process of installation and also afterwards.
Trenchlesspedia Explains Short-Term Bending Stress
Most of the pipe materials used today has elastic characteristics that help the pipe retain its integrity for longer periods of time thus providing a longer problem free service life. A buried pipe is subject to loads from all around but especially from the top soil and structures under which it is buried. The pipe is subject to the constant load from the top soil and structure but also from moving loads such as traffic which is not constant. As the load moves over the pipe, the pipe will experience a short term bending stress, which is normal. Once the load is removed the stress is relieved, however; if the load is not removed, the deformation of the pipe will continue till failure. It is important therefore while designing plastic systems such as pipes to consider the time under load such as pressure, weight, moving loads, etc. that the pipe will experience in its designed life.