ABSTRACT
Ring deflection is defined as the ratio of change in vertical diameter to the original diameter, d = /D. See Figure 7-1. Diameter D is the diameter to the neutral surfaces of the cross section of the wall. For most pipe analyses, it is sufficiently accurate to use the mean diameter, (OD+ID)/2. The error of using mean diameter increases for reinforced concrete pipes, pipes with ribs or stiffener rings, etc. Ring deflection is the result of: 1. inflation or deflation of the pipe, 2. flexing of the ring, 3. cracking of the ring into segments, and 4. plastic hinging (or crushing) of the pipe walls. Ring deflections of rigid and flexible pipes are two different phenomena. Each is analyzed separately.
