Pipe joint design considerations are a critical component for the overall performance of culvert and storm drain installations. Experience has shown that the component responsible for many culvert and sewer performance problems and failures can be traced back to the pipe joint. The structural and hydraulic performance of the joint affects the stability of backfill and soil envelope around the pipe, the line and grade of the culvert, integrity of the overlying embankment and pavement, and compliance to storm and sanitary sewer permits.
Structural design methods have been developed for moment-transfer and moment-release joints in reinforced concrete, corrugated steel, and thermoplastic culverts in NCHRP Web-Only Document 190: Structural Design of Culvert Joints. The proposed structural design methods provide values of shear force, and bending moment or rotation associated with earth loads and vehicle loads. In addition, a new pipe joint test frame which focused on structural performance was developed to establish whether joints have the capacity to accommodate the expected shear forces, moments and rotations.
For hydraulic performance there has been no investigation for joint leakage of water infiltration or exfiltration. In addition, gaskets, o-rings or other seals used in joints normally feature natural or synthetic rubber that can exhibit time dependent response (e.g. creep under sustained load, or stress reductions under sustained deformations). Therefore, changes in contact pressures are expected between the surfaces of the seal and the surfaces of the pipe or band, so the ability to resist internal or external fluid pressure may change with time. Test methods need to be developed to establish whether specific joints in specific products remain watertight under short and long-term operation.
The objective of this research is to develop recommended test methods for joint leakage (i.e., watertightness) in AASHTO standard format. The test method should consider the AASHTO Standard Practice for Pipe Joint Selection for Highway culvert and Storm Drains –AASHTO Designation: PP63-09.
Agency final report was submitted to AASHTO SCOBS and AASHTO SOM/TS 4b - Flexible and Metallic Pipe. (NCHRP Staff: W. Dekelbab)