Drummond, Fairfield, Wamuziri
Non-Pressure Pipes Systems # 2001 Munich
First Order Second Moment (FOSM) analysis techniques, employed in the development of limit state design codes, allow designers to account for the variations and random nature of the material properties and load effects inherent in the design of engineered structures. A generated non-linear equation is used in conjunction with an existing design formula to model the load-deformation behaviour to failure of a flexible plastic duct in free-air compression. The duct was modelled as if it were subjected to the BS EN 50086 : 19941 parallel plate compression test load of 450 N at which the internal vertical diametral strain (VDS) must not exceed 5%. The duct was modelled with a predetermined internal diameter and wall thickness. The statistics of those random variables considered were modelled using normal and lognormal distributions. Duct reliability was evaluated by imposing a deformation due to an applied vertical load and calculating the reliability under assumed random variations in the pipe diameter, pipe wall thickness and material modulus of elasticity. The FOSM analysis provided a more rational description of duct behaviour.
Author(s) : Fairfield, Campbell, Reid
This work examines the wear properties and erosion resistance of plastic pipes under dynamic fluid impact and cavitation conditions. Testing to evaluate the performance of a range of plastics was undertaken. A test rig was calibrated for : flow stability, pressure hysteresis, frictional head loss, time to target...
Author(s) : Fairfield, Reid, Hounsome, Edwards, Sibbald
This paper provides estimates of the draw force needed to pull sub-ducts or cables through a series of typical ducted utility networks. Variables such as : coefficient of friction between the outside of the cable and inside of the duct, the main duct’s vertical diameter, the cable bundle or sub-duct’s external...
Author(s) : Fairfield, Hounsome, Reid
This paper presents a method of optimising the distribution of plastic in a twin-walled, corrugated duct. This could be used to achieve maximum stiffness for minimum linear mass or a desired target stiffness for any envisaged market for the product. Spreadsheet optimisation routines1 based on a generalised reduced...