DESIGN OF THIN WALL REINFORCED CONCRETE PIPE USING DIMENSION RATIO (DR)

Dimension Ratio is defined as the ratio of the internal pipe diameter to the pipe wall thickness. The Caltrans culvert research leading to the development and use of the Dimension Ratio (DR) design parameter and the research conducted by Hydro Conduit Corporation on thin wall reinforced concrete pipe were instrumental in establishing design lateral pressures. These values are related to dimension ratios consistent with the three bedding and backfill methods currently used by Caltrans. A design table has been developed with diameters ranging from 24 inches to 84 inches with 10 foot, 20 foot and 40 foot overfills. In its first application on a Caltrans project at Pacheco Pass, a cost savings of 150,000 was realized on the installation of twin 108-inch reinforced concrete pipes.