SPIDA Method for Reinforced Concrete Pipe Design

Kurdziel, John M.; McGrath, Timothy J.; ,

SPIDA Method for Reinforced Concrete Pipe Design

by John M. Kurdziel, American Concrete Pipe Assoc, Vienna, United States,
Timothy J. McGrath, American Concrete Pipe Assoc, Vienna, United States,

Document Type: Proceeding Paper

Part of: Creative Application of Materials Engineering

Abstract:

The required supporting strength of buried pipe is affected by the total load that is imposed upon the pipe and the manner in which the pipe is supported by the surrounding soil. The installation conditions have a significant impact on both the magnitude of the load and the quality of the pipe support, thus the use of the term 'soil structure interaction.' The classic procedure for designing reinforced concrete pipe is the indirect design method which is based on: (1) determining the moment that will occur at the pipe invert under the specified loading conditions, (2) determining a three-edge bearing load or 'D-load' that produced the same moment and, (3) the designing the pipe reinforcing for that D-load. This method has been in use for many years and has proven reliable. Direct design methods determine the actual moments, thrusts and shears in the entire buried pipe and design the methods that assume a soil pressure distribution on the pipe have also been successfully used for many years. The advent of finite element modeling of soil behavior now allows an even of direct design method in which the actual soil conditions around a pipe are accurately modeled in computer programs that determine the design forces within the pipe. This paper will demonstrate the differences between the various design methods by analyzing an actual instalation with both methods. The finite element analyses were completed with both methods. The finite element analyses were completed with the computer program SPIDA. SPIDA is an acronym for Soil Pipe Interaction Design and Analysis.

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