Numerical Modeling of a Structural Behavior of Reinforced Concrete Pipes with Modified Steel Cage

Reinforced concrete pipes (RCPs) are made of concrete and steel reinforcements, which have been widely used for sewerage, water drainage, and industrial wastewater conveyance. There are two major design methods for the RCP: direct design and indirect design methods. In both designs, due to the existence of tensile stresses at both the inner and outer surfaces of the RCP, the standard practice is to place the circumferential reinforcements in two layers along the pipe thickness. ASTM C76 is a tabulated designated RCP specification, which categorizes the RCPs into five classes based on the concrete strength and load-bearing capacity. However, the task of placing two cages of reinforcement is time-consuming, expensive, and sometimes unnecessary, especially for some pipes in classes III, IV, and V. Therefore, this study aims to investigate the feasibility of reducing the RCP’s conventional double cage circumferential reinforcements to one and proposes a proper location for the successor equivalent cage in the pipe thickness through a three-dimensional non-linear finite element analysis (FEA). The FEA models were verified with three experimental tests using the three edge-bearing tests (TEB) method. The numerical models were developed for RCPs for classes III, IV, and V for pipe diameters ranging from 24 to 72 in. Three different locations along the pipe thickness were considered for the equivalent reinforcement cage. The results showed that one cage of reinforcements in some pipes satisfies all the ASTM requirements, thereby making it possible for manufacturers to produce reinforced concrete pipes with a smaller amount of steel reinforcements, saving time and cost.