Prototype Testing of Load-Bearing Characteristics of Large-Diameter Reinforced Concrete Cylinder Pipes under External Loading

ABSTRACT To investigate the bearing capacity and mechanical properties of large-diameter reinforced concrete cylinder pipes (RCCPs) under external loading, prototype tests were designed based on municipal drainage engineering in the Xiong’an New Area. The strain response of large-diameter RCCPs to external loading was quantified. The results show that the strain of the pipe is positively correlated to the external load, and the deformation of the inner and outer reinforcements is generally consistent with the deformation of the corresponding inner and outer concrete layers. Under external loading, the steel cylinder of the composite structure is subjected to overall tensile forces. The inner concrete layer and its reinforcement experience tensile stresses at the crown and invert, and compressive stresses at the springline. Conversely, the outer concrete layer and its reinforcement are subjected to compressive stresses at the crown and invert, whereas tensile stresses develop at the springline. The structural response evolves through three distinct stages: the elastic stage (<131 kN), plastic stage (131∼276 kN), and failure stage (>276 kN). The maximum crack widths measured were 0.28 mm at the springline, 0.51 mm at the crown, and 0.41 mm at the invert. These findings provide valuable references for the structural optimization of large-diameter RCCP and their application in deep-buried pipeline engineering.