Research on ultimate capacity and flexural stiffness of novel pipe roofing structure

This study developed a novel pipe roofing structure, called secant pipe roofing structure (SPRS), which is widely used in the support field of underground stations. Its flexural studies are essential since the structure is subject to bending load conditions. However, the influence of parameters and methods for predicting ultimate load capacity still needs more attention. Therefore, this study comprehensively investigated the flexural performance of SPRSs via experimental and numerical methods. A total of four SPRS specimens were prepared and tested under in-plane bending. The test results show that all specimens exhibited remarkable ductility. The load vs. displacement curves of SPRSs during the whole testing process were discussed in detail. Besides, numerical simulation of the flexural performance of SPRSs was carried out and an extensive parameter analysis was also made to ascertain the influences of several key variables. Finally, the support vector machine (SVM) and back propagation (BP) models were introduced to predict the ultimate capacity of SPRS. The accuracy and reliability of the developed models were examined according to the available experimental observations and simulated results by finite element (FE) analysis. This investigation provides a valuable reference for the design and application of SPRS in underground stations support.