Flexural Performance of UHPC Plate with Ribs in Comprehensive Utility Tunnel

Abstract:

To address issues such as multi-compartment design， heavy self-weight， and susceptibility to cracking and water leakage in prefabricated assembled reinforced concrete （RC） box utility tunnels， this paper proposes a ribbed ultra-high performance concrete （UHPC） utility tunnel structure. Static loading tests were conducted on UHPC plates with three different cross-sectional shapes， rectangular， trapezoidal， and flat， with varying rib heights， to analyze the effects of parameters such as reinforcement ratio， rib height-to-width ratio， steel strength， and UHPC compressive and tensile strengths on the flexural behavior of the components. The results indicate that all specimens exhibit under-reinforced failure， with the steel reinforcement yielding while the compressive capacity of the UHPC is fully utilized. Under the same material usage， the rectangular ribbed plate demonstrates significantly higher load-bearing capacity and stiffness than the trapezoidal ribbed and flat plates. A 50 mm increase in rib height improved the load-bearing capacity by approximately 20%. Increasing the reinforcement ratio， rib height， steel strength， and UHPC tensile strength effectively enhances the load-bearing performance of the ribbed UHPC plates. In particular， using steel reinforcement with a yield strength exceeding 785 MPa or a reinforcement ratio above 2.5% cause the failure mode to shift from under-reinforced to an appropriately reinforced mode.