Research on the Removal Sequence of Arch Rib Assembly Supports for Concrete-Filled Steel Tubular Tied Arch Bridges

The main bridge of the Bayi Bridge project in Yangxin County is a concrete-filled steel tubular tied arch bridge with a calculated span of 127.04 m. The steel pipe arch ribs adopt a dumbbell-shaped cross-section, are manufactured in seven longitudinal sections, and are constructed using the support method. The tie beams are fully prestressed concrete structures. The design guidance plan is to remove the arch rib assembly bracket after completing the arch rib steel pipe concrete construction. Considering that during the construction process of steel pipe concrete top pressure injection, the arch rib assembly support bears a large load and has high safety risks, an optimization plan is proposed to remove the arch rib assembly support first after the steel pipe arch rib assembly is completed, and then top pressure injection of steel pipe concrete. To analyze the optimization effect, a finite element model was established using Midas Civil analysis software to analyze the stress of the two schemes. The results showed that the maximum stress of the steel pipe arch rib in the optimized scheme increased by 11.7 MPa, reaching 128.4 MPa, which is less than the material design strength; The compressive stress of the upper and lower chord concrete decreased by 1.8 MPa and 2.4 MPa respectively; The difference in arch rib deformation has little impact on the selection of the two schemes, and can be solved by setting pre camber; The tensioning of N2 and N7 prestressed steel tendons has little effect on the structural stress, and the optimized plan meets the stress requirements.