Hoisting Construction Technology for Through-Truss Steel Tubular Concrete Arch Bridge Arch Ribs

Literature Overview

The paper by Wang Wei, Yuan Ye, and Zhou Jie (2025), published in Journal of Xuzhou University of Technology (Natural Science Edition) (Vol. 40, No. 2, pp. 8-12), reports on the hoisting construction technology for the arch ribs of the 170-meter Hongkou Bridge, a through-truss steel tubular concrete (STC) arch bridge. This work, supported by the Zhejiang Province "Sharp Soldiers" and "Leading Geese" R&D Plan (2023C03183), addresses the critical construction engineering challenges associated with the erection of large-span STC arch ribs, which combine the structural efficiency of steel tubular concrete with the geometric complexity of through-truss arch configurations.

Core Technical Challenges

The construction of through-truss STC arch ribs presents a unique set of engineering challenges that distinguish them from conventional steel arch or concrete arch construction:

• Weight and geometry: A 170-meter span arch rib assembly, even before concrete infill, represents a massive structural component with complex three-dimensional geometry. The through-truss configuration adds lateral bracing members that increase the assembly complexity significantly.
• Erection methodology selection: The choice between single-segment (single-frame) hoisting and overall (integrated) hoisting has profound implications for construction safety, equipment requirements, and project schedule.
• Cable suspension system design: The temporary cable system used to support the arch rib during erection must account for multiple load combinations that differ fundamentally from permanent structural design conditions.

Comparison of Hoisting Methodologies

The study's finite element analysis and cable force comparison reveal that overall hoisting requires achieving high-precision three-dimensional assembly on the ground, which significantly reduces high-altitude work risks but imposes substantially higher demands on the cable suspension system's load-bearing capacity. The ground assembly process requires precise alignment of multiple steel tube segments and truss members, with dimensional tolerances that must be controlled to within tight limits to ensure proper fit-up during the integrated lift.

Cable Suspension System Design Considerations

The cable suspension system design for STC arch rib erection must account for several composite factors that are identified in this study:

1. Relaxation effects: Steel cables and wire ropes exhibit time-dependent relaxation under sustained load, which can lead to progressive sag and misalignment of the suspended arch rib during the erection sequence. The design must incorporate pre-tensioning strategies that compensate for predicted relaxation over the erection duration.
2. Wind-induced vibration: The large surface area and flexible geometry of the partially erected arch rib make it susceptible to wind-induced oscillations, particularly vortex shedding and galloping. The cable system must provide adequate damping or the arch rib must be designed with sufficient aerodynamic stability.
3. Unbalanced loading: During the sequential erection process, the load distribution on the cable system is inherently asymmetric. The design must identify the most critical load cases and ensure adequate safety margins.
4. Impact loads: The dynamic effects of lifting operations, cable tensioning, and connection procedures introduce impact factors that must be included in the structural analysis.

The study recommends a strength safety factor of at least 2.5 for the cable suspension system, which is notably higher than typical permanent structural safety factors. This elevated safety factor reflects the consequences of failure during construction (which could result in loss of life and project abandonment) and the inherent uncertainties in construction load predictions.

Numerical Simulation Methodology

The finite element analysis conducted in this study incorporates several environmental and construction parameters that are critical for realistic simulation:

• Temperature effects: Steel expansion and contraction due to ambient temperature variations can significantly affect the dimensional fit of the arch rib segments and the cable system geometry.
• Wind speed parameters: The wind loading on the suspended arch rib must be modeled with appropriate wind profiles and gust factors.
• Wire rope angle effects: The inclination angle of the suspension cables directly affects the load distribution and the equilibrium geometry of the suspended assembly.

Engineering Practice Implications

For engineers involved in the construction of STC arch bridges, this study provides several actionable insights:

• The overall hoisting approach, while demanding higher ground assembly precision and greater cable system capacity, offers a significantly safer construction methodology by minimizing high-altitude work. This aligns with the industry trend toward "ground-based assembly, integrated lifting" construction strategies.
• The cable suspension system design must adopt a comprehensive load combination approach that includes relaxation, wind, unbalanced loading, and impact effects simultaneously, rather than treating them as independent design cases.
• The recommended safety factor of 2.5 for the cable system should be adopted as a minimum design criterion for similar projects, with consideration for additional margin in projects with adverse site conditions or limited construction experience.

Key Reflections

The Hongkou Bridge case study illustrates the increasing sophistication required in STC arch bridge construction as spans continue to grow. The integration of finite element analysis with practical construction parameters demonstrates the value of construction-phase simulation in ensuring safety and quality. However, the study's findings should be contextualized within the specific site conditions, material properties, and construction sequence of the Hongkou Bridge project. Engineers applying these principles to different projects must perform project-specific analyses rather than directly transferring the safety factors or cable configurations. The emphasis on ground-based assembly and integrated lifting represents a meaningful evolution in construction methodology that reduces risk exposure for workers and improves dimensional quality control.