Construction Monitoring Technology for Steel-Concrete-Filled Arch Bridges

Literature Overview

This paper by Su Jidong and Xu Qiang, published in "Agricultural Mechanization Research" (2005, Vol. 27, No. 1, pp. 227-228), describes the construction monitoring technology for steel-concrete-filled (SCF) arch bridges. The authors are affiliated with the Hainan Provincial Highway Survey and Design Institute and the Harbin Municipal Engineering Design and Research Institute. This research addresses the practical challenges of constructing large-span SCF arch bridges using the cable hoisting and cable-stayed support construction method, with emphasis on arch axis line control and dynamic adjustment through stay cables.

Technical Background

SCF arch bridges combine the advantages of steel pipe (lightweight, high strength, rapid construction) and concrete (cost-effective, durable, high compressive strength) in a composite structural system. For large spans (typically exceeding 200 m), the construction method significantly affects the final geometry and structural performance of the arch.

The cable hoisting and cable-stayed support method involves:

Erecting individual steel pipe segments by cable crane
Connecting segments to form the arch rib
Using stay cables (temporary) to control the arch axis line
Filling concrete into the steel pipe
Releasing stay cables after concrete hardening

Construction Monitoring Parameters

Key Monitoring Items

Monitoring Parameter	Measurement Method	Control Criteria
Arch axis line elevation	Total station, GPS	Design profile ±5 mm
Arch rib horizontal position	Total station	Design position ±5 mm
Stay cable tension	Load cells, dynamometers	Design tension ±10%
Steel pipe segment deflection	Inclinometers, strain gauges	Calculated limits
Concrete pumping pressure	Pressure gauges	Within pump capacity
Temperature effects	Thermometers, RTDs	Compensation applied

Construction Sequence and Monitoring Integration

The construction process requires careful sequencing to ensure:

Segment fabrication control: Steel pipe segments must meet dimensional tolerances (typically ±2 mm for length, ±1 mm for diameter)
Erection sequence: Segments are erected from both abutments toward the crown, or from the crown toward the abutments
Stay cable installation: Temporary stay cables are installed at predetermined intervals to control the arch profile during construction
Concrete filling: Concrete is pumped into the steel pipe in controlled stages to avoid excessive lateral pressure
Stay cable release: After concrete reaches sufficient strength, stay cables are released in a controlled sequence

Arch Axis Line Control Technology

The arch axis line is the critical geometric parameter that determines the structural efficiency of the arch. Any deviation from the design axis line results in:

Additional bending moments in the arch rib
Reduced load-carrying capacity
Potential instability under asymmetric loading
Aesthetic and functional concerns

The monitoring system described in this paper uses:

Real-time total station measurements at each segment connection
Dynamic adjustment of stay cable tensions based on measured deviations
Temperature compensation for thermal expansion effects
Wind load consideration during erection operations

Dynamic Adjustment Method

The dynamic adjustment process involves:

Measuring the current arch axis line position after each segment installation
Comparing with the design profile
Calculating the required stay cable tension adjustments
Implementing tension changes using hydraulic jacks
Re-measuring to verify the correction

This iterative process ensures that the constructed arch profile converges to the design geometry despite construction tolerances, material variability, and environmental effects.

Engineering Practice Considerations

Steel Pipe Quality Requirements

For SCF arch bridge construction, the steel pipe segments must meet:

Dimensional tolerances per GB/T 17395 or equivalent
Surface quality suitable for concrete filling (no internal protrusions)
Weld quality verified by NDT (UT, MT, or PT)
Material certification per the design specification (typically Q345, Q390, or Q420)

Concrete Filling Considerations

The concrete used for filling must be designed for:

Pumpability through long distances (slump 160-220 mm or self-consolidating)
Low lateral pressure on the steel pipe wall
High compressive strength (C40-C60 typical)
Durability in the expected service environment

The filling process must be controlled to avoid:

Excessive lateral pressure causing pipe deformation
Segregation or bleeding that creates voids
Thermal cracking from hydration heat
Incomplete fill that leaves air pockets

Welding and Assembly Quality

The steel pipe segments are typically connected by:

Butt welding with full-penetration welds
Flange connections with bolted joints
Combined weld-bolt connections

Welding quality is critical because:

Weld defects can initiate cracks under cyclic loading
Weld residual stresses affect the steel-concrete composite action
Weld geometry affects the flow of concrete during filling

Quality control measures include:

Welder qualification and certification
Weld procedure qualification (WPQ)
Non-destructive testing (UT, MT, or RT) of all welds
Visual inspection of all welds
Dimensional verification of weld preparation

Reflections and Key Insights

This paper provides a practical overview of the construction monitoring technology for SCF arch bridges, emphasizing the integration of measurement, analysis, and adjustment in a real-time feedback loop. The dynamic adjustment approach using stay cables is particularly innovative, as it allows the arch profile to be corrected during construction rather than after completion.

A key insight is that construction monitoring is not merely a verification activity but an active control process. The monitoring data directly drives construction decisions, such as stay cable tension adjustments, segment alignment corrections, and concrete filling sequence modifications.

The paper also highlights the importance of considering environmental effects (temperature, wind) during construction. These effects can cause significant deviations from the design profile if not properly compensated for in the monitoring and adjustment process.

For engineers involved in SCF arch bridge projects, this research underscores the need for:

Comprehensive monitoring plans developed during the design phase
Skilled monitoring personnel with both measurement and structural analysis capabilities
Real-time data processing and interpretation systems
Clear communication channels between monitoring, construction, and design teams

Summary

This paper provides a practical description of construction monitoring technology for SCF arch bridges, emphasizing dynamic arch axis line control through stay cable adjustment. The integration of real-time measurement, analysis, and correction is essential for ensuring that the constructed arch profile meets design requirements. For engineers involved in large-span SCF arch bridge projects, this research highlights the importance of comprehensive monitoring plans, skilled personnel, and real-time data-driven decision-making to achieve the intended structural performance and geometric accuracy.