Research on Calculated Temperature Values for Steel Tube Concrete Dumbbell-Shaped Arches

Literature Overview

This paper by Huang Fuyun, Chen Baochun, and Ke Tingxian from Fuzhou University and Fuzhou Ring Expressway Co., Ltd., published in the Journal of Fuzhou University (Natural Science) in 2011, investigates the temperature calculation values for CFST dumbbell-shaped arch bridges. The research was supported by Fuzhou University's Talent Fund (0822460). The study uses a finite element method validated by measured temperature field data from an actual bridge to analyze closure temperature, effective temperature, and average temperature effects.

Core Technical Content

Temperature effects are critical design considerations for long-span CFST arch bridges because the steel tube and concrete infill have different thermal expansion coefficients. The dumbbell-shaped arch configuration—comprising two parallel steel tubes connected by cross members—introduces additional complexity in thermal behavior.

Temperature Calculation Parameters

Temperature Parameter	Definition	Typical Value Range (Fujian Region)
Closure temperature	Temperature at which arch is closed during construction	Based on 28-day average ambient temperature post-concreting
Maximum effective temperature	Maximum temperature difference causing maximum thermal stress	Close to local maximum ambient temperature
Minimum effective temperature	Minimum temperature causing minimum thermal stress	Close to local minimum daily average temperature
Average temperature	Uniform temperature causing axial expansion/contraction	Regional average ambient temperature

Key Research Findings

The calculated closure temperature primarily depends on the 28-day average ambient temperature after concrete pouring and the diameter of the dumbbell-shaped chord tubes.
The maximum effective temperature is approximately equal to the local maximum ambient temperature.
The minimum effective temperature is approximately equal to the local minimum daily average temperature.
The study provides recommended maximum and minimum effective temperature values for different regions in Fujian Province.

Engineering Practice Integration

For steel pipe manufacturers supplying dumbbell-shaped arch tubes, understanding the thermal design requirements is essential for several reasons:

Pipe diameter selection directly influences the closure temperature calculation, which affects the construction sequencing and temporary works design.
Material selection should consider the thermal cycling the tubes will experience over the bridge's service life.
Welding procedure development must account for the residual stresses that interact with thermal stresses during service.

The discussion of JTG D60-2004 temperature provisions reveals potential inadequacies in standard temperature values for specific regional conditions. This highlights the importance of site-specific temperature monitoring rather than relying solely on code-prescribed values.

Key Insights and Reflections

This research addresses a practical problem that is often underappreciated in bridge engineering. Temperature effects can induce stresses comparable to or exceeding those from live loads in long-span arch bridges. For CFST dumbbell-shaped arches, the thermal behavior is particularly complex because:

The two parallel tubes may experience differential heating (sun-facing vs. shaded tubes)
The concrete infill acts as a thermal mass, creating temperature gradients within the tube
The dumbbell geometry creates coupled thermal-mechanical responses between the chord tubes and cross members

The finding that closure temperature depends on the 28-day average temperature after concreting is practically significant because it directly links construction scheduling decisions to the structural thermal baseline. Engineers should document and control the closure temperature as a critical construction parameter, as deviations from the design closure temperature will alter the thermal stress distribution throughout the bridge's lifetime.