Mechanical Performance of Large-Span Bailey Truss Steel Tube Construction Platforms in Extreme Cold Environments

Literature Overview

This paper, published in the Journal of Shenyang Jianzhu University (Natural Science) in 2022 by Xu Man, Wang Fan, Wang Qinghe, Liu Changyong, and Wei Chenyang, investigates the mechanical behavior of large-span Bailey truss steel tube construction platforms under extreme cold conditions. The research addresses a critical practical problem in high-latitude construction: how does the mechanical performance of temporary steel structures degrade as ambient temperatures drop from normal construction temperatures to extreme cold levels? The study was funded by the National Natural Science Foundation of China and local science and technology programs in Tianjin and Shenyang, reflecting the practical urgency of this research topic.

Research Methodology and Model Validation

The authors employed a two-stage approach: first, they validated their ABAQUS finite element modeling technique against existing Bailey truss test results, ensuring the accuracy of their simulation framework; second, they applied the validated model to analyze the behavior of a specific Bailey truss steel tube construction platform under temperatures ranging from 20°C to -50°C. This validation-first methodology is commendable and essential for ensuring that the subsequent parametric analysis produces reliable results.

The temperature-dependent analysis considers the reduction in material properties of both the steel tubes and the Bailey truss components as temperature decreases. Steel materials exhibit increased yield strength and reduced ductility at low temperatures, with the risk of brittle fracture increasing as the material transitions from ductile to brittle behavior. The specific steel grade used in the platform construction determines the temperature at which this transition occurs, and the study's findings have direct implications for material selection in cold-region construction.

Quantitative Results and Temperature Effects

The following table summarizes the key quantitative results obtained from the temperature-dependent analysis:

The results reveal several critical trends. First, the Bailey truss stress increases dramatically from 85.0 MPa at 20°C to 232.2 MPa at -50°C, representing a 173% increase. Second, the steel tube column stress increases from 9.9 MPa to 108.3 MPa, a tenfold increase that highlights the sensitivity of the support system to temperature reduction. Third, the out-of-plane displacement of the Bailey truss grows from 0.7 mm to 36.6 mm, which is particularly concerning because out-of-plane instability can trigger progressive collapse. Finally, the bearing capacity decreases by approximately 15.4%, from 561.8 kN to 475.5 kN, which represents a significant reduction in the safety margin for the construction platform.

Engineering Implications and Safety Considerations

The findings of this research have direct implications for the design and use of temporary steel construction platforms in cold regions. The 15.4% reduction in bearing capacity at -50°C means that platforms designed for a given load at normal temperatures may be overloaded under extreme cold conditions, even if the actual applied loads remain unchanged. This has serious safety implications for construction workers operating on these platforms.

The increase in out-of-plane displacement is particularly concerning from a stability perspective. Out-of-plane buckling of Bailey truss members can initiate a chain reaction of failures, especially in large-span platforms where the truss members are slender. The steel tube column diameter and wall thickness become increasingly important design parameters as temperature decreases, as the study notes that their influence on stress variation grows with lower temperatures.

From a quality control perspective, this research highlights the need for temperature-specific inspection and load testing protocols in cold-region construction. Standard inspection procedures developed for normal temperatures may not detect the increased stress concentrations and reduced load margins that occur at extreme cold temperatures. Engineers should consider implementing additional monitoring of platform deflections and member stresses during cold weather construction periods.

Key Reflections and Study Insights

This paper addresses a practically important and often overlooked aspect of temporary steel structure design: the significant degradation of mechanical performance under extreme cold conditions. The quantitative results—particularly the dramatic increase in stresses and displacements, and the 15.4% reduction in bearing capacity—provide compelling evidence that temperature effects cannot be ignored in cold-region construction. The validation-first methodology gives confidence in the reliability of the findings, and the specific engineering case study provides actionable insights for practitioners. The out-of-plane instability issue is especially critical and warrants further investigation into bracing requirements and connection design for cold-region Bailey truss platforms. Engineers working in high-latitude construction should treat temperature as a primary design variable, not a secondary consideration, and should ensure that temporary steel structures maintain adequate safety margins across the full range of expected service temperatures.