Design Optimization and Mechanical Performance Research of Steel Tube Concrete Pier Columns

Literature Overview

This paper by Huang Wanpeng, Hou Keke, Zhao Tongyang, Liu Shilei, Jiang Hongyi, and Yuan Xiao was published in the Journal of Mining and Rock Strata Control Engineering in 2024 (Vol. 6, No. 6, pp. 29-43). The authors are affiliated with the School of Energy and Mining Engineering at Shandong University of Science and Technology and Liaocheng Zhongkuang Machinery Co., Ltd. in Shandong Province. Funded by the National Natural Science Foundation of China (Grant No. 51774195) and the State Key Laboratory of Coal Resource Efficient Mining and Clean Utilization Open Fund (Grant No. 2021-KFYB-020), this research addresses the structural optimization and mechanical performance of steel tube concrete pier columns for underground roadway support applications.

Research Background and Engineering Requirements

The study addresses a specific engineering challenge in underground mining: the design of support structures for roadways with heights of 2.5 to 3.0 meters. Traditional steel tube concrete pier columns have limited bearing capacity and may not adequately meet the support requirements for such roadways, particularly in conditions with high ground stress or poor rock mass quality. The authors propose an innovative solution: steel tube concrete pier columns with internal steel sections (内配型钢钢管混凝土墩柱), which combine the benefits of steel tube confinement with the additional strength provided by internal steel sections.

Design Requirements and Constraints

Structural Design and Optimization

The authors designed steel tube concrete pier columns with specific aspect ratios to meet the roadway dimensions. The key design innovation is the incorporation of internal steel sections (such as H-beams or channel sections) within the steel tube, creating a composite column that leverages the strengths of both steel and concrete.

Comparison of Column Configurations

The internal steel section provides additional axial load capacity and improves the post-buckling behavior of the column by providing internal support against local buckling of the steel tube wall.

Experimental and Theoretical Results

Short Column Performance Comparison

The study conducted comparative axial compression tests on ordinary steel tube concrete short columns and internal steel section steel tube concrete short columns. The results demonstrated clear advantages of the internal steel section configuration:

The internal steel section steel tube concrete pier columns exhibited significantly reduced local bulging and core concrete damage compared to ordinary steel tube concrete columns. Both lateral and longitudinal deformations were smaller, and the failure behavior was more gradual, indicating better ductility and post-peak load-bearing capacity.

Long Column Performance Study

The study also investigated the axial compression mechanical performance of steel tube concrete long columns, examining the effects of steel tube diameter on the elastic and plastic limit strains:

With increasing steel tube diameter, the elastic limit strain increased from 0.1% to 0.6%, and the plastic limit strain increased from 2.0% to 6.7%. This indicates that larger diameter steel tubes provide greater ductility and deformation capacity, which is beneficial for accommodating ground movements and stress redistributions in underground mining environments.

Effect of Aspect Ratio on Long Columns

The bearing capacity of steel tube concrete long columns was found to be significantly affected by the aspect ratio (length-to-diameter ratio). As the aspect ratio increases, the bearing capacity decreases markedly, and the failure mode transitions from crushing to pronounced buckling deformation. This finding is consistent with classical column stability theory but provides specific quantitative data for steel tube concrete columns in the context of underground mining applications.

Engineering Application and Practice Recommendations

The research provides practical guidance for the design of steel tube concrete pier columns in underground mining roadways:

1. Internal steel sections are recommended: For roadways with heights of 2.5-3.0 meters, the incorporation of internal steel sections within the steel tube concrete pier columns provides a significant improvement in bearing capacity (approximately 500 kN increase) and ductility, making them suitable for demanding support conditions.
2. Aspect ratio control is critical: For long columns, the aspect ratio must be carefully controlled to prevent excessive reduction in bearing capacity. The design should ensure that the aspect ratio remains within a range that provides adequate stability against buckling.
3. Steel tube diameter selection: Larger diameter steel tubes provide greater elastic and plastic deformation capacity, which is beneficial for accommodating ground movements. However, the selection must balance structural efficiency with material costs and installation constraints.
4. Failure mode consideration: The transition from crushing to buckling failure with increasing aspect ratio requires different design approaches. Short columns should be designed for crushing resistance, while long columns should be designed for buckling resistance with appropriate safety factors.

Reflections on Underground Support Design

This study contributes to the ongoing evolution of underground support design in mining engineering. The integration of internal steel sections within steel tube concrete columns represents a practical innovation that addresses the specific challenges of roadway support in mining environments.

The finding that the internal steel section configuration provides more gradual failure behavior is particularly important for mining safety. In underground environments, the gradual failure of support structures allows for warning signs and evacuation time, whereas sudden failure can lead to catastrophic collapse. The improved ductility of the internal steel section columns directly contributes to mine safety.

The study also highlights the importance of considering the full range of column behaviors—from short column crushing to long column buckling—in the design of underground support systems. Engineers must understand the transition between these failure modes and design accordingly, which requires a comprehensive understanding of both material properties and structural stability principles.

Summary

The research by Huang Wanpeng and colleagues presents a systematic investigation of steel tube concrete pier columns with internal steel sections for underground roadway support applications. The experimental and theoretical results demonstrate that the internal steel section configuration provides approximately 500 kN increase in ultimate bearing capacity, reduced local bulging and core concrete damage, and improved ductility compared to ordinary steel tube concrete columns. The study also provides valuable data on the effects of steel tube diameter and aspect ratio on the mechanical performance of long columns, including the elastic and plastic limit strain ranges and the transition from crushing to buckling failure modes. These findings offer practical guidance for engineers designing support structures in underground mining roadways, contributing to both the structural efficiency and safety of mining operations.