Blast Shock Wave Pressure Distribution on Steel Tube Concrete Column Surface: Experimental Study and Numerical Simulation

Literature Overview

The research by Cui Ying, Zhao Junhai, Zhang Changguang, and Sun Shanshan, published in Journal of Beijing University of Technology (2014, Vol. 40, No. 12, pp. 1828-1836), presents a comprehensive experimental and numerical investigation of blast shock wave pressure distribution on the surface of steel tube concrete columns. Funded by multiple national and provincial research grants including the National Natural Science Foundation (Project 41202191), the Ministry of Education Doctoral Fund (20110205130001), the China Postdoctoral Science Foundation (2012M520079; 2013T60868), and the Shaanxi Provincial Natural Science Foundation (2011JM7002), this study addresses the critical challenge of accurately predicting blast loading effects on structural components.

The authors, from Xi'an Shiyou University's School of Mechanical Engineering and Chang'an University's School of Building and Civil Engineering, conducted physical blast tests and developed validated finite element models to investigate shock wave propagation and pressure distribution characteristics.

Core Technical Content and Experimental Setup

The experimental program involved detonating explosives at controlled distances from steel tube concrete columns to generate blast shock waves. The key experimental parameter was the scaled distance, defined as the charge distance divided by the cube root of the explosive mass (Z = d/m^(1/3)). The primary test condition employed a scaled distance of 1.1 m/kg^(1/3), which represents a typical design scenario for blast-resistant structures.

Pressure Measurement Configuration

Multiple pressure sensors were deployed on the column surface to capture:

• Peak overpressure at various locations
• Positive phase pressure impulse
• Pressure time-history curves
• Spatial distribution of pressure around the column circumference

Key Experimental Findings

The experimental results revealed several important characteristics of blast loading on steel tube concrete columns:

Numerical Simulation and Mesh Sensitivity Analysis

A critical contribution of this study is the systematic investigation of mesh size effects on numerical simulation accuracy. The authors recognized that blast wave propagation involves complex fluid-structure interaction phenomena that are highly sensitive to spatial discretization.

Mesh Size Investigation Results

The study concluded that a mesh size of 20 mm for both air and explosive domains provides an optimal balance between accuracy and computational efficiency for scaled distances not less than 1.1 m/kg^(1/3).

Validation Against Experimental Data

The numerical simulation results with 20 mm mesh size showed good agreement with experimental measurements, with errors decreasing as mesh size decreased. This validation confirms the reliability of the simulation approach for blast loading analysis.

Damage Assessment Methodology

The study emphasizes that blast damage assessment must consider both peak pressure and positive phase pressure impulse:

• Peak pressure: Governs instantaneous stress response and potential brittle failure
• Positive phase impulse: Governs cumulative energy input and ductile failure modes
• Combined criterion: Damage assessment should employ a combined criterion that accounts for both parameters

This finding is consistent with established blast design methodologies but provides specific quantitative data for steel tube concrete columns that can inform design code development.

Engineering Practice Recommendations

Based on the experimental and numerical findings, the following recommendations are provided for blast-resistant design of steel tube concrete structures:

1. Mesh refinement protocol: For blast analysis of steel tube concrete columns at scaled distances of 1.1 m/kg^(1/3) or greater, use 20 mm mesh size for air and explosive domains to ensure acceptable accuracy without excessive computational cost.
2. Pressure mapping: Deploy pressure measurement arrays or use validated numerical models to obtain spatial pressure distribution data, as uniform pressure assumptions may significantly underestimate local stress concentrations.
3. Damage criteria: Employ combined peak pressure and impulse criteria for damage assessment, recognizing that different failure modes are governed by different loading parameters.
4. Boundary condition modeling: Ensure proper representation of column support conditions in numerical models, as the experimental results demonstrate that boundary constraints significantly affect structural response.

Key Questions and Reflections

Several important questions emerge from this research:

• How do the findings change for scaled distances below 1.1 m/kg^(1/3), where plastic deformation may occur?
• What is the effect of column cross-section geometry and reinforcement configuration on pressure distribution?
• Can the mesh size recommendation be generalized to different column sizes and blast scenarios?
• How does the presence of surrounding structures or obstacles affect shock wave interaction with the column?

The study's focus on mesh sensitivity is particularly valuable for practical engineering applications, as it provides clear guidance for numerical analysts on the level of discretization required for reliable results.

Study Insights and Implications

This literature makes significant contributions to the field of blast-resistant structural engineering by providing validated experimental data and numerical simulation guidelines for steel tube concrete columns. The mesh sensitivity analysis is particularly practical, offering engineers a clear methodology for balancing accuracy and computational efficiency in blast analysis. The emphasis on combined pressure and impulse damage criteria reinforces the need for comprehensive damage assessment approaches that go beyond simple peak pressure comparisons. For engineers involved in protective design of critical infrastructure, this study provides a foundation for more accurate blast loading analysis and damage prediction.