Zhuojin Pipe Fitting Co., LtdAxial Compression Performance of Concrete-Filled Steel Tubular Columns with Steel Fiber Self-Stress Self-Consolidating Concrete
Literature Overview
This paper, published in the Journal of Civil Engineering Management (Volume 34, Issue 2, 2017, pp. 1-4) by Lu Yiyan, Yan Bo, Li Na, and Li Shan from Wuhan University, presents experimental research on the axial compression performance of concrete-filled steel tubular (CFST) columns incorporating steel fiber self-stress self-consolidating concrete (SFSSC). Funded by the Ministry of Education Doctoral Point Special Fund Project (20110141110002), the study tested six short column specimens with varying combinations of initial self-stress and steel fiber volume fraction, analyzing the effects on bearing capacity, stiffness, and deformation capacity. The results demonstrate that initial self-stress significantly enhances bearing capacity and stiffness but reduces deformation capacity, while steel fiber addition mitigates the deformation capacity reduction and improves the confinement effect of the steel tube on the concrete.
Technical Background
Self-Stress Concrete
Self-stress concrete (also known as expansive concrete or self-stressing concrete) incorporates expansive agents that generate internal expansion upon hydration. When this expansion is restrained by the steel tube, it creates beneficial initial compressive stresses in the concrete that can:
- Close micro-cracks and improve durability
- Enhance the bond between steel and concrete
- Increase the effective confinement pressure
- Improve the overall composite action
Steel Fiber Concrete
Steel fibers added to concrete provide:
- Enhanced post-cracking tensile capacity
- Improved ductility and toughness
- Crack width control
- Enhanced aggregate interlock
- Improved resistance to spalling under impact or fire
Self-Consolidating Concrete
Self-consolidating concrete (SCC) offers:
- Excellent flowability without vibration
- Reduced risk of voids in confined spaces
- Improved concrete placement quality inside steel tubes
- Better surface finish
- Reduced labor requirements
Combined SFSSC System
The combination of all three properties in a single concrete mix represents an advanced material system designed to maximize the performance of CFST columns. The challenge lies in achieving all three properties simultaneously without compromising workability, strength, or durability.
Experimental Program
Specimen Configuration
| Specimen ID | Concrete Type | Self-Stress Level | Steel Fiber Volume | Description |
|---|---|---|---|---|
| CFS1 | SFSSC | Yes | Present | Steel fiber + self-stress |
| CFS2 | SFSSC | Yes | Present | Steel fiber + self-stress (different ratio) |
| CSS1 | SSC | Yes | None | Self-stress only |
| CS1 | SC | No | None | Self-consolidating only (control) |
| CFS3 | SFSSC | Yes | Present | Steel fiber + self-stress |
| CFS4 | SFSSC | Yes | Present | Steel fiber + self-stress (different ratio) |
Test Parameters
| Parameter | Range/Values | Notes |
|---|---|---|
| Column diameter | Standard |