Effect of Expansive Agent on Concrete Filled Steel Tube

The shrinkage of concrete is one of the main causes of cavity in concrete filled steel tube (CFST). In this paper, the effect of a kind of lab-made expansive agent on the deformation of CFST is studied. The laser displacement sensor combined with the round straight steel tube mould was adopted to test the deformation of concrete from the initial setting to 1 day after pouring, and the mechanical micrometer method was used to test deformation after 1 day in the laboratory. The full-scale model test was carried out to monitor the effect of expansive agent in CFST at the project site. The results show that, the addition of expansive agent produced significant expansion in the first 3 days, with the expansion basically compensating the autogenous shrinkage of the concrete; influenced by thermal deformation, the constraint action of steel tube to the core concrete in temperature rise stage was far greater than that in cooling stage. Compared with expansion produced in temperature rise stage, it is more important to produce expansion in cooling stage to solve the cavity problem of CFST.

Download Full-text

Improvement of Volume Stability in Core Concrete of Concrete-Filled Steel Tube

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.52-54.1097 ◽

2011 ◽

Vol 52-54 ◽

pp. 1097-1106

Author(s):

De Bin Yang ◽

Shui Xing Zhou ◽

Ming Chen ◽

Wei Wang ◽

Xiao Yi Zhang

Keyword(s):

Tube Wall ◽

Steel Tube ◽

Concrete Filled Steel Tube ◽

Volume Stability ◽

Expansive Agent ◽

Shrinkage Effect ◽

Key Factor ◽

Curing Condition ◽

Water Saturated ◽

Core Concrete

Due to the concrete self-shrinkage, frequent load application and temperature fluctuation, and so on，the gap formed between the inner tube wall and the core concrete surfaces would decrease the performance of concrete-filled steel tube (CFST). To prevent this cavity problem, various types of expansive agents and aggregates were used in this study to improve the volume stability of core concrete. Comparative experiments with mortars and concrete were carried out respectively under standard curing condition and under enclosed curing condition which simulated the environment in steel tube. The results could be summarized as follows: ● Two types of expansive agents, ZY type expansive agent mainly containing sulfates and aluminates and M type expansive agent mainly containing magnesium oxide, presented different expansive behaviors with curing ages in mortar and concrete. Two types of expansive agents combined with each other could produce complementary and superimposition effects to improve continuously the volume stability of mortar and concrete. ● Sufficient water supply is the key factor for the formation and maintenance of expansion. The volume change caused by the self-shrinkage effect of core concrete could not be effectively off-set with whether two types expansive agents or their compounds under enclosed environment in which water was scarce and could not be supplied from outside. ● When some water-saturated ceramsite were used to partially replace aggregates in core concrete,the volume expansion performance of core concrete improved dramatically with the water storage and supply effects of water-saturated ceramsite.

Download Full-text

Push-Out Test on Bond Property of Micro-Expansive Concrete-Filled Steel Tube Columns

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.163-167.610 ◽

2010 ◽

Vol 163-167 ◽

pp. 610-614 ◽

Cited By ~ 1

Author(s):

Kai Cheng Xu ◽

Meng Cheng Chen ◽

Fang Yuan

Keyword(s):

Bond Strength ◽

Composite Structures ◽

Steel Tube ◽

Conventional Concrete ◽

Concrete Filled Steel Tube ◽

Expansive Agent ◽

Expansive Concrete ◽

Expansion Behavior ◽

Bond Property ◽

Cfst Columns

The shrinkage/expansion behavior and bond carrying capacities of 4 short, micro-expansive concrete-filled steel tube (MCFST) and 3 short, conventional concrete-filled steel tube (CFST) columns were experimentally investigated. The results indicate that pre-stress is produced in the core concrete under the confined by the steel tube. Both expansive agent and water cement ratio have important influence on expansive behaviors of MCFST. The current work also indicates that the MCFST columns have higher bond strength than conventional CFST columns and this recommends a new method to improve the bond strength of composite structures.

Download Full-text

The Study on Force Behavior of Concrete Filled Steel Tube Lattice Wind Turbine Tower with Three Limb Columns

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.178-181.179 ◽

2012 ◽

Vol 178-181 ◽

pp. 179-183 ◽

Cited By ~ 1

Author(s):

Yang Wen

Keyword(s):

Energy Dissipation ◽

Bearing Capacity ◽

Wind Turbine ◽

Steel Tube ◽

Hysteretic Behavior ◽

Scale Model ◽

Concrete Filled Steel Tube ◽

Wind Turbine Tower ◽

Tower Structure ◽

Energy Dissipation Capacity

This paper refers to currently the 1.5MW cone tube type wind-driven generator tower, design the model of the concrete-filled steel tube wind turbine tower with three limb columns, and research on the force performance, such as the change of internal force, the process of failure, hysteretic behavior, bearing capacity, ductility and energy dissipation capacity by the pseudo-static experiment on the scale model of wind turbine tower. The study shows that the P- hysteretic curve of lattice concrete-filled steel tube wind-driven generator tower with three limb columns is asymmetric, relatively full “spindle” and the phenomenon of “knead shrink” is not obvious, which account for it has good force behavior and energy dissipation capacity. This kind of tower structure, of which the reverse bearing capacity is greater than the positive, and the reverse ductility coefficient is less than the positive, indicates that it’s reverse plastic deformation ability of the tower structure is weaker than it’s positive.

Download Full-text

Experimental Study on Flexural Behavior of Concrete Filled Steel Tube Girder Bridges

IABSE Symposium, Weimar 2007: Improving Infrastructure Worldwide ◽

10.2749/weimar.2007.0624 ◽

2007 ◽

Author(s):

Won Jong Chin ◽

Jae Yoon Kang ◽

Eun Suk Choi ◽

Jung Woo Lee ◽

Byung Suk Kim

Keyword(s):

Experimental Study ◽

Steel Tube ◽

Flexural Behavior ◽

Concrete Filled Steel Tube ◽

Girder Bridges

Download Full-text

A thermal-driven method based on Brillouin fiber-optic sensors for the quantitative identification of subsurface cavities in concrete-filled steel tube structures

Journal of Civil Structural Health Monitoring ◽

10.1007/s13349-020-00464-7 ◽

2021 ◽

Author(s):

Shilin Gong ◽

Xin Feng ◽

Guanhua Zhang

Keyword(s):

Fiber Optic ◽

Fiber Optic Sensors ◽

Steel Tube ◽

Concrete Filled Steel Tube ◽

Quantitative Identification ◽

Subsurface Cavities

Download Full-text

Flexural behavior of composite concrete-filled steel tube roof structure under symmetrical concentrated loads

Structures ◽

10.1016/j.istruc.2021.03.047 ◽

2021 ◽

Vol 32 ◽

pp. 1250-1259

Author(s):

Lianguang Wang ◽

Xue Li ◽

Bailing Chen ◽

Haiyang Gao

Keyword(s):

Steel Tube ◽

Flexural Behavior ◽

Concentrated Loads ◽

Concrete Filled Steel Tube ◽

Roof Structure

Download Full-text

Stone prism encased concrete-filled steel tube columns subjected to axial compression

Structures ◽

10.1016/j.istruc.2021.05.058 ◽

2021 ◽

Vol 33 ◽

pp. 1853-1867

Author(s):

Yong Ye ◽

Yang Liu ◽

Zi-Xiong Guo ◽

Rachel Chicchi

Keyword(s):

Axial Compression ◽

Steel Tube ◽

Concrete Filled Steel Tube

Download Full-text

Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

Advances in Structural Engineering ◽

10.1177/13694332211009322 ◽

2021 ◽

pp. 136943322110093

Author(s):

Zhenzhen Liu ◽

Yiyan Lu ◽

Shan Li ◽

Jiancong Liao

Keyword(s):

Axial Compression ◽

Steel Fiber ◽

Steel Tube ◽

Shear Capacity ◽

Recycled Concrete ◽

Recycled Aggregate ◽

Superposition Method ◽

Fiber Reinforced ◽

Concrete Filled Steel Tube ◽

Shear Span

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio ( D/t), shear span-to-depth ratio (λ), axial compression ratio ( n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As λ is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

Download Full-text