Residual Strength of Concrete Filled RHS Stub Columns after Exposure to High Temperatures

2002 ◽  
Vol 5 (2) ◽  
pp. 123-134 ◽  
Author(s):  
Lin-Hai Han ◽  
Hua Yang ◽  
Shu-Liang Cheng
Keyword(s):  
High Temperatures ◽  
Residual Strength ◽  
Axial Strain ◽  
Steel Tube ◽  
Hollow Section ◽  
Tubular Columns ◽  
Mechanics Model ◽  
Influence Of Temperature On ◽  
Strain Relationship ◽  
Stub Column

Tests are reported on twenty-six concrete filled steel tube of rectangular section after being exposed to high temperatures, to investigate the influence of temperature on section capacity and load-deformation behavior. The main parameter varied is temperature, from 20°C to 900°C. A mechanics model is described in this paper for the behaviour of concrete-filled RHS (Rectangular Hollow Section) columns after exposed to high temperatures, and is a development of the analysis (Han et al, 2001a) used when only normal temperatures apply. The predicted load versus axial strain relationship is in good agreement with stub column test results. Simplified models are derived for the section capacities and the modulus of elasticity of the composite sections. It was found in general, that the higher the exposure temperature, the higher the loss of section capacities and elastic modulus which resulted. The tests have shown the importance of the influence of high temperatures on the performance of concrete filled steel tubes. The work in this paper provides a basis for further theoretical study on the residual strength of concrete filled steel tubular columns.

scholarly journals Effect of Cross-Sectional Aspect Ratio on Rectangular FRP-Concrete-Steel Double-Skin Tubular Columns under Axial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Bing Zhang ◽  
Xia-Min Hu ◽  
Wei Wei ◽  
Qian-Biao Zhang ◽  
Ning-Yuan Zhang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Axial Stress ◽  
Axial Strain ◽  
Steel Tube ◽  
Confined Concrete ◽  
Cross Sectional ◽  
Tubular Columns ◽  
Double Skin ◽  
Frp Tube

Hybrid FRP-concrete-steel double-skin tubular columns (hybrid DSTCs) are novel hollow columns consisting of an outer FRP tube, an inner steel tube, and the concrete between the two tubes. Hybrid DSTCs possess important advantages, such as excellent corrosion resistance as well as remarkable seismic resistance. However, existing studies are mainly focused on hybrid DSTCs with a circular cross section or a square cross section. When a column is subjected to different load levels in the two horizontal directions, a rectangular column is preferred as it can provide different bending stiffness and moment capacity around its two axes of symmetry. This paper presents an experimental study on rectangular DSTCs with a particular focus on the effect of the cross-sectional aspect ratio (i.e., the ratio of the breadth to the width of the rectangular cross section). The effect of the cross-sectional shape of the inner steel tube (i.e., both elliptical and rectangular inner steel tubes were used) and the effect of FRP tube thickness were also investigated experimentally. Experimental results show that a larger aspect ratio will have no negative effect on the confinement effect in rectangular DSTCs; a rectangular DSTC with a larger aspect ratio generally has a larger ultimate axial strain and a higher axial stress at the ultimate axial strain; rectangular DSTCs with an elliptical steel tube generally have better performance than corresponding specimens with a rectangular steel tube. An existing model, which was developed based on a model for rectangular FRP-confined concrete columns and a model for circular DSTCs, is verified using the test results of the present study. The model generally provides close predictions for the peak axial stress of the confined concrete but yields conservative predictions for the ultimate axial strain for rectangular DSTCs.

Cold-formed elliptical concrete-filled steel tubular columns subjected to monotonic and cyclic axial compression

2019 ◽  
Vol 23 (7) ◽  
pp. 1383-1396 ◽  
Author(s):  
Youwu Xu ◽  
Jian Yao ◽  
Xin Sun
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Axial Strain ◽  
Residual Deformation ◽  
Steel Tube ◽  
Superposition Method ◽  
Fe Model ◽  
Hoop Strain ◽  
Tubular Columns ◽  
Stub Columns

Concrete-filled steel tubular columns are widely used in structural systems, and elliptical concrete-filled steel tubular columns are receiving more and more attention. An experimental study on cold-formed elliptical concrete-filled steel tubular stub columns was carried out under monotonic and cyclic axial compression. The failure modes, axial load–displacement curves, ultimate loads, hoop strain–axial strain behavior, strength deterioration, and residual deformation were obtained and discussed. Complementary finite element models considering the complex non-uniform confinement between steel tube and concrete were developed and validated by experimental results. Then, the validated FE model was used to study the influence of aspect ratio, yield strength of steel, and compressive strength of concrete on the axial capacity of elliptical concrete-filled steel tubular stub columns. Finally, a relatively simple superposition method was put forward to predict the axial bearing capacity of elliptical concrete-filled steel tubular stub columns. Compared with the test data, both the numerical method and superposition method can generate accurate predictions.

Elasto-Plastic Analysis of Concrete-Filled Circular Steel Tubular Stub Columns after Exposed to High Temperatures

2008 ◽  
Vol 400-402 ◽  
pp. 763-768 ◽  
Author(s):  
Fa Xing Ding ◽  
Zhi Wu Yu ◽  
Jin Ping Ou
Keyword(s):  
High Temperatures ◽  
Axial Strain ◽  
Steel Tube ◽  
Fortran Program ◽  
Stress Strain ◽  
Concrete Core ◽  
Concentric Cylinders ◽  
Circular Steel Tube ◽  
Plastic Analysis ◽  
Stub Columns

Based on the research achievements of the mechanical properties of concrete at uniaxial compression and steel at uniaxial tension after exposed to high temperatures, the axisymmetric- triaxial-compressive stress-strain relationships of concrete and multiaxial stress-strain relationships of steel after exposed to high temperatures was suggested. Based on continuum mechanics, the mechanical model of concentric cylinders of circular steel tube with concrete core of entire section loaded after exposed to high temperature was determined. By applying Elasto-Plastic Analysis Method, theoretical calculation formulas for composite elastic modulus and composite stress-strain relationships of concrete-filled circular steel tubular (CFST) stub columns were proposed and a FORTRAN program was developed and the load-axial strain relationships of CFST stub columns after exposed to high temperatures were analyzed. The analysis results were in reasonable agreement with the experiment ones from references.

Effects of Sustained Pre-Load on Residual Strength and Stiffness of Concrete-Filled Steel Tube after Exposure to High Temperatures

2008 ◽  
Vol 400-402 ◽  
pp. 769-774
Author(s):  
Jing Si Huo ◽  
Guo Wang Huang ◽  
Yan Xiao
Keyword(s):  
High Temperatures ◽  
Residual Strength ◽  
Axial Load ◽  
Room Temperature ◽  
Steel Tube ◽  
Load Level ◽  
Stiffness Index ◽  
Test Results ◽  
Strength And Stiffness ◽  
Stub Columns

This paper experimentally investigated the effects of axial load level on the residual strength and stiffness of concrete-filled steel tubular (CFT) stub columns which were heated and cooled down to room temperature under sustained axial load. Eight stub columns were axially loaded and heated to specified high temperatures in a purpose-built electric furnace. After the specimens cooled down to room temperature while the axial load was kept constant, the stub columns were loaded to failure. The test results show that not only the axial load level and the high temperature exposure have significant effects on the residual strength and stiffness of stub column, but the residual strength index and stiffness index of the fire-damaged CFT stub columns with pre-load are remarkably different from those without pre-load. From the test results, it is recommended that the sustained axial load effects and the fire cooling phase should be taken into consideration in assessing the fire-damaged CFT columns.

scholarly journals Axial Behavior of Concrete-Filled Double-Skin Tubular Stub Columns Incorporating PVC Pipes

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1434
Author(s):  
Muhammmad Faisal Javed ◽  
Haris Rafiq ◽  
Mohsin Ali Khan ◽  
Fahid Aslam ◽  
Muhammad Ali Musarat ◽  
...  
Keyword(s):  
Steel Tube ◽  
Tube Material ◽  
Steel Tubes ◽  
Tubular Columns ◽  
Axial Capacity ◽  
Double Skin ◽  
Axial Behavior ◽  
Pvc Pipe ◽  
The Cost ◽  
Stub Columns

This experimental study presents concrete-filled double-skin tubular columns and demonstrates their expected advantages. These columns consist of an outer steel tube, an inner steel tube, and concrete sandwiched between two tubes. The influence of the outer-to-inner tube dimension ratio, outer tube to thickness ratio, and type of inner tube material (steel, PVC pipe) on the ultimate axial capacity of concrete-filled double-skin tubular columns is studied. It is found that the yield strength of the inner tube does not significantly affect the ultimate axial capacity of concrete-filled double-skin tubular composites. With the replacement of the inner tube of steel with a PVC pipe, on average, less than 10% strength is reduced, irrespective of size and dimensions of the steel tube. Hence, the cost of a project can be reduced by replacing inner steel tubes with a PVC pipes. Finally, the experimental results are compared with the existing design methods presented in AISC 360-16 (2016), GB51367 (2019), and EC4 (2004). It is found from the comparison that GB51367 (2019) gives better results, followed by AISC (2016) and EC4 (2004).

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