Fire Resistance of Reinforced Concrete Columns with Square Cross Section

2007 ◽  
Vol 10 (4) ◽  
pp. 353-369 ◽  
Author(s):  
Bo Wu ◽  
Zhou Hong ◽  
Gui-He Tang ◽  
Chao Wang
Keyword(s):  
Cross Section ◽  
Fire Resistance ◽  
Axial Load ◽  
Load Ratio ◽  
Concrete Columns ◽  
Eccentricity Ratio ◽  
Explosive Spalling ◽  
Strength Concrete ◽  
Axial Load Ratio ◽  
Simulation Results

Calculation of the fire resistance of 480 square cross section normal strength concrete (NSC) columns and 480 high strength concrete (HSC) columns, made with siliceous aggregate, is presented in this paper. The variables considered in the study include concrete strength (NSC and HSC), dimension of column cross section, axial load ratio, load eccentricity ratio (i.e., ratio of load eccentricity to dimension of column cross section), and steel ratio (i.e., ratio of longitudinal reinforcement to cross-sectional area of column). Explosive spalling of HSC exposed to fire is also considered approximately. Simulation results show that: (1) increasing the dimension of column cross section, reducing the axial load ratio, and reducing the load eccentricity ratio are all effective measures for improving the fire resistance of both NSC and HSC columns subjected to concentric axial load or eccentric axial load; (2) increasing the steel ratio has no significant influence on the fire resistance of concentrically loaded NSC and HSC columns, but has some positive effect on the fire resistance of eccentrically loaded NSC and HSC columns; (3) explosive spalling of HSC has a significant detrimental influence on the fire resistance of HSC columns. Based on simulation results, a simplified formula is empirically developed to enable determination of the fire resistance of both NSC and HSC columns, and is shown to be applicable to concrete columns with square cross section.

Yield Displacement Calculation Method of High-Strength Concrete Shear Wall

2013 ◽  
Vol 353-356 ◽  
pp. 3382-3386 ◽  
Author(s):  
Hua Jing Zhao ◽  
Xing Wen Liang ◽  
Can Song
Keyword(s):  
Cross Section ◽  
High Strength Concrete ◽  
Axial Load ◽  
Load Ratio ◽  
High Strength ◽  
Shear Wall ◽  
Strength Concrete ◽  
Axial Load Ratio ◽  
Yield Displacement ◽  
Calculation Results

Considering high compressive strength of high-strength concrete, it is assumed that concrete compressive stress of the cross-section compression zone is linear distribution when the cross-section of high-strength concrete shear wall reaches yield situation. Based on the plane section assumption, the yield curvature formula of shear wall section is obtained by using moment - curvature analysis method. The parameters effecting yield curvature of high-strength concrete shear wall are studied by using the yield curvature formula. The results show that longitudinal reinforced yield strain is the most influencing factor of the yield curvature in addition to axial load ratio. This paper presents yield curvature formula considering the impact of axial load ratio and boundary reinforcement yield stress through the regression analysis of calculation results. On this basis, the vertex yield displacement formula of high-strength concrete shear wall is proposed, and the calculation results of formula correspond to the vertex yield displacement experimental values of the 12 high-strength concrete cantilever wall well.

Fire Resistance Evaluation of Reinforced Concrete Columns Using Axial Load Ratio and Slenderness Ratio

2014 ◽  
Vol 905 ◽  
pp. 268-272
Author(s):  
In Hwan Yeo ◽  
Bum Yean Cho ◽  
Jae Hong An ◽  
Byung Youl Min
Keyword(s):  
Fire Resistance ◽  
Axial Load ◽  
Slenderness Ratio ◽  
Load Ratio ◽  
Cost Effective ◽  
Concrete Columns ◽  
Accurate Estimation ◽  
Structural Members ◽  
Standard Fire ◽  
Resistance Performance

Since the column members in buildings deal with both vertical and horizontal loads, appropriated amount of load should be estimated in order to evaluate the fire resistance performance of the columns under loaded condition. However, according to the ISO 834, the international standard for the evaluation of structural members, the fire resistance performance evaluation of column members is only based on the displacement and displacement rate under loaded condition in a standard fire. The purpose of this study is to suggest appropriate axial load ratios for the evaluation of fire resistance performance. The test conducted in this study produced appropriate axial load ratios for different slenderness ratios. They are expected to contribute to more accurate estimation of fire resistance performance and more efficient and cost-effective structural design.

Reliability Analysis of High-Strength Concrete Columns during a Fire

2014 ◽  
Vol 629-630 ◽  
pp. 273-278 ◽  
Author(s):  
Jian Zhuang Xiao ◽  
Qing Hai Xie ◽  
Yi Zhao Hou ◽  
Zhi Wei Li
Keyword(s):  
Reliability Analysis ◽  
Fire Resistance ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
Axial Loading ◽  
High Strength ◽  
Concrete Columns ◽  
Explosive Spalling ◽  
Strength Concrete ◽  
High Strength Concrete Columns

A reliability analysis was conducted on high-strength concrete (HSC) columns during a fire. The influences of fire’s randomness and explosive spalling of concrete were investigated. The fire resistance for axial loading capacity of HSC columns was in terms of steel yield strength and concrete compressive strength with considering the effect of elevated temperatures. The load random variables included dead load and sustained live load. The JC method was applied to calculate the reliability index of the fire resistance of axially loaded HSC columns. It was found that the randomness of fire and explosive spalling of concrete had a significant influence on reliability of HSC columns.

Cyclic Lateral Load Test on T-Shaped Reinforced Concrete Columns

2013 ◽  
Vol 718-720 ◽  
pp. 1923-1927
Author(s):  
Fu Lai Qu ◽  
Gui Rong Liu ◽  
Pei Yuan Tian ◽  
Lu Yang Qi
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Load ◽  
Cyclic Load ◽  
Load Ratio ◽  
Concrete Columns ◽  
Load Test ◽  
Axial Load Ratio ◽  
Cyclic Lateral Load ◽  
The Web

Based on the experiment of eight reinforced concrete T-shaped columns under low cyclic load, the factors which affect bearing capacity and seismic behavior, such as limb length, axial load ratio, stirrup ratio and the arrangement of longitudinal bars, etc., are analyzed. Tests results show that the bearing capacity of the columns increases, but the ductility is decreased with an increase of axial load ratio. The bearing capacity of T-shaped column increases when the web gets longer, while its deformability and ductility decrease. Besides, increase of stirrup ratio and longitudinal bars in the end of the web also have effect on the ductility of the columns.

Fire Resistance Performance of Welded Built-up Square CFT Columns with Reduced Intumescent Paint

2015 ◽  
Vol 6 (2) ◽  
pp. 103-112
Author(s):  
SunHee Kim ◽  
KyongSoo Yom ◽  
SungMo Choi
Keyword(s):  
Stress Concentration ◽  
Fire Resistance ◽  
Axial Load ◽  
Load Ratio ◽  
Functional Design ◽  
Steel Tubes ◽  
Composite Effect ◽  
Axial Load Ratio ◽  
The Law ◽  
Resistance Performance

Welded built-up square CFT columns are widely employed in construction field thanks to their structural efficiencies by avoiding stress concentration area and improving workability in fabrication and maximizing the composite effect enabled by bent ribs. Although welded built-up square CFT columns have structural advantages over other members and are widely used, they are classified as non-fireproof in Korea because the steel tubes are directly exposed to a fire. Thus, fire coating required for the columns by the law results in inefficient design. This study suggests welded built-up square CFT columns with reduced coating to enable improved fire-resistance performance for 2˜3 hours. The purpose of the study is to analyse their fire-resistance performance using the variable of axial Load ratio which is the major factor in the performance and suggest efficient functional design with reduced coating.

Experimental Study on the Influence of Boundary Condition on the Behavioral Characteristics of CFT Square Columns under Constant Axial Load upon a Fire

2011 ◽  
Vol 82 ◽  
pp. 521-526 ◽  
Author(s):  
Heung Youl Kim ◽  
Kyung Hoon Park ◽  
Ki Hyuk Kwon
Keyword(s):  
Boundary Condition ◽  
Cross Section ◽  
Fire Resistance ◽  
Axial Load ◽  
Load Ratio ◽  
Steel Tube ◽  
Section Size ◽  
Cft Column ◽  
Major Factors ◽  
Resistance Performance

The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-section size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-section size was 360mm by 360mm. In the specimens with cross-section size of 280 mm × 280mm, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.

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