scholarly journals Study a Structural Behavior of Eccentrically Loaded GFRP Reinforced Columns Made of Geopolymer Concrete

2020 ◽  
Vol 6 (3) ◽  
pp. 563-575
Author(s):  
Hussein Talab Nhabih ◽  
Ahmed M. Hussein ◽  
Marwa Marza Salman
Keyword(s):  
Ultimate Load ◽  
Concrete Columns ◽  
Concrete Column ◽  
Geopolymer Concrete ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Gfrp Bars ◽  
Short Columns ◽  
Steel Bars ◽  
Normal Strength

This study investigated a modern composite material, which is a short geopolymer concrete column (GPCC) reinforced by GFRP bars. The structural performances of GPCC subjected to eccentric load were studied and compared to the normal strength concrete column (NSCC) reinforced by steel bars. In this study, the primary experimental parameters were the reinforcement bars types, load eccentricity, and concrete types. Seven short columns were tested: three normal strength concrete columns reinforced by steel bars, three geopolymer concrete columns reinforced by GFRP bars and one normal strength concrete column without reinforcement. The model dimensions chosen in the present study was a square section of 130×130 mm and a total height of 850 mm. It was shown that the steel bars contribute about 16.47% of column capacity under concentric load. Comparing with the normal strength concrete column, a geopolymer concrete column reinforced by GFRP bars showed a little increase in ultimate load (5.17%) under concentric load. Under the load eccentricity of 130 mm, a geopolymer concrete column reinforced by GFRP bars showed a significant increase in the ultimate load (69.37%). Under large eccentricity, a geopolymer concrete column reinforced by GFRP bars has an outstanding effect on the columns' ultimate load capacity. Also, the sine form can be utilized for GPCC to find the lateral deflection along with the column high at different load values up to the failure.

Experimental Study of AFRP-Confined Square and Circular Concrete Columns Using Fiber Bragg Grating Sensors

2020 ◽  
Vol 982 ◽  
pp. 175-180
Author(s):  
Yi Liu ◽  
Yue Ting Yang ◽  
Jing Zeng ◽  
Ling Chen
Keyword(s):  
Fiber Bragg Grating ◽  
High Strength Concrete ◽  
Ultimate Load ◽  
High Strength ◽  
Concrete Columns ◽  
Bragg Grating ◽  
Concrete Column ◽  
Strength Concrete ◽  
Fiber Bragg Grating Sensors ◽  
Short Columns

An experimental investigation on square and circular high-strength concrete short columns confined with aramid fiber-reinforced polymer (AFRP) sheets was conducted in this study. Fiber Bragg grating sensors have been applied successfully in monitoring of the strains of the AFRP-confined square and circular concrete columns. The experimental results demonstrate that two types of axial force-strain curves were observed depending on the form of the column. Results show fiber Bragg grating sensors have good repeatability and the ultimate load of the circular concrete column is larger than that of the square concrete column. The interlaminar strains of AFRP and high-strength concrete have also been attained. It helps to analyze the constraint effect of the concrete column and compute the ultimate load of the square and circular concrete column.

Design-oriented axial stress–strain model for partially fiber-reinforced-polymer-confined normal-strength concrete

2020 ◽  
Vol 23 (16) ◽  
pp. 3481-3495
Author(s):  
Junlong Yang ◽  
Jizhong Wang ◽  
Ziru Wang
Keyword(s):  
Axial Stress ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Confined Concrete ◽  
Normal Strength Concrete ◽  
Stress Strain ◽  
New Model ◽  
Strength Concrete ◽  
Reinforced Polymer ◽  
Normal Strength

Due to the influence of “arching action” in fiber-reinforced polymer (FRP) partially confined concrete columns as a result of the unconfined regions, the confinement of the concrete columns wrapped with discrete FRP strips is less efficient when compared with full wrapping schemes. This study comprehensively investigates the difference of the the confinement mechanism between fully and partially FRP confined circular normal-strength concrete and thus presents a new design-oriented model to predict the stress–strain relationships of partially FRP confined normal-strength concrete. The formulas used to determine the strength and corresponding strain of several key points on the stress–strain curves are also proposed by the regression analysis according to a reliable test database from the relevant literature. Besides, another selected database including 100 FRP partially wrapped circular concrete columns is also collected for model verification. The results show that better performance can be achieved by the new model compared with the selected models in predicting the ultimate conditions of partially FRP confined concrete. Finally, some specimens are chosen to assess the performance of the new model in predicting the complete axial stress–strain curves. The comparisons reveal that satisfactory accuracy and good agreement can be achieved between the theoretical predictions and experimental observations.

Is it reasonable to use high-strength concrete columns under fire conditions?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Oliver Bahr
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Fire Performance ◽  
Normal Strength Concrete ◽  
Cross Sectional ◽  
Content Type ◽  
Strength Concrete ◽  
Normal Strength ◽  
High Strength Concrete Columns

PurposeThis paper aims to answer two questions. First, are there any differences in the fire performance of columns made of normal and of high-strength concrete? Second, under which circumstances does the fire design govern the cross-sectional dimensions of concrete columns? Is it feasible to replace columns out of normal strength concrete by more slender high-strength concrete columns?Design/methodology/approachThe author conducted numerical studies using the finite element code “Infocad” of the German company “Infograph”. The studies included the effect of different parameters on the fire performance of columns out of normal and high-strength concrete, i.e. the load ratio and eccentricity, boundary conditions and times of fire exposure.FindingsResults from the numerical investigations showed that high-strength concrete columns suffer much more from heating than normal strength concrete columns. This is the outcome of the unfavourable mechanical properties of high-strength concrete at elevated temperatures. Although the relative fire performance of columns out of high-strength concrete is worse than that of columns out of normal strength concrete, initial load reserves are beneficial to achieve even high fire ratings.Originality/valueMany researchers addressed in experimental and numerical studies the fire performance of columns out of normal and high-strength concrete. A special emphasis was often laid on the spalling of fire-exposed high-strength concrete. However, there are no systematic investigations when the fire design governs the cross-sectional dimensions of high-strength concrete columns. Based on a previous comparison of the relative fire performance of columns out of normal and high-strength concrete, this paper, hence, addresses the question whether there is a reasonable lower limit for the use of these columns. This is an important aspect for designers since there is a tendency to replace columns out of normal strength concrete by columns out of high-strength concrete. Higher concrete strengths allow for smaller cross sections of the columns, and designers may, hence, increase the usable space of buildings.

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