scholarly journals A Comparative Study on the Efficiency of CFRP and GFRP in the Improvement of Compressive Strength, Acoustic Impedance and Bracing of Filled and Hollow Concrete Columns in Different Layers and Ages

2016 ◽  
Vol 9 (5) ◽  
pp. 110 ◽  
Author(s):  
Mohammadreza Zarringol ◽  
Mohammadehsan Zarringol
Keyword(s):  
Compressive Strength ◽  
Comparative Study ◽  
Ultimate Strength ◽  
Acoustic Impedance ◽  
Concrete Columns ◽  
Concrete Surface ◽  
Ultrasonic Waves ◽  
Shear Strengthening ◽  
Surface Strength ◽  
Strengthening Method

<p>FRP technique is growing in popularity as a modern strengthening method. When it comes to FRP, concrete surface strength plays a determining role in the bond between FRP and concrete. This paper aims to compare the efficiency of CFRP and GFRP in the improvement of compressive strength, acoustic impedance and bracing of filled and hollow concrete columns in different layers and ages. In doing so, we carried out various tests on 18 samples in the ages of 3, 7, 14, 28, 42 and 90 days. According to the results, the strength of un-braced carbon and glass increased by 19-40% and 8-43% respectively and the strength of braced carbon and glass increased by 17-25% and 10-82% respectively. The compressive strength increased by 66% in one-layer CFRP hollow column, 96% in two-layer CFRP hollow column, 123% in three-layer CFRP hollow column, 36% in one-layer GFRP hollow column, 63% in two-layer GFRP hollow column, 105% in three-layer GFRP hollow column, 71% in one-layer CFRP filled column, 138% in two-layer CFRP filled column, 154% in three-layer CFRP filled column, 45% in one-layer GFRP filled column, 79% in two-layer GFRP filled column, and 144% in three-layer GFRP filled column. The ultimate strength of the beams with flexural-shear strengthening was higher than other beams. Also, the increased percentage of fiber resulted in the increased speed of ultrasonic waves. </p>

scholarly journals Study on the compensating calcium ion method for existing concrete based on crystal infiltration waterproof materials

2021 ◽  
Vol 293 ◽  
pp. 02059
Author(s):  
Yang Dishan ◽  
Yan Tongyu ◽  
Lin Yubin ◽  
Li Jiyu ◽  
Ruan Xiaofei ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Concrete Surface ◽  
Strengthening Effect ◽  
Surface Strength ◽  
Before And After ◽  
Key Factor ◽  
Concrete Strengthening ◽  
Better Than ◽  
Strengthening Method

The quality of the the existing concrete surface in its repairing and strengthening is the key factor affecting the together working performance. The effective method to solve this problem is to use permeable crystal waterproof material to strengthen the existing concrete surface. In view of the existing old concrete which lacks free Ca2+ in the interior, the method of compensating calcium ion strengthening is proposed based on the action mechanism of permeable crystalline waterproof material. On the basis of DPS, calcium ion compensating agent Ca (OH)2, Na2SiO3 (sodium silicate) and Na2CO3 (potassium carbonate) solutes are added to prepare composite reinforcement solution for impregnation strengthening of concrete. Scanning electron microscopy (SEM) was used to observe the microstructure of the concrete before and after strengthening. It showed that after the entry of silicate ions, C-S-H colloid was formed by reaction with Ca (OH)2, and C-S-H gel blocked some pores, which made the inner microstructure more compact. The results of compressive strength before and after concrete strengthening show that the strengthening effect of calcium ion compensation method for low-strength concrete is better than that of permeable crystallization material strengthening method. The strength of C5 and C15 grade concrete is increased by 36.1% and 6% respectively, and the surface strength of 13.7 MPa concrete is increased by 16.7%.

scholarly journals Finite Element Modeling of Axially Loaded CFRP-Confined Rectangular Reinforced Concrete Columns

2016 ◽  
Vol 2 (8) ◽  
pp. 414-425 ◽  
Author(s):  
Hamed Akbarpour ◽  
Masoumeh Akbarpour
Keyword(s):  
Compressive Strength ◽  
Ultimate Strength ◽  
Fiber Orientation ◽  
Concrete Strength ◽  
High Strength ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Strength Concrete ◽  
Reinforced Polymer ◽  
Number Of Layers

This paper investigates numerically the behaviour of rectangular RC columns strengthened with carbon fiber reinforced polymer (CFRP) composites under uniaxial loading. For this a reason, a parametric study is conducted and the effects of CFRP layers number, compressive strength of unconfined concrete, and fiber orientation on the behaviour of such columns have been studied. The number of CFRP layers has been changed from one to five layers while the fibers are oriented transversely. Compressive strength of unconfined concrete has been increased from 26 MPa to 45 MPa. In addition, three different fiber orientations are considered. The results show that an increase in the number of CFRP layers would enhance the ultimate strength of specimens. Although increasing the number of layers would not increase the ultimate strength of specimens exponentially, but the rate of strength gain would also decrease. Moreover, it is shown that lateral strains increase as the layer number increases. The effect of unconfined concrete strength on the ultimate strength is less for low strength concrete than high strength concrete. Evaluating the effect of fiber orientation shows that the maximum ultimate strength is obtained from transverse orientation and as the angle of orientation increases, the ultimate strength decreases.

scholarly journals Predicting the behavior of reinforced concrete columns confined by fiber reinforced polymers using data mining techniques

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Sahar Y. Ghanem ◽  
Heba Elgazzar
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Compressive Stress ◽  
Compressive Strain ◽  
Concrete Columns ◽  
Steel Reinforcement ◽  
Fiber Reinforced Polymers ◽  
Stress And Strain ◽  
Fiber Reinforced ◽  
The Impact

AbstractFiber Reinforced Polymer (FRP) usage to wrap reinforced concrete (RC) structures has become a popular technology. Most studies about RC columns wrapped with FRP in literature ignored the internal steel reinforcement. This paper aims to develop a model for the axial compressive strength and axial strain for FRP confined concrete columns with internal steel reinforcement. The impact of FRP, Transverse, and longitudinal reinforcement is studied. Two non-destructive analysis methods are explored: Artificial Neural Networks (ANNs) and Regression Analysis (RA). The database used in the analysis contains the experimental results of sixty-four concrete columns under the compressive concentric load available in the literature. The results show that both models can predict the column's compressive stress and strain reasonably with low error and high accuracy. FRP has the highest effect on the confined compressive stress and strain compared to other materials. While the longitudinal steel actively contributes to the compressive strength, and the transverse steel actively contributes to the compressive strain.

Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

2014 ◽  
Vol 894 ◽  
pp. 45-49 ◽  
Author(s):  
Luisa Pani ◽  
Lorena Francesconi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Ultrasonic Wave ◽  
Ultrasonic Test ◽  
Ultrasonic Waves ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Static Modulus ◽  
Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

scholarly journals Strengthening Effect of the External Prestressing Method That Simulated a Deterioration Bridge

2021 ◽  
Vol 11 (6) ◽  
pp. 2553
Author(s):  
Sang-Hyun Kim ◽  
Jong-Sup Park ◽  
Woo-Tai Jung ◽  
Jae-Yoon Kang
Keyword(s):  
Compressive Strength ◽  
Strengthening Effect ◽  
Reinforcement Effect ◽  
Loading Test ◽  
Yield Load ◽  
Existing Structures ◽  
External Prestressing ◽  
The Difference ◽  
Existing Structure ◽  
Strengthening Method

Various methods for strengthening existing structures have been developed owing to the increase in human and property damages caused by the deterioration of structures. Among the various reinforcing methods, the external prestressing method increases the usability and safety of a structure by directly applying tension to the weak tensile area that suffers the greatest deflection during the structure usage. The external prestressing method is advantageous in reducing cracks caused by the introduced tension and restoration of the deflection. Since the strengthening method is applied to deterioration bridges, the strengthening effect is affected by the condition of the existing structure. However, studies on the strengthening effect according to the degree of deterioration are insufficient. Therefore, the behavior according to the strengthening status was analyzed, and the strengthening effect was identified in this study by simulating the deteriorated bridge, reducing the compressive strength and reinforcement quantity, and conducting a four-point loading test. As a result of the experiment, a reinforcement effect of 215% crack load, 161% yield load, and the difference in behavior according to the reinforcement parameters were confirmed.

Assessment of Residual Ultimate Strength of VLCC According to Damage Extents and Average Compressive Strength of Stiffened Panel

2014 ◽  
Author(s):  
Ji-Myung Nam ◽  
Joonmo Choung ◽  
Se-Yung Park ◽  
Sung-Won Yoon
Keyword(s):  
Compressive Strength ◽  
Ultimate Strength ◽  
Probabilistic Approach ◽  
Stiffened Panel ◽  
Moment Capacity ◽  
Hull Girder ◽  
Damage Area ◽  
Damage Indices ◽  
Smith Method ◽  
Average Compressive Strength

This paper presents the prediction of residual ultimate strength of a very large crude oil carrier considering damage extents due to collision and grounding accidents. In order to determine extents of damage, two types of probabilistic approaches are employed: deterministic approach based on regulations based on ABS [1], DNV [2], and MARPOL [3] and probabilistic approach based on IMO probability density functions (PDFs) (IMO guidelines [4]). Hull girder ultimate strength is calculated using Smith method which is dependent on how much average compressive strength of stiffened panel is accurate. For this reason, this paper uses two different methods to predict average compressive strength of stiffened panel composing hull girder section: CSR formulas and nonlinear FEA. Calculated average compressive strength curves using CSR formulas (IACS [5, 6]) and nonlinear FEA are imported by an in-house software UMADS. Residual ultimate moment capacities are presented for various heeling angles from 0° (sagging) to 180° (hogging) by 15° increments considering possible flooding scenarios. Three regulations and IMO guidelines yield minimum of reduction ratios of hull girder moment capacity (minimum of damage indices) approximately at heeling angles 90° (angle of horizontal moment) and 180° (angle of hogging moment), respectively, because damage area is located farthest from neutral axis.

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