scholarly journals COMBINING EBR CFRP SHEET WITH PRESTRESSED NSM STEEL STRANDS TO ENHANCE THE STRUCTURAL BEHAVIOR OF PRESTRESSED CONCRETE BEAMS

2021 ◽  
Vol 27 (8) ◽  
pp. 637-650
Author(s):  
M. Obaydullah ◽  
Mohd Zamin Jumaat ◽  
U. Johnson Alengaram ◽  
Md. Humayun Kabir ◽  
Muhammad Harunur Rashid
Keyword(s):  
Prestressed Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Element Model ◽  
Control Specimen ◽  
Flexural Performance ◽  
Flexural Failure ◽  
Prestressing Force ◽  
Cfrp Sheet ◽  
Strengthening Technique

In this study, a combined strengthening technique is used to improve the flexural performance of prestressed concrete beams using CFRP sheets as EBR and prestressed steel strands as NSM. Seven prestressed beams were tested under four-point loading with one control specimen, one EBR CFRP sheet strengthened specimen, one NSM steel strand without prestress strengthened specimen and four specimens strengthened with a combination of EBR CFRP sheet and NSM steel strands prestressed from 0% to 70% of their tensile strength. The flexural responses and failure modes of the specimens were investigated and the variations due to the level of prestressing force in the PNSM steel strands were also assessed. A finite element model (FEM) was developed using ABAQUS to verify the flexural responses of the strengthened specimens. The test results revealed that the combined strengthening technique remarkably enhanced the flexural performance of the specimens. The serviceability, first crack, yield, and ultimate load capacities improved up to 44%, 49%, 55% and 70%, respectively when compared with the control specimen. The combined technique also ensured the flexural failure of the specimens with significant enhancement in stiffness and energy absorption. The results of the FEM model exhibited excellent agreement with the experimental results.

Investigating the Load–Deflection of FRP Material in Concrete Beams Wrapped with CFRP in Universal Testing Machine (UTM)

2018 ◽  
Vol 15 (2) ◽  
pp. 744-751
Author(s):  
S. Margaret Jesse ◽  
V. M. Shanthi
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Testing Machine ◽  
Reinforced Concrete Beams ◽  
Flexural Failure ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Strength And Stiffness

Strengthening Reinforced Concrete (RC) beams using FRP laminate becomes one of the main strengthening techniques. Failure of these beams is usually controlled by the bond strength between the laminate and the concrete. This paper presents the results of experimental investigation on six reinforced concrete beams, with various types, which were tested under two-point loading. The aim of the work was to study the efficacy of Carbon Fiber Reinforced Polymer (CFRP) sheets in enhancing the beam strength and stiffness from shear failure or flexural failure. The strengthening and deflection of the beams were carried out with cyclic loading. Experimental data on ultimate load, deflection and failure modes of each of the beams were obtained. For the comparison of CFRP sheet with cement concrete and the retrofitted specimens absorbs more energy, the CFRP beams yield a good result.

An Study on the Flexural Performance of Reninforced Concrete Beams Considering Loading History with Pre-Stressed Cfrp Sheets

2011 ◽  
Vol 105-107 ◽  
pp. 853-856
Author(s):  
Zhe Li ◽  
Gang Li ◽  
Qin Zhao ◽  
Shuai Zhang
Keyword(s):  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Impact Factors ◽  
Cfrp Sheets ◽  
Flexural Performance ◽  
Reinforced Polymer ◽  
Secondary Load ◽  
Cfrp Sheet

For the effect of nonpre-stressed carbon fiber reinforced polymer (CFRP) Sheet Strengthening concrete beams to improve bending stiffness and crack resistance is not satisfactory, and it is difficult to totally unloading on the actual reinforcement, so in this paper, ANSYS is used to research the strengthened effectiveness and impact factors of pre-stressed CFRP reinforced concrete beams considering the secondary load.

Experimental Research on the Flexural Performance of the Strengthened Concrete Beams with Prestressed CFRP

2011 ◽  
Vol 255-260 ◽  
pp. 105-108
Author(s):  
Guo Wen Yao ◽  
Yan Li Wei ◽  
Shi Ya Li
Keyword(s):  
Failure Modes ◽  
Concrete Beams ◽  
Flexural Stiffness ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Flexural Performance ◽  
Load Carrying ◽  
Cycle Loading ◽  
Strengthened Beam ◽  
Three Stages

Three-bending experiments were performed on RC beams strengthened with prestressed CFRP under static and cycle loading. Prestressed CFRP obviously increases the load-carrying capacity and fatigue life of strengthened RC beam. And it greatly increases the flexural stiffness of strengthened beam. The failure modes of the beams go through concrete cracking, CFRP debonding from concrete and beam fractured. The vertical flexibility history at midspan is decomposed into three stages. And then fatigue damage is defined by flexural stiffness and its evolvement shows three stages of nucleation, growth and mutation.

The Flexural Performance of Pre-Damaged Reinforced Concrete Beam Strengthened with CFRP in Seawater Environment

2012 ◽  
Vol 166-169 ◽  
pp. 1736-1739
Author(s):  
Yu Tian Wang ◽  
Xiu Li Du ◽  
Fu Xiang Jiang ◽  
Wei Zhang
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Strengthening Effect ◽  
Flexural Capacity ◽  
Flexural Performance ◽  
Seawater Environment

Experiments on flexural behavior of strengthened pre-damaged reinforced concrete beams with CFRP and those exposed to seawater for different time have been carried out. By comparison, the rule of seawater effecting on failure modes of beams, fissure condition, strain development and flexural capacity, and so on have been studied. The results show that reinforcement treatment on the mechanical damaged reinforced concrete beams with bonding CFRP can effectively improve their flexural capacity and stiffness, and constrain the development of cracks. With the extension of time under seawater environment, although performance of pre-damaged beam strengthened with CFRP is influenced significantly, the strengthening effect is still more reliable.

Shear Behavior of CFRP Prestressed Concrete Beams without Stirrups

2011 ◽  
Vol 266 ◽  
pp. 126-129 ◽  
Author(s):  
Zuo Hu Wang ◽  
Xiu Li Du ◽  
Jing Bo Liu
Keyword(s):  
Prestressed Concrete ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Shear Span ◽  
Compression Failure ◽  
Concrete Members ◽  
Prestressed Beams

Five beams were tested up to failure to study the shear behavior of concrete beams prestressed with fiber reinforced polymer (FRP). Different factors were taken into consideration: the type of prestressing tendons and the shear span ratio. The shear failure modes and the influence of different factors on shear behavior were investigated in details. The test results showed that FRP prestressed beams without stirrups had two shear failure modes: diagonal compression failure and shear compression failure; the shear span ratio was the most important factor to determine the failure mode and shear capacity of the prestressed beams. The shear capacity of concrete members prestressed with FRP tendons was lower than that of concrete beams prestressed with steel cables.

scholarly journals Analysis of Prestressing in Precast Prestressed Concrete Beams

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jakub Kraľovanec ◽  
Martin Moravčík ◽  
Jozef Jošt
Keyword(s):  
Numerical Analysis ◽  
Service Life ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Direct Methods ◽  
Actual State ◽  
Indirect Methods ◽  
Remaining Service Life ◽  
Prestressing Force ◽  
Precast Prestressed Concrete

Abstract Knowledge of prestressing force’s value is in the case of prestressed concrete structure the most important basis for defining load-carrying capacity and remaining service life. Numbers of prestressed concrete structures are about to reach their limit of service life and they are exhibiting signs of deterioration due to the conceptional errors, inadequate maintenance and environmental distress. All of these factors negatively influence the actual state of prestressing. Thus, it is essential to determine the value of prestressing force considering the degradation of materials, such as corrosion of prestressing strands or wires. While assessing structure in service, it is difficult to apply magnetoelastic sensors or use other direct methods for determining the state of prestressing. Hence, the indirect methods enable to analytically calculate the prestressing force based on the results of measurement, e.g. strain, stress, deflection, or width of the crack. The present paper focuses on numerical analysis of prestressing in a twosome of precast prestressed concrete beams. For the numerical analysis, two indirect methods are applied, specifically Saw-cut method and Crack initiation method. Finally, the results are discussed and recommendations for the experimental campaign are summarized.

Study on Damaged Reinforced Concrete Beams Strengthened with Basalt Fiber Polymer Sheets

2012 ◽  
Vol 446-449 ◽  
pp. 2941-2944 ◽  
Author(s):  
Hua Nan He ◽  
Wei Dong
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Reference Beam ◽  
Basalt Fiber ◽  
Reinforced Concrete Beams ◽  
Steel Bar ◽  
Polymer Sheets ◽  
Fiber Sheet ◽  
Strengthening Technique

In practical concrete structures, once reinforced concrete beams serve in case of over cracking or are even damaged due to sudden overloading, it is necessary to repair or strengthened the damaged members for purpose of restoring the structural capacities and keeping the structures working well. At present FRP strengthening technique is one of the most accepted methods available in civil engineering. This paper particularly presents a new FRP material，basal fiber, which is applied to strengthen flexural behaviors of reinforced concrete beams suffering from different amplitudes of cracking damage. Herein, total 4 reinforced concrete beams were tested including one reference beam and three beams strengthened with basalt fiber polymer sheets. The three strengthened beams were preloaded to an expected load and then strengthen by basalt fibers under loading. The test parameters are involved in different pre-loads and layers of basalt fiber sheets. During test some flexural behaviors were obtained in terms of variation of strain in concrete, steel bar and basalt fiber sheet, flexural deflection, collapse loads and the failure modes as well as cracking properties of R.C beams strengthened with basalt fiber sheets. The results of test indicated that flexural behaviors of the beams strengthened under loading with basalt fiber polymer could be improved in different degree with varied initial flexural moment and numbers of basalt fiber.

Hardness and flexural performance of 3D orthogonal carbon/glass fibers hybrid composites under thermal-oxidative aging

2021 ◽  
pp. 152808372198927
Author(s):  
Juanzi Li ◽  
Wei Fan ◽  
Tao Liu ◽  
Lili Xue ◽  
Linjia Yuan ◽  
...  
Keyword(s):  
Failure Modes ◽  
Hybrid Composites ◽  
Glass Fibers ◽  
Flexural Modulus ◽  
Three Dimensional ◽  
Accelerated Aging ◽  
Flexural Performance ◽  
Flexural Failure ◽  
The Matrix ◽  
Experimental Findings

This study reports the hardness and flexural performance of the three-dimensional (3 D) orthogonal carbon/glass hybrid fiber/bismaleimide composites subjected to the accelerated aging conditions for 10, 30, 90, 120, and 180 days at 250 °C in an air environment. The rate of reduction in the flexural performance and failure modes were observed, in general, to be related to the aging time. The experimental findings revealed that the significant decline in the flexural performance of the samples aged for less than 30 days was predominantly attributed to the matrix degradation, while for the longer aging durations, the cracks in the composites and decomposition of the residual matrix were responsible for the gradual reduction in the flexural performance. The unaged and 30 days aged samples suffered a brittle failure represented by the macro-cracks and fiber breakage, while the cracked fiber/matrix interface and loosened fiber bundles were the main failure modes for the samples aged for longer times. The changes in the flexural failure modes resulted due to the severe degradation of the matrix under an extreme thermo-oxidative environment. Subsequently, a nonlinear relationship relating the flexural modulus to hardness was proposed.

scholarly journals Shear Strengthening of Reinforced Concrete Beams Using GFRP Wraps

10.14311/800 ◽  
2006 ◽  
Vol 46 (1) ◽  
Author(s):  
M. A. A. Saafan
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Structural Behavior ◽  
Shear Strengthening ◽  
Premature Failure ◽  
Web Reinforcement ◽  
Strengthening Technique

The objective of the experimental work described in this paper was to investigate the efficiency of GFRP composites in strengthening simply supported reinforced concrete beams designed with insufficient shear capacity. Using the hand lay-up technique, successive layers of a woven fiberglass fabric were bonded along the shear span to increase the shear capacity and to avoid catastrophic premature failure modes. The strengthened beams were fabricated with no web reinforcement to explore the efficiency of the proposed strengthening technique using the results of control beams with closed stirrups as a  web reinforcement. The test results of 18 beams are reported, addressing the influence of different shear strengthening schemes and variable longitudinal reinforcement ratios on the structural behavior. The results indicated that significant increases in the shear strength and improvements in the overall structural behavior of beams with insufficient shear capacity could be achieved by proper application of GFRP wraps.

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