scholarly journals Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw-Thread Steels

2018 ◽  
Vol 2018 ◽  
pp. 1-30
Author(s):  
Xiaopeng Gao ◽  
Zhongfan Chen ◽  
Xiaomeng Ding ◽  
Erxiang Dong
Keyword(s):  
Failure Load ◽  
Ductile Failure ◽  
Flexural Behavior ◽  
Screw Thread ◽  
Test Results ◽  
Cracking Behavior ◽  
Near Surface ◽  
Four Point Bending ◽  
Calculation Results ◽  
Near Surface Mounted

An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. A total of ten full-scale stone slabs were tested under a four-point bending loading to investigate the effect of groove dimension, reinforcement ratios, and reinforcement materials on the flexural performance of stone slabs. The test results included failure characteristics, yield and ultimate capacities, deflection of midspan, and cracking behavior of stone slabs. The test results indicate that with the increase of groove height and groove width, cracking load and middeflection decrease by 6.4%–14.18%; however, failure load and middeflection increase by 4.7%–41.2%. Cracking load, failure load, and failure displacement of stone slabs adopting NSM screw-thread steels increased by 10.9%, 167%, and 617%, respectively, under the maximum reinforcement ratios of 0.629% over the control slab without NSM bars. Meanwhile, with the increase of reinforcement ratios, the failure mode transforms from brittle failure to ductile failure. The calculation results of strength are in agreement with the experimental results. Finally, it can be concluded that NSM CFRP bars are more effective than NSM screw-thread steels to improve flexural capacity with the same reinforcement ratios.

Experimental Study on the Flexural Behavior of Stone Slabs with near Surface Mounted Steel Bar

2014 ◽  
Vol 919-921 ◽  
pp. 128-132
Author(s):  
Er Xiang Dong ◽  
Zhong Fan Chen ◽  
Ming Xu
Keyword(s):  
Ductile Failure ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Flexural Behavior ◽  
Test Results ◽  
Near Surface ◽  
Steel Bar ◽  
Test Parameters ◽  
Stone Slab ◽  
Near Surface Mounted

Six stone slabs with near surface mounted steel bar were tested to study the flexural behavior of stone slab. The test parameters included the slotting dimension and steel reinforcement ratio. The test results show that the measure of near surface mounted steel bar can significantly increase the flexural capacity and ultimate deflection. The flexural behavior of stone slabs with near surface mounted steel bar is less affected by the slotting dimension; steel reinforcement ratio is the important factor influencing flexural behavior. With higher steel reinforcement ratio, the failure mode has transformed from brittle fracture into ductile failure; cracking load, ultimate load and displacement are largely increased by 10.2%131.9%617%. The mid-span section strain distribution complies with the plane-section assumption. Stone slabs with near surface mounted steel bar can fully exert the strength of stone and steel bar.

Flexural Behavior of NSM CFRP - Stone Composite Beams: Experimental Investigation

2012 ◽  
Vol 517 ◽  
pp. 881-886 ◽  
Author(s):  
Zi Xiong Guo ◽  
Yong Ye ◽  
Bao Cheng Liu ◽  
Yang Liu
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Reinforcement Ratio ◽  
Flexural Behavior ◽  
Test Results ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Reinforced Beams ◽  
Test Parameters ◽  
Near Surface Mounted

A technique for increasing the flexural behavior of stone beams using near-surface mounted (NSM) carbon fiber reinforced polymer (CFRP) rods is proposed. Four granite beams were tested under monotonic loading to investigate the effectiveness of this technique. One conventional stone beam was kept unreinforced as the control specimen and three beams were reinforced with NSM CFRP rods. The main test parameters included rod diameters and reinforcement ratios. Three types of failure modes were observed during testing, namely, abrupt fracture for conventional stone beams, flexure failure for moderately-reinforced beams and flexure-shear failure for over-reinforced beams, respectively. Test results showed that reinforcing with NSM CFRP could significantly enhance the flexural behavior of stone beams. For specimens with a reinforcement ratio of 0.14%, an average increase up to 91.0% in the ultimate load with respect to that of the control beam was obtained and the deformation capacity was dramatically increased. For specimens with a reinforcement ratio of 0.28%, though flexural behavior was greatly enhanced, an unfavorable shear failure was observed.

Experimental Study on Flexural Performances of Concrete Beams Strengthened with Near-Surface Mounted (NSM) FRP Reinforcement

2010 ◽  
Vol 163-167 ◽  
pp. 3634-3639
Author(s):  
Li Li Sui ◽  
Tie Jun Liu ◽  
Feng Xing ◽  
Yu Xiang Fu
Keyword(s):  
Experimental Study ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Flexural Stiffness ◽  
Test Results ◽  
Near Surface ◽  
Bending Performance ◽  
Bending Capacity ◽  
Frp Reinforcement ◽  
Near Surface Mounted

This paper illustrates the results of an experimental study on the bending performance of concrete beams strengthened with near-surface mounted (NSM) FRP reinforcement. The critical parameter of the embedded length of NSM-FRP plates was investigated in particularly. The test results indicated that NSM-FRP reinforcement can significantly improve the strength and crack resistance capacity of the concrete beam, reducing the size of cracks. The embedded length of the NSM-FRP plate has distinct influence on the cracking and bending capacity, the flexural stiffness, and the crack developments of the concrete beam. As the embedded length increased, the bending capacity and the flexural stiffness increased correspondingly and the crack developed more intensively.

STRENGTHENING OF PRESTRESSED HOLLOW CORE SLABS WITH OPENINGS USING NSM-CFRP STRIPS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Karam Mahmoud ◽  
Steven Foubert ◽  
Ehab El-Salakawy
Keyword(s):  
Original Structure ◽  
Test Results ◽  
Hollow Core ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Industrial Buildings ◽  
Near Surface Mounted ◽  
Parking Garages ◽  
Strengthening Technique

Precast, prestressed, hollow-core (HC) slabs are extensively used in many structures such as parking garages, commercial and industrial buildings. It is common for such structures to undergo changes while still in service, which may result in a reduction of their strength. One of these changes is to add in-situ openings at different locations along the slab to accommodate services such as intake/exhaust ducts or utility conduits. Near surface mounted (NSM) strengthening technique has proved to be an adequate technique that can be employed to restore or enhance the performance of the original structure. In this paper, the effect of openings and the efficiency of using NSM carbon fiber reinforced polymer (CFRP) strips as strengthening technique are investigated. A total of three full-scale prestressed HC slabs were tested; one without opening, one with an opening in the pure flexural zone and one with strengthened opening. Test results showed the presence of opening along the flexure span had a significant adverse effect on the post-cracking flexural stiffness, cracking load and the ultimate capacity of the slab. However, strengthening the opening with two strips of NSM-CFRP effectively enhanced the post-cracking stiffness, increased the ductility of the member and restored the flexural strength deficit incurred as a result of cutting the opening, and provided a net increase in flexural capacity.

Experimental Study on Flexural Behavior of Damaged Concrete Beams Strengthened with NSM-CFRP Strips

2012 ◽  
Vol 256-259 ◽  
pp. 1012-1016
Author(s):  
Gu Sheng Tong ◽  
Yong Xiang Wang ◽  
Qiu Lan Wu ◽  
Yong Sheng Liu
Keyword(s):  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Rc Beams ◽  
Near Surface ◽  
Damage Level ◽  
Reinforced Polymer ◽  
Near Surface Mounted ◽  
Strengthen Effect ◽  
Capacity Loading

In order to investigate the strengthen effect of different embedment lengths of the NSM strip on different damage levels. A series of tests were conducted on damaged reinforced concrete (RC) beams in flexure strengthened with near surface mounted (NSM) carbon- fiber-reinforced polymer (CFRP) strips, and initial cracking load, ultimate capacity, loading-deflection curves, and failure modes are examined and analyzed in the paper. The results showed that not only the initial cracking loads and ultimate capacities of the beams are significantly increased，but also the flexural stiffness of the beams in the yield and ultimate behavior stages are improved by using NSM-CFRP strips. The strengthen effect on lower damage level RC beams has no obvious difference with that on non-damaged RC beams. Anchoring of the strip end can increase the ultimate load capacities and decrease the ductility of RC beams. Debonding was found to be the primary failure mode in all cases.

scholarly journals EFFICIENCY OF FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAMS BY NEAR SURFACE MOUNTED CARBON FIBER REINFORCEMENT POLYMER RODS AND EXTERNALLY BONDED SHEETS

2021 ◽  
Vol 25 (Special) ◽  
pp. 4-100-4-114
Author(s):  
Wissam S. Abdullah ◽  
◽  
Hassan F. Hassan ◽  
Keyword(s):  
Load Capacity ◽  
Reference Beam ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Ultimate Load Capacity ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Cfrp Sheet ◽  
Externally Bonded ◽  
Near Surface Mounted

This study investigated the flexural behavior of reinforcement concrete beam strengthened with different techniques. The purpose of this research to study the various techniques of strengthening and knowing the effect of each technique on the beam behavior .Ten simply supported beams tested in this study. The total length of the beams and clear span were 1800mm and 1650mm, respectively. The cross section was (180×250) mm. Tested beams were divided into two categories’ the first category consist of one beams and considered as reference, while the second category consist of nine beams divided into Two groups according to the Strengthening techniques such as near surface mounted (NSM) and external bonded reinforcement (EBR).The experimental results showed improvement in ultimate load capacity for strengthened beams ranging from (6 to 89%) for NSM and (31 to 96%) for EBR and reduction in deflection for strengthened beams ranging from (6 to 43%) as compared with reference beam. When the number and length of CFRP bars are increased, the number of cracks increase while the width of the cracks and the spacing decrease, and the same observation is made when the width of the CFRP sheet is increased. The experimental load capacities of strengthened beams were compared with the design provisions given by ACI440.2R-17 guideline for NSM and EBR technique and EC2 guideline for EBR technique, the average ratio (1.2 and 0.97) respectively ,which showed that reasonable and a good agreement for all strengthened beams.

Flexural Behavior of RC Beams Strengthened with Near Surface Mounted Prestressed FRP

2007 ◽  
Author(s):  
Sung-Nam Hong ◽  
Jae-Hyun Park ◽  
Jong-Sup Park ◽  
Jun-Myung Park ◽  
Dong-Suk Yang ◽  
...  
Keyword(s):  
Flexural Behavior ◽  
Rc Beams ◽  
Near Surface ◽  
Near Surface Mounted

Flexural Behavior and Ductility of Concrete Beams Strengthened with Near-Surface Mounted GFRP Bars

2010 ◽  
Vol 163-167 ◽  
pp. 3610-3614 ◽  
Author(s):  
Hai Xia Zhang ◽  
Ling Wang ◽  
Guo Rui Liu
Keyword(s):  
Cross Section ◽  
Ultimate Load ◽  
Rectangular Cross Section ◽  
Reinforced Concrete Beam ◽  
Flexural Behavior ◽  
Near Surface ◽  
Displacement Ductility ◽  
Gfrp Bars ◽  
Near Surface Mounted ◽  
Strengthened Beam

The objective of this study is to investigate the flexural behaviors and ductility of reinforced concrete beam with near-surface mounted (NSM) GFRP bars. A total of 5, simply supported rectangular cross-section beams strengthened with NSM GFRP bars and two control beams are tested in this paper. The mode of failure, load-deflection relationship, strain distributions along the height of the beam on mid-span cross-section, and ductility of the beams are analyzed. The studies indicate that the yield and ultimate load have a significant increase compared with the control specimen. Especially, the ultimate load has a more measurable improvement than the yield load. The strain distribution along the height of specimen shows a clear nonlinear characteristic as a result of the crack propagating and steel yield. Also, the studies show that GFRP bars has played an important role in the flexural capacity of the strengthened beam during the stage from the yield to the failure of the beam. Besides, the strengthened beam is considered to be ductile using the displacement ductility index.

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