BOND AND SHEAR-STRENGTHENING PERFORMANCE OF FRCM COMPOSITES

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Adel Younis ◽  
Usama Ebead
Keyword(s):  
Rc Beam ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Test Results ◽  
Shear Strengthening ◽  
Double Shear ◽  
Structural Improvement ◽  
Load Carrying ◽  
Double Shear Test ◽  
Fabric Reinforced Cementitious Matrix

This paper is aimed at studying the bond and shear-strengthening performance of fabric reinforced cementitious matrix (FRCM) systems. Three FRCM systems were compared, namely, polyparaphenylene benzobisoxazole (PBO)-FRCM, Carbon-FRCM, and Glass-FRCM. At first, six double-shear specimens were tested to investigate the FRCM/concrete bond, with the test variables including the fabric type and the bond length. After that, seven shear-critical reinforced concrete (RC) beams were tested under three-point loading, considering the fabric type and strengthening configuration (full/intermittent) as the test variables. As for the double-shear test results, the failure observed was fabric/matrix debonding in carbon-FRCM, matrix/concrete debonding in PBO-FRCM, and fabric rapture in glass-FRCM. The FRCM/concrete bond increased with the bonded length, and the PBO-FRCM showed the highest bond to concrete. Regarding the RC beam tests, the FRCM-strengthened beams showed the same failure mode that is debonding at the FRCM/concrete interface. Nonetheless, FRCM had successfully strengthened the beams in shear: an average gain of 57% in the load carrying capacity was achieved as compared to the non-strengthened reference. Indeed, the full-length strengthening resulted in a better structural improvement compared to the intermittent-strengthening configuration. Amongst the three systems, carbon-FRCM systems were the most efficient in shear-strengthening RC beams.

scholarly journals BEHAVIOUR OF REINFORCED CONCRETE BEAMS WITHOUT STIRRUPS SUBJECTED TO STEEL REINFORCEMENT CORROSION

2016 ◽  
Vol 22 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Rizwan AZAM ◽  
Ahmed K. EL-SAYED ◽  
Khaled SOUDKI
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Longitudinal Reinforcement ◽  
Rc Beams ◽  
Test Results ◽  
Structural Behaviour ◽  
Three Point Bending ◽  
Load Carrying ◽  
Crack Widths

The effect of corrosion on the structural behaviour of reinforced concrete (RC) beams without stirrups was experimentally investigated. A total of seven medium-scale RC beams without stirrups were constructed. The beams measured 150 mm wide, 250 mm deep and 1700 mm long. The test variables included: three different longitudinal reinforcement ratios (0.91%, 1.21%, and 1.82%) and two different corrosion levels (3% and 10%). Four beams were subjected to artificial corrosion whereas three beams acted as control un-corroded. Following the corrosion phase, all beams were tested to failure in three point bending. Corrosion crack widths and cracking patterns were recorded at different stages of corrosion. The effect of different longitudinal reinforcement ratios on the rate of corrosion was observed. Test results revealed that the beams with higher reinforcement ratios experienced slower corrosion rate compared to beams with lower reinforcement ratios. All control beams failed in shear whereas corroded beams failed in bond. There was a significant reduction in the load carrying capacity of the corroded beams without stirrups compared to the control beams.

FRCM SHEAR STRENGTHENING FOR CONCRETE BEAMS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Adel Younis ◽  
Usama Ebead ◽  
Kshitij C. Shrestha
Keyword(s):  
Shear Zone ◽  
Carbon Fibers ◽  
Shear Failure ◽  
Load Capacity ◽  
Full Length ◽  
Rc Beams ◽  
Test Results ◽  
Shear Strengthening ◽  
Strength Enhancement ◽  
Fabric Reinforced Cementitious Matrix

This paper presents the results of an experimental study carried out to examine the efficacy of Fabric-Reinforced Cementitious Matrix (FRCM) in strengthening RC beams susceptible to shear failure. In this paper, seven shear-critical RC beams, of 2,500 mm in length, 150 mm in width, and 330 mm in depth, were tested under three-point loading until failure. Two main test variables were considered, which are: a) Strengthening material: carbon, polyparaphenylene benzobisoxazole (PBO), or glass FRCM, and b) Strengthening application pattern: a single full-length FRCM plate or a set of intermittent and spaced FRCM strips were applied along the critical shear zone. The test results confirmed the efficacy of FRCM strengthening in improving the load capacity of shear-critical RC beams. The FRCM-strengthening contributed to increases in the load capacity ranged between 31% and 100% compared to the reference specimen. The full-length strengthened specimens generally showed a better strength enhancement compared to the intermittent counterparts when using the same FRCM material. Such intuitive observation assures the importance of the amount of strengthening material applied in the critical shear zone. Besides, specimens utilizing carbon fibers in its FRCM strengthening material showed the highest strength enhancement among the three systems.

scholarly journals Shear Strengthening of RC Beams Using Sprayed Glass Fiber Reinforced Polymer

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Sayed Mohamad Soleimani ◽  
Nemkumar Banthia
Keyword(s):  
Carrying Capacity ◽  
Concrete Surface ◽  
Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Glass Fiber Reinforced Polymer ◽  
Shear Strengthening ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Carrying

The effectiveness of externally bonded sprayed glass fiber reinforced polymer (Sprayed GFRP) in shear strengthening of RC beams under quasi-static loading is investigated. Different techniques were utilized to enhance the bond between concrete and Sprayed GFRP, involving the use of through bolts and nuts paired with concrete surface preparation through sandblasting and through the use of a pneumatic chisel prior to Sprayed GFRP application. It was found that roughening the concrete surface using a pneumatic chisel and using through bolts and nuts were the most effective techniques. Also, Sprayed GFRP applied on 3 sides (U-shaped) was found to be more effective than 2-sided Sprayed GFRP in shear strengthening. Sprayed GFRP increased the shear load-carrying capacity and energy absorption capacities of RC beams. It was found that the load-carrying capacity of strengthened RC beams was related to an effective strain of applied Sprayed GFRP. This strain was related to Sprayed GFRP configuration and the technique used to enhance the concrete-FRP bond. Finally, an equation was proposed to calculate the contribution of Sprayed GFRP in the shear strength of an RC beam.

scholarly journals Effect of Preload Level on Flexural Load-carrying Capacity of RC Beams Strengthened by Externally Bonded FRP Sheets

2015 ◽  
Vol 9 (1) ◽  
pp. 426-434 ◽  
Author(s):  
Guibing Li ◽  
Aihui Zhang ◽  
Yugang Guo
Keyword(s):  
Carrying Capacity ◽  
Concrete Strength ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Test Results ◽  
Damage Level ◽  
Cfrp Sheets ◽  
Flexural Performance ◽  
Load Carrying ◽  
Externally Bonded

Most of the laboratory tests investigated the flexural performance of un-preloaded or undamaged RC beams strengthened with CFRP composites. However, in engineering applications, the structural member must carry a certain load or damage. There is a lack of systematical investigations on the effects of preload or damage level on the flexural load-carrying capacity of CFRP-strengthened RC beams. This paper tested 22 RC beams to investigate the influence of preload level on flexural load-carrying capacity of CFRP-strengthened RC beams. The test variables are preload level, amount of CFRP sheets, tension rebar ratio, and concrete strength. The test results show that if the preload level is not more than 80% of the yielding strength of the original beam, the preload or damage level does not influence the flexural load-carrying capacity of CFRP-strengthened RC beams. However, the ultimate flexural load-carrying capacity is significantly poor than that of RC beam strengthened under a preload level not more than 80% of the yielding strength, if the RC beams are strengthened under a preload level more than 90% of the yielding strength.

Experimental Research of Effect on Carrying Capacity of Normal Section of CFRP-Strengthened Beams for CFRP Debonding

2012 ◽  
Vol 193-194 ◽  
pp. 1192-1196
Author(s):  
Ze Jun Liu ◽  
Hai Ping Meng
Keyword(s):  
Carrying Capacity ◽  
Reduction Factor ◽  
Rc Beam ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Concrete Member ◽  
Normal Section ◽  
Load Carrying ◽  
Ultimate Carrying Capacity ◽  
Suggested Formula

By the experiment of 13 RC beam strengthened with CFRP, the paper mainly study the effect on the load carrying capacity of normal section of CFRP-strengthened beams for CFRP debonding. The results show that for the strengthened beams without any anchorage at plate-end, they lost load carrying capacity soon after CFRP debonded and quitted working, or went on carrying load like an ordinary RC beam. Besides, the formula for the effective CFRP strain when CFRP end debonded was proposed. For the strengthened beams with sufficient anchorage at plate-end, the strengthened beams should be simplified as simply supported unbonded concrete member after CFRP debonded. A reduction factor was adopted to modify the ultimate tension strain derived from the planar section assumption. The calculated results of ultimate carrying capacity were in reasonable agreement between the suggested formula and the test results.

Susceptibility of strain-hardening cementitious composite to curing conditions as a retrofitting material for RC beams

2021 ◽  
Vol 16 ◽  
pp. 155892502110203
Author(s):  
Mohammad Iqbal Khan ◽  
Galal Fares ◽  
Yassir Mohammed Abbas ◽  
Wasim Abbass ◽  
Sardar Umer Sial
Keyword(s):  
Strain Hardening ◽  
Environmental Conditions ◽  
Carrying Capacity ◽  
Flexural Behavior ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Curing Conditions ◽  
Flexural Members ◽  
Load Carrying ◽  
Curing Regime

Strain-hardening cement-based composites (SHCC) have recently been developed as repair materials for the improvement of crack control and strength of flexural members. This work focuses on strengthening and flexural enhancement using SHCC layer in tensile regions of flexural members under three different curing conditions. The curing conditions simulate the effect of different environmental conditions prevailing in the central and coastal regions of the Arabian Peninsula on the properties of SHCC as a retrofitting material. In this investigation, beams with SHCC layer were compared to control beams. The beams with SHCC layer of 50-mm thickness were cast. The results revealed that the flexural behavior and the load-carrying capacity of the normal concrete beam specimens under hot and dry environmental conditions were significantly reduced, lowering the ductility of the section. However, compressive strength is comparatively unaffected. Similarly, the hot curing conditions have also led to a notable reduction in the loading capacity of the beam with SHCC layer with a slight effect on its stiffness. On the other hand, steam-curing conditions have shown improvement in load-carrying capacity and a reduction in section ductility of the beam with SHCC layer. It was found that the structural unit retrofitted with SHCC layer was a curing-regime dependent as the tensile and strain-hardening properties of SHCC are highly sensitive to the alteration in the cement hydration process. A normal curing regime was found effective and satisfying the practical, cost, and performance requirements. Accordingly, a normal curing regime could be implemented to retrofit reinforced concrete (RC) beams with SHCC layers as recommended in the study.

scholarly journals The Assessment of Using CFRP to Enhance the Behavior of High Strength Reinforced Concrete Corbels

2021 ◽  
Vol 28 (1) ◽  
pp. 71-83
Author(s):  
Mazin Abdulrahman ◽  
Shakir Salih ◽  
Rusul Abduljabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Strength ◽  
Load Capacity ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Ultimate Load Capacity ◽  
Load Carrying ◽  
Externally Bonded ◽  
Effective Depth

In this research, an experimental study is conducted to investigate the behavior and strength of high strength reinforced concrete corbels externally bonded with CFRP fabric sheets and Plates with different patterns taking into account the effect of adopted variables in enhancing the ultimate strength; the effect of shear span to effective depth (a/d), configuration, type and amount of bonding. Eleven high strength reinforced corbels were cast and tested under vertical loads. Test results showed there was an improvement in the behavior and load carrying capacity of all strengthened corbels. An increasing in the ultimate strength of strengthened corbel by inclined CFRP strips reached to (92.1%) while the increasing reached to (84.21%) for using one horizontal CFRP Plates compared to un-strengthened reference specimen. Also, it can be conducted that the increase of (a/d) ratio from (0.6 to 0.8) resulted in decreasing by 21.05% in ultimate load capacity of corbels and from (0.4 to 0.6) by 31.25% and 58.69% in cracking and ultimate loads respectively Using CFRP .

scholarly journals Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
N. Aravind ◽  
Amiya K. Samanta ◽  
Dilip Kr. Singha Roy ◽  
Joseph V. Thanikal
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Glass Fiber Reinforced Polymer ◽  
Flexural Strengthening ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Carrying

AbstractStrengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

Load-carrying capacity of RC members in the viaducts of Railway where ASR occurred

2019 ◽  
Author(s):  
Mototsugu Hirota ◽  
Keishi Chikami
Keyword(s):  
Maintenance Management ◽  
Beam Specimen ◽  
Rc Beam ◽  
Load Carrying Capacity ◽  
Loading Test ◽  
Damage Level ◽  
Railway Company ◽  
Load Carrying ◽  
Water Blocking ◽  
Rc Slab

<p>In Japan, measures against ASR have been started since the late 1980s, but it is no exaggeration to say that all buildings built before that may be affected by ASR. Deterioration and damage due to ASR are remarkable in the section from around TsubameSanjo Station on the Joetsu Shinkansen operating in East Japan Railway Company to around Niigata Station, and there are situations where maintenance management is difficult. Currently, if there are major defects in regular inspections, we will carry out surface treatment etc., but we are starting to study how to prevent the ingress of water at the stage of minor defects in order to prevent the progression of ASR. When waterproofing the surface of a structure in which a crack or the like is generated by ASR, the effects of water blocking effect and reduction of the amount of water in concrete are not well known. In this report, RC slab members exposed and stored for about 15 years (about 40 years after completion) were used as RC beam specimens, and were dried to some extent on the assumption that moisture was blocked, and a loading test was performed. As a result of the loading test, the maximum strength of the RC beam specimen was larger than the calculated shear strength. From this result, it is considered that the damage level of the current ASR does not have the effect of reducing the shear resistance so much.</p>

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