scholarly journals Retrofitting of SCC Deep Beams With Circular Openings Using CFRP

2021 ◽  
Vol 39 (7) ◽  
pp. 1092-1104
Author(s):  
Nabeel A. Al-Bayati ◽  
Dhiyaa H. Muhammad ◽  
Nawfal A. Abdul Jabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Fiber Reinforced Polymer ◽  
Hardened Concrete ◽  
Use Of Self ◽  
Load Path ◽  
Deep Beams ◽  
Self Compacting Concrete ◽  
Reinforced Polymer ◽  
Ultimate Failure

The main objectives of this study are: encouraging the production and use of self-compacting concrete, use of materials which are lightweight, easy to use, and highly efficient in the retrofitting of reinforced concrete buildings. Six deep beams specimens (L= length of 1400mm, h= height of 400mm, and b= width of 150mm) were cast using self-compacting concrete. The location of the openings is in the middle of assumed load path. Five patterns were adopted to arrange carbon fiber reinforced polymer (CFRP) strips. The cylinder compressive strength of the concrete was approximately equal for all beams and was about (44 MPa) at 28 days age. All the beams have the same steel reinforcement for shear and flexure. There have been many tests for fresh and hardened concrete. The reinforced concrete deep beams were tested up to (60%) of the ultimate load of control beams to simulate degree of damage, and then released the load. After that, the beams were retrofitted using (CFRP) strips, and then the beams were tested to failure. The study was focused on determining the vertical mid-span deflection, ultimate load, the load that causes first shear and flexural cracks, and mode of failure. The results showed that, the best increase in the ultimate failure load was (27.27%) and achieved using the inclined strips pattern and the pattern of vertical and horizontal strips together. Reduction in the deflection values for the retrofitted beams compared to the control beam by about (12-13%) due to restrictions imposed by CFRP strips and the...

scholarly journals Strengthening of self-compacting reinforced concrete deep beams containing circular openings with CFRP

2018 ◽  
Vol 162 ◽  
pp. 04015
Author(s):  
Nabeel Al-Bayati ◽  
Bassman Muhammad ◽  
Murooj Faek
Keyword(s):  
Ultimate Load ◽  
Test Results ◽  
Load Path ◽  
Deep Beams ◽  
Self Compacting Concrete ◽  
Reinforced Polymer ◽  
Web Reinforcement ◽  
Externally Bonded ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper shows the behavior of reinforced self-compacting concrete deep beams with circular openings strengthened in shear with various arrangements of externally bonded Carbon Fibre Reinforced Polymer (CFRP). Six simply supported deep beams were constructed and tested under two points load up to the failure for this purpose. All tested beams had same geometry, compressive strength, shear span to depth ratio, main flexural and web reinforcement. The variables considered in this study include the influence of fiber orientation, utilizing longitudinal CFRP strips with vertical strips and area of CFRP. The test results indicated that the presence of the circular openings in center of load path reduce stiffness and ultimate strength by about 50% when compared with solid one, also it was found that the externally bonded CFRP can significantly increase the ultimate load and enhance the stiffness of deep beam with openings.

scholarly journals Strengthening of Continuous Reinforced Concrete Deep Beams with Large Openings Using CFRP Strips

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3119
Author(s):  
Mohammed Riyadh Khalaf ◽  
Ali Hussein Ali Al-Ahmed ◽  
Abbas AbdulMajeed Allawi ◽  
Ayman El-Zohairy
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Fe Analysis ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Deep Beams ◽  
Reinforced Polymer ◽  
Beam Depth ◽  
Strength And Stiffness ◽  
Strengthening Technique

To accommodate utilities in buildings, different sizes of openings are provided in the web of reinforced concrete deep beams, which cause reductions in the beam strength and stiffness. This paper aims to investigate experimentally and numerically the effectiveness of using carbon fiber reinforced polymer (CFRP) strips, as a strengthening technique, to externally strengthen reinforced concrete continuous deep beams (RCCDBs) with large openings. The experimental work included testing three RCCDBs under five-point bending. A reference specimen was prepared without openings to explore the reductions in strength and stiffness after providing large openings. Openings were created symmetrically at the center of spans of the other specimens to represent 40% of the overall beam depth. Moreover, finite elements (FE) analysis was validated using the experimental results to conduct a parametric study on RCCDBs strengthened with CFRP strips. The results confirmed reductions in the ultimate load by 21% and 7% for the un-strengthened and strengthened specimens, respectively, due to the large openings. Although the large openings caused reductions in capacities, the CFRP strips limited the deterioration by enhancing the specimen capacity by 17% relative to the un-strengthened one.

Flexural behavior of fire damaged self-compacting concrete beams strengthened with fiber reinforced polymer (FRP) wrapping

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mervin Ealiyas Mathews ◽  
Anand N ◽  
Diana Andrushia A ◽  
Tattukolla Kiran ◽  
Khalifa Al-Jabri
Keyword(s):  
Elevated Temperature ◽  
Carbon Fiber ◽  
Ultimate Load ◽  
Research Work ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Content Type ◽  
Reinforced Polymer

PurposeBuilding elements that are damaged by fire are often strengthened by fiber wrapping techniques. Self-compacting concrete (SCC) is an advanced building material that is widely used in construction due to its ability to flow and pass through congested reinforcement and fill the required areas easily without compaction. The aim of the research work is to examine the flexural behavior of SCC subjected to elevated temperature. This research work examines the effect of natural air cooling (AC) and water cooling (WC) on flexural behavior of M20, M30, M40 and M50 grade fire-affected retro-fitted SCC. The results of the investigation will enable the designers to choose the appropriate repair technique for improving the service life of structures.Design/methodology/approachIn this study, an attempt has been made to evaluate the flexural behavior of fire exposed reinforced SCC beams retrofitted with laminates of carbon fiber reinforced polymer (CFRP), basalt fiber reinforced polymer (BFRP) and glass fiber reinforced polymer (GFRP). Beam specimens were cast with M20, M30, M40 and M50 grades of SCC and heated to 925ºC using an electrical furnace for 60 min duration following ISO 834 standard fire curve. The heated SCC beams were cooled by either natural air or water spraying.FindingsThe reduction in the ultimate load carrying capacity of heated beams was about 42% and 55% for M50 grade specimens that were cooled by air and water, respectively, in comparison with the reference specimens. The increase in the ultimate load was 54%, 38% and 27% for the specimens retrofitted with CFRP, BFRP and GFRP, respectively, compared with the fire-affected specimens cooled by natural air. Water-cooled specimens had shown higher level of damage than the air-cooled specimens. The specimens wrapped with carbon fiber could able to improve the flexural strength than basalt and glass fiber wrapping.Originality/valueSCC, being a high performance concrete, is essential to evaluate the performance under fire conditions. This research work provides the flexural behavior and physical characteristics of SCC subjected to elevated temperature as per ISO rate of heating. In addition attempt has been made to enhance the flexural strength of fire-exposed SCC with wrapping using different fibers. The experimental data will enable the engineers to choose the appropriate material for retrofitting.

Numerical Analysis of Reinforced Concrete Beam Strengthened with CFRP or GFRP Laminates

2016 ◽  
Vol 707 ◽  
pp. 51-59 ◽  
Author(s):  
Osama Ahmed Mohamed ◽  
Rania Khattab
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

The behaviour of reinforced concrete beam strengthened with Carbon Fiber Reinforced Polymer (CFRP) and Glass fiber reinforced polymer GFRP laminates was investigated using finite element models and the results are presented in this paper. The numerical investigation assessed the effect of the configuration of FRP strengthening laminates on the behaviour of concrete beams. The load-deflection behaviour, and ultimate load of strengthened beam were compared to those of un-strengthened concrete beams. It was shown that using U-shaped FRP sheets increased the ultimate load. The stiffness of the strengthed beam also increased after first yielding of steel reinforcing bars. At was also observed that strengthening beams with FRP laminates to one-fourth of the beam span, modifies the failure of the beam from shear-controlled near the end of the unstrengthened beam, to flexure-controlled near mid-span. CFRP produced better results compared GFRP in terms of the ability to enhance the behavior of strengthenened reinforced concrete beams.

scholarly journals Effect of Shear Span to Effective Depth Ratio on the Behavior of Self-Compacting Reinforced Concrete Deep Beams Containing Openings Strengthened with CFRP

2019 ◽  
Vol 26 (1) ◽  
pp. 1-9
Author(s):  
Nabeel A. Al-Bayati ◽  
Bassman R. Muhammed ◽  
Muroj F. Oda
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
General Trend ◽  
Load Path ◽  
Deep Beams ◽  
Web Openings ◽  
Shear Span ◽  
Depth Ratio ◽  
Effective Depth ◽  
Strengthened Beam

Results of test on seven simply supported self-compacting reinforced concrete deep beams, including six of these beams containing circular openings in center of load path are reported in this paper. The objective of the tests was determined the influence of, changing shear span to effective depth ratio a/d, the existence of circular openings in shear span and using inclined strips of carbon fiber polymer (CFRP) on behavior of deep beams. The general trend in crack pattern, the load-deflection response, and the mode of failure of reinforced SCC deep beams were also investigated. All specimens had the same geometry, details of the flexure and shear reinforcement in both vertical and horizontal directions and they were tested under symmetrical two-point loads up to failure. The experimental results revealed that the web openings within shear spans caused an important reduction in the deep beam capacity by 50% when compared with the corresponding solid beam. The increase a/d ratio from 0.8 to 1.2 decreases the ultimate load by 21.7% and 22.5 % for the reference unstrengthened beam and strengthened beam, respectively, also it was found that the externally inclined CFRP strips in deep beams increased the ultimate strength up to 39.5%, and enhanced the stiffness of deep beams with openings.

Reinforced Concrete Deep Beams with Openings Strengthened Using FRP – A Review

2014 ◽  
Vol 1025-1026 ◽  
pp. 938-943 ◽  
Author(s):  
Siew Choo Chin ◽  
Nasir Shafiq ◽  
Andri Kusbiantoro ◽  
Mohd Fadhil Nuruddin
Keyword(s):  
Reinforced Concrete ◽  
Fiber Reinforced Polymer ◽  
Future Research ◽  
Deep Beams ◽  
Chemical Attack ◽  
Reinforced Polymer ◽  
Essential Services ◽  
Rc Deep Beams ◽  
Strength And Stiffness ◽  
Modern Building

In the modern building construction, different size of openings are provided in the web of reinforced concrete (RC) deep beams to accommodate utility pipes and ducts of essential services such as electricity cable, telephone network and air-conditioning network. However, accommodation of such openings caused reduction in beam strength, stiffness and caused excessive cracking and deflection. Many investigations were conducted to study the behaviour of openings in beams and relevant strengthening options to reinstate the lost capacity. One of the strengthening options considered lamination of fiber reinforced polymer (FRP) sheets due to its superior properties such as high tensile strength and stiffness, high resistance to corrosion, excellent fatigue performance and good resistance to chemical attack. FRP lamination has been widely accepted by the research community and practicing engineers in the construction industry as the material for strengthening and rehabilitation of common problems. However, quite limited literatures contained the use of FRP to strengthen RC deep beams with openings. This paper discussed the review of eleven different articles contained study of RC deep beams with openings together with effects of strengthening using FRP sheets. The outcome of this review paper outlined the way forward and future research focus in this area.

Research on the Flexural Behaviour of Reinforced Concrete Beams Strengthened with CFRP

2011 ◽  
Vol 194-196 ◽  
pp. 1781-1784
Author(s):  
Hua Wei ◽  
Ji Ye Zhang ◽  
Da Wei Zhu ◽  
Zhi Yuan Peng ◽  
Hai Jun Wang
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Experimental Result ◽  
Reinforced Polymer ◽  
Flexural Member ◽  
Good Agreement

In order to clear the influence of carbon fiber reinforced polymer (CFRP) on the bearing capacity of reinforced concrete beams, tests of three reinforced concrete beams strengthened with CFRP are carried out. Experimental result shows that CFRP can effectively increase bearing capacity of flexural member, and can restrain the development of crack. Cracking load, yield load and ultimate load are significantly increased. At the same time numerical simulation is done; it is good agreement with experimental results.

scholarly journals Rehabilitation of Reinforced Concrete Deep Beams Using Carbon Fiber Reinforced Polymers (CFRP)

2018 ◽  
Vol 12 (8) ◽  
pp. 179 ◽  
Author(s):  
Shereen K. H. Hassan ◽  
Mu`tasim S. Abdel-Jaber ◽  
Maha Alqam
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Carrying Capacity ◽  
Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Fiber Reinforced ◽  
Deep Beams ◽  
Reinforced Polymer ◽  
Cfrp Composites ◽  
Load Carrying

Reinforced concrete structures that incorporates deep beams are generally susceptible to deterioration due to weathering effects and sulphur attacks, under-design in the detailing of concrete cover and/or reinforcement, and construction errors. In lieu of demolishing and replacing these structures, rehabilitation and strengthening using carbon fiber composites becomes a cost-effective viable alternative. Recent advances in research and innovation have introduced concrete repair and strengthening systems that are primarily based on fiber reinforced polymer composites. These systems have offered engineers the opportunity to provide additional stability to the structural elements in question and to restore the damaged portions back to their original load carrying capacity.  This paper investigates the effect of Carbon Fiber Reinforced Polymer (CFRP) composites in enhancing the flexural performance of damaged reinforced concrete deep beams. Two types of CFRP composites and epoxy were used in the experimental investigation carried out and as described by this paper: 1) high strength carbon fiber reinforced polymer (CFRP) plates, commercially known as MBrace Laminate, that are bonded using an epoxy resin specifically suited for the installation and used to strengthen existing structural members; and, 2) MBrace Fiber 230/4900, a 100% solids, low viscosity epoxy material that is used to encapsulate MBrace carbon, glass, and aramid fiber fabrics so that when it cures, it provides a high performance FRP sheet.Test samples were divided into four groups: A control group, and three rehabilitated test groups with CRFP fibers, where the main variable among them was the percent length of CRFP used along the bottom beam extreme surface between supports (i.e, for two of the groups reinforced with MBrace laminates), and the use of MBrace Fiber 230/4500 CRFP sheets on the 4th beam along its vertical sides as well as the bottom extreme face between supports. All beams had similar cross-sectional dimensions and reinforcement, and were designed to fail in flexure rather than shear. The results show that CFRP composites, both laminated and sheet type, have increased the load carrying capacity in comparison to the control specimen, where observations were recorded pertaining to the delayed formation of vertical flexural cracks at the section of maximum moment, and diagonal shear cracks at beam ends. The increase in the load carrying capacity varied among the three rehabilitated test group beams, with the 4th group showing the highest ultimate load carrying capacity when compared to the control specimen. 

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