Download or read book Numerical Analysis on the Behaviour of CFRP Shear strengthened RC Deep Beams with Large Square and Circular Openings written by Chee Wei Shim and published by . This book was released on 2015 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents a finite element analysis to investigate the behaviour of reinforced concrete deep beams with square and circular openings. Deep beams are always constructed at the lower floors as transfer beams to transfer the loads from the entire building to the foundations. Reinforced concrete (RC) acts as one of the most essential building materials and it is widely used in the construction due to its low pricing, efficiency and strength of the reinforced concretes as well as its stiffness. Openings are inevitable for the architectural and mechanical purpose to accommodate the conduits. However, presence of openings in the deep beams will significantly reduce the load capacity of the deep beams, as well as excessive cracking and deflection. Strengthening by Carbon Fibre Reinforced Polymer helps in regain the load bearing capacity of the deep beams. Researches were focus on the experimental work and hence this study conducted in terms of the numerical aspects and finite element analysis. ANSYS CivilFEM 12.0, a finite element modelling and analysis software, was used to analysis the deep beams. Three - dimensional modelling of RC deep beams was adopted in this study. A total of 14 beams including one control beam were modelled as simply supported beam with openings where the locations of the openings were at the support which was 300 mm from the edge of the beams. Two incremental loads were applied at the 800 mm from the edge of the beams. The beams was symmetrical in shape. The beams had the cross sections of 120 mm x 600 mm and 2400 mm in length with square and circular openings. The objectives of this study were to determine the most effective strengthening method by using CFRP in terms of load-deflection behaviours, crack patterns, stress and strain contours. This study was validated by experimental results. Various strengthening methods were used to identify the most effective method of strengthening which included orientation of CFRP in vertical alignment (90o), horizontal alignment (0o), whole piece, cut strips, surface strengthening and U-wrap strengthening. Deep beams with openings failed due to shear cracks because of the sharp edges of the openings. From the finding, the square opening and circular opening experienced a reduction of 62.0% and 51.3% in beam capacity, respectively. From the various strengthening configurations of CFRP, configuration with vertical alignment, whole piece and U-wrap strengthening method was the most effective method. CFRP restored the load bearing capacity with most effective method by 63.0% and 85.0% for deep beams with square and circular openings respectively. A comparison between the numerical and experiments results showed that a comparable agreement on the load deflection behaviours and strong agreement on the crack patterns.

Download or read book Shear Strengthening of RC Deep Beams with Large Openings Using Carbon Fiber Reinforced Polymers CFRP written by Foo Sheng Tong and published by . This book was released on 2015 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research deals with the experimental study of the behaviour of reinforced concrete deep beams with or without large rectangular openings as well as openings strengthened using externally bonded Carbon Fiber Reinforced Polymer (CFRP) composites in shear. The structural behaviour, including the load deflection, cracking patterns, failure mode, and effectiveness of the CFRP wraps were investigated. A total of four (4) specimens of beams with compressive strength of 35 MPa were tested to induce shear failure under 4 points loading test, which included one solid deep beam acted as a control beam (CB), one of which was tested without strengthening (US-BRO), and the remaining beams were strengthened with CFRP wraps in varying configurations around the opening (S-BRO-1, S-BRO-2). The beam had a cross section of 120 mm in width and 600 mm in depth as well as a length of 2400 mm. All the test specimens had a same geometry, main reinforcement arrangements and openings location. All the preparatory works of specimen materials were conducted in Laboratory FKASA. The examined parameter was the effect of configurations of the CFRP wraps used for the shear strengthening. The inclusion of un-strengthened large rectangular openings in the shear zone of a reinforced concrete deep beam leads to a reduction of ultimate beam strength by approximately 70%. The application of CFRP wraps with the presented strengthening configurations restricted the propagation of the diagonal crack and effectively increases ultimate load-carrying capacity as well as the ductility of the beam. The strength re-gains by U-shaped strengthening configuration around the openings was approximately 36% as compared to the beam with un-strengthened openings. However, the deep beam with U-shaped CFRP with horizontal fiber strengthened at the top and bottom chords of the openings were not capable to restore the control beam's original structural strength remarkably. The beam only managed to re-gain about 41% of the control beam's capacity.

Download or read book Experimental Study on the Behaviour of Reinforced Concrete Deep Beams with Large Circular Openings Strengthened Using CFRP written by Wen Khai Chong and published by . This book was released on 2015 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental research was conducted to study the behaviour of unstrengthen RC deep beams with openings and strengthened using Carbon Fiber Reinforced Polymer (CFRP). Strengthening configuration of CFRP-wrap used in this study were U-wrap and surface-wrap which applied with one layer of CFRP and in vertical alignment (90o). Four RC deep beams which included a solid control beam, a beam with two large circular openings, beams with two large circular openings strengthened using U-wrap and surface-wrap were tested to failure under four-point loading. All the beam specimens were in a dimension of 120 x 600 mm and 2400 mm in length. The support and loading point were located at 300 mm and 800 mm from the edge of the RC deep beams, respectively. Circular openings was designed with a standard of 0.45h which considered as large circular openings in a diameter of 270 mm that located 435 mm from the edge of the RC deep beams. Shear span-to-depth ratio (a/h) in this study was 0.83 in which the distance between the loading point and the support was 500 mm in order for the beam specimens to fail in shear region. RC deep beam with large circular openings, NS-BCO greatly reduced the beam strength, approximately 51.20 % as compared to the control beam. On the other hand, RC deep beam with circular openings strengthened using U-wrap, UW-BCO increases the beam strength up to almost 85.0 % as compared to NS-BCO. Hence, the most effective strengthening method was U-wrap, UW-BCO which re-gained the beam strength up to 90.28 % as compared to control beam.

Download or read book Strengthening of Reinforced Concrete Deep Beams Having Large Square Openings in Shear Zone with Carbon Fiber Reinforced Polymer CFRP Wrap written by Kin Mun Ng and published by . This book was released on 2015 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Typically, the reinforced concrete (RC) deep beam with large openings are facing some severe problems such as the interruption of natural load transfer by concrete struts acting in compression which can cause an intensive reduction in strength; and the clearly visible cracks in serviceability conditions. The CFRP has become an alternative solution to this issue and being extensively used as an external reinforcement to resolve the strength requirements in structural systems due to extremely strong yet light weight, outstanding fatigue properties, excellent corrosion resistance and easy yet efficient application on concrete. This experimental study is focuses on the investigation of the effect of CFRP wrap in strengthening RC deep beams with large square openings located in shear zone. Three approaches are under consideration; the first is the determination of natural load transfer in normal deep beam without opening, the second is the large square openings in deep beam without CFRP strengthening, and the third is the large square openings in deep beam with CFRP attached around the openings. A total of four RC deep beams which included a solid RC control beam, a deep beam with two large square openings, and two beams with two large square openings strengthened by using CFRP strips in different strengthening configurations, were tested to failure under four point loading to determine the relative structural behaviour such as ultimate load, failure mode, crack patterns, and load deflection behaviour. All RC deep beams were designed in a dimension of 120 x 600 mm and 2400 mm in length. The width and height of large square openings were in a dimension of 270 x 270 mm and located 300 mm from the edge of the deep beam. The loading point and support were located at 800 mm and 300 mm from the edge of the deep beam, respectively. RC deep beam with large square openings, US-BSO was significantly reduced the beam capacity by 61.76 % as compared to solid control beam, CB. However, the RC deep beam with large square openings strengthened by CFRP strips wrapped in U-shaped, SU-BSO has increases the beam capacity by 62.77 % compared to US-BSO. From the results obtained, it was found that the most effective CFRP strengthening method for RC deep beam with large square openings was U-shaped, which recovered the beam capacity up to 62.24 % as compared to solid control beam.

Download or read book Reinforced Concrete Deep Beams written by F K Kong and published by CRC Press. This book was released on 1991-05-01 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contents of this book have been chosen with the following main aims: to review the present coverage of the major design codes and the CIRIA guide, and to explain the fundamental behaviour of deep beams; to provide information on design topics which are inadequately covered by the current codes and design manuals; and to give authoritative revie

Download or read book Eexperimental and Numerical Studies on Behaviour of Frp Strengthened Deep Beams with Openings written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinforced concrete deep beams are widely used as transfer girders in offshore structures and foundations, walls of bunkers and load bearing walls in buildings. The presence of web openings in such beams is frequently required to provide accessibility such as doors and windows or to accommodate essential services such as ventilating and air conditioning ducts. Enlargement of such openings due to architectural/mechanical requirements and/or a change in the building's function would reduce the element's shear capacity, thus rendering a severe safety hazard. Limited studies have been reported in the literature on the behavior and strength of RC deep beams with openings. When such enlargement is unavoidable adequate measures should be taken to strengthen the beam and counteract the strength reduction. The present experimental investigation deals with the study of deep beams containing openings and the validation of results with FEM model using ANSYS. A total of 5 deep beams with openings are casted without shear reinforcements and are tested under three-point loading. Test specimen has a cross section of 150x460 mm and a total length of 1200 mm. Two circular openings, one in each shear span, are placed symmetrically about the mid-point of the beam. The structural response of RC deep beams with openings was primarily dependent on the degree of the interruption of the natural load path. Externally bonded GFRP shear strengthening around the openings was found very effective in upgrading the shear strength of RC deep beams. The strength gain caused by the GFRP sheets was in the range of 68-125%. Finite element modeling of RC deep beams containing openings strengthened with GFRP sheets is studied using ANSYS and the results are compared with experimental findings.

Download or read book Concrete Beams with Openings written by M. A. Mansur and published by CRC Press. This book was released on 1999-01-29 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book compiles state-of-the-art information on the behavior, analysis, and design of concrete beams containing transverse openings. Discussions include the need, effects, and classification of openings as well as the general requirements for fulfilling design pure bending, combined bending, and shear - illustrated with numerical examples torsion alone or in combination with bending and shear large rectangular openings as well as opening size and location on beam behavior methods for analyzing ultimate strength and serviceability requirements effects of torsion in beams large openings in continuous beams and their effects on possible redistribution of internal forces as well as guidelines and procedures for the design of such beams effect of prestressing on the serviceability and strength of beams with web openings design against cracking at openings and ultimate loads Concrete Beams with Openings serves as an invaluable source of information for designers and practicing engineers, especially useful since little or no provision or guidelines are currently available in most building codes.

Download or read book Static and Dynamic Shear Behavior of Uniformly Loaded Reinforced Concrete Deep Beams written by Robert A. Crist and published by . This book was released on 1971 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Behavioral equations were developed for reinforced concrete deep beams, especially in the realm of shear capacity. A series of static and dynamic beam tests was performed to aid in the development of this objective. Static shear behavior equations for deep beams were derived on the lower boundary of reinforced concrete deep beam data represented by research from this report and other research comprising 73 tests. Equations for a total static shear capacity are given which conservatively predict shear capacities of the beam tests considered. (Author).

Download or read book Finite Element Analysis of RC Deep Beams with Openings Strengthened by Carbon Fiber Reinforced Polymer CFRP written by Chun Mun Seow and published by . This book was released on 2015 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Shear Behaviour of Reinforced Concrete Beams written by Zarrog Mohammed Zarrog Othman and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural Behavior of Reinforced Concrete Deep Beams Strengthened in Flexure with CFRP written by Mustafa Mohammed Raheem and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research presents an analytical and experimental investigation for the use of flexural CFRP sheets as a strengthening technique to improve the shear capacity of reinforced concrete deep beams. The analytical work presents a new analysis method that is developed to predict the response of reinforced concrete deep beams with and without flexural CFRP strengthening. The method utilizes the truss analogy approach that is extended from the Strut-and-Tie Model (STM) for unstrengthened beams. In contrary to STM, the new method is used to capture the full structural response of unstrengthened beams by modeling a single truss. On the other hand, the new method is used to predict the entire response of strengthened beams by assuming the beam to be composed of two parallel compatible trusses. The first truss has its lower chord member composed of the steel bars while the second truss has its lower chord member composed of the flexural CFPR sheets. By imposing the compatibility condition of a statically indeterminate truss, the contribution of each truss is realized. The experimental work was conducted on three deep beam specimens with identical rectangular cross-sectional area. The first beam was tested as a control beam, and the other two beams were strengthened in flexure with four layers of flexural CFRP sheets anchored by two different flexural anchorage devices. The first strengthened beam was anchored with GFRP patches applied to both sides of the beam. The second strengthened beam was anchored with side GFRP bars inserted longitudinally to both sides of the beam. The comparison between the analytical and experimental results showed reasonable agreement and asserted the validity of the analytical approach and methodology developed in this study.

Download or read book Strengthening of Concrete Deep Beams with Extreme Discontinuities Using Near surface Mounted Composites written by Moustafa Seifeddin Mansour and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Installation of a web opening that fully interrupts the natural load path in concrete deep beams produces regions of extreme discontinuities and reduces the shear strength. This research examined the effectiveness of using near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) reinforcement to restore the shear strength of deep beams with extreme discontinuities. The strut-and-tie model (STM) procedures were utilized to develop three different strengthening solutions around the discontinuity regions. A total of eight deep beam specimens (150 x 500 x2700 mm) with a shear span-to-depth ratio of a/h = 0.8 were constructed and tested. One beam was solid. Seven beams had a square opening in the middle of the shear span with an opening height ratio of ho/h = 0.2. Six beams were strengthened with NSM-CFRP around the discontinuity regions. Three-dimensional finite element (FE) models were developed to simulate the nonlinear behavior of the tested specimens. Experimental results were compared to predictions of the FE models and the STM design solutions to examine their accuracy and validity. Installation of the web opening resulted in a 40% reduction in the shear strength. The NSM-CFRP strengthening solutions fully restored the original shear strength, except in two cases where only 93% and 94% of the capacity were restored. The laboratory test results were used to determine the optimal NSM-CFRP strengthening solution. The STM based on provisions of the American Concrete Institute provided realistic and consistent predictions for the nominal strength of the tested specimens with an average predicted-to-measured strength ratio of 1.01±0.09. In contrast, the STM predictions based on provisions of the Canadian Standards Association tended to be conservative with an average predicted-to-measured strength ratio of 0.71±0.29. Predictions of the FE models were sensitive to the mesh size and the concrete constitutive law adopted in the analysis. The inclusion of a bond-slip model between the CFRP and concrete resulted in up to a 5% reduction in the predicted strength. The use of a small mesh size of 15 mm and a “user” concrete constitutive law rather than a “default” law yielded more accurate predictions that were insignificantly different from those obtained from the tests

Download or read book Behaviour of Shear critical Reinforced Concrete Beams Strengthened with Fiber Reinforced Cementitious Mortar written by Rizwan Azam and published by . This book was released on 2016 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensive research has been conducted on strengthening of shear-critical reinforced concrete (RC) beams, particularly using fiber reinforced polymer (FRP) strengthening systems. This previous research has helped to better understand the behaviour of shear strengthening systems and has improved the performance of existing shear strengthening systems. However, there is still a potential to further improve upon the performance of existing shear strengthening systems. A cement-based composite system is an innovative strengthening system that has similar benefits (such as light weight, ease of installation and non-corroding) to FRP systems, but overcomes some of the draw backs (such as poor compatibility with concrete substrate, lack of vapour permeability and fire resistance) of using epoxy as bonding agent in FRP systems. A cement-based composite replaces the epoxy with cementitious mortar and the fiber sheets with fabric or grids. The current study presents the results of an experimental study conducted to investigate the effectiveness of cement-based composite systems in comparison to an existing epoxy-based system (carbon fiber reinforced polymer, CFRP) to strengthen shear-critical RC beams. Two types of cement-based systems were investigated in this study: carbon fiber reinforced polymer (CFRP) grid embedded in mortar (CGM) and carbon fabric reinforced cementitious mortar (CFRCM). The experimental study consisted of two phases. Phase I focused on flexural testing of seven medium-scale shear-critical reinforced concrete (RC) beams. The objective of this phase was to evaluate the potential of FRCM shear strengthening. The test variables included the type of FRCM (carbon FRCM or CFRCM and glass FRCM or GFRCM) and the strengthening scheme (side bonded vs. U-wrapped). Phase II was designed based on results of Phase I study, and it consisted of flexural testing of twenty (20) large-scale shear-critical RC beams strengthened with cement-based systems. The objective of this phase was to evaluate the effectiveness of the two types of cement-based strengthening systems in comparison to the existing epoxy-based FRP system. The test variables included: the shear span to depth ratio (slender and deep beams), amount of internal transverse steel reinforcement and type of strengthening system (CFRCM, CGM and CFRP). The results showed that the cement-based systems (CFRP grid in mortar and CFRCM) performed better compared to the epoxy-based system (CFRP sheet) in terms of the increase in shear capacity relative to the ultimate strength of the strengthening systems. The results also showed that the bond of cement-based system with the concrete substrate was sufficient that u-wrapping may not be required; the studied side-bonded systems did not exhibit signs of premature debonding. This is in contrast to most FRP fabric strengthening systems were u-wrapping is required for adequate bond. In addition, cement-based systems exhibited a better ability to control diagonal (shear) crack widths compared to the epoxy-based system tested, providing a greater reduction in diagonal crack width despite the relative lower ultimate strength and stiffness of the cement-based systems. Shear strengthening resulted in reduced shear strength contribution from stirrups. The strengthened beams with stirrups exhibited steeper shear cracks compared to control unstrengthened beams with stirrups. Similarly, the presence of stirrups reduces the shear strength contribution from strengthening. Again, the addition of stirrups results in steeper shear cracks which intersect fewer fibers tows in the strengthening system which results in a reduced shear strength contribution from strengthening layer. Lastly, the existing models to predict the ultimate load of strengthened shear-critical RC beams were evaluated and modifications to these methods were proposed.

Download or read book Strengthening and Repairing of RC Deep Beams Using CFRP and GFRP written by Amr Hussein A. Zaher and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are many reasons to upgrade an existing structure such as building code changes, accidents, design errors or building use changes. Few years ago the construction industry began using fibre reinforced polymer (FRP) for structural reinforcement, typically in combination with other building materials such as wood, steel and concrete. FRP show multiple attractive properties, such as low weight to strength ratio, non-corrosiveness high fatigue strength, and case of application. This study investigated different techniques to improve the performance of RC deep beams under two concentrated vertical loads using advanced composite materials (CFRP and GFRP sheets). The primary aim of this research was to study the behaviour of deep beams strengthened and repaired in shear using carbon and glass fibres.Thirteen RC deep beam specimens were simply supported with span lengths L=1500 mm and cross sections 140 x 450 mm. The tested beams were subjected to the effects of two concentrated loads with spacing of 560, 360 and 160 mm and were divided into five groups. The test results show that the deep beams strengthened by CFRP sheets & GFRP sheets provided improvement in ultimate loads. The maximum increase in ultimate loads reached 106% & 81% respectively and the decrease in deflection for beams was attributed to the type, configurations and orientation of the FRP sheets. An analytical model was done based on code equations to predict the deformational behaviour of RC deep beams shear-strengthened with FRP composites , and obtain the failure loads by using three codes equations and compare the results with the experimental results. The proposed analytical model gave good compliance with the experimental results.

Download or read book Shear Behavior of Reinforced Concrete T beams Strengthened with Carbon Fiber Reinforced Polymer CFRP Sheets and CFRP Anchors written by Yun Gon Kim and published by . This book was released on 2011 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is the evaluation of shear behavior of full-scale reinforced concrete T-beams strengthened with carbon fiber reinforced polymer (CFRP) sheets and CFRP anchors. Although the CRFP material has high tensile strength, premature failure due to debonding CFRP sheets prevents utilizing that strength. The use of CFRP anchors prevents this failure, so the CFRP sheets are able to reach ultimate strain. The current shear design is based on plasticity, which assumes that all steel (ductile material) stirrups, across the critical section yield at ultimate. However the strain in the CFRP (brittle material), is essential to estimate the shear contribution of CFRP. To evaluate the validity of CFRP strengthening for shear, 24 tests were conducted with several parameters including shear-span-to-depth ratio, depth of beams, different transverse reinforcement ratios, and the layout of CFRP strips. In addition, a simple shear behavior model was developed to explain the differences between ductile and brittle material. From test observation, the use of CFRP anchors resulted in U-wrap application to perform like continuous wrapping which implies that a CFRP strip reached rupture strain because the anchors prevented debonding failure. However, all FRP strips did not rupture simultaneously because the strain distribution across a critical crack was not uniform. The average strain across the critical crack was about 0.005. Therefore a conservative value of effective strain (0.004) was selected for design purposes. In addition, when a beam is strengthened with CFRP, interactions between the contributions of the CFRP, steel or concrete must be taken into account. Factors ka, ks, and kf were introduced in the proposed shear design equations. Factor ka reflects the change in the material contributions as the shear span to depth ratio (a/d ratio) changes in deep beams. Factors ks and kf account for the change in steel or CFRP shear contribution due to the change in the critical crack angle as well as the interactions between the steel and FRP transverse reinforcement. As the amount of either steel or FRP material increase, the efficiency of the other material decreases.

Download or read book Effects of Circular Openings in RC Deep Beams at Top of Shear Span Near Support written by Mohamad Mirzan Yusof and published by . This book was released on 2014 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Analysis of Reinforced Concrete Beam Strengthened with CFRP or GFRP Laminates written by and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: