Download or read book Shear Behaviour of Disturbed Regions in Reinforced Concrete Beams with Corrosion Damaged Shear Reinforcement written by Christopher Andrew Suffern and published by . This book was released on 2008 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion of reinforcing steel is a major problem facing infrastructures owners with billions of dollars spent in repairing our aging infrastructure. One of the first steps in the repair process is to quantify the strength degradation in a reinforced concrete element caused by the corrosion of reinforcing steel. An understanding of the forces involved in the load carrying mechanisms is imperative; the transfer of shear forces in reinforced concrete beams is one of these load carrying mechanisms. The shear transfer mechanism is different near the end of beams, adjacent to point loads, and near changes in cross section. These regions are known as disturbed regions. Structural engineers have a good understanding of the shear transfer mechanism in disturbed regions. However, the effects of corroded shear reinforcement in these regions have not been widely investigated. The current study is comprised of an experimental program and analytical strut and tie modeling aimed at quantifying the strength reduction that occurs in disturbed regions of reinforced concrete beams with corroded shear reinforcement. The feasibility of strengthening a beam with dry lay-up carbon fibre reinforced polymer (CFRP) to repair the damage caused by corrosion of the shear reinforcement was also investigated. In the experimental study, a total of 16 reinforced concrete beams were cast. The specimens were 350 mm deep, 125 mm wide and 1850 mm long. Three shear-span to depth ratios (1.0, 1.5, 2.0) were selected. Each specimen was reinforced in flexure with two 25M bars and the shear reinforcement was 10M spaced at 150 mm on centre. The specimens were corroded for 21 days, 60 days, and 120 days corresponding to low, medium, and high corrosion levels. In addition, three specimens were constructed without shear reinforcement in the shear-span in order to compare the results from the corroded specimens. One specimen was also corroded to a high level and repaired with dry lay-up CFRP. The specimens were corroded using an accelerated corrosion technique. There was evidence of cracking of the cover concrete in all specimens, and in the more severely corroded specimens delamination of the cover concrete was recorded. The stiffness of the corroded specimens was less than their corresponding control specimen, and a strength reduction was evident in most specimens. The maximum recorded strength reduction was 52% compared to the companion uncorroded specimen. It was revealed that a more critical case occurs when the corroded shear reinforcement was shifted during placement or was inclined closer to the direction of the compressive force flow. Also, it was observed that the corroded shear reinforcement still provides limited ductility in comparison to the un-corroded reinforcement. A strut and tie model was developed based on the experiments to explain the behaviour of disturbed regions with corroded shear reinforcement. The model consisted of direct and indirect struts. The effects of corrosion were expressed in terms of a reduction in the stirrup cross-section, a reduction of compressive strength due to corrosion cracking, and a reduction in the concrete cross section width. It was hypothesized that the corrosion crack width influences the concrete compressive strength in the strut; consequently, a mathematical model was developed that related the reduction in concrete compressive strength with corrosion crack width. Also, a relationship between reinforcing steel mass loss and corrosion crack width was utilized from the published literature. An effective cross section width was obtained by reducing the width by the damaged concrete cover. The results from these models were input into a strut and tie model as a reduction in concrete compressive strength. The output from the strut and tie model was the ultimate shear strength of the specimen. The developed models were compared with a model from the literature and compared with the experimental results. The major contribution of this research is to allow designers to analyze disturbed regions with corroded shear reinforcement and determine the strength degradation; subsequently, one can determine what strengthening procedure would be most appropriate.

Download or read book Shear Capacity Assessment of Corrosion damaged Reinforced Concrete Beams written by and published by . This book was released on 2003 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Shear Behaviour of Reinforced Concrete Beams Without and with Small Amounts of Shear Reinforcement written by Frederik Autrup and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Behaviour of Shear Damaged Reinforced Concrete Beams Strengthened with External Post tensioning and Clamping written by Thuraichamy Guganesan Suntharavadivel and published by . This book was released on 2008 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last few decades, there has been a rapid increase in the volume and weight of heavy vehicles using national road networks. More than half of the bridges around the world are over forty years old. The deterioration of these existing bridges due to increased traffic loading, progressive structural aging, and reinforcement corrosion from severe environmental conditions has become a major problem in most countries. Several techniques have been used to strengthen these structures around the world. External post-tensioning is one of the widely used strengthening techniques in many countries due to its advantages over other methods. Furthermore, flexural strengthening using external post-tensioning has become a well established technique over the past few decades. However, when external post-tensioning is used to strengthen shear damaged reinforced concrete members, unlike flexural damage, the efficiency is significantly reduced by existing shear cracks. This research study was carried out to investigate the behaviour of reinforced concrete beams with existing shear cracks when strengthened by external means. The study consists of two parts: experimental investigations of reinforced concrete beams with different parameters and numerical analysis of reinforced concrete beams using simplified theoretical formulation and finite element modelling. To study the behaviour of shear damaged concrete beams, two different strengthening techniques, namely external post-tensioning and external clamping, were used. In addition to the strengthening, the effect of cracks on the behaviour of reinforced concrete beams was investigated by repairing such cracks using epoxy resin injection. Experimental results showed that existing shear cracks have a substantial effect on the member capacity when strengthened by external posttensioning. Although there are concerns about the practical applications of external clamping, the experimental results suggest that external clamping could be a more effective technique than external post-tensioning to reduce the effect of existing shear cracks on the behaviour of concrete beams. Furthermore, proper repair of the shear cracks could significantly reduce their impact. In the numerical analysis, a simplified mathematical approach was developed to estimate the capacity of shear damaged reinforced concrete beam by expanding the modified compression field theory (MCFT). In addition to the simplified theoretical formulation, a finite element model was developed using the commercial finite element package, Abaqus. Comparison between the predicted behaviour using finite element analysis (FEA) and the experimental data illustrated that the developed finite element model could be used as a reliable tool to estimate the capacity of shear damaged reinforced concrete beams. A parametric study was conducted to investigate the effect of different parameters such as concrete strength, amount of shear reinforcement and crack width, using the developed finite element model. From the numerical study, it was concluded that the simplified approach developed in this study can be used as a reliable and conservative technique to predict the member capacity of a cracked reinforced concrete beam strengthened by external means. Furthermore, the parametric study showed that crack width is the most sensitive parameter that affects the capacity of a cracked beam strengthened by external post-tensioning. Based on this research study it can be concluded that existing shear cracks have a substantial effect on the behaviour of reinforced concrete beams strengthened by external post-tensioning. The simplified mathematical approach developed in this study can be used to estimate the capacity of such beams.

Download or read book Shear Capacity Assessment of Corrosion damaged Reinforced Concrete Beams written by William C. Farrow and published by . This book was released on 2002 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented here is a study to determine the effect of shear reinforcement corrosion on the shear capacity in conventionally reinforced concrete (CRC) bridge elements. A total of 14 CRC beams were tested using three stirrup spacings (8, 10, and 12-inch). Six of the beams included the influence of a 4-inch thick deck, and both positive and negative moment regions were considered. The CRC beams were subjected to an accelerated corrosion process to produce the damage states. Inspection techniques were used to visually correlate corrosion damage with actual structural performance. Severe corrosion damage was shown to have significant effect on the shear performance of the CRC beams. Findings indicate that current inspection ratings for corrosion damage may not adequately identify the extent of structural deterioration.

Download or read book The Shear Strength Behavior of Reinforced Concrete Beams with Orthogonal Shear Reinforcement written by David R. Bonneville and published by . This book was released on 1974 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Different Techniques for Repair of Shear span Corrosion damaged RC Beams written by Hesham Elhuni and published by . This book was released on 2013 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deterioration of reinforced concrete structures due to reinforcement corrosion is a serious problem that faces concrete infrastructure worldwide. Effect of the rebar corrosion in the shear span on the structural behaviour is not fully addressed in the published literature. This study examined the effects of corrosion of the longitudinal reinforcement in the shear span on the structural behaviour of RC beams and the effectiveness of three rehabilitation schemes on the structural performance of such beams.

Download or read book Shear Behavior of Concrete Beams Reinforced with High Performance Steel Shear Reinforcement written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The current shear design provisions of the ACI 318 specifications limit the yield strength in transverse reinforcement to 60 ksi. Advancement in technology has led to the fabrication of High Performance steel. Use of HP steel in reinforced concrete could lead to cost savings by reducing the amount of steel required due to the inherited high strength and increase of the service life of structural members due to its enhanced corrosion resistance. This research is undertaken to examine the use of high performance steel as a feasible reinforcement material for reinforced concrete structures. Commercially available steel, Micro-Composite Multi-Structural Formable (MMFX), conforming to ASTM A 1035, was selected for this study. MMFX steel has minimum yield strength of 100 ksi. This experimental program comprised eighteen tests using nine large-scale reinforced concrete beams subjected to static loading up to failure. The key parameters considered in experimental program were the steel type and the amount of shear reinforcement. This research investigated crack width, modes of failure, deflection, stirrup strain, ultimate load carrying capacity and the behavior of the MMFX steel as transverse reinforcement for concrete beams. Results from the experimental program show that by utilizing the higher yield strength and consequently reducing the reinforcement ratio of MMFX steel, the beams can achieve almost the same load-carrying capacity as the beams reinforced with conventional Grade 60 steel. Also, beams reinforced with MMFX showed similar deflections at service load as the beams reinforced with Grade 60 steel. Therefore, reduction in the reinforcement ratio of MMFX steel, did not affect the serviceability of these beams. Analysis shows that the ACI 318, CSA, and AASHTO LRFD design codes can closely predict the ultimate shear strength for beams reinforced with high performance steel having yield strength up to 100 ksi. The beams were also analyzed using a well-established Mo.

Download or read book Shear Behaviour of Continuous Concrete Beams Reinforced with GFRP Bars written by Karam Abdou Awad Mahmoud and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuous beams represent main structural elements in most reinforced concrete (RC) structures such as parking garages and overpass bridges. Deterioration of such structures due to corrosion of steel reinforcement is common in North America. To overcome the corrosion problems, the use of fiber-reinforced polymer (FRP) bars and stirrups becomes a viable alternative to steel reinforcement. However, to date, the shear behaviour of FRP-RC continuous beams has not been explored yet. As such, the objective of this study is to investigate the shear behaviour of such beams. In this study, twenty four full-scale continuous concrete beams were constructed and tested. The test beams had rectangular cross section with 200-mm width and a height of 300, 550 or 850 mm and were continuous over two equal spans. The main investigated parameters were concrete strength, type and ratio of longitudinal reinforcement, type and ratio of transverse reinforcement and beam effective depth. Moreover, a 3-D nonlinear finite element model (FEM) was constructed to simulate the behaviour of FRP-RC continuous beams. The model was verified against the experimental results and validated against test results from previous studies. Then, the verified/validated model was used to conduct a parametric study to investigate the effect of a wide range of the parameters on the shear behaviour of GFRP-RC beams. The experimental and FEM results showed that shear-critical GFRP-RC continuous beams exhibited moment redistribution. Also, it was observed that increasing the concrete strength and the longitudinal reinforcement ratio increased the shear strength significantly. Moreover, the presence of GFRP stirrups significantly enhanced the shear strength of the tested beams. Regarding the size effect, test results showed that there was adverse or no size effect on the shear strength of GFRP-RC continuous beams when they failed in the interior shear span while beams failed in the exterior shear span exhibited clear size effect. Furthermore, a comparison between the test results and the provisions of the available models and FRP standards and design guidelines in North America revealed that these design provisions can be safely applied to continuous beams.

Download or read book Effect of Detailing of Shear Reinforcement on Behavior of Reinforced Concrete Beams written by Frank K. H. Park and published by . This book was released on 1987 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Behavior of High Performance Steel as Shear Reinforcement for Concrete Beams written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to study the feasibility of using high performance steel as shear reinforcement for concrete beams. High performance steel is characterized by enhanced corrosion resistance and higher strength in comparison to conventional Grade 60 steel reinforcement. Advantages of using higher strength steel include the ability to design for longer span lengths and/or reducing the amount of material needed for design. This could greatly reduce the overall costs of construction for future structures. Nine reinforced concrete beams were constructed using No. 9 longitudinal bars and No. 3 bars for the stirrups. The main variables considered in the study are the stirrup spacing and the type of reinforcing steel material. Testing was performed using a single concentrated load positioned closer to one end of the beam, which allowed for two tests per beam. Research findings indicate that using MMFX stirrups increases the overall shear strength and enhances serviceability by distributing cracks and reducing crack width. Pairing high performance longitudinal and transverse reinforcement shows an optimum design in terms of strength gain and reduction in crack width. Enhanced serviceability behavior can be attributed to the better bond characteristics of MMFX steel in comparison to conventional Grade 60 steel. Test results suggest that combining high performance steel with high strength concrete could lead to a better utilization of the materials. Analysis shows that the ACI 318-05, CSA, and AASHTO LRFD design codes can conservatively be used for the design of high performance steel up to a yield strength of 80 ksi. Detailed analysis using the Modified Compression Field Theory can be used to accurately predict the behavior of the beams.

Download or read book Shear Behavior of Fiber Reinforced Concrete Beams with Stirrups written by Sugiarto Loni and published by . This book was released on 1983 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Shear Behaviour of Slender RC Beams with Corroded Web Reinforcement written by Abdulaziz Alaskar and published by . This book was released on 2013 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research study examined the effect of corrosion of web reinforcement (stirrups) on the shear behaviour of slender reinforced concrete (RC) beams.

Download or read book Shear Behavior of Reinforced Concrete Beams with Different Shear Reinforcement Arrangements written by Geoffrey Oramasionwu and published by . This book was released on 1984 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Theoretical Investigation on the Shear Behaviour of High Strength Reinforced Concrete Beams Using Digital Image Correlation written by Touhami Tahenni and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this chapter an experimental investigation is carried out on high strength concrete beams without transverse reinforcement and with transverse reinforcement. The beams were tested in bending under two concentrated loads using the technique of digital image correlation. In the test setup, the shear zone which is defined by the area of beam between the support point and the loading point was studied by the camera of high resolution. The Gom-Aramis software was used to record and analyse the numerical images by determination of the deformation of concrete in the compressed zone of the beam, to calculate the opening, the spacing and the length of the diagonal cracks. The experimental shear strength of the beams was compared with the theoretical values predicted by the different design codes, such as the American ACI 318, the British Standard BS 8110, the European Eurocode 2, the New Zealand NZS 3101 and the Indian Standard IS456. The results show that all the design codes underestimate the contribution of high strength concrete to the shear resistance of reinforced concrete beams, and greatly overestimate the contribution of transverse reinforcement. The European Eurocode 2 is the only one among the four code models that gives the best prediction of the ultimate shear strength of high strength concrete.

Download or read book One way Shear Behaviour of Large Lightly reinforced Concrete Beams and Slabs written by Edward Graeme Sherwood and published by . This book was released on 2008 with total page 1094 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focuses on improving our understanding of the behaviour of large, lightly-reinforced concrete beams and one-way slabs subjected to shear. Empirically-based shear design methods, particularly those in the widely-used American Concrete Institute design code for concrete structures (ACI-318) do not accurately predict the behaviour of these important structural elements, and may produce unsafe designs in certain situations. Furthermore, the research community has not reached consensus on the exact mechanisms of shear transfer in reinforced concrete. This has slowed the replacement of empirically-based methods with rational methods based on modern theories of the shear behaviour of reinforced concrete. Shear failures in reinforced concrete are brittle and sudden, and typically occur with little or no warning. Furthermore, they are difficult to predict due to complex failure mechanisms. It is critical, therefore, that shear design methods for reinforced concrete be accurate, rational and theoretically sound. An extensive experimental program consisting of load-testing thirty-seven large-scale reinforced concrete beams and slabs has been performed. The results conclusively show that the ACI shear design method can produce dangerously unsafe designs for thick concrete flexural elements constructed without transverse reinforcement. However, safe predictions of the failure loads of small-scale elements are produced. It is shown that the ACI design method does not account for the size-effect in shear, in which the shear stress causing failure decreases as the beam depth increases. Detailed measurements of flexural and shear stresses in the experimental specimens indicated that aggregate interlock is the primary mechanism of shear transfer in slender, lightly-reinforced concrete beams. It is also shown that the size-effect can be explained by reduced aggregate interlock capacity in members with widely spaced cracks. Digital three-dimensional topographical maps of the surfaces of failure shear cracks were constructed by scanning the surfaces with a laser profilometer. It was shown that concrete made with larger aggregate produced rougher cracks with a higher aggregate interlock capacity. The shear strength of reinforced concrete is therefore directly related to the roughness of failure shear cracks, and by extension the aggregate size, since larger aggregates produce cracks with larger asperities with improved aggregate-interlock capacity. Acoustic-emission monitoring techniques were employed to characterize fracturing in large concrete beams. Extensive studies on the ACI 318-05 requirements for crack control steel show that they do not adequately prevent the formation of wide cracks, as they do not require a minimum bar diameter for crack control reinforcement. It is shown that the ACI 318-05 requirements for crack control steel were based partly on questionable interpretations of published experimental studies on crack widths in large beams. Various methods to eliminate the size effect in shear are explored, including the use of stirrups or longitudinal reinforcement distributed over the beam height. Beam/slab width is shown to have no effect on failure shear stress. It is concluded that the ACI shear design method should be replaced with a rational, theoretically-sound shear design method. Modifications to Canadian shear design methods are recommended.

Download or read book Shear and Punching Shear in RC and FRC Elements written by fib Fédération internationale du béton and published by fib Fédération internationale du béton. This book was released on 2010-12-01 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: fib Bulletin 57 is a collection of contributions from a workshop on "Recent developments on shear and punching shear in RC and FRC elements", held in Salò, Italy, in October 2010. Shear is one of a few areas of research into fundamentals of the behaviour of concrete structures where contention remains amongst researchers. There is a continuing debate between researchers from a structures perspective and those from a materials or fracture mechanics perspective about the mechanisms that enable the force flow through a concrete member and across cracks. In 2009, a Working Group was formed within fib Task Group 4.2 "Ultimate Limit State Models" to harmonise different ideas about design procedures for shear and punching. An important outcome of this work was the ensuing discussions between experts and practitioners regarding the shear and punching provisions of the draft fib Model Code, which led to the organization of the Salò workshop. Invited experts in the field of shear and FRC gave 18 lectures at the workshop that was attended by 72 participants from 12 countries in 3 different continents. The contributions from this conference as compiled in this bulletin are believed to represent the best of the current state of knowledge. They certainly are of general interest to fib members and especially helpful in the finalization of the 2010 fibModel Code. It is hoped that this publication will stimulate further research in the field, to refine and harmonize the available analytical models and tools for shear and punching design.