Download or read book Numerical Studies on Bond Strength of Reinforced Concrete Specimens Exposed to Fire written by Ram Suresh and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, a non-linear finite element approach is used to study the bond-mechanism of steel and concrete at elevated temperatures. The paper describes the various factors governing the bond strength of steel and concrete at ambient and elevated temperatures. The model is capable to account for the reduction in the strength of concrete and steel at high temperatures. The results foam the model show good agreement with published numerical work at ambient temperature. The behaviour of the bond between concrete and steel at elevated temperatures reveal significant reduction of its bond resistance. Predicted results show that the reinforced concrete will attain a total collapse at lower stress levels at higher temperatures in comparison to condition at ambient temperature.

Download or read book Concrete at High Temperatures written by Zdeněk P. Bažant and published by Prentice Hall. This book was released on 1996 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the increased use of concrete in high temperature environments, it is essential for engineers to have a knowledge of the properties and mathematical modelling of concrete in such extreme conditions. Bringing together, for the first time, vast amounts of data previously scattered throughout numerous papers and periodicals, this book provides, in two parts, a comprehensive and systematic review of both the properties and the mathematical modelling of concrete at high temperatures. Part I provides a comprehensive description of the material properties of concrete at high temperatures. Assuming only a basic knowledge of mathematics, the information is presented at an elementary level suitable for graduates of civil engineering or materials science. Part II describes the response of concrete to high temperatures in precise terms based on mathematical modelling of physical processes. Suitable for advanced graduate students, researchers and specialists, it presents detailed mathematical models of phenomena such as heat transfer, moisture diffusion, creep, volume changes, cracking and fracture. Concrete at High Temperatures will prove a valuable reference source to university researchers and graduate students in civil engineering and materials science, engineers in research laboratories, and practising engineers concerned with fire resistance, concrete structures for nuclear reactors and chemical technology vessels.

Download or read book Advances on bond in concrete written by FIB – International Federation for Structural Concrete and published by FIB - International Federation for Structural Concrete. This book was released on 2022-12-01 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural behavior of reinforced concrete elements strongly depends on the interaction between the reinforcing bars and the surrounding concrete, which is generally referred as “bond in concrete”. In service conditions, the reinforcement-to-concrete bond governs deformability through the tension stiffening of concrete surrounding the bar as well the crack development and crack width. At Ultimate Limit State, bond governs anchorage and lap splices behavior as well as structural ductility. When plain (smooth) bars were used, the steel-to-concrete bond was mainly associated with “chemical adhesion/friction” that is related to the surface roughness of the rebar. As steel strengths increased the need to enhance interaction between steel and the surrounding concrete was recognized, and square twisted rebars, indented rebars or, later on, ribbed rebars came into the market, the latter being the type of deformed bar most commonly adopted since the 1960/70s. When ribbed rebars became widely used, several research studies started worldwide for better understanding the interaction between ribs and the surrounding concrete. Researchers evidenced the development of micro-cracks (due to the wedge action of the ribs) towards the external face of the structural element. If confinement is provided by the concrete cover, by transverse reinforcement or by an external transverse pressure, the full-anchorage capacity is guaranteed and a pull-out failure occurs, with crushing of concrete between the ribs. On the contrary, with lesser confining action, a splitting failure of bond occurs; the latter may provoke a brittle failure of the lap splice or, in some cases, of anchorages. However, after many years of research studies on bond-related topics, there are still several open issues. In fact, new materials entered into the market, as concrete with recycled aggregates or fibre reinforced concrete; the latter, having a kind of distributed reinforcement into the matrix (the fibres), provides a better confinement to the wedge action of the ribs. In addition, concrete and steel strength continuously increased over the years, causing changes in the bond behavior due to differences in mechanical properties of materials but also to the different concrete composition at the interface with the steel rebar causing a different bond behavior. Moreover, the lower water/cement ratio of these high-strength concrete makes the bleeding phenomena less evident, changing the concrete porosity in the upper layers of the structural element and thus making the current casting position parameters no-longer reliable. Finally, concrete with recycled aggregates are becoming more important in a market that is looking forward to a circular economy. As such, all the experimental results and database that allowed the calibration of bond rules now present in building codes for conventional concrete, may be not be representative of these new types of materials nowadays adopted in practice. Furthermore, after more than 50 years of service life, structural elements may not satisfy the current safety requirements for several reasons, including material degradation (with particular reference to steel corrosion) or increased loads, by also considering the seismic actions that were non considered by building codes at the time of the original design. The structural assessment of existing structures requires proper conceptual models and new approaches for evaluating the reliability of existing structures by also considering the remaining expected service life. In addition, specific rules for older materials, as plain smooth bars, should be revised for a better assessment of old structures. Last, but not least, interventions in existing structures may require new technologies now available such as post-installed rebars. While many advances have been achieved, there remain areas where a better understanding of bond and its mechanisms are required, and where further work is required to incorporate this understanding into safe and economic rules to guide construction and maintenance of existing infrastructures. These aspects were widely discussed within the technical community, particularly in the fib Task Group 2.5 and in the ACI 408 Committee dealing with bond and anchorage issues. Furthermore, special opportunities for discussing bond developments were represented by the International Conferences on ‘Bond in Concrete’ held each decade since 1982 as well as by joint workshops organized by fib TG2.5 and ACI 408. Within this technical collaboration, this Bulletin was conceived, and, thus, it collects selected papers presented at the joint fib-ACI Convention Session on Bond in Concrete held in Detroit (USA) in 2017. The bulletin is based on four main Sections concerning: - General aspects of bond - Anchorages and laps of bars and prestressing tendons - Bond under severe conditions - Degradation of bond for corrosion - Bond in new types of concrete The main aim of the Bulletin is to shed some new lights on the advances in understanding and application of bond related issues achieved over the last few years, and identify the challenges and priorities to be addressed in the next years. Another important aspect of the bulletin is to provide practical information from research findings.

Download or read book Issues in Engineering Research and Application 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Engineering Research and Application: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Noise Control Engineering. The editors have built Issues in Engineering Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Noise Control Engineering in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Engineering Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book 10th International Conference on FRP Composites in Civil Engineering written by Alper Ilki and published by Springer Nature. This book was released on 2021-11-26 with total page 2516 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume highlights the latest advances, innovations, and applications in the field of FRP composites and structures, as presented by leading international researchers and engineers at the 10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), held in Istanbul, Turkey on December 8-10, 2021. It covers a diverse range of topics such as All FRP structures; Bond and interfacial stresses; Concrete-filled FRP tubular members; Concrete structures reinforced or pre-stressed with FRP; Confinement; Design issues/guidelines; Durability and long-term performance; Fire, impact and blast loading; FRP as internal reinforcement; Hybrid structures of FRP and other materials; Materials and products; Seismic retrofit of structures; Strengthening of concrete, steel, masonry and timber structures; and Testing. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.

Download or read book Characteristics of Reinforced Concrete Bond at High Strain Rates written by Eric Jacques and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the on-going intensity of research in the field of protective structural design, one topic that has been largely ignored in the literature is the effect of high strain rates on the bond between reinforcing steel and the surrounding concrete. Therefore, a comprehensive research program was undertaken to establish the effect of high strain rates on reinforced concrete bond. The experimental research consisted of the construction and testing of fourteen flexural beam-end bond specimens and twenty-five lap-spliced reinforced concrete beams. The physical and material properties of the specimens were selected based on a range of design parameters known to significantly influence bond strength. In order to establish a baseline for comparison, approximately half of the total number of specimens were subjected to static testing, while the remainder were subjected to dynamic loading generated using a shock tube. The strain rates generated using the shock tube were consistent with those obtained for mid- and far-field explosive detonation. Results of the beam-end and lap splice beam tests showed that the flexural behaviour of reinforced concrete was significantly stronger and stiffer when subjected to dynamic loading. Furthermore, the high strain rate bond strength was always greater than the corresponding low strain rate values, yielding an average dynamic increase factor (DIF) applied to ultimate bond strength of 1.28. Analysis of the low and high strain rate test results led to the development of empirical expressions describing the observed strain rate sensitivity of reinforced concrete bond for spliced and developed bars with and without transverse reinforcement. The predictive accuracy of the proposed DIF expressions was assessed against the experimental results and data from the literature. It was found that the dynamic bond strength of reinforced concrete can be predicted with reasonably good accuracy and that the proposed DIF expressions can be used for analysis and design of protective structures. An analytical method was also developed to predict the flexural load-deformation behaviour of reinforced concrete members containing tension lap splices. The analysis incorporated the effect of reinforcement slip through the use of pseudo-material stress-strain relationships, in addition to giving consideration to the effect of high strain rates on bond-slip characteristics and on the material properties of concrete and steel. A comparison of the analytical predictions with experimental data demonstrated that the proposed analysis technique can reasonably predict the flexural response of beams with tension lap splices. The results also demonstrated that the model is equally applicable for use at low- and high-strain rates, such as those generated during blast and impact.

Download or read book Interfacial Transition Zone in Concrete written by J.C. Maso and published by CRC Press. This book was released on 2004-03-01 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important new state-of-the-art report prepared by RILEM Technical Committee 108 ICC. It has been written by a team of leading international experts from the UK, USA, Canada, Israel, Germany, Denmark, South Africa, Italy and France. Research studies over recent years in the field of cement science have focused on the behaviour of the interfaces between the components of cement-based materials. The techniques used in other areas of materials science are being applied to the complex materials found in cements and concretes, and this book provides a significant survey of the present state of the art.

Download or read book Bond Characteristics of High Strength Concrete written by Mehdi Alavi-Fard and published by . This book was released on 1999 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bond of Reinforcement in Concrete written by fib Fédération internationale du béton and published by fib Fédération internationale du béton. This book was released on 2000-01-01 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In 1993, the CEB Commission 2 Material and Behavior Modelling established the Task Group 2.5 Bond Models. It's terms of reference were ... to write a state-of-art report concerning bond of reinforcement in concrete and later recommend how the knowledge could be applied in practice (Model Code like text proposal)... {This work} covers the first part ... the state-of-art report."--Pref.

Download or read book Probabilistic Characterization of Bond Behavior at Rebar Concrete Interface in Corroded RC Structures written by Ahmad Soraghi and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adequate rebar-concrete bonding is crucial to ensure the reliable performance of reinforced concrete (RC) structures. Many factors (such as the concrete properties, concrete cover depth, transverse reinforcement, and the presence of corrosion) affect the bond behavior, and consequently the structural performance. This bond behavior is typically described by a bond stress-slip relationship, where there are two critical quantities: bond strength ̶ the maximum shear stress that bond can withstand, and peak slip ̶ the slippage at the interface when the bond strength is reached. It is understood that the bond deteriorates when corrosion is present and behaves differently under two distinct bond failure modes (i.e., splitting and pull-out). While many prior studies have focused on the influence of the aforementioned factors on the bond strength, the impact of the failure mode coupled with corrosion on the bond stress-slip relationship and structural performance have not been thoroughly investigated. This study is aimed to address this issue. In this study, first a probabilistic bond failure mode prediction model that considers various influencing factors including loading type and corrosion is developed in this study. This study uses the bond testing results of 132 beam-end specimens subjected to monotonic and cyclic loading and adopts classification methods to develop the prediction model, which is then used to evaluate the impact of bond behavior on the reliability of a RC beam with a lap splice. Then, multivariate nonlinear regression with all-possible subset model selection and symbolic multi-gene regression are adopted for probabilistic model development for bond strength and peak slip under the two bond failure modes considering corrosion. In particular, a comprehensive bond dataset collected from bond tests on the beam and beam-end specimens in the literature and from the experimental testing conducted in this study, and a criterion to specify the bond failure mode is also proposed. Next, incorporating bond in the structural analysis is investigated. Since in reality, perfect bonding does not exist, especially in beam and column or column and footing connections, reinforcement slip occurs as a result of imperfect bonding. Reinforcement slip in the footing of a RC column can significantly influence the lateral displacement of the column, a critical structural response under lateral loads such as seismic loading. Many past researchers studied and developed models to capture the anchorage slip of rebar; however, a model that can reflect the actual bond-slip relationship (especially in the presence of corrosion) and yet be simple-to-use for structural analysis is not well developed. In this study, a new simple bar stress-slip macromodel is developed to predict reinforcement anchorage slip given a rebar stress. The proposed rebar anchorage slip model is derived by implementing a macromodel solution based on a simple bond stress distribution function that captures the bond stress distribution numerically obtained from a real bond-slip relationship. Available experimental bond stress-slip data collected from literature are used to optimize the model parameter in the proposed bond stress distribution function, which reflects the impact of the structural parameters on the rebar slippage such as concrete strength and corrosion level. The proposed rebar slip model is then incorporated into a fiber beam-column model for numerical analysis, and is further validated by comparing flexural behavior of several RC columns (with and without corrosion) based on the numerical model with the experimental data. The results demonstrate the importance of incorporating rebar slippage and corrosion effect on bond. Using this fiber beam-column model, seismic performance of an example RC bridge column is evaluated, and one can conclude the rebar slip plays a critical role in the seismic evaluation. As the proposed rebar slip macromodel provides simple formulation and it is explicitly expressed with a model parameter that can be updated easily to incorporate new information, it is practical for application in the structural analysis.

Download or read book Experimental and Numerical Study of Steel Fiber Reinforced Concrete Structures Subjected to Internal Explosion written by Nikhil Vasant Moon and published by . This book was released on 2020 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigates the effect of an accidental explosion of a steam boiler in a boiler room on steel fiber reinforced concrete (SFRC) structure in an industrial facility, using nonlinear analysis in ABAQUS FEA software. The mechanical properties of SFRC are calculated through testing at the UTA Civil Engineering Laboratory Building. Steel fiber dosages in concrete at different volume fractions are examined for the mechanical properties of concrete. In total, 9 (4" x 8") cylindrical specimens for compressive strength and modulus of elasticity test, 9 (4" x 8") cylindrical specimens for tensile strength test, and 9 (6" x 6" x 21") beam specimens for modulus of rupture test were produced and tested after 28 days of curing. Modulus of Elasticity is found for the different volume fractions of SRFC by stress vs strain curve from experimental tests. Adding 1% of steel fiber in concrete can increase the modulus of elasticity by 11%, compressive strength by 22%, tensile strength by 42%, and modulus of rupture by 32 %. Using the concrete properties obtained from experimental results, numerical analysis is done to find the effect of the Steam Boiler explosion on SFRC boiler room using nonlinear analysis in ABAQUS FEA software. Dynamic/Explicit loading condition is considered for analysis. It's found that adding 1% steel fiber by volume fraction can increase the overall capacity of concrete structure by 26%, decrease strain by 21%, and decrease the deflection by 23%. Parametric studies are also carried out at 1% SFRC by different arrangements of Steam Boiler closed room - with a rigid roof, with a frangible roof and circular vent in the roof. It's found that the reflected pressure due to explosion can be significantly reduced on the surrounding walls. In case, roof with circular vent the stresses decrease by 50%, strain decrease by 70% and with frangible roof stress decrease by 31%, strain by 38% and strain decrease by 38%.

Download or read book Fire Performance of Frp strengthened Concrete Flexural Members written by Pratik Prashant Bhatt and published by . This book was released on 2021 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last three decades, fiber reinforced polymer (FRP) materials have emerged as a promising solution for strengthening and retrofitting of concrete structural members owing to its high strength and durability properties. However, FRP undergoes rapid degradation in strength, modulus, and bond properties due to softening of polymer matrix and bonding adhesive even at moderately elevated temperatures. Therefore, an FRP-strengthened concrete member experiences rapid loss in capacity and stiffness resulting in lower fire resistance than an un-strengthened concrete member. The fire response of FRP-strengthened concrete structural members is influenced by several factors, and thus fire resistance evaluation requires advanced analysis. While several studies are available on fire resistance evaluation of FRP-strengthened reinforced concrete (RC) beams, limited information available on fire performance of FRP-strengthened concrete slabs. Moreover, the available studies on beams do not fully account for all the important factors influencing fire response of strengthened structural members. To address some of the knowledge gaps and to develop a fundamental understanding on the fire resistance of FPR-strengthened RC flexural members, experimental and numerical studies were carried out. As part of experimental studies, a series of tests were conducted at both material level and structural level. For material property characterization, uniaxial tensile tests and double lap shear tests were conducted at elevated temperatures to evaluate high temperature tensile strength of FRP and bond strength of FRP-concrete interface, respectively. For structural fire resistance characterization, tests were conducted on five FRP-strengthened concrete T-beams and two FRP-strengthened concrete slabs, wherein effect of strengthening level, reinforcement ratio, load levels, as well as insulation thickness and configuration was evaluated. As part of numerical studies, a macroscopic finite element based model, originally developed for strengthened RC beams, was further enhanced for evaluating thermo-mechanical response of strengthened RC slabs under fire conditions. The model accounts for temperature dependent material properties, as well as geometric and material nonlinearity. The novelty of model lies in consideration of temperature induced bond degradation through use of different temperature dependent bond-slip relations and in conducting a member level structural analysis rather than analyzing a single critical section. The model was validated using the above generated test data by comparing various response parameters and was applied to quantify the effect of critical factors influencing the fire resistance of FRP-strengthened concrete beams and slabs, through a set of parametric studies. Results from these studies indicate that the fire resistance of FRP-strengthened RC flexural members is significantly influenced by insulation geometry, fire scenario, and load levels, and is moderately influenced by strengthening level or reinforcement ratio. The generated test data as well as those reported in literature were utilized to develop machine learning (ML) based approach for predicting fire resistance of FRP-strengthened concrete beams. Three different ML algorithms, namely support vector regression, random forest regression, and deep neural networks, were successfully trained over the compiled dataset to develop fire resistance prediction models for strengthened RC beams. The accuracy of the trained models was determined by comparing the predictions from the model for an un-seen dataset Results indicate that ML based approaches can be effectively utilized for developing simplified tools for predicting fire resistance of strengthened concrete beams with different geometrical configuration, load levels, reinforcement ratio, and strengthening level.

Download or read book Advanced Concretes and Their Structural Applications Volume II written by Zhigang Zhang and published by Frontiers Media SA. This book was released on 2023-07-10 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Composites for Construction written by Lawrence C. Bank and published by John Wiley & Sons. This book was released on 2006-07-21 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first textbook on the design of FRP for structural engineering applications Composites for Construction is a one-of-a-kind guide to understanding fiber-reinforced polymers (FRP) and designing and retrofitting structures with FRP. Written and organized like traditional textbooks on steel, concrete, and wood design, it demystifies FRP composites and demonstrates how both new and retrofit construction projects can especially benefit from these materials, such as offshore and waterfront structures, bridges, parking garages, cooling towers, and industrial buildings. The code-based design guidelines featured in this book allow for demonstrated applications to immediately be implemented in the real world. Covered codes and design guidelines include ACI 440, ASCE Structural Plastics Design Manual, EUROCOMP Design Code, AASHTO Specifications, and manufacturer-published design guides. Procedures are provided to the structural designer on how to use this combination of code-like documents to design with FRP profiles. In four convenient sections, Composites for Construction covers: * An introduction to FRP applications, products and properties, and to the methods of obtaining the characteristic properties of FRP materials for use in structural design * The design of concrete structural members reinforced with FRP reinforcing bars * Design of FRP strengthening systems such as strips, sheets, and fabrics for upgrading the strength and ductility of reinforced concrete structural members * The design of trusses and frames made entirely of FRP structural profiles produced by the pultrusion process

Download or read book Computational Methods for Fracture written by Timon Rabczuk and published by MDPI. This book was released on 2019-10-28 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a collection of 17 scientific papers about the computational modeling of fracture. Some of the manuscripts propose new computational methods and/or how to improve existing cutting edge methods for fracture. These contributions can be classified into two categories: 1. Methods which treat the crack as strong discontinuity such as peridynamics, scaled boundary elements or specific versions of the smoothed finite element methods applied to fracture and 2. Continuous approaches to fracture based on, for instance, phase field models or continuum damage mechanics. On the other hand, the book also offers a wide range of applications where state-of-the-art techniques are employed to solve challenging engineering problems such as fractures in rock, glass, concrete. Also, larger systems such as fracture in subway stations due to fire, arch dams, or concrete decks are studied.

Download or read book Concrete Solutions written by Michael Grantham and published by CRC Press. This book was released on 2016-09-19 with total page 649 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete Solutions contains the contributions from some 30 countries to Concrete Solutions, the 6th International Conference on Concrete Repair (Thessaloniki, Greece, 20-23 June 2016). Strengthening and retrofitting are major themes in this volume, with NDT and electrochemical repair following closely, discussing the latest advances and technologies in concrete repair. The book brings together some interesting and challenging theoretical approaches and questions if we really understand and approach such topics as corrosion monitoring correctly. Concrete Solutions is an essential reference work for those working in the concrete repair field, from engineers to architects and from students to clients. The Concrete Solutions Series of international conferences on concrete repair began in 2003 with a conference held in St. Malo, France in association with INSA Rennes. Subsequent conferences have seen the Series partnering with the University of Padua (Italy) in 2009, with TU Dresden (Germany) in 2011 and with Queen’s University Belfast (Northern Ireland) in 2014. In 2016 Thessaloniki (Greece) hosted the conference, partnering with both Aristotle University of Thessaloniki (AUTH) and Democritus University of Thrace (DUTH). The next conference in the series will be held in 2019 in Istanbul.

Download or read book NBS Special Publication written by and published by . This book was released on 1962 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: