Bond and Anchorage of Lap Splices of Reinforcing Bars with Different Deformation Properties PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Bond and Anchorage of Lap Splices of Reinforcing Bars with Different Deformation Properties PDF full book. Access full book title Bond and Anchorage of Lap Splices of Reinforcing Bars with Different Deformation Properties by Antoine Makhlouf. Download full books in PDF and EPUB format.
Author: Antoine Makhlouf Publisher: ISBN: Category : Reinforcing bars Languages : en Pages : 166
Book Description
Beams were designed to include two reinforcing bars in tension, spliced at the center of the span. The splice length was selected so that the bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The bars were plain round Grade 60 bars with the splice length machined to simulate #6 (20 mm) deformed bars with parallel deformation pattern and different deformation geometries. No transverse reinforcement was provided in the splice region. The beam was loaded in positive bending and designed with constant moment region at the center of the beam. At each load increment, the deflection at the center of the beam was recorded and flexural cracks were marked and their widths measured. The variables were the bar rib face angle, rib spacing, and rib height. The results of this study were combined with results of previous investigations by Prof. Hamad to come up with recommendations concerning optimum rib geometries of deformed bars with superior bond-slip characteristics.
Author: Antoine Makhlouf Publisher: ISBN: Category : Reinforcing bars Languages : en Pages : 166
Book Description
Beams were designed to include two reinforcing bars in tension, spliced at the center of the span. The splice length was selected so that the bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The bars were plain round Grade 60 bars with the splice length machined to simulate #6 (20 mm) deformed bars with parallel deformation pattern and different deformation geometries. No transverse reinforcement was provided in the splice region. The beam was loaded in positive bending and designed with constant moment region at the center of the beam. At each load increment, the deflection at the center of the beam was recorded and flexural cracks were marked and their widths measured. The variables were the bar rib face angle, rib spacing, and rib height. The results of this study were combined with results of previous investigations by Prof. Hamad to come up with recommendations concerning optimum rib geometries of deformed bars with superior bond-slip characteristics.
Author: FIB – International Federation for Structural Concrete Publisher: FIB - International Federation for Structural Concrete ISBN: 2883941637 Category : Technology & Engineering Languages : en Pages : 326
Book Description
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.
Author: Ghassan Khaled Jumah Publisher: ISBN: Category : Deformations (Mechanics) Languages : en Pages : 174
Book Description
The theory of reinforced concrete is based on stress transfer between steel and concrete. In order for the steel to develop its full yield force in tension, there should be some bond between that steel and the surrounding concrete. With the deformed bars, used in reinforced concrete construction since many decades, the problem of bond was the topic for many research programs dedicated for the investigation of the factors influencing that bond, Some of these factors are : bar size, cover thickness, spacing between embedded bars, and deformation properties of the bar itself. The objective of our research work was to investigate the effect of rib geometry or rib deformation properties on the bond-slip characteristics of deformed reinforcing bars. For that purpose, plain round Grade 60 bars 20.6 mm (0.811 in.) in diameter were machined to simulate #6 bars. Fifty six of these test bars were tested in eccentric pullout tests. The specimen was a concrete block with a 10-in. length and a 12in.xl2in. cross section. The bar was embedded along the 10-in. length and was loaded in tension until failure of the specimen in a V-notch splitting mode, where the test was halted. Such a short embedment length (10 in.^ for the test bar was chosen in order to avoid yielding of the bar and to minimize the difference in tensile stresses between the loaded-end and the free-end of the bar. The load and the free-end slip of the bar was monitored during the test. Seven series of pullout specimens were prepared and tested, and replicates were included to check the reliability of the test setup and the obtained results. In series ONE and FOUR, the main variable was the rib face angle where five rib face angles were investigated, 30, 45, 60, 75, and 90 degrees. The concrete compressive strength in series ONE was 3000 psi while in series SIX, it was 6000 psi. The main variable in series TWO and FIVE was the rib spacing. Five values of rib spacings were investigated, 0.3 in. (0.37 db), 0.35 in. (0.43 dO, 0.4 in. (0.49 db), 0.45 in. (0.55 db), and 0.5 in. (0.62 db). The rib height was investigated in series THREE and SIX with two different concrete compressive strengths, 3000 and 6000 psi respectively. Four values of rib heights were investigated; 0.04 in. (0.05 db), 0.06 in. (0.074 db), 0.08 in. (0.1 db), and 0.1 in. (0.124 db). Based on the test results of the first six series, the values for the variables in the seventh series were decided upon. In this last series, the rib spacing was kept constant and equal to 0.4 in. (0.49 db), and four combinations of rib face angles and rib heights were tested. The first two combinations had a rib face of 45 degrees and two different rib heights, 0.06 in. (0.074 db) and 0.08 in. (0.1 db), while the other two had a rib face angle 60 degrees with two different rib heights, 0.06 in. (0.074db) and 0.08 in. (0.1 db).
Author: fib Fédération internationale du béton Publisher: fib Fédération internationale du béton ISBN: 9782883940505 Category : Technology & Engineering Languages : en Pages : 448
Book Description
"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.
Author: Eric Jacques Publisher: ISBN: Category : Languages : en Pages :
Book Description
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.
Author: Publisher: ISBN: Category : Anchorage (Structural engineering) Languages : en Pages : 160
Book Description
The use of a few large-diameter reinforcing bars for the construction of precast concrete bridge bents allows simplified construction by reducing the number of alignments to be made in the field. These bars are grouted into ducts in a precast concrete cap beam. In the proposed precast concrete substructure system, the grouted bars carry tensile forces across the joint between the column and cap beam. This joint is the yielding element in the structural system, and it is crucial to the performance of the structure that the bars yield before other failure mechanisms, including bond failure, occur. However, the cap beam is typically insufficient to anchor the bar, as the depth of the beam is substantially less than the American Association of State Highway and Transportation Officials (AASHTO) bridge code allows. For this project, 17 pullout tests were conducted to determine the bond characteristics and development length of large-diameter bars grouted into ducts. The bars tested ranged in size from #8 to #18. Pullout tests conducted with embedment lengths of at least six bar diameters yielded the reinforcing bar, while the test conducted with an embedment length of 14 bar diameters resulted in bar fracture. The tests and subsequent analysis showed that the bond of these grouted connections is significantly better than the bond of bars cast directly into concrete. The development lengths needed to fully anchor the bar are therefore within the depth available in the cap beam.
Author: Civil Engineering Research Foundation Publisher: American Society of Civil Engineers ISBN: Category : Technology & Engineering Languages : en Pages : 104
Book Description
This report describes the development and implications of a new concrete reinforcing bar with significantly improved bond strength.
Author: Antoine Makhlouf
Author: Antoine Makhlouf
Author: FIB – International Federation for Structural Concrete
Author: 
Author: Ghassan Khaled Jumah
Author: fib Fédération internationale du béton
Author: Eric Jacques
Author: Leroy Albert Lutz
Author: 
Author: Civil Engineering Research Foundation
Author: Kamran Farhadi