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This study investigates the numerical analysis of concrete breakout strength of cast in place anchors in shear within synthetic fiber reinforced concrete (SYN-FRC). A three dimensional, full-scale model was developed using the ABAQUS 6.14 software. The 3D solid elements with consideration of material nonlinearities were chosen to stimulate the SYN-FRC beam anchorage. The numerical analysis was conducted with a fixed loading rate of 300lb per step to obtain the behavior of fiber-reinforced concrete breakout with design-mix compressive strength of 4,000 psi and fiber volume fraction of 0%, 0.5%, 1.0%, and 1.5%. An inverse analysis was used to calibrate the material model defined in the ABAQUS software with experimental data from previous research since fiber reinforced concrete cannot be modeled precisely with the random distribution of fibers in the concrete matrix. Only compression tests and slump tests were performed to testify the results of the tests with the previous experimental data. Since a good agreement between results was observed, the tensile strength, flexure strength, and anchor shear test results for SYN-FRC were directly used to model in ABAQUS. It was discovered that the compressive strength of the concrete decreased as the fiber reinforcement increased, which can contribute to reducing workability and increased air voids from poor consolidation. In contrast, using synthetic fibers leads to an increase in tensile, flexure, and the anchorage capacity of concrete for the cast-in-place anchor loaded in shear. From the numerical analysis, the Modulus of elasticity increased by 2.8%, 5.0%, and 5.1% for the fiber volume fraction of 0.5%, 1.0%, and 1.5%, respectively, in comparison to the empirical computation of Elastic Modulus. Therefore, from numerical analysis, a parametric study was conducted to evaluate the Elastic Modulus for synthetic fiber reinforced concrete by calibrating load-deflection behavior from physical tests.
This study aims to investigate numerically, the effect of anchor groups on concrete breakout strength using nonlinear finite element analysis. Steel headed studs were cast in place within concrete of different amounts of steel fibers. Different proportions of steel fibers (0%, 0.5%, 1%,1.5%) were utilized within steel fiber reinforced concrete (SFRC) for the numerical simulation.The physical properties of SFRC were modelled with respect to its composite compressive and tensile strength obtained from the experiments. The analysis was conducted on the concrete breakout strength of anchor bolts within SFRC. A good agreement was achieved between the numerical and the experimental results. The numerical results show that the concrete breakout cone radius decreases, and the concrete breakout strength increases as the percentage of steel fiber in the mix increases. The increase in the breakout strength with respect to plain concrete was around 47%, 84%, and 92% as the steel fiber percentage increased to 0.5%, 1% and 1.5%respectively. The grouping effect of anchors was quantified by conducting a numerical analysis on the concrete breakout strength of single anchor under uniaxial tensile loading. A grouping effect factor was found out, which signifies the percentage of load required to break out a concrete cone when the grouping effect takes place. The numerical analysis found out that the grouping effect factor is 0.8, 0.82, 0.84, 0.84 for SFRC 0%, 0.5%, 1%, 1.5% respectively. A parametric study was carried out, understand the effects of anchor bolt embedded length and its diameter n the concrete breakout strength. The nonlinear finite element analysis shows that increasing the embedded length of the anchor bolt from 2.5" to 3.5" increases the breakout strength by 25%, 26.6%, 26.7% and 26.5% for SFRC 0%, 0.5%, 1%, 1.5% respectively.
This study investigates the effects of Polypropylene fibers on the concrete breakout strength of cast in place anchors in shear under different loading rates. The steel headed anchors were cast within concrete specimens of different amounts of Polypropylene fibers. Four differing mixtures were produced using, 0, 0.5, 1, and 1.5% fibers by volume of the mixture. Their physical properties were calculated through testing at the Civil Engineering Laboratory Building. In total, 16 cylindrical specimens, 4" in diameter and 8" in height, and 6 beam specimens, 6"x6"x20" were produced and tested. After 28 days of curing, the specimens were tested for their compressive and tensile strengths, as well as their modulus of rupture. The results of the tests were then analyzed. It was discovered that as the fiber reinforcement approached 1% and over, the compressive strength of the concrete decreased which was attributed to reduce workability and increasing air voids from poor consolidation. In contrast, using Polypropylene fibers leads to increase the concrete tensile strength and the concrete shear breakout capacity for the anchor. Also, it's found that the cone of influence increase as the anchor embedded length or edge distance increase. Cone of influence control the anchor shear mode failure, once the cone of influence is high that leads to steel failure proceeded by concrete spall, for that mode of failure increasing fiber dosage 1.0% leads to decrease load failure 55% and decrease displacement 50%. Loading rate will play a major roll to determine the failure load, once the loading rate is higher that will provide a higher impact load, where increasing loading rate 150% leads to decrease load failure 25% and increase displacement 15%.
This research investigates the effects of steel fibers on the concrete breakout of the cast-in-place headed stud anchors in tension. High strength anchors (F1554 G105) is used in this study for varying steel fiber dosage of 0.0%, 0.5% and 1.0% by volume fraction of concrete. The physical properties of steel fiber reinforced concrete were calculated through various test at the Civil Engineering laboratory Building. In total, 9-cylinder specimens of 4" diameter and 8" height, and 9 beam specimens, 6"x6"x20" were made and tested. After 28 days of curing, the specimens were tested for their compressive strength and modulus of rupture, as well as 9-cylinder specimens of 6" diameter and 12" height to test for split tensile test. Nine headed stud anchors were installed and tested in the various mixtures. The depth of anchor embedment is kept constant, and the spacing between anchors is specified as per ACI 318-14. No grouping action was found. CCD method (ACI 318-14) is modified in order to predict the concrete breakout capacity of the cast-in-place anchor. The experiment revealed that the increase in dosage of fiber fraction increases the compressive strength of the concrete by 35% and 48% for 0.5% and 1% respectively compared from normal weight concrete without steel fibers. The breakout strength of concrete in tension increased by 77% for 0.5% volume fraction of steel fiber in concrete and increased 107% for 1.0% volume fractions of steel fiber in concrete in comparison with 0.0% Steel fiber reinforced concrete. It is found that the diameter of cone of concrete reduced as the dosage of steel fibers increased and the failure angle increased as the dosage of steel fibers increased.
This research investigates the effect of anchor groups on concrete breakout strength within steel fiber reinforced concrete (SFRC) under tension load. High strength steel headed studs (F1554 Grade 105) in grouping action were cast-in-place within concrete specimens of different amounts of steel fibers. Four types of concrete mix designs were produced in the lab by using different amounts of steel fibers (0%, 0.5%, 1%, and 1.5%) by volume fraction of the mixture. The physical properties of steel fibers reinforced concrete were calculated through testing of specimens at the Civil Engineering Laboratory Building (CELB). In total, 12 cylinder specimens of 4-inch diameter and 8-inch height for compressive strength, 12 cylinder specimens of 6-inch diameter and 12-inch height for split tensile test, 12 beam specimens of 6*6*20 inch for modulus of rupture and flexural behavior. 4 concrete beams of 54*18*10 inch were cast-in-place with 12 sets of anchor groups were installed and tested after 28 days of curing. Embedment depth and distance between anchors for all group sets are kept constant. The effective embedment depth and the spacing between two anchors in grouping action are specified as per ACI 318-19.The experiments revealed that the increase of the amount of the steel fiber fraction increases the concrete breakout strength of anchor groups in tension by 43.33%, 73.42%, and 81.1% for 0.5%, 1.0%, and 1.5% volume fraction of steel fibers respectively. The research shows that the diameter of the concrete failure cone was reduced by increasing steel fibers. The failure angle increased by 14.6%, 48.5%, and 70% for 0.5%, 1.0%, and 1.5%. The concrete breakout strengths for anchor groups were compared with single anchors were tested at the same conditions. The anchors group effect reduces the concrete breakout strength by (19.45%, 16.8%, 15.7%, and 14%) for (0.0, 0.5, 1.0, and 1.5%) steel fiber compared with single anchor. Concrete compressive strength increased by (9.5%, 25.5%, and 17.5%) for (0.5%, 1%, and 1.5%) steel fibers respectively. The split tensile strength increased by (20.5%, 32.63%, and 35.35%) for (0.5%, 1%, and 1.5%) steel fibers and the flexural of concrete increased also by (3.7%, 9.8%, and 16.4%). Finally compare the experimental results of the concrete breakout strength with modified Concrete Capacity Design Method (CCD).
This study investigates the effects of Polypropylene fibers on the concrete breakout of post-installed screw anchor bolts. Concrete anchors were installed within concrete specimens of differing amounts of Polypropylene fibers. Four differing mixtures were produced using, 0, 0.5, 1, and 1.5% fibers by volume of the mixture. Their physical properties were calculated through testing at the Civil Engineering Laboratory Building (CELB). In total, 16 cylindrical specimens, 4" in diameter and 8" in height, and 6 beam specimens, 6"x6"x20" were produced and tested. After 28 days of curing, the specimens were tested for their compressive and tensile strengths, as well as their modulus of rupture. Additionally, twenty screw anchors were installed and tested in the varying mixture types. The results of the tests were then analyzed. It was discovered that as the fiber reinforcement approached 1% and over, the compressive strength of the concrete decreased which was attributed to reduced workability and increasing air voids from poor consolidation. Although the compressive strengths of the 1% and 1.5% were reduced, there was a linear trend between the addition of fiber reinforcement and tensile breakout capacity, however the results also showed a relationship between the compressive strength of the concrete and the tensile breakout capacity. Regression analysis was performed and the CCD method modified in order to predict the breakout capacity of a post-installed anchor. In conclusion, the addition of fiber reinforcement will lead to an increase in the breakout capacity of an anchor, while the reduction in compressive strength of a specimen will lead to a decrease in the breakout capacity of an anchor. Due to loss in workability the addition of fibers can also lead to poor consolidation which can lead to a reduction in the compressive strength, and thus a reduction in the breakout capacity of the anchor.
This book sheds light on the shear behavior of Fiber Reinforced Concrete (FRC) elements, presenting a thorough analysis of the most important studies in the field and highlighting their shortcomings and issues that have been neglected to date. Instead of proposing a new formula, which would add to an already long list, it instead focuses on existing design codes. Based on a comparison of experimental tests, it provides a thorough analysis of these codes, describing both their reliability and weaknesses. Among other issues, the book addresses the influence of flange size on shear, and the possible inclusion of the flange factor in design formulas. Moreover, it reports in detail on tests performed on beams made of concrete of different compressive strengths, and on fiber reinforcements to study the influence on shear, including size effects. Lastly, the book presents a thorough analysis of FRC hollow core slabs. In fact, although this is an area of great interest in the current research landscape, it remains largely unexplored due to the difficulties encountered in attempting to fit transverse reinforcement in these elements.
Das Buch stellt den aktuellen Stand der kompletten Befestigungstechnik für Beton und Mauerwerk mit Einlegeteilen (Ankerschienen, Kopfbolzen), Dübeln (Metallspreizdübel, Hinterschnittdübel, Verbunddübel, Betonschrauben, Kunststoffdübel) und Setzbolzen umfassend dar. Die Befestigungselemente und ihre Wirkungsmechanismen werden ausführlich beschrieben und das Tragverhalten im ungerissenen und gerissenen Beton untersucht. Weiterhin werden das Korrosionsverhalten, das Verhalten bei Brandbeanspruchung sowie bei Erdbeben- und Schockbeanspruchung behandelt. Von besonderer internationaler Aktualität ist die Bemessung gemäß der europäischen und amerikanischen Normung. Praxisorientierte Kriterien zur Auswahl von Befestigungsmitteln und Bemessungsbeispiele runden das Werk zu einem einzigartigen Handbuch ab.
Reinforced concrete shear walls are commonly used to provide lateral strength and stiffness to concrete buildings in seismic regions. Typically installed in the wall face, mechanical anchors are responsible for connecting various nonstructural systems to the main structure. During an earthquake, anchors in reinforced concrete structural elements need to retain their strength and stiffness, despite the inevitable presence of cracks and damage in the concrete, developed as a consequence of the lateral cyclic loading. Anticipating damage to the concrete, which will naturally influence anchor response, current guidelines to qualify anchors for seismic applications require adequate performance in cracked concrete to assure minimal anchor load loss. However, these guidelines are based on anchor performance in pure flexural cracks, as this is the typical damage condition occurring in reinforced concrete frame elements, which has been studied for decades. The response of anchors to a mix of flexure and shear cracks, i.e., the complex situation realized in shear-flexure structural components such as shear walls, however, has largely not been studied. To address the paucity of data regarding anchor behavior in cracked concrete, the behavior of anchors installed horizontally in three full-scale reinforced concrete shear walls with different aspect ratios (wall height/length) is studied in this dissertation. Notably, two types of post-installed anchors were investigated in these tests, namely: i) expansion anchors and ii) bonded anchors. One slender and two identical low-aspect ratio walls were designed according to current U.S. design codes. Simulated seismic loading was imposed at the top of the wall using an equivalent cyclic displacement history, while uniform compression was applied on the slender and one of the two identical low-aspect ratio shear walls. One of the low aspect ratio walls was tested without axial compression to investigate its effect on the anchor response. Anchors were continuously loaded to their design tension while the walls were cycled. The slender full-scale wall failed in a predominantly flexural mode, precipitated by buckling and fracture of the boundary reinforcement. The two identical full-scale low-aspect ratio walls failed in a mixed flexure-shear response, with severe web concrete crushing and buckling and rupture of the boundary reinforcement. Anchor axial load and displacement data, continually measured during the wall cyclic tests, confirmed the sensitivity of the performance of anchors amidst the presence of a variety of cracked concrete conditions, especially in walls prone to develop large shear stress and shear induced damage when subjected to lateral cyclic loads. Following the wall cyclic tests, tension failure tests performed on the anchors indicated that their residual tension load capacity was significantly compromised by concrete damage. Such damage was concentrated in specific wall regions, such as the boundary elements and the plastic hinge region in slender walls, or along the diagonal struts, the boundary elements and near the base of low-aspect ratio walls. Of the two types of anchors tested, expansion anchors observed the most significant load loss (and consequentially axial displacement) in the presence of both the wall cyclic loading and the residual tests on the anchors themselves. Following the experimental program, a multiple vertical line finite element model was used to predict the response of each of the tested full-scale shear walls. Numerical analyses cross-comparison with test results demonstrated a high level of accuracy of the selected modeling approach. As such, an expanded parametric study was conducted to understand the extent of severe concrete strains on the crack distribution and width, using a smeared crack approach. Wall models designed for the parametric study were intended to explore different geometry, reinforcement and axial compression to study the damage distribution within the wall elevation. Crack pattern distribution plots developed using the parametric study results were used to identify regions where anchors would be vulnerable to load loss upon achievement of service, design and severe seismic damage. Ultimately, the findings from this dissertation shed light on the vulnerability of anchors placed in reinforced concrete shear walls, where damage in the form of mixed mode cracking and spalling can be expected. Future design guidelines would benefit from precluding crack sensitive anchors in the most highly damaged regions of these essential lateral force resisting components of the structural system.