Academic literature on the topic 'Flexural punching'
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Journal articles on the topic "Flexural punching"
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Ozden, Sevket, Ugur Ersoy, and Turan Ozturan. "Punching shear tests of normal- and high-strength concrete flat plates." Canadian Journal of Civil Engineering 33, no. 11 (November 1, 2006): 1389–400. http://dx.doi.org/10.1139/l06-089.
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Experimental research was conducted to investigate the punching shear performance of flat plates. A large number of slab specimens of normal- and high-strength concrete were tested under concentric and eccentric loads. The effects of flexural reinforcement and the use of steel fiber reinforcement were investigated. Experimental expressions were developed for the computation of residual slab strength. Experimentally observed punching shear capacities were compared with those from the provisions of Canadian Standards Association (CSA) standard CSA-A23.3-04. The results indicate that concrete strength plays an important role in punching capacity and slab rigidity. Slabs with a higher percentage of flexural reinforcement show an increase in punching capacity. The use of steel fibers results in improved strength and stiffness while also enhancing the postpeak deformability and residual strength. The empirical expressions developed provide reasonably good predictions of residual slab capacities. CSA-A23.3-04 expressions result in conservative punching shear capacity predictions for concentrically loaded slabs and provide good agreement with the experimentally observed punching shear capacities for eccentrically loaded slabs.Key words: reinforced concrete, flat plate, punching shear, strength, high-strength concrete, eccentric loading, slab re inforcement ratio, steel fiber reinforced concrete.
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Ju, Minkwan, Kyoungsoo Park, and Cheolwoo Park. "Punching Shear Behavior of Two-Way Concrete Slabs Reinforced with Glass-Fiber-Reinforced Polymer (GFRP) Bars." Polymers 10, no. 8 (August 9, 2018): 893. http://dx.doi.org/10.3390/polym10080893.
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This study investigated the punching shear behavior of full-scale, two-way concrete slabs reinforced with glass fiber reinforced polymer (GFRP) bars, which are known as noncorrosive reinforcement. The relatively low modulus of elasticity of GFRP bars affects the large deflection of flexural members, however, applying these to two-way concrete slabs can compensate the weakness of the flexural stiffness due to an arching action with supporting girders. The test results demonstrated that the two-way concrete slabs with GFRP bars satisfied the allowable deflection and crack width under the service load specified by the design specification even in the state of the minimum reinforcement ratio. Previous predicting equations and design equations largely overestimated the measured punching shear strength when the slab was supported by reinforced concrete (RC) girders. The strength difference can be explained by the fact that the flexural behavior of the supporting RC beam girders reduces the punching shear strength because of the additional deflection of RC beam girders. Therefore, for more realistic estimations of the punching shear strength of two-way concrete slabs with GFRP bars, the boundary conditions of the concrete slabs should be carefully considered. This is because the stiffness degradation of supporting RC beam girders may influence the punching shear strength.
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Pang, Rui, Longji Dang, Hongmei Ni, Shuting Liang, and Qianqian Li. "Experimental study on punching shear behavior of hollow floor slab-column reinforced connection." Advances in Structural Engineering 22, no. 7 (December 21, 2018): 1531–43. http://dx.doi.org/10.1177/1369433218819565.
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This article presents an experimental study on hollow floor slab-column-reinforced connections, which are enhanced by installing locally solid zone of slab around the column and hidden beam in the floor. To investigate the punching-shear behavior of hollow floor slab-column-reinforced connections, six hollow floor slab-column-reinforced connections under vertical load were conducted on three types of connections with different thickness, namely, two hollow floor slab-column-reinforced connections without punching component, two hollow floor slab-column-reinforced connections with bent-up steel bars, and two hollow floor slab-column-reinforced connections with welding section steel cross bridging. Meanwhile, the strength, stiffness, failure mode, and ductility of hollow floor slab-column-reinforced connections with punching components were obtained and compared with the hollow floor slab-column-reinforced connections without punching component. The results showed that hollow floor slab-column-reinforced connections had the double failure characteristics including punching shear and flexural failure, and flexural failure was the main failure mode as a result of installing hidden beam. The hollow floor slab-column-reinforced connections with punching components exhibited higher initial stiffness and higher loading capacity than hollow floor slab-column-reinforced connections without punching components, but welding section steel cross bridging have a better on improving the connections’ punching-shear capacity than bent-up steel bars.
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Kang, Tae Jin, Kyung Ho Jung, Jong Kyoo Park, Jae Ryoun Youn, and Seung Goo Lee. "Effect of Punching Density on the Mechanical and Thermal Properties of Needle-punched Nonwoven Carbon/Phenolic Composites." Polymers and Polymer Composites 10, no. 7 (October 2002): 521–30. http://dx.doi.org/10.1177/096739110201000704.
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The effects of changes in the fibre orientation on the mechanical properties of nonwoven composites were investigated through 3-point bending, short beam shear and tensile tests. Oxidized polyacrylonitrile(PAN) carded webs were needle-punched, and then carbonized to fabricate carbon composites with phenolic resin. The interlaminar shear, tensile and flexural strengths increased with increasing punching density. However, the rate of increase reduced and interlaminar shear and tensile strengths decreased with excessive punching density. The erosion rate and the insulation index were calculated by means of a torch test. The ablation resistance increased with increasing punching density, but no significant increase in the erosion rate with increasing punching density above 477 penetrations per square centimetre was found. The thermal conductivity of needle-punched nonwoven carbon/phenolic composites increased with increasing punching density.
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Salim, Muhamad Saifuddin, Z. A. Mohd Ishak, Dody Ariawan, and Mohd Zharif Ahmad Thirmizir. "Effect of Alkaline Treatment to Wettability and Flexural Properties of Kenaf Nonwoven Fibre Mat Reinforced Epoxy Composites Produced by Resin Transfer Moulding." Applied Mechanics and Materials 754-755 (April 2015): 99–105. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.99.
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This paper focuses on the study of the effect of chemical treatments of fibres by alkalization on the flexural and impact properties of epoxy matrix composites reinforced by kenaf fibre (KF) produced via resin transfer moulding (RTM) technique. The reinforcement consists of KF nonwoven fiber mat fabricated using needle punching method. Prior to punching process, KF are subjected to alkali treatments with Sodium hydroxide (NaOH) at 3, 6 and 9% for a period of 3h at room temperature. The composites were reinforced with kenaf nonwoven mat at 40% by volume. Effect of alkaline treatment concentration to wettability of KF towards epoxy resins are measured by means of contact angle and surface energy analysis. Influences of alkaline treatment on the flexural properties are studied to determine the optimum conditions of alkaline treatment. As concentration of NaOH in alkaline treatment increased, the experimental results show that the flexural properties of composites increases. For 6% NaOH treatment, the flexural strength and flexural modulus improved by 7.88 MPa to 81.38 Mpa and from 4.79 GPa to 5.41GPa compared to untreated fibre composites. However, as the concentration of NaOH increase to 9%, the bending properties reduced significantly.
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Xue, Hui Zhong, Hong Guan, and Yi Li. "Preliminary Collapse Simulation of a Reinforced Concrete Flat Plate Substructure Using Spring Connection Modelling." Applied Mechanics and Materials 638-640 (September 2014): 1445–48. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1445.
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To investigate progressive collapse behavior of reinforced concrete (RC) flat plate structures, a reliable and efficient numerical approach is developed in this study using spring connection modelling. This connection unit aims to simulate complicate punching shear behavior at critical regions surrounding the columns. Five springs are used as the connection elements: two for flexural and integrity steel bars and three for concrete contributions. The flexural and integrity steel bars embedded in the columns are modeled explicitly, which enables the model to present the structural behavior post punching shear failure. Bending and shear actions are represented by two concrete springs. The third concrete spring is assigned axial action property to restrain two end nodes of the connection on the model. In particular, the punching shear spring controls the connection unit when punching shear failure occurs. To apply the connection unit, the regions of slab-column connections are partitioned from the slab regions according to the critical shear surfaces. Then the connection unit links two corresponding nodes on the two edges formed from the partition. A physical experiment of a RC flat plate substructure under progressive collapse is simulated. Result comparison demonstrates that the numerical model has the capability to capture the structural behavior in progressive collapse. However, further improvement of the modelling technique is necessary to enhance numerical accuracy.
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Mufti, Aftab A., and Tarek K. Hassan. "Finite element analysis and theoretical study of punching shear strength of concrete bridge decks." Canadian Journal of Civil Engineering 32, no. 2 (April 1, 2005): 449–53. http://dx.doi.org/10.1139/l04-106.
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The problem of punching shear usually arises in reinforced concrete slabs subjected to concentrated loads and particularly in concrete bridge decks due to development of an internal arching system. Ongoing research revealed that the governing mode of failure of concrete bridge decks is not flexure and that using a flexural design method usually led to unnecessary high levels of steel reinforcement. This paper examines the applicability of nonlinear finite element formulation of restrained concrete bridge decks. A general purpose finite element program ANACAP was employed in this study. The accuracy of the nonlinear finite element analysis is demonstrated using test results conducted by other researchers. The results of the finite element analysis are also compared with those obtained from a rational model. The experimental results and the theoretical model provide insight to the fundamental behavior of concrete bridge decks.Key words: bridges, concrete, deflections, FRP, punching, reinforcement, slabs.
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Vainiūnas, Povilas, Vladimiras Popovas, and Andrei Jarmolajev. "PUNCHING SHEAR BEHAVIOUR ANALYSIS OF RC FLAT FLOOR SLAB-TO-COLUMN CONNECTION." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, no. 2 (June 30, 2002): 77–82. http://dx.doi.org/10.3846/13923730.2002.10531255.
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The paper presents information about theoretical investigations and based on computer modelling and analysis research methods of flat floor slab-to-column joint behaviour for punching” obtained by authors. Main principles of calculation and design methods of flat slab-to-column support under punching according to variety of international design coded are observed and compared. The design problems of beamless floor systems for shear with bending are discussed. The set of variables, such as lateral flexural reinforcement, bending moment to shear force ratio, span-to-slab depth ratio and slab thickness to column depth ratio, which may have an influence on flat two-ways floor slab punching shear strength is established and computer modelling analysis methods are applied to investigate the problem.
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Urban, Tadeusz, Łukasz Krawczyk, and Michał Gołdyn. "Experimental investigations of punching shear concrete slabs with different types of transverse reinforcement." Budownictwo i Architektura 13, no. 3 (September 11, 2014): 193–200. http://dx.doi.org/10.35784/bud-arch.1820.
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The results of support zone thick concrete slabs experimental investigation are presented in the paper. The experimental program consisted of 4 square reinforced concrete flat models to 1:2 scale made of the same concrete with the same dimensions and the same flexural reinforcement. The aim of tests was proved the influence of different transverse reinforcement types on punching shear load capacity. One of the models was a comparative slab made without transverse reinforcement. In the other slabs three types of transverse reinforcement were used: typical stirrups enclosing flexure reinforcement, stirrups situated between flexure reinforcement and ladders. The test results show a few percent difference in load capacity between models with transverse reinforcement, the most effective were typical stirrups enclosing the main reinforcement.
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Chen, Cheng-Chih, and Shun-Long Chen. "Strengthening of Reinforced Concrete Slab-Column Connections with Carbon Fiber Reinforced Polymer Laminates." Applied Sciences 10, no. 1 (December 30, 2019): 265. http://dx.doi.org/10.3390/app10010265.
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This study presents the structural behavior and punching shear strength of the concrete slab-column connections strengthened with carbon fiber reinforced polymer (CFRP) laminates. The variables considered for the twelve specimens included the compressive strength of the concrete, the ratio of the tensile steel reinforcement, and the amount of the CFRP laminates. Square concrete slabs were simply supported along four edges. During the test, monotonically concentrated load was applied to the stub column located at the center of the slab. The punching shear strength, stiffness, and mode of failure were investigated. Test results demonstrated that increasing the compressive strength of concrete, ratio of the steel reinforcement, and amount of the CFRP laminates led to an increase in the punching shear strength of the slabs. Moreover, the CFRP laminates were effective in appreciably increasing the punching shear strength of the slab-column connections. An analytical approach was conducted to calculate the punching shear strength of the slab-column connections strengthened with CFRP laminates. Based on the theory of reinforced concrete members, the application of the CFRP laminates increased the flexural strength of the slab and resulted in an increase of the effective depth of the slab section. Consequently, the punching shear strength was increased. The results of the analytical calculation revealed that the analytical work accurately predicted the experimental punching shear strength.
Dissertations / Theses on the topic "Flexural punching"
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Bono, Matthew P. (Matthew Paul). "Tilt-up concrete panels : an investigation of flexural stresses and punching shear during lifting." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66823.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 75).
Tilt-up construction is becoming more popular in the United States due to its ease of construction, reliability, and relatively low construction and maintenance costs. In its most typical form, a concrete panel is cast on the ground. After the concrete sets and has reached a prescribed compressive or flexural strength, a crane lifts the panel off the ground and hoists it into place. The flexural stresses during liftoff are often times greater than those corresponding to service loads. Concentrations of high shear stress and the associated punching shear in the vicinity of the pick points could result in pullout. For these reasons, it is particularly important to design the concrete and steel reinforcement to handle the flexural and shear stresses associated with panel erection. This thesis investigates the flexural stresses and punching shear of a concrete panel designed for tilt-up. Finite element models confirm static hand calculations, and experimental results indicate that these models appropriately predicted erection stresses. The acceptability of the design provided is confirmed.
by Matthew P. Bono.
M.Eng.
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Pettigrew, Christopher S. "Flexural, Shear, and Punching Shear Capacity of Three 48-Year-Old Prestressed Lightweight Concrete Double-Tee Bridge Girders." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3852.
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The Icy Springs Bridge in Coalville, Utah carries 2nd South Street over the Weber River west of Interstate 80. The bridge is owned by Coalville City and was originally constructed in 1965 as a single-span 51-foot long bridge using prestressed concrete double-tee girders. In the fall of 2013 the original bridge was replaced with a new 80-foot long single span bridge using prestressed concrete decked bulb-tee girders. The original girders were salvaged and transported to the Systems, Materials, and Structural Health Lab (SMASH Lab) where a series of tests were performed to determine the total losses in the prestressing of the strands, the flexural and shear capacities of the girders, and the punching shear capacity of the reinforced concrete deck. The results of these tests were compared to the values calculated using methods outlined in the 2012 American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications, the current bridge design code used by most departments of transportation, and a finite element model using the computer program ANSYS. For the shear and punching shear test results, the AASHTO LRFD Bridge Design Specifications was conservative and was able to predict the type of failure that occurred. However, the tested flexural results were below the calculated flexural capacities using the AASHTO LRFD Bridge Design Specifications. A finite element model was created and calibrated to the test results for the various loading and support conditions. The actual tested material properties were compared to the material properties used in the finite element analyses to determine the difference between the actual girders and the theoretical models. Funding for this project was provided by the Utah Transportation Center.
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Zhang, Xuesong, and n/a. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051104.153239.
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Failure criteria play a vital role in the numerical analysis of reinforced concrete structures. The current failure criteria can be classified into two types, namely the empirical and theoretical failure criteria. Empirical failure criteria normally lack reasonable theoretical backgrounds, while theoretical ones either involve too many parameters or ignore the effects of intermediate principal stress on the concrete strength. Based on the octahedral shear stress model and the concrete tensile strength under the state of triaxial and uniaxial stress, a new failure criterion, that is, the simplified unified strength theory (UST), is developed by simplifiing the five-parameter UST for the analysis of reinforced concrete structures. According to the simplified UST failure criterion, the concrete strength is influenced by the maximum and intermediate principal shear stresses together with the corresponding normal stresses. Moreover, the effect of hydrostatic pressure on the concrete strength is also taken into account. The failure criterion involves three concrete strengths, namely the uniaxial tensile and compressive strengths and the equal biaxial compressive strength. In the numerical analysis, a degenerated shell element with the layered approach is adopted for the simulation of concrete structures. In the layered approach, concrete is divided into several layers over the thickness of the elements and reinforcing steel is smeared into the corresponding number of layers of equivalent thickness. In each concrete layer, three-dimensional stresses are calculated at the integration points. For the material modelling, concrete is treated as isotropic material until cracking occurs. Cracked concrete is treated as an orthotropic material incorporating tension stiffening and the reduction of cracked shear stiffness. Meanwhile, the smeared craclc model is employed. The bending reinforcements and the stirrups are simulated using a trilinear material model. To verify the correctness of the simplified UST failure criterion, comparisons are made with concrete triaxial empirical results as well as with the Kupfer and the Ottosen failure criteria. Finally, the proposed failure criterion is used for the flexural analysis of simply supported reinforced concrete beams. Also conducted are the punching shear analyses of single- and multi-column-slab connections and of half-scale flat plate models. In view of its accuracy and capabilities, the simplified UST failure criterion may be used to analyse beam- and slab-type reinforced concrete structures.
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Papanicolaou, Catherine, Thanasis Triantafillou, Ioannis Papantoniou, and Christos Balioukos. "Strengthening of two-way reinforced concrete slabs with Textile Reinforced Mortars (TRM)." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244048746186-75760.
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An innovative strengthening technique is applied for the first time in this study to provide flexural strengthening in two-way reinforced concrete (RC) slabs supported on edge beams. The technique comprises external bonding of textiles on the tension face of RC slabs through the use of polymer-modified cement- based mortars. The textiles used in the experimental campaign comprised fabric meshes made of long stitch-bonded fibre rovings in two orthogonal directions. The specimens measured 2 x 2 m in plan and were supported on hinges at the corners. Three RC slabs strengthened by textile reinforced mortar (TRM) overlays and one control specimen were tested to failure. One specimen received one layer of carbon fibre textile, another one received two, whereas the third specimen was strengthened with three layers of glass fibre textile having the same axial rigidity (in both directions) with the single-layered carbon fibre textile. All specimens failed due to flexural punching. The load-carrying capacity of the strengthened slabs was increased by 26%, 53%, and 20% over that of the control specimen for slabs with one (carbon), two (carbon) and three (glass) textile layers, respectively. The strengthened slabs showed an increase in stiffness and energy absorption. The experimental results are compared with theoretical predictions based on existing models specifically developed for two-way slabs and the performance of the latter is evaluated. Based on the findings of this work the authors conclude that TRM overlays comprise a very promising solution for the strengthening of two-way RC slabs.
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Elgabbas, Fareed Mahmoud. "Development and structural testing of new basalt fiber-reinforced-polymer (BFRP) bars in RC beams and bridge-deck slabs." Thèse, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8734.
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L'avancée de la technologie des PRF a suscité l'intérêt de l'introduction de nouvelles fibres, comme la fibre de basalte, qui a un potentiel d'offrir une solution efficace, lorsqu’utilisée dans les structures en béton, soit sur la résistance à la corrosion, la durabilité et la rentabilité. En outre, les codes et les guides disponibles, ne fournissent pas de recommandations pour l'utilisation de barres en PRFB puisque les recherches passées dans ce domaine sont limitées. Donc, des travaux de recherche sont nécessaires pour caractériser et comprendre le comportement des barres de PRFB dans les éléments en béton armé. En conséquence, les objectifs principaux sont d'évaluer les caractéristiques à court et long terme des barres de PRFB nouvellement développées, ainsi que d'évaluer les performances structurales de ces nouvelles barres comme renforcement interne dans les poutres et les dalles de pont et d'introduire ce nouveau renforcement dans les codes et les guides de dimensionnement. Les tests expérimentaux ont été faits en trois parties. La première partie porte sur le développement de trois nouvelles barres et tendons en PRFB pour déterminer leurs propriétés physiques et mécaniques. Les performances à long terme et de durabilité ont été réalisées en conditionnant les barres de PRFB dans une solution alcaline simulant les conditions humides dans le béton pour déterminer la compatibilité comme renforcement interne dans les éléments en béton. Par la suite, les propriétés ont été déterminées et comparées avec des spécimens non conditionnés (référence). La seconde partie a porté sur sept dalles de pont en béton armé grandeur réelle avec les bords restreints, simulant les tabliers de pont les plus utilisés en Amérique du Nord, pour évaluer la performance des dalles renforcées de PRFB et d'acier. Les dalles mesurent 3000 mm de long × 2500 mm de large × 200 mm d'épaisseur. Les dalles ont été testées jusqu'à la rupture sous une charge concentrée au centre de celles-ci simulant l'empreinte d'une roue d'un camion. Les capacités en poinçonnement sont prédites en utilisant les exigences réglementaires disponibles, et sont comparées aux résultats expérimentaux. La troisième partie de cette étude portait sur les essais de 14 poutres en béton de 3100 mm de long × 200 mm de large × 300 mm de profond pour examiner le comportement en flexion et les performances en service des barres de PRFB avec deux états de surfaces: fini sablé et crénelé. Les poutres ont été testées en flexion en quatre points avec une portée libre de 2700 mm jusqu'à la rupture. Les résultats sont introduits et discutés en terme : du comportement de la fissuration, des flèches, de la capacité en flexion et des modes de ruptures. De plus, le coefficient d'adhérence (kb) des barres de PRFB est déterminé et comparé avec les recommandations des codes et guides actuels. Les résultats sont introduits et discutés en terme : du comportement de la fissuration, des flèches, de la capacité en flexion et des modes de ruptures. De plus, le coefficient d'adhérence des barres de PRFB est déterminé et comparé avec les recommandations des codes et guides actuels. Les résultats de l'étude concluent sur la viables pour la production des barres de PRFB pour respecter les exigences des codes actuelles. Également, les résultats d'essai indiquent que les barres de PRFB ont de bonnes propriétés mécaniques et peuvent être placées dans la même catégorie que les barres de PRFV, soit grade III. De plus, le comportement des poutres et des dalles de pont renforcées de PRFB est similaire que pour un renforcement en PRFV et PRFC et les exigences réglementaires sont applicables pour les barres de PRFB.Abstract: The advances in fiber-reinforced-polymer (FRP) technology have spurred interest in introducing new fibers, such as basalt FRP (BFRP), which has the potential to offer an efficient solution when implemented in concrete structure, such as corrosion resistant, durable and cost-effective. Furthermore, the available design codes and guides do not provide any recommendations for the use of BFRP bars since fundamental studies and relevant applications are still limited. Therefore, investigations are needed to characterize and understand the behavior of BFRP bars in concrete members. Consequently, the main objectives of this experimental investigation are to evaluate the short- and long-term characteristics of newly developed BFRP bars, as well as evaluate the structural performance of these new bars as internal reinforcement for concrete beams and bridge-deck slabs to introduce these new reinforcing bars to the design codes and guides. The experimental tests were completed through three parts. The first part was conducted on three newly developed BFRP bars and tendons to investigate their physical and mechanical properties. Durability and long-term performance were assessed by conditioning the BFRP bars in an alkaline solution simulating the moist concrete environment to determine their suitability as internal reinforcement for concrete elements. Thereafter, the properties were assessed and compared with the unconditioned (reference) values. The second part of this study was conducted on seven full-scale edge-restrained concrete bridge-deck slabs simulating actual slab-on-girder bridge-deck that is commonly used in North America to evaluate the performance of concrete bridge-deck slabs reinforced with BFRP and steel bars. The deck slabs measured 3000 mm long × 2500 mm wide × 200 mm deep. The slabs were tested up to failure under single concentrated load acting on the center of each slab simulating the footprint of sustained truck wheel load. The punching shear capacities were predicted using the available provisions, and compared with the experimental results. The third part of this study included testing of fourteen concrete beams of 3100 mm long × 200 mm wide × 300 mm deep to investigate the flexural behavior and serviceability performance of sand-coated and ribbed BFRP bars in concrete beams. The beams were tested under four-point bending over a clear span of 2700 mm until failure. The results are introduced and discussed in terms of cracking behavior, deflection, flexure capacity, and failure modes. In addition, the bond-dependent coefficient (kb) of the BFRP bars was determined and compared with the recommendations of the current FRP design codes and guides. The findings of this study concluded the feasibility of producing BFRP bars meet the requirements of the current FRP standards. Also, the test results revealed that the BFRP bars had good mechanical behavior and could be placed in the same category as grade II and grade III GFRP bars. Moreover, the behavior of the concrete bridge-deck slabs and beams reinforced with BFRP bars was quite similar to the counterparts reinforced with glass- and carbon-FRP bars and the available FRP provisions are applicable for BFRP bars. The beam test results yielded an average bond-dependent coefficient (kb) of 0.76±0.03 and 0.83±0.03 for the sand-coated and ribbed BFRP bars, respectively.
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Bagge, Niklas. "Structural assessment procedures for existing concrete bridges : Experiences from failure tests of the Kiruna Bridge." Doctoral thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63000.
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Assessing existing bridges is an important task in the sustainable management ofinfrastructure. In practice, structural bridge assessments are usually conducted usingtraditional and standardised methods, despite knowledge that these methods oftenprovide conservative estimates. In addition, more advanced methods are available, suchas nonlinear finite element (FE) analysis, that are used for research purposes and cansimulate the structural behaviour of bridges more accurately. Therefore, it would beuseful to develop practical and reliable procedures for refined assessments using theseadvanced techniques.Focusing on the ultimate load-carrying capacity of existing concrete bridges, this thesispresents a procedure for structural assessments. The fundamental idea is to improve theassessment successively, as necessary to predict bridges’ structural behaviour adequately.The procedure involves a multi-level assessment strategy with four levels of structuralanalysis, and an integrated framework for safety verification. At the initial level (Level 1)of the multi-level strategy, traditional standardised methods are used, no failures arecovered implicitly in the structural analysis and action effects are verified using localresistances calculated using analytical models. In the subsequent enhanced levels (Levels2 – 4), nonlinear FE analysis is used for stepwise integration of the verification of flexural,shear-related and anchorage failures into the structural analysis. The framework for safetyverifications includes partial safety factor (PSF), global resistance safety factor (GRSF) andfull probabilistic methods. Within each of these groups, verifications of desired safetymargins can be conducted with varying degrees of complexity.To demonstrate and evaluate the proposed structural assessment procedure, comparativestudies have been carried out, based on full-scale tests of a prestressed concrete bridge.This was the Kiruna Bridge, located in the northernmost city in Sweden, which was duefor demolition as part of a city transformation project, necessitated by large grounddeformations caused by the large nearby mine. Thus, it was available for destructiveexperimental investigation within the doctoral project presented in this thesis. The bridgehad five continuous spans, was 121.5 m long and consisted of three parallel girders with a connecting slab at the top. Both the girders and slab were tested to failure to investigatetheir structural behaviour and load-carrying capacity. Non-destructive and destructivetests were also applied to determine the residual prestress forces in the bridge girders andinvestigate the in situ applicability of methods developed for this purpose. The so-calledsaw-cut method and decompression-load method were used after refinement to enabletheir application to structures of such complexity. The variation of the experimentallydetermined residual prestress forces was remarkably high, depending on the sectioninvestigated. There were also high degrees of uncertainty in estimated values, and thusare only regarded as indications of the residual prestress force.Level 1 analysis of the multi-level assessment strategy consistently underestimatedcapacity, relative to the test results, and did not provide accurate predictions of the shearrelatedfailure observed in the test. With linear FE analysis and local resistance modelsdefined by the European standard, Eurocode 2, the load-carrying capacity wasunderestimated by 32 % for the bridge girder and 55 % for the bridge deck slab. At theenhanced level of structural analysis (Level 3), nonlinear FE analyses predicted thecapacities with less than 2 % deviation from the test results and correctly predicted thefailure mode. However, for existing bridges there are many uncertainties, for instance,the FE simulations were sensitive to the level of residual prestressing, boundaryconditions and assumed material parameters. To accurately take these aspects intoaccount, bridge-specific information is crucial.The complete structural assessment procedure, combining the multi-level strategy andsafety verification framework, was evaluated in a case study. Experiences from theprevious comparative studies were used in an assessment of the Kiruna Bridge followingthe Swedish assessment code. The initial assessment at Level 1 of the multi-level strategyand safety verification, using the PSF method, indicated that the shear capacity of one ofthe girders was critical. The most adverse load case (a combination of permanent loads,prestressing and variable traffic loads) was further investigated through enhancedstructural analyses implicitly accounting for flexural and shear-related failures (Level 3).Nonlinear FE analysis and safety evaluation using the PSF method, several variants of theGRSF method and the full probabilistic analysis for resistance indicated that the permittedaxle load for the critical classification vehicle could be 5.6 – 6.5 times higher than thelimit obtained from the initial assessment at Level 1. However, the study also indicatedthat the model uncertainty was not fully considered in these values. The modeluncertainty was shown to have strong effects on the safety verification and (thus)permissible axle loads. The case study also highlighted the need for a strategy forsuccessively improving structural analysis to improve understanding of bridges’ structuralbehaviour. The refined analysis indicated a complex failure mode, with yielding of thestirrups in the bridge girders and transverse flexural reinforcement in the bridge deck slab,but with a final shear failure of the slab. It would be impossible to capture suchcomplexity in a traditional standardised assessment, which (as mentioned) indicated thatthe shear capacity of the girder limited permissible axle loads. However, nonlinear FEanalyses are computationally demanding, and numerous modelling choices are required.Besides a strategy for rationally improving the analysis and helping analysts to focus oncritical aspects, detailed guidelines for nonlinear FE analysis should be applied to reduce the analyst-dependent variability of results and (thus) the model uncertainty. Clearly, toensure the validity of bridge assessment methods under in situ conditions, theirevaluations should include in situ tests. This thesis presents outcomes of such tests, therebyhighlighting important aspects for future improvements in the assessment of existingbridges.
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Rossi, Mariana. "Flat Slabs with Different Longitudinal Reinforcement Ratios Under Horizontal Cyclic Loading." Master's thesis, 2021. http://hdl.handle.net/10362/118272.
Full textAbstract:
The following dissertation studies the behavior of flat slabs when subjected to
constant vertical loads and cyclic horizontal displacements, as a continuation of previous
studies developed at FCT/UNL. The main focus of this research is to study the influence
of flexural reinforcement on the seismic response of flat slabs. Therefore, three reinforced
concrete flat slabs with varying flexural reinforcement ratio were tested, two having the
same top reinforcement ratio of !=0,64% and one with !=1,34%. One of the specimens
with lower longitudinal ratio was reinforced with studs as specific punching shear
reinforcement. All slabs had overall dimensions of 4,15 × 1,85 × 0,15 m3 and a gravity
shear ratio, ratio between the gravity load and the punching shear resistance,
approximately equal to 55%.
For a more complete analysis the results obtained were compared to two other
specimens from previous experimental campaigns also conducted at FCT/UNL. These
two slabs were designed with top flexural reinforcement ratio (!=0,96%) that lies
between the two tested in this dissertation, one with no shear-reinforcement and the other
with headed studs.
Results showed that the reduction of flexural reinforcement resulted in a more
ductile behavior of the specimens and in a higher drift capacity. The high flexural ratio
added to one specimen improved the maximum unbalanced moment capacity but also
made the slab fail in a more brittle mode. As expected, the specimen with shear headed
studs supported the highest drifts and ended up not failing during this experimental
campaign, reaching the test setup upper limit.A presente dissertação estuda o comportamento de lajes fungiformes submetidas a carga vertical constante e carregamento horizontal cíclico, sendo a continuação de trabalhos realizados anteriormente no Departamento de Engenharia Civil da FCT/UNL. O principal objetivo deste trabalho é estudar a influência da variação da taxa de reforço longitudinal na resposta sísmica de lajes fungiformes. Assim, três modelos de lajes fungiformes com variação da taxa de armadura longitudinal foram fabricados e testados, dois com a mesma taxa de !=0,64% e outro com !=1,34%. Um dos modelos com baixa taxa de armadura longitudinal foi reforçado com reforço específico ao punçoamento. Todas as lajes possuíam as mesmas dimensões de 4,15 × 1,85 × 0,15 m3 e razão entre a carga vertical e a resistência ao punçoamento aproximadamente igual a 55%. Para uma análise mais completa, os resultados obtidos foram comparados com outros dois modelos testados anteriormente na FCT/UNL. Estas duas lajes possuíam uma taxa intermédia de reforço longitudinal (!=0,96%), uma sem armadura específica de punçoamento e a outra contendo “shear studs”. Os resultados mostraram que a redução da taxa de armadura longitudinal resultou num comportamento mais dúctil das lajes e numa capacidade maior de deslocamentos horizontais. A utilização da taxa mais elevada de armadura longitudinal laje melhorou a capacidade máxima de momentos não balanceados, mas também fez com que a estrutura tivesse uma rotura mais frágil. Como esperado, o modelo com “studs” suportou os maiores “drifts” e acabou não rompendo durante o ensaio, devido a ter sido atingido o limite do sistema de ensaio.
Book chapters on the topic "Flexural punching"
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Min, K. H., J. M. Yang, D. Y. Yoo, and Y. S. Yoon. "Flexural and Punching Performances of FRP and Fiber Reinforced Concrete on Impact Loading." In Advances in FRP Composites in Civil Engineering, 410–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17487-2_89.
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Daniel Ronald Joseph, J., J. Prabakar, and P. Alagusundaramoorthy. "Flexural Behavior of Concrete Sandwich Panels Under Punching Load and Four-Point Bending—Experimental and Analytical Study." In Lecture Notes in Civil Engineering, 771–81. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0365-4_66.
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Barros, J., M. Rezazadeh, I. Costa, H. Baghi, M. Hosseini, M. Mastali, and J. Laranjeira. "Flexural and shear/punching strengthening of RC beams/slabs using hybrid NSM-ETS technique with innovative CFRP laminates." In Insights and Innovations in Structural Engineering, Mechanics and Computation, 1500–1505. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2016. http://dx.doi.org/10.1201/9781315641645-246.
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Hawkins, Neil M., and Carlos E. Ospina. "Effect of slab flexural reinforcement and depth on punching strength." In fib Bulletin 81. Punching shear of structural concrete slabs: Honoring Neil M. Hawkins, 117–40. fib. The International Federation for Structural Concrete, 2017. http://dx.doi.org/10.35789/fib.bull.0081.ch07.
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Soares, Luis F. S., and Robert L. Vollum. "Influence of flexural continuity on punching resistance at edge columns." In fib Bulletin 81. Punching shear of structural concrete slabs: Honoring Neil M. Hawkins, 299–318. fib. The International Federation for Structural Concrete, 2017. http://dx.doi.org/10.35789/fib.bull.0081.ch15.
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Gayed, Ramez B., Chandana Peiris, and Amin Ghali. "Flexure-induced punching of concrete flat plates." In fib Bulletin 81. Punching shear of structural concrete slabs: Honoring Neil M. Hawkins, 73–100. fib. The International Federation for Structural Concrete, 2017. http://dx.doi.org/10.35789/fib.bull.0081.ch05.
Full textConference papers on the topic "Flexural punching"
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Ebead, Usama, and Huda Saeed. "Flexural Punching Shear Capacities of Steel Strengthened Slabs." In Modern Methods and Advances in Structural Engineering and Construction. Singapore: Research Publishing Services, 2011. http://dx.doi.org/10.3850/978-981-08-7920-4_s2-a23-cd.
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Joh, C., H. Hwang, and B. Kim. "Punching shear and flexural strengths of ultra high performance concrete slabs." In HPSM 2008. Southampton, UK: WIT Press, 2008. http://dx.doi.org/10.2495/hpsm080111.
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Lampropoulos, Andreas, James N. Duncan, and Ourania T. Tsioulou. "Punching shear resistance of UHPFRC." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.0866.
Full textAbstract:
<p>Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) is a high performance cementitious material with enhanced strength in tension and compression and significantly high energy absorption in the post crack region. Its mix composition is not much dissimilar from that of normal strength concrete. The main difference is that only fine aggregates are used in order to enhance the homogeneity of the mix, while microsilica is used to improve the density of the mix thereby reducing voids and defects. A high percentage of steel fibres is used to increase the tensile strength and at the same time to provide ductility.</p><p>UHPFRC has been recently introduced in applications such as bridge decks, thin slabs and for the strengthening of existing elements. Even if there are various published studies on the compressive, tensile and flexural characteristics of UHPFRC, the punching shear performance of UHPFRC without additional steel bars has not been sufficiently studied. In this paper an extensive experimental work has been conducted on UHPFRC tiles with various thicknesses and various percentages of steel fibres and tests have been conducted under a concentrated load. Using the experimental results, the punching shear characteristics of the various UHPFRC mixes have been evaluated and shear resistance values have been proposed.</p>
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Landler, Josef, and Oliver Fischer. "Punching Shear Capacity of Steel Fiber Reinforced Concrete Slab- Column Connections." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.0467.
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<p>To design flat slabs directly supported on columns, the punching shear resistance of the slab is a main factor. It can be increased in the vicinity of the slab-column connection with punching shear reinforcement, like bent up bars or shear studs, to bear the high reaction forces. However, the usage of punching shear reinforcement requires the knowledge of special design rules and often leads to problems and deficiencies in construction.</p><p>Fiber reinforced concrete seems to be a promising alternative to conventional punching shear reinforcement. To investigate the load bearing behavior of the slab-column connection using fiber reinforced concrete, a total of eight punching shear tests were performed. The specimens were realized with a typical top and bottom flexural reinforcement, but without punching shear reinforcement. Varied parameters were the slab thickness with 250 mm and 300 mm and the fiber content V<sub>f</sub> with 0.5 Vol.-% and 1.0 Vol.-%. To investigate the influence of modern fiber types, normal- and high-strength steel fibers with normal- and double-hooked-ends were used.</p><p>In all eight experimental tests, the intended punching shear failure was achieved. The capable load using fiber reinforced concrete increased by 20 % to 50 % compared to the reference tests without steel fibers, depending on the fiber type and the fiber content V<sub>f</sub>. Additionally, this load increase was accompanied by a significant improvement in ductility. The post-cracking behavior was noticeably influenced by the used steel fiber type. An influence of the slab thickness or steel fiber type on the shear strength contributed by the fiber reinforced concrete could not be determined.</p>
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Xu, Fei, Tak-Ming Chan, and Ju Chen. "Punching Shear Mechanism Based Design of Concrete-Filled CHS T-Joints under In-Plane Bending." In 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.7513.
Full textAbstract:
The in-plane bending behaviour of concrete-filled circular hollow section (CHS) T-joints was examined in this paper. The main failure mode, the punching shear of the chord-wall, was observed from the test of four large-scale joints with the diameter ratio of brace to chord (β) ranging from 0.44 to 0.85. The tube-wall deformation was measured to assess the governing failure mode of the composite joints. Complementary finite element (FE) methodology was verified against the experimental findings and the validated FE models were used to further investigate the mechanical behaviour and the design methodology. The feasibility to apply a fracture criterion in the material-level to a large-scale structural simulation was evaluated. The validated FE modes could successfully capture the tube-wall fracture initiation and propagation. Based on both experimental and numerical investigations, it was shown that the capacity of composite joints was governed by the ultimate strength limit, i.e. punching shear strength, due to the infill concrete that mitigated both inward and outward deformation on the compressive and tensile sides, respectively. The analytical model was established to reveal the composite actions between the tube and the inner concrete, and to elaborate the development of the flexural section-resistance. Finally, the design equation was proposed and could well predict the moment capacity.
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Low, Hin Foo, Sih Ying Kong, and Daniel Kong. "A Review on Prestressed Transfer Plate Analysis and Design." In IABSE Conference, Kuala Lumpur 2018: Engineering the Developing World. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2018. http://dx.doi.org/10.2749/kualalumpur.2018.1037.
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<p>Prestressed transfer plate consists of a thick cast in-situ post-tensioned concrete slab supporting multi-storey shear walls at building transition level. Compared to conventional reinforced concrete transfer beams, it offers savings in concrete volume of 10-15%, cuts steel reinforcement content by 35-50% and significantly reduces formwork usage which eventually helps to achieve lower carbon footprint for a more sustainable transfer floor construction. The design of prestressed transfer plates is complicated owing to its two-way bending behaviour and irregular load path from reactions of numerous shear walls. This paper elaborates the analysis of prestressed transfer plates and discusses their interaction effect with shear walls. It also explains the design of interfacing shear for thick plate construction with multi-layer casting in addition to various design considerations including flexural and punching shear design based on relevant codes of practice.</p>
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Rambach, J. M., and F. Tarallo. "Simple Analytical Models for Beams and Slabs Under Soft Impacts at Medium Speed." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48583.
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A simply supported reinforced concrete slender beam is modeled by 3 rigid consecutive elementary beams, the median beam being connected to the others by 2 viscous and elastoplastic spiral springs. The model can be assimilated as a non linear SDOF system convenient for the motion study of beams within flexural deformation domain, with displacements up to the height of the beam. The characteristics of the visco-elastoplastic springs are tuned so as be consistent with the beam motion before and after impact: the rigidity of the elastic domain of the springs is consistent with natural vibration frequencies which may be reduced after the impact due to subsequent damages. The motion of the beam during and after the impact is analyzed with such model: the values of the main mechanical characteristics (rigidity, plastic limit, viscous damping) may then be obtained. The impact tests performed by VTT (Finland) on one-way concrete slabs consolidate this approach and give consistent experimental values for the elastoplastic laws to be introduced in the model. With this experimental validation, the model may be used as a predictive tool for resistance and for displacements, as far as reinforced concrete beams and slabs are concerned. A thin reinforced concrete slab, simply supported along its 4 edges, is modeled by 4 to 5 rigid trapezoidal elementary slabs connected together by visco-elastoplastic spiral springs along the hinges. A non linear SDOF system is then developed to capture the behavior of such a slab within a flexural deformation domain, with displacements up to the slab thickness. The mechanism involving large shear deformations under the impact (“punching cone”) is taken into account by adding a second degree of freedom. The existing tests on reinforced concrete slabs submitted to medium velocity impacts found in literature may be used to consolidate this approach and to specify the values to be introduced in the model. The model will be used to analyze the forthcoming results (in terms of resistance and displacements) of VTT impact tests on simply supported reinforced concrete slabs. The behavior of civil works structures submitted to impacting missiles can nowadays be analyzed either with sophisticated FE calculation codes, or with analytical models. These analytical models may constitute simple but useful engineer’s tools for sensitivity analyses and for results checking of the necessary more sophisticated computation codes, in terms of resistance and in terms of displacement. They may be simply implemented on any spreadsheet software.
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Yang, Zhijun, Youdun Bai, and Xin Chen. "Nonlinear Response Compensation of Flexure-Hinge Based Guiding Mechanism Using Bi-Linear Control Input." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-68066.
Full textAbstract:
The flexure-hinge (FH) based guiding mechanism, such as fast tool servo (FTS) or micro-lens-array punching machine, is widely used in micro/nano precision engineering, due to their good linearity of stiffness. The major design advantage of FHs for this application was the absence of backlash and friction in the direction of the motion. This provides very smooth, high-precision operating characteristics without inducing evident wear which is commonly associated with high speeds or continuous operation. The dynamic model of FH can be simplified as a spring-mass-damping system, both the stiffness and frequency of a mechanism play significant roles in its dynamic performance. However, the relationship between dynamic response and the input function is nonlinear. In order to achieve precision displacement output under different excitation frequency, nonlinear input compensation should be considered. In this paper, an innovative method is provided to handle this kind of problem, where the stiffness of the guiding mechanism can be adjusted, such that the output amplitude scale can be remained the same at any excitation frequency, therefore, it become a linear system, the input is very easy to control. The tension stiffening is used to change the stiffness and thus the frequency, and the relationship between the change rate of frequency and tension force is also revealed. Finally, the control strategy is given, and an example is given to show the efficient of the presented method.