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1
Peng, Liying. "Shear strength of beams by shear-friction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ38638.pdf.
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2
Zhang, Ling. "The behaviour of granular material in pure shear, direct shear and simple shear." Thesis, Aston University, 2003. http://publications.aston.ac.uk/14162/.
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In biaxial compression tests, the stress calculations based on boundary information underestimate the principal stresses leading to a significant overestimation of the shear strength. In direct shear tests, the shear strain becomes highly concentrated in the mid-plane of the sample during the test. Although the stress distribution within the specimen is heterogeneous, the evolution of the stress ratio inside the shear band is similar to that inferred from the boundary force calculations. It is also demonstrated that the dilatancy in the shear band significantly exceeds that implied from the boundary displacements. In simple shear tests, the stresses acting on the wall boundaries do not reflect the internal state of stress but merely provide information about the average mobilised wall friction. It is demonstrated that the results are sensitive to the initial stress state defined by K0 = sh/sv. For all cases, non-coaxiality of the principal stress and strain-rate directions is examined and the corresponding flow rule is identified. Periodic cell simulations have been used to examine biaxial compression for a wide range of initial packing densities. Both constant volume and constant mean stress tests have been simulated. The characteristic behaviour at both the macroscopic and microscopic scales is determined by whether or not the system percolates (enduring connectivity is established in all directions). The transition from non-percolating to percolating systems is characterised by transitional behaviour of internal variables and corresponds to an elastic percolation threshold, which correlates well with the establishment of a mechanical coordination number of ca. 3.0. Strong correlations are found between macroscopic and internal variables at the critical state.
3
Erzin, Yusuf. "Strength Of Different Anatolian Sands In Wedge Shear, Triaxial Shear, And Shear Box Tests." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604689/index.pdf.
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Past studies on sands have shown that the shear strength measured in plane strain tests was higher than that measured in triaxial tests. It was observed that this difference changed with the friction angle φ
cv at constant volume related to the mineralogical composition. In order to investigate the difference in strength measured in the wedge shear test, which approaches the plane strain condition, in the triaxial test, and in the shear box test, Anatolian sands were obtained from different locations in Turkey. Mineralogical analyses, identification tests, wedge shear tests (cylindrical wedge shear tests (cylwests) and prismatic wedge shear tests (priswests)), triaxial tests, and shear box tests were performed on these samples. In all shear tests, the shear strength measured was found to increase with the inclination &
#948
of the shear plane to the bedding planes. Thus, cylwests (&
#948
= 60o) iii yielded higher values of internal friction &
#966
by about 3.6o than priswests (&
#948
= 30o) under normal stresses between 17 kPa and 59 kPa. Values of &
#966
measured in cylwests were about 1.08 times those measured in triaxial tests (&
#948
&
#8776
65o), a figure close to the corresponding ratio of 1.13 found by past researchers between actual plane strain and triaxial test results. There was some indication that the difference between cylwest and triaxial test results increased with the &
#966
cv value of the samples. With the smaller &
#948
values (30o and 40o), priswests yielded nearly the same &
#966
values as those obtained in triaxial tests under normal stresses between 20 kPa and 356 kPa. Shear box tests (&
#948
=0o) yielded lower values of &
#966
than cylwests (by about 7.9o), priswests (by about 4.4o), and triaxial tests (by about 4.2o) under normal stresses between 17 kPa and 48 kPa. It was shown that the shear strength measured in shear box tests showed an increase when &
#948
was increased from 30o to 60o
this increase (about 4.2o) was of the order of the difference (about 3.6o) between priswest (&
#948
= 30o) and cylwest (&
#948
= 60o) results mentioned earlier. Shear box specimens with &
#948
= 60o, prepared from the same batch of any sample as the corresponding cylwests, yielded &
#966
values very close to those obtained in cylwests.
4
Ifju, Peter G. "The shear gage and compact shear specimen for shear property measurements of composite materials." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39976.
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Techniques for shear property measurements for composite and isotropic materials were investigated. A new strain gage called the shear gage was conceived, designed, and tested for routine shear characterization on notched shear specimens. The shear gage integrates the shear strain in the entire test section of the losipescu and compact shear specimens. The result was consistent and accurate determination of the shear stress/strain response of materials. Prior knowledge of material properties or shear strain distributions were not required. Deficiencies in the losipescu shear test were automatically compensated when shear gages were placed on the two faces of the specimen.
The shear gages were tested on composite and isotropic materials and produced higher accuracy and consistency than could be produced using current technology. Moir© interferometry was used to evaluate the ability of the shear gage to measure the average shear strains. The results from the evaluation program confirmed the attributes of the concept.Ph. D.
5
Basak, Sankarananda. "Dynamics of stratified shear layer with horizontal shear /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3185923.
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6
Tozser, Oliver. "Shear analysis using shear friction, size effect and prestressing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ38645.pdf.
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7
Pinilla, Camilo Ernesto. "Numerical simulation of shear instability in shallow shear flows." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115697.
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The instabilities of shallow shear flows are analyzed to study exchanges processes across shear flows in inland and coastal waters, coastal and ocean currents, and winds across the thermal-and-moisture fronts. These shear flows observed in nature are driven by gravity and governed by the shallow water equations (SWE). A highly accurate, and robust, computational scheme has been developed to solve these SWE. Time integration of the SWE was carried out using the fourth-order Runge-Kutta scheme. A third-order upwind bias finite difference approximation known as QUICK (Quadratic Upstream Interpolation of Convective Kinematics) was employed for the spatial discretization. The numerical oscillations were controlled using flux limiters for Total Variation Diminishing (TVD). Direct numerical simulations (DNS) were conducted for the base flow with the TANH velocity profile, and the base flow in the form of a jet with the SECH velocity profile. The depth across the base flows was selected for the' balance of the driving forces. In the rotating flow simulation, the Coriolis force in the lateral direction was perfectly in balance with the pressure gradient across the shear flow during the simulation. The development of instabilities in the shear flows was considered for a range of convective Froude number, friction number, and Rossby number. The DNS of the SWE has produced linear results that are consistent with classical stability analyses based on the normal mode approach, and new results that had not been determined by the classical method. The formation of eddies, and the generation of shocklets subsequent to the linear instabilities were computed as part of the DNS. Without modelling the small scales, the simulation was able to produce the correct turbulent spreading rate in agreement with the experimental observations. The simulations have identified radiation damping, in addition to friction damping, as a primary factor of influence on the instability of the shear flows admissible to waves. A convective Froude number correlated the energy lost due to radiation damping. The friction number determined the energy lost due to friction. A significant fraction of available energy produced by the shear flow is lost due the radiation of waves at high convective Froude number. This radiation of gravity waves in shallow gravity-stratified shear flow, and its dependence on the convective Froude number, is shown to be analogous to the Mach-number effect in compressible flow. Furthermore, and most significantly, is the discovery from the simulation the crucial role of the radiation damping in the development of shear flows in the rotating earth. Rings and eddies were produced by the rotating-flow simulations in a range of Rossby numbers, as they were observed in the Gulf Stream of the Atlantic, Jet Stream in the atmosphere, and various fronts across currents in coastal waters.
8
Ishtewi, Ahmad M. "Shear Capacity of Fiber-Reinforced Concrete Under Pure Shear." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1354725447.
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9
Dillon, Patrick. "Shear Strength Prediction Methods for Grouted Masonry Shear Walls." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/4395.
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The research in this dissertation is divided between three different approaches for predicting the shear strength of reinforcement masonry shear walls. Each approach provides increasing accuracy and precision in predicting the shear strength of masonry walls. The three approaches were developed or validated using data from 353 wall tests that have been conducted over the past half century. The data were collected, scrutinized, and synthesized using principles of meta-analysis. Predictions made with current Masonry Standards Joint Committee (MSJC) shear strength equation are unconservative and show a higher degree of variation for partially-grouted walls. The first approach modifies the existing MSJC equation to account for the differences in nominal strength and uncertainty between fully- and partially-grouted walls. The second approach develops a new shear strength equation developed to perform equally well for both fully- and partially-grouted walls to replace and improve upon the current MSJC equation. The third approach develops a methodology for creating strut-and-tie models to analyze or design masonry shear walls. It was discovered that strut-and-tie modeling theory provides the best description of masonry shear wall strength and performance. The masonry strength itself provides the greatest contribution to the overall shear capacity of the wall and can be represented as diagonal compression struts traveling from the top of the wall to the compression toe. The shear strength of masonry wall is inversely related to the shear span ratio of the wall. Axial load contributes to shear strength, but to a lesser degree than what has been previously believed. The prevailing theory about the contribution of horizontal shear reinforcement was shown to not be correct and the contribution is much smaller than was originally assumed by researchers. Horizontal shear reinforcement principally acts by resisting diagonal tensile forces in the masonry and by helping to redistribute stresses in a cracked masonry panel. Vertical reinforcement was shown to have an effect on shear strength by precluding overturning of the masonry panel and by providing vertical anchorages to the diagonal struts.
10
Nolph, Shawn Mark. "In-plane shear performance of partially grouted masonry shear walls." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Summer2010/s_nolph_050710.pdf.
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Thesis (M.S. in civil engineering)--Washington State University, May 2010.Title from PDF title page (viewed on July 21, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 96-97).
11
GUPTA, ARUN KUMAR. "DETERMINATION OF SEISMIC PARAMETER OF RCC TALL BUILDING USING SHEAR CORE , SHEAR WALL AND SHEAR CORE WITH OUTRIGGER." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18840.
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This report covers the detailed explanation about the determination of seismic parameter of
RCC tall building using shear core, shear wall and shear core with outrigger. Building are
subjected to various loads such as dead load, live load ,wind load and seismic load. Seismic
load has extreme adverse effect on building so it is necessary to perform seismic analysis This
paper describe about the response of building when it is subjected to seismic load , this
response can be shown by story drift and base shear. Seismic analysis has been performed on
(G+30) building which is located in zone 4 using ETABS software. Analysis has been
performed according to IS 1893 PART 1 (2016). This paper gives total rule to manual as wells
programming examination of seismic coefficient technique.
12
Crane, Charles Kennan. "Shear and shear friction of ultra-high performance concrete bridge girders." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34745.
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Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired.
In order to efficiently utilize UHPC in bridge construction, it is necessary to create new design recommendations for its use. The interface between precast UHPC girder and cast-in-place concrete decks must be characterized in order to safely use composite design methods with this new material.
Due to the lack of reinforcing bars, all shear forces in UHPC girders have to be carried by the concrete and steel fibers. Current U.S. codes do not consider fiber reinforcement in calculating shear capacity. Fiber contribution must be accurately accounted for in shear equations in order to use UHPC.
Casting of UHPC may cause fibers to orient in the direction of casting. If fibers are preferentially oriented, physical properties of the concrete may also become anisotropic, which must be considered in design.
The current research provides new understanding of shear and shear friction phenomena in UHPC including:
*Current AASHTO codes provide a non-conservative estimate of interface shear performance of smooth UHPC interfaces with and without interface steel.
*Fluted interfaces can be created by impressing formliners into the surface of plastic UHPC. AASHTO and ACI codes for roughened interfaces are conservative for design of fluted UHPC interfaces.
*A new equation for the calculation of shear capacity of UHPC girders is presented which takes into account the contribution of steel fiber reinforcement.
*Fibers are shown to preferentially align in the direction of casting, which significantly affects compressive behavior of the UHPC.
13
Wasiewicz, Zbigniew Feliks. "Sliding shear in low rise shear walls under lateral load reversals." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5129.
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14
Carter, Katherine Anne. "Shear banding in polymeric fluids under large amplitude oscillatory shear flow." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11746/.
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In this thesis, I theoretically explore shear banding of entangled linear polymer solutions and melts in large amplitude oscillatory shear strain (LAOStrain) and stress (LAOStress) protocols. This work moves beyond that of Moorcroft and Fielding [2013, 2014] who showed time-dependent shear banding in shear startup and step stress protocols. These protocols are only transiently time-dependent. LAOStrain and LAOStress have a sustained time-dependence. I consider the criteria derived in [Moorcroft and Fielding 2013] to predict the onset of shear banding in the transient material response for shear startup and step stress, relative to the triggers of shear banding in LAOStrain and LAOStress. I find that stability to the formation of shear banded flow in the LAOS protocols can be understood - to a good approximation - by the known triggers of shear banding in these simpler transiently time-dependent protocols. I employ the Rolie-Poly (RP) model [Graham et al. 2003] to investigate the existence of shear banding in LAOStrain and LAOStress over a wide range of imposed amplitudes and frequencies. I find shear banding to occur in the alternance state (where time-translational invariance is achieved), even in materials that are known to remain homogeneous at the steady state. For each protocol I consider the relative influence of the constraint-release stress relaxation RP parameter and entanglement number (Z) on the intensity of shear banding across the phase space. I find significant shear banding to occur in both LAOStrain and LAOStress for experimentally-realistic values of Z, both in materials that shear band to steady state, and those that don't. The main results of these investigations are submitted for publication in the Journal of Rheology [Carter et al. 2016]. Finally, I consider the shortcomings of using a single-mode RP model when characterising the full chain dynamics of entangled linear polymers in flow. I employ a multimode approach and fit a power-law spectrum to experimental linear rheology data and investigate time-dependent shear banding in the presence of higher-order relaxation dynamics. For this, I use the simpler shear startup protocol and investigate the limits under which significant shear banding exists for well-entangled polymers and discuss the possible importance of considering edge fracture as a mechanism for shear banding.
15
Voronkov, Igor. "Shear Alfvén waves and shear flow instabilities in the Earth's magnetosphere." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0003/NQ34851.pdf.
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16
Li, Yao. "Shear behaviour of sand in bi-directional direct simple shear tests." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37279/.
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In geotechnical engineering, soil is subject to shear stress, as well as normal stress. In many cases, soil is sheared along multiple directions, such as an embankment under earthquake loading and foundation soil of a structure under a complex loading. In recent years, significant research has been devoted to understanding the static and cyclic shear behaviour of sand under complex stress conditions. To investigate the shear behaviours of soils, a few testing devices have been specifically developed. The most commonly used apparatuses are direct shear, direct simple shear, and hollow cylinder apparatuses. While each has its own merits, they share one common limitation. That is the soil specimens are sheared along only one direction in these devices, making it impossible to study the soil responses under multiple shear stresses encountered in many geotechnical engineering problems. It is widely acknowledged that testing stress path has a significant effect on shear stress, so specimens must be examined under a stress path similar to in-situ. In many cases, a simple shear apparatus closely duplicates the stress conditions in soil elements, and a bi-directional direct simple shear apparatus can create complex stress conditions. To investigate the shear behaviour of soils subject to complex loading conditions, several studies of multidirectional simple shear testing were performed on the first commercially available Variable Direction Dynamic Cyclic Simple Shear (VDDCSS) system. In the VDDCSS, the secondary shear actuator acting at 90 degrees to the primary shear actuator enables it to add shear stress in any horizontal direction. Various previously unexplored complex stress paths were tested in this study using the VDDCSS. Sand samples of Leighton Buzzard sand (Fraction B) were first subjected to consolidation shear stresses under drained conditions along different directions (from 0° to 180° to the X direction of the apparatus), followed by monotonic or cyclic secondary shear stresses along 0° until failure occurs. The magnitude and direction of the consolidation shear stress on the static and cyclic secondary shear behaviours of sand were systematically studied. In undrained static tests, soil strength was the lowest when the angles between the two shears stresses were near 90°, and the strength was the highest at 0°. In addition, a smaller angle produced a more brittle response, and a greater angle led to a more ductile response. The effect of stress path (the direction of consolidation shear stresses) was found to be more significant in tests with a greater magnitude of consolidation shear stresses, and the relationship between the angles (between the first shear stresses and secondary shear stresses) and shear behaviours was much more complex when the magnitude of consolidation shear stresses was increased. In drained static tests, the evidence of non-coaxiality was obtained. The non-coaxiality was the greatest at the initial stage of shearing, and it decreased to zero at higher shear strains. The degree of non-coaxiality was affected by the relative density of the specimen, vertical stress, level and direction of consolidation shear stress. In addition, the non-coaxiality was significantly affected by the consolidation shear stress, and the effect increased at a greater magnitude of consolidation shear stresses. The non-coaxiality increased as the angle was increased. In stress-controlled undrained dynamic tests, there was no significant difference in pore water generation rate among samples with consolidation shear stresses in different directions. However, samples with different directions of consolidation shear stresses failed at different numbers of cycles and in different directions. Liquefaction resistance was decreased by the increased magnitude of consolidation shear stress. In most of the tests with consolidation shear stress, the levels of liquefaction resistances were lower than that without consolidation shear stress. In strain-controlled undrained dynamic tests, liquefaction resistance (shear strength) was decreased from 0° to 90°, and increased from 90° to 180°. Liquefaction resistance in tests with consolidation shear stresses were lower than those without consolidation shear stress.
17
Sadrizadeh, Sasan. "Instabilities in Pulsating Pipe Flow of Shear-Thinning and Shear-Thickening Fluids." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-82037.
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In this study, we have considered the modal and non-modal stability of fluids with shear-dependent viscosity flowing in a rigid straight pipe. A second order finite-difference code is used for the simulation of pipe flow in the cylindrical coordinate system. The Carreau-Yasuda model where the rheological parameters vary in the range of 0.3 < n < 1.5 and 0.1 < λ < 100 is represents the viscosity of shear- thinning and shear thickening fluids. Variation of the periodic pulsatile forcing is obtained via the ratio Kω/Kο and set between 0.2 and 20. Zero and non-zero streamwise wavenumber have been considered separately in this study. For the axially invariant mode, energy growth maxima occur for unity azimuthal wave number, whereas for the axially non-invariant mode, maximum energy growth can be observed for azimuthal wave number of two for both Newtonian and non-Newtonian fluids. Modal and non-modal analysis for both Newtonian and non-Newtonian fluids show that the flow is asymptotically stable for any configuration and the pulsatile flow is slightly more stable than steady flow. Increasing the maximum velocity for shear-thinning fluids caused by reducing power-low index n is more evident than shear-thickening fluids. Moreover, rheological parameters of Carreau-Yasuda model have ignored the effect on the peak velocity of the oscillatory components. Increasing Reynolds number will enhance the maximum energy growth while a revers behavior is observed by increasing Womersley number.
18
Mondo, Eleonora. "Shear Capacity of Steel Fibre Reinforced Concrete Beams without Conventional Shear Reinforcement." Thesis, KTH, Bro- och stålbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41016.
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While the increase in shear strength of Steel Fibre Reinforced Concrete (SFRC) is well recognized, it has yet to be found common application of this material in building structures and there is no existing national standard that treats SFRC in a systematic manner. The aim of the diploma work is to investigate the shear strength of fibre reinforced concrete beams and the available test data and analyse the latter against the mostpromising equations available in the literature. The equations investigated are:Narayanan and Darwish’s formula, the German, the RILEM and the Italian guidelines. Thirty articles, selected among over one hundred articles taken from literature, have been used to create the database that contains almost 600 beams tested in shear. This large number of beams has been decreased to 371 excluding all those beams and test that do not fall within the limitation stated for this thesis. Narayanan and Darwish’s formula can be utilized every time that the fibre percentage, the type of fibres, the beam dimensions, the flexural reinforcement and the concrete strength class have been defined. On the opposite, the parameters introduced in the German, the RILEM and the Italian guidelines always require a further characterization of the concrete (with bending test) in order to describe the post‐cracking behaviour. The parameters involved in the guidelines are the residual flexural tensile strengths according to the different test set‐ups. A method for predicting the residual flexural tensile strength from the knowledge of the fibre properties, the cylindrical compressive strength of the concrete and the amount of fibres percentage is suggested. The predictions of the shear strength, obtained using the proposed method for the residual flexural tensile strength, showed to be satisfactory when compared with the experimental results. A comparison among the aforementioned equations corroborate the validity of the empirical formulations proposed by Narayanan and Darwish nevertheless only the other equations provide a realistic assessments of the strength, toughness and ductility of structural elements subjected to shear loading. Over the three investigated equations, which work with the post‐cracking characterization of the material, the Italian guideline proposal is the one that, due to its wide domain of validity and the results obtained for the gathered database of beams, has been selected as the most reliable equation.
19
Esfandiari, Afshin. "Shear strength of structural concrete members using a uniform shear element approach." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/7130.
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The simplest shear problem involves a two-dimensional rectangular element with uniformly distributed reinforcement parallel to the element sides, and subjected to uniform normal stresses and shear stress. Such a uniform shear element will have uniform average stresses in reinforcement and concrete. The simplest model for elements subjected to shear force and bending moment that leads to code provisions uses one uniform shear element. Shear force is assumed to be resisted by a central portion of the cross-section acting as a uniform shear element, while bending moment is assumed to be resisted by the flexural tension reinforcement and concrete compression zone at the cross-section ends. In this thesis, the shear strength of bridge girders and squat shear walls are evaluated using a uniform shear element approach.
Current code shear design provisions for beams are necessarily simplified procedures that are generally conservative. While the extra costs are small for new design, it may lead to unnecessary load restrictions on bridges or unnecessary retrofitting when used for shear strength evaluation. A new shear strength evaluation procedure for structural concrete girders is proposed. The procedure accounts for the influence of more parameters and provides more insight into the failure mode than code design methods. To verify the procedure, predicted trends are compared with Modified Compression Field theory (MCFT) for uniform shear elements, and Response-2000 for beam elements subjected to combined shear and bending moment. Shear strength predictions are also compared with results from strength tests on reinforced and prestressed concrete beams, together with predictions from current code shear design provisions.
The current Canadian building code CSA A23.3 2004 contains new provisions for the seismic design of squat walls that were developed using a uniform shear element approach. These new code provisions are rigorously evaluated for the first time in this study. A new method to account for the flexure-shear interaction at the base of squat shear walls is proposed as well as refinements to the 2004 CSA A23.3 shear strength provisions for squat shear walls. These are verified by comparing the predicted trends with the predictions of MCFT-based nonlinear finite element program VecTor 2.
20
Mercer, Stephen Sterling. "Nonlinear shear response of cantilever reinforced concrete shear walls with floor slabs." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42164.
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The nonlinear shear behaviour of cantilever reinforced concrete shear walls is complex and not fully understood. Design assumptions often oversimplify the wall response and can yield results which do not reflect the true response of the shear wall. One such assumption is analyzing the wall ignoring the effects from multiple floor slabs connected to the wall over its height. Floor slabs can provide a significant increase in wall shear capacity. This thesis examines the nonlinear shear response of walls, including the effect of floor slabs as a wall-slab system, through state-of-the-art nonlinear finite element analysis. Finite element slab models were developed to emulate the 3D slab effect within a 2D analysis environment: a high-end pseudo 3D model for in-depth slab analysis and a simple 2D slab layer model for typical wall analysis. The slab effects are explored through a parametric study varying the wall size, concrete strength, axial load, horizontal steel ratio and the slab dimensions parallel and perpendicular to the wall. The slabs were found to act like large external stirrups which provide additional tension capacity for the slab and limit shear cracking and failure. The slabs can significantly increase the shear capacity of lightly-reinforced walls. Using the developed slab models, the bounds of the slab effect were investigated by a parametric study with lightly to heavily-reinforced walls, with and without axial load, as well as varying the slab spacing. Within this study, the nonlinear response of isolated walls is compared to nonlinear uniformly-loaded membrane models. It is determined that although code-based shear capacity equations are fairly accurate, the membrane models can underestimate the shear stiffness and over predict the ductility. This study also reveals that tightly spaced slabs can increase up to 3 times the isolated wall capacity for walls with minimum horizontal steel, whereas there is little effect for walls with horizontal steel above 1%. Finally, methods were developed to predict the nonlinear shear stress-strain response of isolated walls and the peak shear capacity of wall-slab systems.
21
Qureshi, Farrukh Shahab. "Kinematics of shear deformation of materials under high pressure and shear stress." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18841.
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Li, Chao. "Nominal Shear Strength of Cold-formed Steel Shear Walls Using Osb Sheathing." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115111/.
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In the cold-formed steel construction, the oriented strand board is a common material for shear wall sheathing. an OSB is made by using wood chips as raw materials that undergo high temperature pressing to create a multi-larger structure material. Due to the OSB having a high strength in shear, it is an important material used in the construction field. the thesis is trying to verify published nominal shear strength in AISI-213-07 in the first part. This objective has two parts: the first part is to verify nominal shear strength (Rn) for wind and other in-plane loads for shear wall. the second part is to verify nominal shear strength (Rn) for seismic and other in-plane loads for shear wall. Secondly, the thesis verifies the design deflection equation for nominal shear strength of CFS shear walls with OSB sheathing. the test specimens were divided into eight groups which trying to verify the design deflection equation that was published in AISI-213-07 standard.
23
Janaraj, Thangarajah. "Studies on the in-plane shear response of confined masonry shear walls." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71899/1/Thangarajah_Janaraj_Thesis.pdf.
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The prime aim of this research project is to evaluate the performance of confined masonry walls under in-plane shear with a view to contributing to the national masonry design standard through a set of design clauses. This aim stems from the criticisms of the current provisions of the in-plane shear capacity equations in the Australian Masonry Standard AS3700 (2011) being highly non-conservative. This PhD thesis is an attempt to address this gap in the knowledge through systematic investigation of the key parameters that affects the in-plane shear strength of the masonry walls through laboratory experiments and extensive finite element analyses.
24
Lee, V. "Layered stratified shear flows." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364874.
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Miller, Ronald Lindsay. "Topics in shear instability." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/54962.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Includes bibliographical references.
by Ronald Lindsay Miller.
Viscous destabilization of stratified shear flow -- Organization of rainfall by an unstable jet aloft.
Ph.D.
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Marcos, Ph D. Massachusetts Institute of Technology. "Bacteria in shear flow." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65278.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 68-74).
Bacteria are ubiquitous and play a critical role in many contexts. Their environment is nearly always dynamic due to the prevalence of fluid flow: creeping flow in soil, highly sheared flow in bodily conduits, and turbulent flow in rivers, streams, lakes, and oceans, as well as anthropogenic habitats such as bioreactors, heat exchangers and water supply systems. The presence of flow not only affects how bacteria are transported and dispersed at the macroscale, but also their ability to interact with their local habitat through motility and chemotaxis (the ability to sense and follow chemical gradients), in particular their foraging. Despite the ubiquitous interaction between motility, foraging and flow, almost all studies of bacterial motility have been confined to still fluids. At the small scales of a bacterium, any natural flow field (e.g. turbulence) is experienced as a linear velocity profile, or 'simple shear'. Therefore, understanding the interaction between a simple shear flow and motility is a critical step towards gaining insight on how the ambient flow favors or hinders microorganisms in their quest for food. In this thesis, I address this important gap by studying the effect of shear on bacteria, using a combination of microfluidic experiments and mathematical modeling. In chapter 2, a method is presented to create microscale vortices using a microfluidic setup specifically designed to investigate the response of swimming microorganisms. Stable, small-scale vortices were generated in the side-cavity of a microchannel by the shear stress in the main flow. The generation of a vortex was found to depend on the cavity's geometry, in particular its depth, aspect ratio, and opening width. Using video-microscopy, the position and orientation of individual microorganisms swimming in vortices of various intensities were tracked. We applied this setup to the marine bacterium Pseudoalteromonas haloplanktis. Under weak flows (shear rates < 0.1 s 1), P. haloplanktis exhibited a random swimming pattern. As the shear rate increased, P. haloplanktis became more aligned with the flow. In order to study the detailed hydrodynamic interaction between shear and bacteria, we developed a mathematical model employing resistive force theory. In general, the modeling of a bacterium requires consideration of two factors: the rotating flagellar bundle and the cell body to which the flagella are attached. To make the problem analytically tractable, we study the hydrodynamics around the head and the flagellum separately. In chapter 3, we present a combined theoretical and experimental investigation of the fluid mechanics of a helix exposed to a shear flow. In addition to classic Jeffery orbits, resistive force theory predicts a drift of the helix across streamlines, perpendicular to the shear plane. The direction of the drift is determined by the direction of the shear and the chirality of the helix. We verify this prediction experimentally using microfluidics, by exposing Leptospira biflexa flaB mutant, a non-motile strain of helix-shaped bacteria, to a plane parabolic flow. As the shear in the top and bottom halves of the microchannel has opposite sign, we predict and observe the bacteria in these two regions to drift in opposite directions. The magnitude of the drift is in good quantitative agreement with theory. We show that this setup can be used to separate microscale chiral objects. In chapter 4, a theoretical and experimental investigation of a swimming bacterium in a shear flow is presented. The presence of the cell body results in a novel phenomenon: chiral forces induce not only a lateral drift, but also a reorienting torque on swimming bacteria. For typical flagellated bacteria, the magnitude of this drift velocity is much smaller (-0.7 gm s-1) than typical swimming speeds of bacteria (-50 [mu]m s-1). However, with the addition of a head, the chirality-dependent forces that lead to a lateral drift also lead to a reorienting torque. The model based on resistive force theory predicts that the drift velocity of swimming bacteria is in the same order of magnitude as the swimming speed. Experimental observations of the motile bacteria Bacillus subtilis exposed to shear flows show good agreement with the theoretical prediction. This process is a purely passive hydrodynamic effect, as demonstrated by further experiments showing that bacteria do not behaviorally (i.e. actively) respond to shear. This newly discovered hydrodynamic reorientation can significantly affect any process that involves changes of swimming direction, so that bacterial 'steering' in a flow cannot be understood unless the effects of chiral reorientation are quantified. Because swimming and reorientation are central to the chemotaxis used by many bacteria for foraging, we expect this coupling of motility and flow to play an important role in the ecology of many bacterial species.
by Marcos.
Ph.D.
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Conley, Andrew Keller Herbert Bishop. "New plane shear flows /." Diss., Pasadena, Calif. : California Institute of Technology, 1994. http://resolver.caltech.edu/CaltechETD:etd-10182005-102648.
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Chin, Mei Yun. "Shear resistance of oil palm shell concrete beams with and without shear reinforcement." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14391/.
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In recent years, the use of Oil Palm kernel Shell (OPS) aggregate as coarse aggregate in concrete has received increasing attention due to its environmental and economic benefits. To date, considerable amount of research have been carried out to aid the understanding of its concrete mixture designs and its material properties, but, only limited amount of works have been carried out to aid the current understanding with respect to its shear resistance. The main objective of this research was to investigate the shear resistance of Oil Palm kernel Shell Concrete (OPSC), and to compare with the conventional Normal Weight Concrete (NWC) through experimental and analytical study. The experimental work carried out in this research involved destructive testing of forty-five numbers of beam specimens, of which twenty-nine beams (24 casted with OPSC and 5 casted with NWC) were casted without shear reinforcement while the remaining sixteen beams (11 casted with OPSC and 5 casted with NWC) were casted with shear reinforcement. The main variables for beams casted without shear reinforcement were the concrete strength (fcu), overall section depth (h), longitudinal reinforcement (ρ), and span to depth ratio (a/d). Whilst the main variables for beams casted with shear reinforcement were concrete strength (fcu), shear reinforcement (ρs) and inclination of shear cracks (Θ). For beams casted without shear reinforcement, three distinct failure mechanisms were observed from the tests: the shear compression mechanism (associated with a/d < 2.5); the diagonal tension mechanism (associated with a/d = 2.5 and ρ = 0.88%); and the shear mechanism (associated with a/d ≥ 2.5 and ρ > 0.88%). Whilst for OPSC beams casted with shear reinforcement, shear compression failure was observed for the tests. A comparative study was carried out to investigate if there are any differences on the ultimate shear resistance and the shear failure mechanism between the OPSC beams and NWC beams. In general, all specimens (OPSC and NWC) were found to fail in similar failure mechanism; however, some variations have been noted in the ultimate resistance with respect to span to depth ratio, concrete strength, and longitudinal steel ratio (for beams without shear reinforcement) and concrete strength (for beams with shear reinforcement). An analytical study was carried out using the upper bound approach to evaluate the observed shear failure mechanisms, and hence, to predict the failure loads. A theoretical model was developed for each of the casting condition. In addition, design models based on Eurocode 2 (EC2) and BS8110 have been developed. In all cases, the proposed models achieved good agreement with the test results.
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Azad, Bawan. "Shear strengtth of prestressed concrete beams without shear reinforcement : A comparison between equations." Thesis, KTH, Betongbyggnad, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302428.
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A new version of EN 1992-1-1, Eurocode 2 for Design of Concrete Structures, is under development and one of the most discussed topics is shear capacity for prestressed concrete beams without shear reinforcement, partly because shear failure occurs suddenly and can have catastrophic consequences. For the new version of Eurocode, there are a total of three proposed equations to replace the two equations that currently exist in EN 1992-1-1 for shear capacity of prestressed concrete beams without shear reinforcement. One of the proposed equations is intended to replace the equation intended for beam regions where bending cracks do not occur. The other two equations are proposed for beam regions where bending cracks occur. One of the proposed equations for beam regions with bending cracks, is based on critical shear crack theory and takes the normal force in consideration, while the other equation for beam regions with bending cracks is like the one found today in Eurocode, an empirical equation, where the contribution of normal force is empirical. In this thesis, all equations have been set against each other and compared with the help of nonlinear finite element analyzes and experiments which Dr. De Wilder has done in his doctoral thesis. The impact of the prestressing force on the shear force capacity of beams has also been investigated. The results show that the equations for beam regions that do not have bending cracks give identical shear force capacities. While the equation which is based on critical shear crack theory takes the shear span into consideration and captures the effect of the shear span correctly, which the other proposed equation and the one found in Eurocode today do not and are on the unsafe side for increasing shear spans. Furthermore, it turned out that the equation which is based on critical shear crack theory was rather conservative, while the equation that exists today in Eurocode gives approximately the same shear capacity as the other proposed equation. Furthermore, it was found that if the amount of longitudinal reinforcement is reduced, at the same time as the prestressing force is unchanged, an insignificant reduction in the shear capacity on prestressed concrete beams is obtained.En ny version av EN 1992-1-1, Eurokod 2 Dimensionering av betongkonstruktioner, är under utveckling och ett av de mest diskuterade ämnena är tvärkraftskapacitet för förspända betongbalkar utan skjuvarmering, bland annat eftersom huvudspänningsskjuvbrott uppstår plötsligt och kan få katastrofala konsekvenser. Till den nya versionen av Eurokoden finns det totalt tre föreslagna ekvationer för att ersätta de två ekvationer som för närvarande finns i EN 1992-1-1 för tvärkraftskapacitet för förspända betongbalkar utan skjuvarmering. En av de föreslagna ekvationerna är tänkt att ersätta ekvationen avsedd för balkregioner där böjsprickor ej uppstår. De andra två ekvationerna är föreslagna för balkregioner där böjsprickor uppstår. En av de föreslagna ekvationerna för balkregioner med böjsprickor är baserad på kritisk skjuvsprickteorin och tar hänsyn till normalkraftens bidrag till tvärkraftskapaciteten, medan den andra föreslagna ekvationen för balkregioner med böjsprickor är likt den som idag finns i Eurokoden, en empirisk ekvation, där normala kraftens bidrag är baserad på ett empiriskt tillägg. I detta examensarbete har alla ekvationer ställts mot varandra och jämförts med hjälp utav icke-linjär finit-elementanalyser samt experiment som Dr. De Wilder gjort i sin doktorsavhandling. Vidare har också förspänningskraftens påverkan på balkars tvärkraftskapacitet undersökts. Resultaten visar att ekvationerna för balkregioner som ej har böjsprickor ger identiska tvärkraftskapaciteter. Medan ekvationen som är baserad på kritisk skjuvsprickteorin tar hänsyn till skjuvspännvidd och fångar effekten av skjuvspännvidden korrekt, vilket den andra föreslagna ekvationen och den som finns i Eurokoden idag inte gör och är på den osäkra sidan för ökad skjuvspännvidd. Dessutom visade det sig att ekvationen som är baserad på kritisk skjuvsprickteori är tämligen konservativ, medan ekvationen som finns idag i Eurokoden ger ungefär samma tvärkraftskapacitet som den andra föreslagna ekvationen. Vidare visade det sig att ifall man minskar mängden längsgående armering, samtidigt som förspänningskraften är oförändrad, så fås en obetydlig minskning utav tvärkraftskapaciteten på förspända betongbalkar.
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Lease, Adam R. "Insulation Impact on Shear Strength of Screw Connections and Shear Strength of Diaphragms." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/44783.
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Several thousand tests throughout the world have been conducted on the shear strength of screw connections in cold-formed steel, however, little to no research has been conducted on how various thicknesses of insulation placed between two sheets of steel, such as a steel panel and structural supporting member, affects a screw's shear strength. Elemental tests were conducted as part of this study at Virginia Tech where rolled fiberglass insulation was placed between two pieces of steel connected by self-drilling screws and tested to failure. The results were compared to the North American Specification for the Design of Cold-Formed Steel Structural Members to determine if the presence of insulation affected the shear and tensile strengths of screw connections involving insulation. A series of diaphragm tests were also preformed to confirm the elemental tests.
While the presence of insulation between two steel sheets connected by screws reduces the shear strength of the connection, the current equations for predicting this strength in the North American Specification are adequate. When the data acquired from this study and the screw shear data obtained in past research were combined, it was clear that the data collected during this study fell within the scatter of the data used to develop Section E4.3 of the North American Specification neglecting the need for modification.Master of Science
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Yung, See Yuen. "Determination of shear wave velocity and anisotropic shear modulus of an unsaturated soil /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20YUNG.
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Tekin, Abdulkadir. "Blind Shear Ram Blowout Preventers: Estimation of Shear Force and Optimization of Ram Geometry." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291178357.
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Beal, Philip Edward. "Estimation of the shear strengths of root reinforced soils." Connect to resource, 1987. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1117654465.
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Bright, Victor M. "Shear horizontal surface acoustic waves." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/14831.
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Bilgen, Sedat. "Shear flocculation of fine cassiterite." Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304300.
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Kim, Kwon Hee. "Shear localization in viscoplastic solids." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14662.
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Scott, Alison Catherine. "Heterogeneity in high-shear granulation." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621989.
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Miller, Evan. "Magnetogenesis through Relativistic Velocity Shear." Thesis, Dartmouth College, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10001975.
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Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday’s law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic ‘battery’ arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.
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Smith, Paul Andrew. "Colloidal gels under oscillatory shear." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/11924.
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We have studied the quiescent structure of dense colloidal gels with varying strength of attraction with confocal microscopy. We have obtained high quality 3-D images that allow quantitative comparison of the different gels by the extraction of the 3-D particle coordinates and subsequent of quantitative measures of the local particle structure. We have observed that the gels have a liquid-like, although frozen in-homogeneous structure. We have found an increase in the average number of bonds per particle for decreasing attraction strength, accompanied by changes in the particle-free void regions. We developed and tested a precision linear parallel-plate oscillatory shear cell designed for light scattering-echo and microscopy experiments. This allows us to study in detail the response of gels with varying strength to low strain oscillatory shear at various frequencies will optical and confocal microscopy and light scattering-echo. We have found that the gels responds elastically to strains below a critical frequency and attraction potential dependent value. Above this critical strain the particles that make up the gel are formed to rearrange, for the strongest gels, small regions of crystal-like order can be induced by the shear and then frozen in place once the shear stops. For gels with lower potentials no ordered regions are observed in the timescale studied, however rearrangements of the voids were observed at lower strains for lower potentials. The apparent ordering is predominantly in 2-D planes and limited to small domains separated by defects or disordered particles. The amount of ordering is found to depend on strain and frequency. These results are interpreted by a simple model based on the timescale for a particle to escape from the potential well.
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Chantry, Matthew James. "Localization in transitional shear flows." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664975.
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In turbulent flows at low Reynolds numbers localized structures are observed which can grow or spontaneously decay. Viewed as a dynamical system, a turbulent evolution forms a path through a phase space built upon exact invariant solutions of the Navier-Stokes equations. The leading stable and unstable manifolds of these solutions organise the local dynamics. In small periodic domains many of these solutions are known. However, to understand the full spatial-temporal nature of turbulence requires localized solutions which are unstable and live in a very high dimensional system. In the first half of this thesis we consider two problems in small, periodic domains where turbulence is global. We consider the geometry of the edge of chaos, a manifold which divides phase space and how such a manifold can be understood in the context of turbulent decay. We demonstrate that the edge is not separate from the turbulent dynamics but is wrapped up into these dynamics. Next we consider how the dynamics on the edge in short pipes are affected by Reynolds number and find new high Reynolds number solutions. In this second half we attack the problem of finding and understanding the origins of localized solutions. These solutions hold the key to expanding the theory towards physically realisable systems. Building upon the short pipe research we find the origin of the first localized pipe flow solution in a bifurcation from a downstream-periodic solution. Moving to a model for plane Couette flow, we attempt to find evidence of homoclinic-snaking as a route to spanwise localization. Instead we find a different route which matches recent work in duct flow. Finally, motivated by questions of how localized structures interact, we introduce a new flow, "localized Couette flow", and investigate the stability of this flow.
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Paudel, Subhash. "Shear thinning in monoclonal antibodies." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32833.
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Master of ScienceDepartment of Physics
Jeremy D. Schmit
Antibodies are large Y-shaped proteins which are used by immune system to identify and neutralize pathogens. Monoclonal antibody therapy is used to treat different patient conditions. There are problems associated with the manufacturability and deliverability of mAb solutions due to the viscous nature of the protein. The viscosity of antibody solutions increases with the increase in concentration and decreases with applied shear. We want to know why these behaviours are seen and to address this problem we have developed a theory describing the rapid viscosity increase with increasing concentration. We use the polymer theory to explain this behaviour. Here antibodies are treated as polymers. The length of the polymer depend on the aggregation. The reptation time increases approximately as the cubic power of size of aggregate (N³ ). We see the shear thinning behaviour is dependent on the Ab-Ab binding energy and find the relationship between the size of the aggregate and the binding energy. We find aggregate size and morphology using several models for Ab-Ab interaction sites. We use the head to head binding (fAb-fAb binding) model to describe aggregation state in our viscosity theory. The size of the aggregate and hence the reptation time is captured by the binding energy. When the binding energy increases the zero shear viscosity increases and the reptation time decreases. Likewise when the binding energy decreases the zero shear viscosity decreases and the reptation time increases. We have yet to find the correct exponents for the shear thinning behaviour of different mAbs which would be our future work.
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Attfield, Peter Richard. "Mechanisms of shear zone deformation." Thesis, Keele University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253688.
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Lyons, John C. "Strength of welded shear studs." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06102009-063157/.
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Baumstein, Anatoly I. Saffman P. G. Saffman P. G. "Nonlinear water waves with shear /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01042008-093737.
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Thomas, Wendy Evelyn. "Shear stress enhances bacterial adhesion /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8056.
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Rychkov, Igor. "Block copolymers under shear flow." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145457.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第11046号
理博第2824号
新制||理||1421(附属図書館)
22578
UT51-2004-J718
京都大学大学院理学研究科物理学・宇宙物理学専攻
(主査)教授 吉川 研一, 教授 小貫 明, 助教授 瀬戸 秀紀
学位規則第4条第1項該当
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Lyčka, Lukáš. "Punching Shear of Flat Slabs." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-408019.
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The use of flat slabs in constructions due to its many functional and economic advantages is wide-spread. Behavior of flat slabs in shear and flexure is a fairly complex problem. Therefore, the punching shear failure belongs to one of the most critical aspects in the design of concrete buildings. Over the last decades several buildings have collapsed due to the failure of the punching shear strength, resulting in loss of lives and financial damages. These disasters revealed gaps in the current (or former) design codes and recommendations. As a part of theoretical framework of the dissertation a method for predicting the punching shear strength of flat slabs was developed. Several experiments on scaled down slabs were conducted in order to verify the proposed method and for optimization of its parameters. Proposed method in development predicts the punching shear for slabs without shear reinforcement according to the EC2 and replaces the area of the shear crack with a system of struts and ties.
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Ambrose, Joseph George. "Deconvolution of lateral shear interferograms." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186610.
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This dissertation develops and presents an existing but little known method to provide an exact solution to the Wavefront Difference Equation routinely encountered in the reduction of Lateral Shear Interferograms (LSI). The method first suggested by Dr. Roland Shack treats LSI as a convolution of the wavefront with an odd impulse pair. This representation casts the Lateral Shear problem in terms of Fourier optics operators and filters with a simplified treatment of the reduction of the LSI possible. This work extends the original proposal applied to line scans of wavefronts to full two-dimensional recovery of the wavefront along with developing the associated mathematical theory and computer code to efficiently execute the wavefront reduction. Further, a number of applications of the wavefront reduction technique presented here are developed. The applications of the filtering technique developed here include optical imaging systems exhibiting the primary aberrations, a model of residual tool marks after fabrication and propagation of an optical probe through atmospheric turbulence. The computer program developed in this work resides on a PC and produces accurate results to a 1/500 wave when compared to ray traced input wavefronts. The combination of the relatively simple concept providing the basis of the reduction technique with the highly accurate results over a wide range of input wavefronts makes this a timely effort. Finally, the reduction technique can be applied to the accurate testing of aspheric optical components.
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Giarola, Diana. "Dynamic interaction between shear bands." Doctoral thesis, Università degli studi di Trento, 2019. https://hdl.handle.net/11572/369094.
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A shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J_2-deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which takes account of the singularity at the shear band tips and permits the analysis of an incident wave impinging on a shear band.
It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.
Moreover, the approach is generalised to study the interaction of multiple shear bands showing that it may lead to resonance and corresponding growth of shear bands, but also to their annihilation. At the same time, multiple scattering may bring about focusing or, conversely, shielding from waves. Due to the difficulties inherent to the experimental analysis of time-harmonic dynamics of shear bands, the proposed mechanical model represents the only practical possibility of analyzing the fine micromechanisms governing material collapse and discloses the complex interplay between dynamics and shear band growth or arrest.
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Giarola, Diana. "Dynamic interaction between shear bands." Doctoral thesis, University of Trento, 2019. http://eprints-phd.biblio.unitn.it/3550/2/DECLARATORIA_ITA.pdf.
Full textAbstract:
A shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J_2-deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which takes account of the singularity at the shear band tips and permits the analysis of an incident wave impinging on a shear band.
It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.
Moreover, the approach is generalised to study the interaction of multiple shear bands showing that it may lead to resonance and corresponding growth of shear bands, but also to their annihilation. At the same time, multiple scattering may bring about focusing or, conversely, shielding from waves. Due to the difficulties inherent to the experimental analysis of time-harmonic dynamics of shear bands, the proposed mechanical model represents the only practical possibility of analyzing the fine micromechanisms governing material collapse and discloses the complex interplay between dynamics and shear band growth or arrest.