The flexural behavior of a light-weight wood-based composite system was studied through destructive experiments. The composite panel system consisted of profiled dimensional lumber, which makes up the surface layers, and 1"-thick boards running across the surface layers. Considering the changes in cross-sections along the panel due to the presence of the embedded boards, classical theories such as the Euler-Bernoulli beam and Kirchhoff-Love plate could not be implemented. Instead, the deflections and maximum failure loads of the composite system under full- and short-span bending tests were measured during their destructive bending testing, and were compared against the mechanical properties of the conventional three-ply CLT panel with the same thickness as the panel with embedded cross-laminations. According to maximum failure loads and deflections, it was concluded that full-span panels with embedded cross-laminations exhibited higher strength and stiffness, whereas short-span panels exhibited higher strength and lower stiffness properties compared to conventional CLT panels.

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[pt] Uma extensa campanha de ensaios de cisalhamento direto foi realizada na Areia da Praia de Ipanema, inspirado em Simões (2015). Os ensaios foram realizados em corpos de prova na condição seca, moldados em seis diferentes domínios de compacidade relativa (CR), desde muito fofo até muito compacto. Para cada domínio de CR, foram realizados ensaios sob dez diferentes valores de tensão normal nominal, variando de 25 a 1250 kPa. Em todos os ensaios, foi utilizado um dispositivo desenvolvido para impedir a rotação do top cap. A grande quantidade e variedade de ensaios permitiu uma análise detalhada de como as características das curvas tensão cisalhante sobre tensão normal versus deslocamento horizontal relativo e deslocamento vertical do top cap versus deslocamento horizontal relativo variaram com as variações de CR e de tensão normal, especialmente o ângulo de atrito de pico e o deslocamento vertical do top cap na ruptura, mostrando contração ou dilatação na ruptura. O ângulo de atrito a volume constante da Areia da Praia de Ipanema parece estar situado entre 30 e 32 graus. Uma curva que relaciona índice de vazios crítico e tensão normal nominal crítica foi obtida a partir dos ensaios de cisalhamento direto na Areia da Praia de Ipanema, sendo análoga à linha de estado crítico proposta por Lee e Seed (1967). Ademais, a alta frequência de aquisição de dados tornou explícito o fenômeno conhecido como stick-slip nas curvas obtidas, mostrando que a amplitude do fenômeno é tanto maior quanto menor a tensão normal nominal. / [en] A comprehensive research program of direct shear tests was carried out on Ipanema Beach Sand, inspired by Simões (2015). The tests were carried out on specimens in dry condition, prepared in six different domains of relative density (Dr), from very loose to very dense. For each Dr domain, tests were performed under ten different values of nominal normal stress, ranging from 25 to 1250 kPa. In all tests, a device developed to prevent the rotation of the top cap was used. The large number and variety of tests allowed a detailed analysis of how the characteristics of the Shear stress over normal stress versus relative horizontal displacement curves and top cap vertical displacement versus relative horizontal displacement curves varied with CR and normal stress variations, especially the peak friction angle and the vertical displacement of the top cap at failure, showing contraction or dilation at failure. The angle of friction at constant volume of the Ipanema Beach Sand seems to be situated between 30 and 32 degrees. A curve relating critical void ratio and critical nominal normal stress was obtained from the direct shear tests run on Ipanema Beach Sand, being analogous to the critical state line proposed by Lee and Seed (1967). Moreover, the high frequency of data acquisition made explicit the phenomenon known as stickslip in the obtained curves, showing that the amplitude of the phenomenon is greater the smaller the nominal normal stress.

The aim of this study is to determine if the mini block sampling technique couldoffer a complement to the Swedish standard StII piston sampler for achieving higherquality samples. The principle is that having a greater diameter the sample is meticulouslytrimmed to the usual geometry, so that the periphery of the sample is not disturbedby the sampling procedure and the same testing equipment can be employed.Hence, the test would provide higher and more accurate values of deformation andshear strength properties.The testing campaign executed for this study includes routine analysis with fallcone tests, CRS oedometer tests, DSS tests, CAUC triaxial tests and sedimentationtests. All of them have been performed on East-Sweden varved clay from Barkarby,Stockholm. Afterwards, the results and the sampling procedure were analysed toevaluate the performance of the mini block sampler.The mini block sampler provided more pronounced preconsolidation pressureson CRS tests as well as higher values of the quality index Mi=ML. DSS tests presenthigher values of undrained shear strength but no difference in shear strain at failure.In addition, the values of shear modulus show stiffer behaviour for block samplesas a prove of better clay structure preservation. Regarding triaxial results, theundrained shear strength values are higher for block samples with higher stresspeaks and lower strain to failure in the stress-strain graphs. Finally, several qualityindex were analysed obtaining better results for block sampling in most of them.It can be concluded that mini block sampler generally presents better qualitysamples than piston sampler for East-Swedish clay. Additionally, it is highlyfavourable for commercial projects due to each block provides up to 8 standard 50mm samples

This thesis evaluates the commonly used geotechnical probing method CPTu, on how different probe configurations impact the resulting evaluated undrained shear strength in soft clay deposits, in comparison to each other and laboratory methods. This is done by performing field investigations on Lindefältet, Södermanlands län, Sweden. Comparison is done on the two Swedish manufacturers of CPTu probes, by different calibration limits, filter types and whether overloading the probe over the calibration limit affects the evaluated undrained shear strength registered. The main conclusions are that one of the manufacturers’ probes registers deviating results in one configuration, that calibration limit has a noticable impact on the results, and that overloading on the probe and filter choice has negliable impact on the results. / I detta examensarbete utvärderas den vanligt förekommande geotekniska sonderingsmetoden CPTu, på hur olika konfigurationer av sonder påverkar den resulterande utvärderade odränerade skjuvhållfastheten i lösa leravlagringar, 9i jämförelse med varandra och med laboratoriemetoder. Detta är genomfört genom fältundersökningar på Lindefältet, Södermanlands län. Jämförelsen gjordes på de två svenska CPTu-tillverkarnas sonder. Detta är gjort med hänsyn till olika kalibreringar av konspetstryck, filtertyper, och huruvida sonden har varit överlastad påverkar den utvärderade skjuvhållfastheten som registreras. De huvudsakliga slutsatserna är att en av tillverkarnas sonder registerar udda värden i en konfiguration, att kalibreringar av konspetstryck har en märkbar påverkan på de resulterande värdena på utvärderade odränerade skjuvhållfastheten, samt att överlastning av sonder och val av filtertyp har liten till omärkbar påverkan på resultatet.

<p>The masonry construction industry represents a historically significant and substantial portion of both existing and new residential, commercial and institutional low- to medium-rise structures across Canada. Although commonly chosen for its aesthetic qualities by architects, structural masonry walls constructed with concrete block units are also an effective lateral force (wind or seismic) resisting system. The purpose of this dissertation is to address what are perceived to be overly conservative and outdated practices within masonry construction and design by adopting analysis and design practices which have had success with similar reinforced concrete wall systems. The results from a test program reporting on the behavior of nine fully-grouted reinforced masonry (RM) structural walls containing confined boundary elements are analyzed and presented according to force-, displacement- and performance-based seismic design considerations. The boundary element containing four vertical bars with lateral confinement stirrups selected represents a readily codified and practically achievable means of achieving seismic performance enhancement. The design and detailing of the specimens represented a range of parameters that would be anticipated to vary within low- to medium-rise RM buildings. In addition, an analytical study is carried out to derive, from first principles of stress equilibrium and strain compatibility, the necessary constitutive material and mechanics-based equations needed to solve for the state of shear stress and strain in an idealized cracked masonry macro-element. The algorithm proposed is validated by comparing the proposed model to existing test data and is further developed towards predicting the design shear strength of RM structural walls. The results from these experimental and analytical research programs are subsequently used to provide a set of proposed code clauses at the end of the thesis. Prescriptive design requirements are proposed for a new category of <em>Special Ductile Masonry Shear Wall</em> containing boundary elements including integration of a new shear strength expression. These clauses have been written with the intention of adoption within the CSA S304.1 and the MSJC North American masonry designs standards.</p> / Doctor of Philosophy (PhD)

yes / A simplified strut-and-tie model including size effect based on the crack band theory is proposed to evaluate the shear capacity of deep beams. Concrete struts are idealized as uniformly tapered prismatic members with a stress relief strip whereas horizontal and vertical shear reinforcements are assumed to be an internally statically indeterminate system. The shear transfer mechanism of concrete and shear reinforcement is then driven by using the energy equilibrium in the stress relief strip and crack band zone of concrete struts. The shear capacity predictions of deep beams obtained from the present models are in better agreement with 637 test results than those determined from strut-and-tie models proposed by ACI 318-08, EC-2, and Tan and Cheng. In addition, the trend of the shear capacity of deep beams against different parameters as predicted by the present models has a consistent agreement with that observed from experimental results. In particular, the present model shows that the normalized shear capacity of deep beams is proportional to (h)−0.25, where h = section overall depth.

The primary objective of this research was to investigate the shear strength of concrete bridge decks with GFRP top-mat reinforcement. Several models currently exist to predict the shear strength during the design process; however, previous research at Virginia Tech indicates that the existing equations are overly conservative. For this research, a series of concrete decks with varying lengths were tested in a laboratory environment in a two-span continuous configuration, during which data was collected on deflections, rebar strain, crack widths, and ultimate load. It was concluded that the existing equations, particularly the guidelines of ACI 440, are grossly over-conservative for GFRP-reinforced concrete bridge decks continuous over multiple supports. It was suggested that this is due to multiple factors, including additional support provided by the typically-neglected steel reinforcement in the bottom mat and a higher shear strength of the uncracked portion of concrete due to higher compressive stresses in the section as a result of the continuous deck configuration. The second objective of this research was to investigate the effects of environmental exposure on the composite deck and the individual GFRP rebar. Three deck specimens were subjected to differing environmental conditions, including one that was placed into service at an interstate weigh station. All three decks were tested in the same manner as those in the shear investigation. Additionally, live load tests were conducted on the weigh station deck during the time it was in place and tensile tests were conducted on rebar that were extracted from the concrete decks. In the live load testing, the GFRP strains increased by more than 200% over the period of service, which was likely due to a combination of a reduction in GFRP stiffness and a greater amount of cracking. During the laboratory tests on the decks, no clear correlation between conditioning and deflections or cracking was found. The ultimate strength actually increased with conditioning, with the weigh station specimen exhibiting the highest shear strength. Finally, the results of the rebar tensile tests suggested a decrease in both modulus of elasticity and ultimate tensile strength of the GFRP with environmental exposure when compared to unconditioned bars. / Master of Science