Search results for "Compres"
showing 10 items of 1107 documents
Behavior of fiber-reinforced concrete columns under axially and eccentrically compressive loads
2010
An experimental investigation into the behavior of 16 short, confined, reinforced concrete columns with and without steel fibers was carried out. The columns with square sections had a concrete core 165 x 165 mm (6.49 x 6.49 in.) at the midsection and were hunched at the ends to apply eccentric loading and prevent boundary effects. The specimens were tested to failure at different strain rates under two loading schemes: concentric compression and eccentric compression with a constant eccentricity. The axial load and axial strains were obtained to evaluate the effects of the presence of steel fibers, the thickness of the cover concrete, and the eccentricity of the applied axial load. The com…
Stainless steel grids for confinement of clay brick masonry columns
2016
This work presents the results of an experimental investigation on the behavior of 21 solid clay brick columns internally strengthened by stainless steel grids placed in the horizontal joints of mortar. This reinforcing technique can be applied as a constructive technique for new construction or as a retrofitting technique for existing structures (old structures to be reconstructed by original constructive method and internal reinforcement). Monotonic compressive loading tests were carried out under concentric and eccentric load. The effects of different numbers of steel grids and eccentricity of the external load were examined. Also, a detailed characterization of the constituent materials…
Three-dimensional poroelastic metamaterials with extremely negative or positive effective static volume compressibility
2018
Abstract Recently, three-dimensional poroelastic metamaterials have been introduced that show an unusual isotropic increase of their effective volume when increasing the hydrostatic pressure of the surrounding air. This behavior corresponds to a negative effective static volume compressibility. Here, we present significantly simplified metamaterial architectures, which are composed of just one rather than eight hollow sealed functional elements within each cubic unit cell. On cubic symmetry microstructured polymer samples made by 3D laser printing, we measure a negative effective compressibility of about κ eff = − 4 . 7 % ∕ bar under pressure control. This value is six times larger than pre…
Analytical stress-strain law of FRP confined masonry in compression: Literature review and design provisions
2017
Abstract The use of Fibre Reinforced Polymer (FRP) wraps has become common in practical applications to retrofit existing columns with poor structural features. Wrapping the member with one or more FRP sheets makes it possible to induce confinement action and enhance strength and ductility. This application has been widely studied and adopted in reinforced concrete members for about twenty years, while its suitability to masonry columns and piers has been investigated during the last decade. The results of several studies were summarized in different design expressions for calculating effective confinement pressure, ultimate compressive stress and strain, and the overall trend of the stress…
Comparative study of illite clay and illite-based geopolymer products
2011
Quaternary (Q-clay) clayey deposits are one of the dominating parts of mineral raw materials of the sedimentary cover at present area of Latvia. These clays can be characterised by illite content up to 75-80 %. Two ways for use of illite clays were studied: conventional and geopolymers method. Purpose of the second mentioned method was showing the influence of alkali (KOH) on the transformation of Q-clay/illite structure. Obtained products were investigated by IR–spectroscopy, DTA and XRD, pore size distribution was determined as well. Some ceramic properties and compressive strength were determined and compared. IR-spectrum showed the effect of alkali on the transformation of Q-clay/illite…
Evolution of grain-size distribution of pumice sands in 1-D compression
2016
Abstract Crushing is one of the micromechanisms that govern the mechanical behaviour of sands at medium-high stresses. It depends on mineralogy, form and strength of single particle, mean stress level, coordination number, time, etc.. It causes changes of grain-size distribution, porosity, number and type of grain contacts, fabric, structure of the material, etc.. Results of an experimental research on the crushing of pumice sands compressed under 1-D conditions to vertical effective stresses σ′v up to 100MPa are reported here. They show marked crushing already at σ′v of about 200kPa. The evolution of the grain-size distribution can be represented by ΔDi= h/(K(1+C exp(–hlgσ′v))) in which ΔD…
Laminated Glass Members in Compression: Experiments and Modeling
2014
It is well known that structural glass members are made by assembling thin laminated panels, which can be connected with different bonding techniques; for instance, with steel devices or with structural adhesives. The latter are very commonly used because they do not reduce the transparency of the member and make it possible to avoid stress concentrations because of the presence of holes. This technique is used to make up columns in glazing structures and different applications of the technique can be found in contemporary architecture. As evidenced by the literature, one of the most important problems in such members is caused by buckling phenomena, resulting from the slenderness of the pa…
On the influence of orientation upon the mechanical behavior of oakwood in a general state of stress
1995
Influence of orientation upon the mechanical behavior of oakwood has been studied. The approach within anisotropic medias mechanics supposes oakwood orthotropic with three orthogonal symmetry axes considered to be the privileged directions that occur during the growth of oaktree. Experimental tests consisted in compression tests under confining pressure realized on cylindric samples of oakwood chopped in 18 privileged directions. Although well known in solid mechanics, our approach is original in mechanics and rheology of wood. The obtained results disclosed an influence of the confining pressure upon the mechanical behavior of oakwood and its anisotropy including different types of anisotr…
Shear strength of steel fiber reinforced concrete beams with stirrups
2006
The present paper proposes a semi-empirical analytical expression that is capable of determining the shear strength of reinforced concrete beams with longitudinal bars, in the presence of reinforcing fibers and transverse stirrups. The expression is based on an evaluation of the strength contribution of beam and arch actions and it makes it possible to take their interaction with the fibers into account. For the strength contribution of stirrups, the effective stress reached at beam failure was considered by introducing an effectiveness function. This function shows the share of beam action strength contribution on the global strength of the beam calculated including the effect of fibers. T…
Characterization process to measure the electrical contact resistance of Gas Diffusion Layers under mechanical static compressive loads
2016
AEM2016. International conference on Advanced Energy Materials, University of Surrey, Guildford, ROYAUME-UNI, 12-/09/2016 - 14/09/2016; Recent research has identified the mechanical properties of the fuel cell internal components (in particular, the Gas Diffusion Layers - GDLs) as key-parameters to obtain high final performances of the generator. The mechanical compression modulus of these components, the stability of their mechanical properties with respect to temperature and humidity, and their ability to interact with water have an impact on the electrical contact resistances in the stack and, by consequence, on the overall performance of the electric generator. Reducing the losses by co…