Search results for "Flexural Strength"
showing 10 items of 170 documents
X-ray diffraction microstructure analysis of mullite, quartz and corundum in porcelain insulators
2005
Abstract The X-ray diffraction microstructure analysis has been performed on commercial samples of the silica and alumina porcelain insulators obtained at 1300 °C, with the same time of firing. The study was carried out on mullite, corundum and quartz by applying several integral breadth methods (i.e. the Williamson–Hall analysis, the Langford method and the Halder–Wagner approximation) and the Fourier analysis (Warren–Averbach method). The apparent crystallite sizes determined for the mullite are direction-dependent (anisotropic) and within each group of samples, on average, the greatest values are obtained along the direction [0 0 1]. With regard to the microstructure of the corundum and …
A DIC-based study of flexural behaviour of roving/mat/roving pultruded composites
2015
Abstract This paper reports a study of the flexural behaviour and resultant failure modes in E-glass/polyester pultruded composites. The digital image correlation (DIC) method is used to estimate the effect of fibre orientation on failure behaviour in thick beams, taking into account the presence of continuous filament mat layer (CFM) in the stacking sequence. In particular, the tests were carried out for specimens with off-axis angle of 0°, 7.5°, 15°, 30°, 45° and 90°. The crack initiation and the failure mechanisms depend on the mutual interaction between the stiffness properties of different areas in the stacking sequence. An influence index (I) was introduced to evaluate the magnitude o…
Earth Construction: The Mechanical Properties of Adobe with the Addition of Laponite
2015
The contribution describes testing of compression strength, flexural strength and abrasion resistance of adobe made up of soil, water and sand (AS), soil, water, sand and straw (ASP), soil, water, sand and laponite nanoparticles (ASN). Embodied energy in materials presents an increasingly high percentage of the energy spent in the whole life cycle of a building. The same applies for carbon dioxide (CO2). Therefore, the development of new sustainable construction materi- als with lower embodied energy and lower CO2 emissions is needed. The use in construction of the brick made from soil, water and sand or straw, called adobe, boasts a millenary tradition and in recent years there has been re…
Strength and ductility of RC jacketed columns: A simplified analytical method
2016
Abstract Reinforced concrete (RC) jacketing is a common method for retrofitting existing columns with poor structural performance. It can be applied in two different ways: if the continuity of the jacket is ensured, the axial load of the column can be transferred to the jacket, which will be directly loaded; conversely, if no continuity is provided, the jacket will induce only confinement action. In both cases the strength and ductility evaluation is rather complex, due to the different physical phenomena included, such as confinement, core–jacket composite action, preload and buckling of longitudinal bars. Although different theoretical studies have been carried out to calculate the confin…
Testing mechanical characteristics of chestnut stakes used in bed sills for stream restoration
2017
Using of wood elements for constructing bed sills in Mediterranean streams, where the banks are not protected by tree vegetation, needs an evaluation of biological and mechanical characteristics for evaluating both the wood durability and the effectiveness of the stream restoration project. Very few studies have dealt both with the decay of mechanical characteristics of wood elements employed for stream restoration works and with the changes over time of physical and chemical wood characters. In this paper, for a wood and stone bed sill located in a stream having no shaded banks, the changes of physical and chemical characters detected after 12, 18, 24, 30, 36, 42 and 48 months on chestnut …
Conceptual design of prestressed slab bridges through one-way flexural load balancing
2013
In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through …
Analytical prediction of load deflection curves of external steel fibers R/C beam–column joints under monotonic loading
2015
Abstract In this paper a simplified analytical model able to reproduce the flexural behavior of external beam–column joints under monotonic loading is presented, to be used for pushover analysis. The subassemblage (beam, column and joint) is subjected to a constant vertical load acting on the column and to a monotonically increasing lateral force applied at the tip of the beam. The model is specific for hooked steel fiber-reinforced concrete (FRC) and is designed to calculate the flexural response in the form of a load–deflection curve, of beam–column subassemblages. No bond failure and shear deformations are considered in the present paper. The model includes shear-to-moment interaction fo…
Modeling of out-of-plane behavior of masonry walls
2009
The flexural behavior of rectangular masonry sections is investigated by considering nonlinear stress-strain in compression and limited-tension material. A preliminary analysis shows that, with variation in the parameters specializing with the adopted conventional constitutive law, the experimentally observed behavior of different kinds of masonry materials can be approximated. Subsequently, moment-curvature dimensionless curves are derived numerically by satisfying the equilibrium equations of the section. In the case of negligible tensile strength these curves exhibit a typical shape that can be approximated by analytical expressions; consequently, suitable functions are proposed that are…
Concrete softening effects on the axial capacity of RC jacketed circular columns
2016
Abstract Among the different strengthening techniques to repair RC structures, reinforced concrete (RC) jacketing is one of the most commonly adopted, especially for columns. Its wide application is due to its easy application and relatively reduced cost with respect to other methods (e.g. FRP wrapping, Shape Memory Alloy active confinement). The target of RC jacketing is to increase axial, flexural capacity and ductility of weak existing members by means of two main effects: confinement action provided by the jacket and composite action between external jacket and inner concrete. Different theoretical studies have been carried out to calculate the strength enhancement due to confinement ac…
Shear strength of High-strength concrete beams: modeling and design recommendations
2014
Abstract In the present paper, the flexural and the shear resistance of high strength reinforced concrete (HSC) beams with longitudinal bars, in the presence of transverse stirrups is analyzed both theoretically and experimentally. The experimental researches here presented are parts of previous researches carried out by the author. Researches refer to HSC beams with high percentages of steel bars failing in shear and in flexure. From the analytical point of view, a model based on the evaluation of the resistance contribution due to beam and arch actions including bond splitting and concrete crushing failure modes is developed and presented. The model was verified against available experime…