Search results for "Structural Engineering"
showing 10 items of 1998 documents
Shear-to-Moment Interaction in Glass Beams with Open Cross Sections
2018
An experimental investigation regarding the flexural behavior of glass beams with a length of 1,200 mm and rectangular, T-shaped, or I-shaped cross sections is presented and discussed. T-shaped and I-shaped cross sections were obtained by assembling laminated glass (LG) panels of 200 mm depth and 12.76 mm thickness through an acrylic adhesive. Three specimens for each series investigated were tested in flexure, focusing on the flexural and shear response of beams through the determination of the load-deflection curves and crack patterns at rupture. The shear span to depth ratio a/d was 2.25, which is a very low value, and interaction of shear and bending moment occurred during the tests. An…
Radiation-induced defects in antiferroelectric thin films
2003
Abstract Radiation effects on highly oriented antiferroelectric (AFE) PbZrO3 (PZ) films with a thickness of approximately 400 nm are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for fusion devices like ITER. The films were prepared by pulsed laser deposition (PLD). The dielectric constant was measured in the frequency range from 1 to 250 kHz in a stepwise cooling mode (∼2 °C min−1) from 400 °C to room temperature before and after irradiation to a fast neutron fluence of 2×1022 m−2 (E>0.1 MeV). After irradiation, the films were annealed in several steps up to ∼400 °C to remove the radiation-induced defects. The results are di…
Simple Plastic Model for Shear Critical SFRC Beams
2010
A simple physical model, for prediction of ultimate shear strength of steel fiber reinforced concrete (SFRC) beams is developed on the basis of a plastic approach originally proposed for reinforced concrete (RC) beams without stirrups. It is founded on the hypothesis that cracks can be transformed into yield lines, and thus is know as Crack Sliding Model (CSM). First, the CSM is improved in order to take into account the shear strength increase for deep beams, due to the arch effect. Then, the effectiveness factors for fibrous concrete under biaxial stresses are evaluated, taking into account the post-cracking tensile strength of SFRC and its ability to control slippage along shear cracks. …
Damage accumulation under variable amplitude loading of welded medium- and high-strength steels
2004
Abstract The paper presents the calculation of cumulative damage for two types of welded joints (butt weld and transverse stiffeners) of four steels (medium to high strength): S355N, S355M, S690Q and S960Q. This calculation is based on experimental data obtained under axial loading and bending with constant and variable amplitudes (Gaussian distribution and Gauss with overload spectrum). The experiments were performed under fully reversed ( R =−1) and pulsating ( R =0) loading. The fatigue life is calculated using the modifications of the Palmgren–Miner–Original rule, according to the Palmgren–Miner–Elementary method, as well as to Haibach’s suggestion. The fatigue life does not depend on t…
Experimental Investigation and Finite Element Analysis of Dynamic Behavior and Damage of Glass/Epoxy Tubular Structures
2011
This paper presents finite element analysis (FEA) of static and dynamic tests of thick filament wound glass/epoxy tubes. The first part involves the validation of elastic properties and identification of damage initiation and its development in dynamic tests. The results of FEA of the dynamic tests without damage appeared satisfactory. An impact model, including material property degradation, is used for damage prediction. The simulated damage is compared with that obtained experimentally. The sizes of projected and cumulated surfaces are of the same order of magnitude as in the experimental measurements.
Approximate Solution on Large Deflection of Glass Panels Subjected to Uniform Pressure
2015
The estimation of the deflection of glass panels under wind pressure is important in designing external facades of buildings. A direct method to compute the large deflections of glass panels under uniform loads such as wind pressure is presented. The model allows for derivation of the load-deflection response of square or rectangular multilayered glass panels subject to uniform loads. The boundary conditions examined are those of four-point discontinuous supports or continuous supports along the four sides. With some assumptions on bending and membrane action of flat glasses, simple analytical expressions were derived from the elastic theory. Viscoelastic effects for multilayered glass pane…
Reconstruction Problem of Reinforced Concrete Beams under Harmonic Excitations
2007
A damage detection method based on harmonic structural vibrations has been applied to reconstruct realistic damage patterns of reinforced concrete beams. It was shown that the application of a hybrid method (genetic algorithm and Levenberg-Marquardt minimization technique) makes it possible to effectively reconstruct the flexural stiffness drops as small as 10-20% with the maximum error of 4%. The error increases to about 7 to 9% with the presence of 1% measurement noise.
Size effects on the plastic collapse limit load of thin foils in bending and thin wires in torsion
2011
Abstract Following a previous paper by the author [Strain gradient plasticity, strengthening effects and plastic limit analysis, Int. J. Solids Struct. 47 (2010) 100–112], a nonconventional plastic limit analysis for a particular class of micron scale structures as, typically, thin foils in bending and thin wires in torsion, is here addressed. An idealized rigid-perfectly plastic material is considered, which is featured by a strengthening potential degree-one homogeneous function of the effective plastic strain and its spatial gradient. The nonlocal (gradient) nature of the material resides in the inherent strengthening law, whereby the yield strength is related to the effective plastic st…
A Multiscale Approach to Polycrystalline Materials Damage and Failure
2014
A two-scale three-dimensional approach for degradation and failure in polycrystalline materials is presented. The method involves the component level and the grain scale. The damage-induced softening at the macroscale is modelled employing an initial stress boundary element approach. The microscopic degradation is explicitly modelled associating Representative Volume Elements (RVEs) to relevant points of the macro continuum and employing a cohesive-frictional 3D grain-boundary formulation to simulate intergranular degradation and failure in the Voronoi morphology. Macro-strains are downscaled as RVEs' periodic boundary conditions, while overall macro-stresses are obtained upscaling the micr…
A theoretical and experimental study to point out the notion of loading mode in damage mechanicsApplication to the identification and validation of a…
2002
A model of fatigue-induced intralaminar cracking in strongly anisotropic laminates is presented. The features of the microscopic phenomenon are explicitly taken into account at the macroscopic level by the use of two variables, which define a new concept in Damage Mechanics that results not only in a coherent model of crack density evolution, but also in a coherent treatment of damage deactivation. Damage evolution indeed is strongly dependent on the local loading mode in each ply where cracking occurs. Experiments on complex lay-ups provided sufficient data for complete calibration of the model. These tests also allowed to validate the theoretical choice of the damage variable. Finally, nu…