Search results for "Structural engineering"
showing 10 items of 1998 documents
Shear capacity in concrete beams reinforced by stirrups with two different inclinations
2014
Abstract A model for the estimation of shear capacity in Reinforced Concrete (RC) beams with web reinforcement is provided by introducing a generalization of classical plastic Nielsen’s model, which is based on the variable-inclination stress-field approach. The proposed model is able to predict the shear capacity in RC beams reinforced by means of stirrups having two different inclinations and longitudinal web bars. A numerical comparison with the results of experimental tests and those provided by a Finite Element Model (FEM) based on the well known theory of Modified Compression Field Theory (MCFT) is carried out for validating the robustness of the proposed model. Finally, a set of para…
Stochastic dynamics of nonlinear systems with a fractional power-law nonlinear term: The fractional calculus approach
2011
Fractional power-law nonlinear drift arises in many applications of engineering interest, as in structures with nonlinear fluid viscous–elastic dampers. The probabilistic characterization of such structures under external Gaussian white noise excitation is still an open problem. This paper addresses the solution of such a nonlinear system providing the equation governing the evolution of the characteristic function, which involves the Riesz fractional operator. An efficient numerical procedure to handle the problem is also proposed.
Gaussian and non-Gaussian stochastic sensitivity analysis of discrete structural systems
2000
Abstract The derivatives of the response of a structural system with respect to the system parameters are termed sensitivities. They play an important role in assessing the effect of uncertainties in the mathematical model of the system and in predicting changes of the response due to changes of the design parameters. In this paper, a time domain approach for evaluating the sensitivity of discrete structural systems to deterministic, as well as to Gaussian or non-Gaussian stochastic input is presented. In particular, in the latter case, the stochastic input has been assumed to be a delta-correlated process and, by using Kronecker algebra extensively, cumulant sensitivities of order higher t…
Pseudo-force method for a stochastic analysis of nonlinear systems
1996
Nonlinear systems, driven by external white noise input processes and handled by means of pseudo-force theory, are transformed through simple coordinate transformation to quasi-linear systems. By means of Itô stochastic differential calculus for parametric processes, a finite hierarchy for the moment equations of these systems can be exactly obtained. Applications of this procedure to the first-order differential equation with cubic nonlinearity and to the Duffing oscillator show the versatility of the proposed method. The accuracy of the proposed procedure improves by making use of the classical equivalent linearization technique.
Structural characterization of Nigerian coals by X-ray diffraction, Raman and FTIR spectroscopy
2010
Abstract The structural parameters of six Nigerian coals were determined by X-ray diffraction, Raman and FTIR spectroscopy. This study reveals that the coals contain crystalline carbon of turbostratic structure with some amount of highly disordered amorphous carbon. The average lateral sizes ( L a ), stacking heights ( L c ) and interlayer spacing ( d 002 ) of the crystallite structures calculated from the X-ray intensities range from 16.47 to 25.70, 8.12 to 13.25 and 3.48 to 3.58 A, respectively. The L a values derived from the Raman spectra analyses using the classical linear relationship between 1/ L a and the D/G band ratio are higher (27.53–34.67 A) than values obtained from X-ray diff…
NUMERICAL-EXPERIMENTAL METHOD FOR THE ANALYSIS OF RESIDUAL STRESSES IN COLD-EXPANDED HOLES
2012
Hole cold expansion is a technique widely used to improve the fatigue life of components with holes, e.g. bolted or riveted joints. As it has been demonstrated in literature by analytical, numerical and experimental analyses carried out by several authors, the compressive residual stresses introduced by the hole cold expansion have a beneficial influence on both the static and the fatigue strength of the treated component, because they reduce significantly the typical stress peaks around the hole due to stress concentration. In the literature, various analyses of the residual stresses introduced by the hole cold expansion have been performed by using several methods such as X-ray diffractio…
Finite element analysis of laser shock peening of 2050-T8 aluminum alloy
2015
Laser shock processing is a recently developed surface treatment designed to improve the mechanical properties and fatigue performance of materials, by inducing a deep compressive residual stress field. The purpose of this work is to investigate the residual stress distribution induced by laser shock processing in a 2050-T8 aeronautical aluminium alloy with both X-ray diffraction measurements and 3D finite element simulation. The method of X-ray diffraction is extensively used to characterize the crystallographic texture and the residual stress crystalline materials at different scales (macroscopic, mesoscopic and microscopic).Shock loading and materials’ dynamic response are experimentally…
A Digital Twin predictive maintenance framework of air handling units based on automatic fault detection and diagnostics
2022
The building industry consumes the most energy globally, making it a priority in energy efficiency initiatives. Heating, ventilation, and air conditioning (HVAC) systems create the heart of buildings. Stable air handling unit (AHU) functioning is vital to ensuring high efficiency and extending the life of HVAC systems. This research proposes a Digital Twin predictive maintenance framework of AHU to overcome the limitations of facility maintenance management (FMM) systems now in use in buildings. Digital Twin technology, which is still at an initial stage in the facility management industry, use Building Information Modeling (BIM), Internet of things (IoT) and semantic technologies to create…
Speckle Interferometry Analysis of Full-bending Behavior of GFRP Pultruded Material
2016
Abstract The use of Glass Fiber Reinforced Polymer materials (GFRP) has increased in the last years even among civil structural engineering due to their high specific strength, lightweight and excellent corrosion resistance. With application of the pultrusion method, the manufacture of large-scale profiles with various cross-section forms became potentially possible with relatively low costs. Usually two different technological approaches are available to realize the element: in the first one a mat-roving-mat sequence is adopted, in the second one only roving is present. Continuous filament mat (CFM, fibers distributed randomly in all directions) is often used to build up laminate thickness…
On the use of Digital Image Correlation (DIC) for evaluating the tensile behaviour of BFRCM strips
2019
Abstract. Fibre Reinforced Cementitious Matrix (FRCM) composites are becoming largely adopted for retrofitting masonry structures. These materials offer several advantages in comparison to Fibre Reinforced Polymer (FRP) composites, such as good resistance to fire and high temperatures, vapour permeability, possibility to be applied on wet surfaces, higher compatibility with the masonry substrate. However, the tensile behavior of FRCM materials is more complex compared to FRP composites, due to the limited tensile strength of the cement-based matrix. For this reason, FRCM materials require appropriate tensile characterization and, in this context, the use of non-conventional measurement syst…