Search results for "Civil engineering"
showing 10 items of 1216 documents
Equivalent Non-Linearization of Hysteretic Systems by Means of RPS
2018
BackgroundThe analysis of elastoplastic systems with hardening (Bouc-Wen systems) under stochastic (seismic) loads needs the evaluation of higher order statistics even in the simplest case of normal distributed input. ObjectiveIn this paper, a non-linearization technique is proposed in order to evaluate the moments of any order of the response. MethodThis technique is developed by means of a nonlinear class of systems whose statistics are a priori known. The parameters of such systems can be chosen in such a way that the two systems are equivalent in a wide sense. Result & ConclusionIn the paper, the strategy to obtain the equivalence and the reliability of the results are discussed.
Experimental Investigation of the Shear Response of Precast Steel-Concrete Trussed Beams
2017
The results of an experimental campaign of three-point bending tests on precast composite beams, named hybrid steel-trussed concrete beams (HSTCBs), are provided. HSTCBs are typically constituted by a precast steel truss embedded in a block of concrete cast in place. Two series of specimens were manufactured, designed such that shear failure would occur, and tested under positive and negative bending moment. The experimental results obtained showed that fragile shear failure occurred in almost all cases, evidencing the crisis of the compressed concrete strut involved in the collapse mechanism. Yielding of the steel members provided ductility to the system, especially in those cases in which…
First Principles Calculations of Atomic and Electronic Structure of TiAl3+- and TiAl2+-Doped YAlO3
2021
In this paper, the density functional theory accompanied with linear combination of atomic orbitals (LCAO) method is applied to study the atomic and electronic structure of the Ti3+ and Ti2+ ions substituted for the host Al atom in orthorhombic Pbnm bulk YAlO3 crystals. The disordered crystalline structure of YAlO3 was modelled in a large supercell containing 160 atoms, allowing simulation of a substitutional dopant with a concentration of about 3%. In the case of the Ti2+-doped YAlO3, compensated F-center (oxygen vacancy with two trapped electrons) is inserted close to the Ti to make the unit cell neutral. Changes of the interatomic distances and angles between the chemical bonds in the de…
Unified theory for analysis of curved thin-walled girders with open and closed cross section through HSA method
2016
Abstract The behaviour of thin-walled structures is deeply influenced by non-uniform torsion and cross section distortion. In this paper the extension of the Hamiltonian Structural Analysis (HSA) Method to thin-walled straight and curved beams is presented. The proposed method solves the structural elastic problem of thin-walled beams through the definition of a Hamiltonian system composed of 1st order differential equations. The method allows engineers to solve the elastic problem by introducing the degrees of freedom and the corresponding compatibility equations, founding equilibrium equations in the variational form. The methodology is explained in the framework of the so-called Generali…
Dehydration of Fructose to 5-HMF over Acidic TiO2 Catalysts
2020
Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated by means of X-ray diffraction (XRD), N2 adsorption isotherms, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements. Special attention was focused on the reaction conditions, both in terms of 5-HMF selectivity and the sustainability of the process, choosing water as the solvent. Among the various process condition…
Hydrogen and Deuterium Incorporation in ZnO Films Grown by Atomic Layer Deposition
2021
Zinc oxide (ZnO) thin films were grown by atomic layer deposition using diethylzinc (DEZ) and water. In addition to depositions with normal water, heavy water (2H2O) was used in order to study the reaction mechanisms and the hydrogen incorporation at different deposition temperatures from 30 to 200 °C. The total hydrogen concentration in the films was found to increase as the deposition temperature decreased. When the deposition temperature decreased close to room temperature, the main source of impurity in hydrogen changed from 1H to 2H. A sufficiently long purging time changed the main hydrogen isotope incorporated in the film back to 1H. A multiple short pulse scheme was used to study th…
The total social costs of constructing and operating a high-speed rail line using a case study of the Riyadh-Dammam Corridor, Saudi Arabia
2019
Introducing a High-Speed Rail technology between the Saudi Arabian cities starts raising many challenging issues of different nature ranging from technical to operational, which require huge investments in infrastructure, operations and maintenance. Background information about the development of HSR worldwide to date is included. However, the main aim of this paper is to determine a methodology to estimate the full cost of travel and provide insights into the working model developed to include the calculations of the total social costs of building a new HSR line for the Riyadh-Dammam corridor in Saudi Arabia and understand in what circumstances it is a suitable technology to use. The Sprea…
Reducing Air Pollutants through Road Innovative Intersections
2013
Road pollutant emissions are correlated mainly to infrastructural capacity and to traffic intensity and typology. With the aim to improve road intersections performances in the last years was designed many new geometric layouts, like turbo roundabouts and flower roundabouts. The main objective of this paper is carried out a comparative analysis between conventional and innovative roundabouts in terms of CO, CO2, NO and PM2,5 vehicular emissions, evaluated by means of COPERT Software which is developed as a European tool for the calculation of emissions from the road transport sector.
A critical perspective on Integrated Project Delivery (IPD) applied in a Norwegian public hospital project
2020
Does the IPD concept deliver as required and expected, and if not, how can that be explained? This paper is a critical realist inspired methodology based on a combination of the inductive and deductive approaches used in case study research. IPD is based on relational contracting between multiple parties, in this case between the Owner, Contractor, MEP subcontractors and a group of Consulting engineers who share control of the project. At the core of the concept is shared risk and opportunities among the parties in the IPD contract. Our theoretical perspectives are based mainly on the Principal-Agent theory (PA), Transaction Cost theory (TC), and its related incentives. This paper reports o…
An empirical analysis of the relation between infrastructure and road accidents
2017
The concern for road safety in Europe is growing bigger. European Union by its means promote the aim of reducing the number of victims of traffic accidents by half in the period 2011-2020. In order to achieve this objective a lot of actions should be developed. One of our concern is the development of the infrastructure, mainly building motorways. Our research aims to study the relation between infrastructure – motorway versus highway and road accidents. Our findings show that is a great relationship between uses of motorways and reducing the number of accidents.