Search results for "CONSTRUCTION"
showing 10 items of 2670 documents
Unmixing of human skin optical reflectance maps by Non-negative Matrix Factorization algorithm
2013
International audience; We present in this paper the decomposition of human skin absorption spectra with a Non-negative Matrix Factorization method. In doing so, we are able to quantify the relative proportion of the main chromophores present in the epidermis and the dermis. We present experimental results showing that we obtain a good estimate of melanin and hemoglobin concentrations. Our approach has been validated by analyzing the human skin absorption spectra in areas of healthy skin and areas affected by melasma on eight patients.
Effects of Laboratory Aging on Properties of Biorejuvenated Asphalt Binders
2017
This paper presents the results from a laboratory investigation on the effects of aging on the properties of two binders recovered from two different sources of Reclaimed Asphalt (RA) and additivated with a biorejuvenator derived from pine trees. It has been already proven that the rejuvenators are able to restore some of the properties of the aged binder present in the RA, but nowadays their effects into the long-term period are not well known. In this regard, the rejuvenated asphalt binders and a virgin binder, defined as a target, have been aged artificially to simulate short-and long-term aging. All binders have been studied conducting physical, chemical, rheological, and performance-re…
Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures
2016
The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.
Numerical model for the characterization of biocomposites reinforced by sisal fibres
2018
Abstract Although several works have been recently published in literature about biocomposites, i.e. on innovative and ecofriendly polymer matrix composites reinforced by natural fibers, there are not studies on the influence of the waviness that various natural fiber present after their extraction. In order to give a contribution to the knowledge of the effects of the fiber waviness on the main mechanical properties of biocomposites, as the longitudinal Young modulus, in the present study a systematic numerical analysis has been carried out by using parametric models properly developed, that let the user to consider the effects of the key influence parameters as the fiber concentrations an…
Experimental Investigation on the Compressive Behaviour of Clay Brick Masonry Columns Confined by BFRP or Steel Wires
2016
This paper presents the results of an experimental research aiming to investigate on the compressive behavior of full size clay brick masonry columns reinforced with Basalt Fiber Reinforced Cementitious Matrix (BFRCM) or with steel wires collaring. Uniaxial compressive tests were performed on eight retrofitted columns and four control specimens. Two masonry strength were considered by varying the mortar grade. Results are presented and discussed in terms of axial stress-strain relationships, failure modes and crack patterns of the specimens tested up to failure. For the limit of investigated variables, comparisons with unreinforced specimens show the ability of these alternative techniques …
Influence of bio-based additives on RAP clustering and asphalt binder rheology
2017
The use of high Reclaimed Asphalt Pavement (RAP) content in Hot Mix Asphalt (HMA) allows developing innovative materials for the construction and/or rehabilitation of sustainable infrastructures. The chemo-physical phenomena occurring during production of HMA containing high RAP content should be investigated and considered for the mix design optimization. In fact, when additives are used as rejuvenators of the aged bitumen, these phenomena can be affected causing significant variations in the mixture characteristics. This paper aims at studying the influence of two bio-based additives specifically on RAP clustering, phenomena which can significantly affect the performance of high-content R…
The development of nature-inspired gripping system of a flat CFRP strip for stress-ribbon structural layout
2021
Abstract The elegant stress-ribbon systems are efficient in pedestrian bridges and long-span roofs. Numerous studies defined corrosion of the steel ribbons as the main drawback of these structures. Unidirectional carbon fiber-reinforced polymer (CFRP) is a promising alternative to steel because of lightweight, high strength, and excellent corrosion and fatigue resistance. However, the application of CFRP materials faced severe problems due to the construction of the anchorage joints, which must resist tremendous axial forces acting in the stress-ribbons. Conventional techniques, suitable for the typical design of the strips made from anisotropic material such as steel, are not useful for СF…
Simple equations for strength and deformability verification of tubular steel wind turbine towers
2021
Abstract Simple analytical expressions for a preliminary design of tubular steel wind turbine towers under flexure and shear are proposed. Expressions derived included local buckling effects, shear to moment interaction, ovalization of cross-section and inelastic rotation of foundation. A finite-element analysis with ABAQUS program was also conducted for examination of the ovalization effects and for the whole response of steel tube in flexure. Numerical and analytical results were compared with the experimental results of recent studies available in the literature, showing good agreement. The range of variable investigated refers to medium and large size steel wind tower with cylindrical s…
Debonding Phenomena in CFRP Strengthened Calcarenite Masonry Walls and Vaults
2009
In this paper the results of an experimental investigation on full-scale reinforced masonry elements like vaults and walls are presented. The masonry type is constituted by calcarenite ashlars and bed joint mortar and the reinforcement is constituted by Carbon Fibre Reinforced Polymer (CFRP) strips. Preliminary experimental results obtained in a previous research by the authors on the local behaviour at the interface CFRP-calcarenite are summarized. Tests with controlled displacement are carried out on out-of-plane loaded walls and cylindrical vaults loaded at a quarter of the span. Results of tests carried out before and after the application of the reinforcement made it possible to evalu…
Experimental validation of a fractional model for creep/recovery testing of asphalt mixtures
2012
Abstract Prediction of asphalt mixtures’ behavior during their service life is a challenge due to its complexity and sensitivity to environmental and loading conditions. It has been proved that, when subjected to loading conditions comparable with most pavement operating conditions, asphalt mixtures behave as linear visco-elastic (LVE) materials. Traditionally the LVE behavior of bituminous material is modeled via creep/recovery functions. In the past, several rheological models constituted by elastic and viscous elements arranged in series or in parallel (analogical models) have been proposed and specified for both bitumen and asphalt mixtures. The corresponding constitutive laws always in…