Search results for "0201 civil engineering"
showing 10 items of 242 documents
A strategy for the finite element modeling of FRP-confined concrete columns subjected to preload
2018
Abstract Compressive behavior of columns strengthened by means of an outer elastic confinement provided e.g. by fiber-reinforced polymer (FRP) jackets has become a main topic in the field of structural retrofitting. In details, the problem of the response assessment of strengthened columns is still under study. Many analytical formulations have been proposed to describe the compressive behavior of confined concrete under both monotonic and cyclic loads. However, the effect of a stress/strain level in the columns already present prior to apply the confinement has been generally neglected until now, also because of the lack of well defined strategies of modeling. In this frame, here, (1) a FE…
Crack growth models for multiaxial fatigue in a ship’s propeller shaft
2021
Abstract A premature fatigue failure of a large intermediate propeller shaft in a shuttle tanker is discussed and analyzed. The short fatigue life consists mainly of a crack growth phase. Life predictions are carried out by crack growth modelling based on engineering fracture mechanics. The purpose of the present investigation is to identify the most likely loading modes based on the evolution of the crack propagation. A Linear Elastic Fracture Mechanics Model (LEFM) is applied with the stress intensity factor range entering the Paris law as a key parameter. Existing formulas for the geometry functions are supplemented by more detailed stress intensity factor calculations pertaining to smal…
Discontinuous FRP-Confinement of Masonry Columns
2020
Recent seismic events, all over the world, demonstrated that masonry constructions are prone to brittle collapses when shear or compression capacity is reached. It is clear that, in many real cases, masonry columns need to be strengthened for enhancing their load-carrying capacity and to develop a more ductile response. The Fiber Reinforced Polymers (FRPs) confinement of masonry columns is a well-known technique that may produce these advantages. Unfortunately, full-wrapping insulates the column from the environment; so interstitial humidity can easily occur and cause the acceleration of the masonry's decay. In order to prevent it, partial-confinement is commonly assessed instead of total-j…
Lessons Learned on the Tensile and Bond Behavior of Fabric Reinforced Cementitious Matrix (FRCM) Composites
2020
Fabric Reinforced Cementitious Matrix (FRCM) composites represent an effective, compatible and cost-efficient solution for strengthening and retrofitting existing structures. A strong research effort was done to investigate the tensile and bond properties of these materials, as well as the overall behaviour of strengthened members. A Round Robin Test was organized by Rilem TC 250-CSM on 28 FRCM composites comprising basalt, carbon, glass, PBO, aramid and steel textiles, embedded in either cement, lime or geopolymer mortars, to collect an experimental dataset and define test protocols. This paper collects the outcomes of this study to highlight fundamental properties of FRCM and to investiga…
Constitutive Numerical Model of FRCM Strips Under Traction
2020
In this paper, the tensile behavior of Fiber Reinforced Cementitious Matrix (FRCM) strips is investigated through Finite Element (FE) models. The most adopted numerical modeling approaches for the simulation of the fiber-matrix interface law are described. Among them, the cohesive model is then used for the generation of FE models which are able to simulate the response under traction of FRCM strips tested in laboratory whose results are available in the technical literature. Tests on basalt, PBO and carbon coated FRCM specimens are taken into account also considering different mechanical ratios of the textile reinforcement. The comparison between FE results and experimental data allows val…
Efficiency of Stress-Strain Models of Confined Concrete With and Without Steel Jacketing to Reproduce Experimental Results
2016
The improvement and the capacity assessment of existing buildings has become the main topic of the last years so that different studies can be found devoted to damaged structures or structures not having a capacity compatible with the safety levels of the actual codes. Reinforced concrete framed structure buildings represent a conspicuous rate of the existing constructions so many efforts are addressed to them. Referring to this type of buildings, a good prediction of strength and deformation capacity requests models able to interpret the constitutive law of concrete confined by internal reinforcement or by eventual external reinforcement applied to increase capacity of cross-sections. Cons…
Stress field model for strengthening of shear-flexure critical RC beams
2017
A model for the design of shear-flexure critical reinforced concrete elements strengthened with fiber-reinforced polymer (FRP) sheets and plates is presented. The model is based on the stress field approach and the equilibrium method and accounts for the different failure modes of FRP, focusing on the debonding of the FRP from the concrete surface. The efficiency of the model in the strength assessment of beams reinforced with FRP by the prediction of the shear-flexure capacity is checked by corroborating the results of several experimental tests found in the literature. Moreover, the presented model's capacity to reproduce experimental behavior is compared with the formulations suggested b…
Shear Capacity Model with Variable Orientation of Concrete Stress Field for RC Beams Strengthened by FRP with Different Inclinations
2021
A design-oriented analytical model able to evaluate the shear capacity of reinforced concrete (RC) beams strengthened with fiber-reinforced polymer (FRP) sheets or strips oriented in any direction is proposed. The formulation of the model is based on the variable-inclination stress-field approach, aiming to extend the provisions of current European standards to beams strengthened in shear using FRP. The main novelty of the model lies in taking into account the possible different inclination of steel stirrup and FRP reinforcement in determining the orientation of a compressed concrete stress field, and in shear strength evaluation, overcoming the approximation of the known models with variab…
Electrochemical discrimination of manufacturing types of pottery from Magna Mater Temple and Fora of Nerva and Caesar (Rome, Italy)
2018
Abstract The voltammetry of immobilized microparticles (VIMP) methodology is applied to a series of pottery samples from the Roman sites of Nerva's Forum (second half of 9th-early 11th A.D), Caesar's Forum (second half of 9th-early 11th A.D) and Magna Mater Temple (III century). The VIMP sampling applied to voltammetric and electrochemical impedance spectroscopy (EIS) measurements was applied by the first time to acquire archaeometric information on archaeological pottery. VIMP measurements using pressed sample pellets on gold electrodes in contact with air-saturated 0.10 M H2SO4 have permitted to detect voltammetric signals for the reduction/oxidation of Fe and Mn minerals as well as catal…
Laboratory and in-situ tests for estimating improvements in asphalt concrete with the addition of an LDPE and EVA polymeric compound
2019
Abstract Pavement deformation is a critical issue in the design of pavement structures and the related mixture. Asphalt concretes may be very sensitive to this problem, in compliance with the viscoelastic behaviour of the adopted bitumen. To improve the material performance, many attempts have been made to introduce in the mixture other materials as “modifiers” or “additives” for increasing the permanent deformation resistance and the elastic modulus of the material. Among the different possible materials, polymers determined significant improvements in the road pavement performance. In this paper, the authors tested the adoption of a specifically engineered polymeric compound, in order to …