Search results for "Retrofitting"
showing 10 items of 58 documents
Increasing the shear capacity of reinforced concrete beams using pretensioned stainless steel ribbons
2017
In this work, the second part of an experimental campaign investigating the efficiency of an alternative retrofitting method for increasing the flexural and/or shear capacity in reinforced concrete beams, based on the use of prestressed stainless steel ribbons and steel angles, is presented and analytically reproduced. This group of tests focuses on the ability of the adopted retrofitting method to improve the shear strength and ultimate deformation of reinforced concrete structural elements. As described in a companion paper, the adopted retrofitting method is alternative to traditional techniques of reinforced concrete retrofitting, being easy to install and usually reversible, and charac…
Experimental in situ behaviour of unreinforced masonry elements retrofitted by pre-tensioned stainless steel ribbons
2014
Abstract The results of in situ tests carried out on unreinforced and reinforced poor rubble masonry full-scale walls in the earthquake prone Messina (Italy) area are presented and discussed. This experimental research was aimed at the assessment of the in plane shear behaviour of ancient masonry strengthened with an innovative system for masonry and retrofitting of reinforced concrete element constituted by three-dimensional pre-tensioned stainless steel ribbons. A comparison between different strengthening configurations was made in order to characterise the behaviour of masonry panels under shear-compression load, focusing attention on the diagonal cracking failure mode. The effectivenes…
Masonry columns confined with fabric reinforced cementitious matrix (FRCM) systems: A round robin test
2021
Abstract The conservation and the preservation of existing masonry buildings, most of them recognized as cultural heritage, require retrofitting techniques that should reduce the invasiveness and assure reversibility and compatibility with the substrate. In this perspective, the strengthening system should be able to improve the bearing capacity of the structural member and, at the same time, to assure mechanical and material compatibility. The use of Fabric Reinforced Cementitious Matrix (FRCM) composites is now recognized to be suitable for these purposes. Indeed, the inorganic matrix has comparable properties with respect to the existing historical mortars while the fabric has relevant t…
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…
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…
Analysis-oriented stress–strain model of CRFP-confined circular concrete columns with applied preload
2018
The compressive behavior of FRP-confined concrete is a current issue in the field of structural retrofitting. The available models well predict the stress–strain behavior under monotonic and cyclic loads. However, in the practical applications, columns that need an increasing of bearing capacity are often strengthened under serviceability load conditions, with a stress and strain state that could change the response of the reinforced systems with respect to the case of the unloaded state. In this paper, the compressive behavior of circular FRP-confined concrete columns with preload is analyzed with the introduction of a modified analysis-oriented model. Differently from the classical formul…
Compressive behaviour of eccentrically loaded slender masonry columns confined by FRP
2018
Abstract Fibre Reinforced Polymer (FRP) confinement represents an effective tool for retrofitting masonry piers or columns enhancing their structural performance. This technique has been widely studied in the literature mainly with reference to short columns, while no extensive information is available on the influence of second order effects on its efficacy in case of slender members. Within this framework, the presented study concerns a simplified method able to assess the effects of FRP confinement on the compressive behaviour of slender masonry columns. A proper constitutive law of FRP confined masonry in compression is adopted for performing a sectional analysis, in which also consider…
Nonlinear Analysis of Reinforced Concrete Frames: Safety Evaluation and Retrofitting Techniques
Optimal design algorithm for seismic retrofitting of RC columns with steel jacketing technique
2020
Abstract Steel jacketing (SJ) of beams and columns is widely employed as retrofitting technique to provide additional deformation and strength capacity to existing reinforced concrete (RC) frame structures. The latter are many times designed without considering seismic loads, or present inadequate seismic detailing. The use of SJ is generally associated with non-negligible costs depending on the amount of structural work and non-structural manufacturing and materials. Moreover, this kind of intervention results in noticeable downtime for the building. This paper presents a new optimization framework which is aimed at obtaining minimization of retrofitting costs by optimizing the position an…
Risk of failure for the salso river railroad steel bridge
2020
Abstract The degradation state of railroad steel bridges is one of the most important and difficult aspects to be interpreted. The use of steel bridges started from 1900, and they are still in service today as railroad bridges. The case study examined was that of a bridge railroad steel bridge having a total length of 112 m and constituted by three isostatic, reticular beams having a Pratt type composition. The substructures (two shoulders and two intermediate piles) are in masonry with a reinforced concrete beam in the upper portion. The structure (steel bridge and piers) is in a degraded state. To determine the degradation level, non-destructive and partially destructive tests were carrie…