Search results for "FRP"

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…

Investigation on Application of Basalt Materials as Reinforcement for Flexural Elements of Concrete Bridges

2015

Basalt polymers are rather new materials for civil engineering; therefore, identification of peculiarities and limitations of application of such polymers in concrete structures (particularly bridges) is of vital importance. This paper experimentally investigates deformation behaviour and cracking of flexural elements, which are predominant parameters governing serviceability of the bridges. Unlike a common practice, the present study is not limited by the analysis of concrete beams reinforced with the polymer bars; it also considers effectiveness of basalt fibre reinforced polymer sheets for repairing the beams. The analysis has revealed that a combination of the high strength and elastici…

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…

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…

Flexural behaviour of concrete corbels containing steel fibers or wrapped with FRP sheets

2005

In the present paper an analytical and experimental investigation referring to the flexural behaviour of reinforced concrete corbels subjected to vertical forces is presented. For fixed shape and dimensions of the corbels the experimental investigation analyses the effects of the following: longitudinal and transverse steel reinforcements; fiber reinforced concrete (FRC) with hooked steel fibers; external wrapping retrofitting technique with a thin layer of carbon fiber sheet (CFRP). The analytical model based on equivalent truss structures, allows one to determine the bearing capacity of corbels, distinguishing the different ultimate states reached. The analytical results are then compared…

Ultimate Shear of RC Beams with Corroded Stirrups and Strengthened with FRP

2019

Transverse reinforcement plays a key role in the response behavior of reinforced concrete beams. Therefore, corrosion of steel stirrups may change the failure mode of elements from bending to shear, leading to a brittle and catastrophic crisis. It is important to strengthen reinforced concrete beams with corroded stirrups to enhance the shear resistance. This paper presents a formulation, based on the modified compression field theory, to estimate the ultimate shear of reinforced concrete beams strengthened with FRP, because of stirrup corrosion. The detrimental effect of corrosion on steel stirrup yield strength was taken into account by introducing an empirical decay law. The effective st…

Nonlinear Analysis of Reinforced Concrete Frames: Safety Evaluation and Retrofitting Techniques

Nonlinear FE analysis of out-of-plane behaviour of masonry walls with and without CFRP reinforcement

2014

Abstract The out-of-plane behaviour of unreinforced and CFRP reinforced masonry wall is studied by means of experimental investigation and numerical FE modelling. The latter is based on a linear constitutive law both for ashlars and mortar joints constituting masonry and the lines of potential delamination are taken into account by means of an interface element with bi-linear law, reproducing the opening failure mode. When reinforcement is introduced, an interface element with bi-linear law is also used, reproducing sliding failure mode. Comparison between numerical and experimental results show the reliability of the modelling. Moreover, a parametric analysis is carried out in order to inv…

Response behaviour of reinforced concrete beams strengthened in shear with FRP

2019

In this paper an analytical model, able to predict the shear-displacement response of slender RC beams reinforced in shear with FRP, is presented. It allows to evaluate the complete strain and stress fields, for each load step, on the basis of the MCFT framework. The key role of the effective strain of FRP reinforcement at failure has been investigated. At the same time, the interaction FRP-steel stirrups has been taken into account by introducing an appropriate factor. It is able to reproduce the decrease of stirrups stress level when an external reinforcement is used. The proposed model has been validate against a database of specimens collected in literature. Results have shown the remar…

Round Robin Testing initiative for fiber reinforced polymer (FRP) reinforcement

2011

An international Round Robin Testing (RRT) programm e on FRP reinforcement was conducted within the framework of the Marie Curie R esearch Training Network, EN- CORE, and with the support of Task Group 9.3 of the International Federation for Structural Concrete (fib). Eleven laboratories and six manufacturers and suppliers participated in this exercise. As part of this exte nsive experimental endeavour, one or more of the following tests were performed by the partic ipating laboratories: 1) tensile tests on FRP bars and strips; 2) tensile tests on FRP lamina tes; 3) double bond shear tests on FRP laminates (Externally Bonded Reinforcement, EBR) an d FRP bars/strip (Near Surface Mounted rein…