1,721,125 research outputs found
Experimental behavior and analytical modeling of corroded steel rebars under compression
No full textThe durability of reinforced concrete structures can be sharply reduced by the corrosion of the steel rebars. This phenomenon is of great concern, since it is one of main cause of degradation in RC structures, almost in non-exceptional conditions. Furthermore, the corrosion effects can influence the seismic behavior, leading to dangerous strain localizations and variations of strength distribution and rotation capacity. This problem is amplified if, due to the corrosion of the reinforcement, longitudinal and/or transversal, the buckling of the steel bars takes place. Main aim of the paper is the evaluation of the influence of the corrosion on the compressive and buckling behavior of corroded steel reinforcement bars. At the scope, a comprehensive experimental survey has been planned and performed, for different values of steel bar length-to-diameter ratios and different amount of corrosion. Furthermore, based on the obtained outcomes, a simplified analytical model is developed for the definition of the constitutive relationships of corroded bars under compression. (C) 2019 Elsevier Ltd. All rights reserved
SEISMIC DESIGN OF STEEL MRF: REMARKS ON THE BASIS OF NON-LINEAR STATIC AND DYNAMIC PROCEDURES
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Riparazione di travi in c.a. danneggiate da incendio con incamiciature in calcestruzzi fibrorinforzati ad elevate prestazioni.
No full textA repair technique for fire damaged beams, based on the application of a jacket in high performance fiber reinforced concrete, is presented herein. Once checked the feasibility and reliability of the system, the performance of the new composed structure is evaluated and compared with the one of the bare element. Finally, the repaired beam is subjected again to fire. The obtained response clearly shows the effectiveness of the proposed tennique
Evaluation of the bearing capacity of fiber reinforced concrete sections under fire exposure
No full textAim of the paper is the evaluation of the bearing capacity of fiber reinforced concrete (FRC) sections, without any traditional steel reinforcement, subjected to different values of the fire duration. At this purpose, bending moment (M)-axial force (N) interaction envelopes are defined, through an analytical model based on the direct integration of the hot or residual mechanical properties of the material, throughout the member cross section. Finally, a parametric survey, specifically related to tunnel segments, with different geometries and FRC materials allows highlighting the worst (or better) scenarios
Structural performance of corroded R.C. beams
No full textThe structural behaviour of six beams subjected to different corrosion rates, under flexural loads is analysed in the paper. Even if the corrosion consequences at local and global level are well known, the prediction of the structural behaviour of corroded elements, or their residual life is far from being assessed, due to the great number of parameters and uncertainties involved. The experimental survey was conducted with the aim of deepening the present knowledge and draw the largest amount of information on both the artificial corrosion process and structural consequences. At the aim, a comprehensive procedure for the analysis of the corrosion effect is followed, with accurate measurements and cataloguing of both the pits distribution and amount and the related crack pattern before the test, to find possible correlations between these properties. The influence of the corrosion degree and location on the failure mode and on the rotation capacity is further analysed and discussed, and the possible formation of unexpected mechanisms is underlined and justified. Finally, a simplified analytical model, already proposed by the authors is validated, showing its effectiveness and limits of applicability
Experimental investigation on the behaviour of concrete ties reinforced with GFRP bars
No full textAim of the paper is the evaluation of the bond transfer mechanism and the following cracking behavior for concrete elements reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. At the scope, an experimental survey has been developed on nine 3000 mm long fie-specimens with square cross-section of 150 mm x 150 mm, reinforced with a 4000 mm long GFRP reinforcing bar embedded in the centerline. Besides the reference element reinforced with conventional steel rebar with diameter equal to 16 mm, nine GFRP bars with the same equivalent diameter and different surface treatments (smooth, sand-coated and helical fiber wrapped surfaces) were taken into account. The specimens were subjected to tensile force and the obtained results have shown how the different surface coating may affect the bond behavior at the concrete - GFRP interface, and the following crack pattern
A simplified methodology for the evaluation of the residual life of corroded elements.
No full textSteel corrosion is one of the most common causes of deterioration of reinforced concrete structures. In fact, the chemical attack causes cracking in the concrete and a number of related effects that weaken the capacity of the composite, as well as reducing the cross section of the rebars. It is therefore extremely valuable to have methods targeted to the evaluation of the structural damage induced by corrosion for estimating the residual load bearing capacity of a structure, and then for planning the maintenance interventions. The aim of this paper is the development of a simplified methodology capable of providing conservative estimates of the residual life of corroded structures. Because of the great amount of results obtained by the authors, general relationships between the corrosion level and the residual strength and ductility of beams are derived, and their evolution is predicted using conventional deterioration models. The methodology proposed is validated using experimental results from literature
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