Search results for "Columns"
showing 10 items of 40 documents
Effects of circular openings on the compressive behaviour of R.C. columns
2014
Core-drilling technique is nowadays always more frequently performed in existing reinforced concrete (RC) structures in order to investigate on the mechanical properties of concrete and for structural health monitoring purposes. Even if the engineering practice discourages to drill columns, this can be often unavoidable. In this last case the presence of the circular opening influences the compressive behavior of the column in terms of load-carrying capacity and axial deformability. The goal of this investigation was the experimental evaluation of the effects induced by circular openings on the behavior of RC columns. Twenty-four reinforced and plain concrete prisms in presence of circular …
Frictional effects in structural behavior of no-end-connected steel-jacketed RC columns: Experimental results and new approaches to model numerical a…
2017
Steel jacketing of reinforced concrete (RC) columns is a common retrofitting technique used to restore bearing and deformation capacity of buildings presenting structural deficiencies. For practical reasons, steel angles are in several cases arranged leaving a gap with the end beams or slabs. Despite this disconnection, the angles are still able to support a non-negligible portion of load because of the frictional forces developed along the column-angle contact interface. In these cases, the definition of computational numerical and analytical models for the assessment of reinforced cross sections becomes more complex and must be handled with care. The actual load-carrying capacity of the a…
Dimensionless analysis of RC rectangular sections under axial load and biaxial bending
2012
This paper proposes a numerical procedure able to provide ultimate curvature and moment domains of rectangular RC sections subjected to combined axial load and biaxial bending. The formulation is carried out in dimensionless terms in order to give results that are valid for classes of sections characterized by the same values of the geometric and mechanical parameters governing the section response. The role of some of these parameters is investigated here. The results show possible correlations linking the actual values of moment and curvature to the values corresponding to two cases of uniaxial bending to be considered separately. © 2012 Elsevier Ltd.
RC column externally strengthened with RC jackets
2013
In this paper the behaviour in compression of RC columns externally strengthened with concrete jacketing is analysed and a cross-section analysis of the jacketed member under axial load and bending moment is developed. The focus was to study the effect of confinement of concrete jacket on concrete core and the behaviour of compressed bars with buckling effects. Some other important aspects such as shrinkage, creep, old to new concrete surfaces and bond split effects were not included in the model because: the use of thick non-shrink grout jacket and a well-roughened surface of old-to-new concrete was supposed; long term effects were included though corrective coefficients for monolithic beh…
Applicability of over-coring technique to loaded RC columns
2014
Stress determination is a very important step in the assessment of the safety of existing reinforced concrete structures. In rock mechanic this goal is achieved with the over-coring technique. The main idea behind such a technique is to isolate a material sample from the stress field in the surrounding mass and monitor its re-equilibrium deformation response. If the materials remains elastic, and elastic properties are known, stresses may be obtained from the corresponding measured strains. The goal of this paper is to evaluate if the over-coring technique is applicable to reinforced concrete members. The results of an experimental investigation on the behaviour of compressed concrete colum…
EFFICACY OF PBO-FRCM STRENGTHENING OF RC COLUMNS IN MRFS
2019
Innovative materials and techniques are widespread used for the strengthening and rehabilita-tion of existing structures. Recent researches have been developed on new fiber reinforced composites in which epoxy resin is replaced by inorganic cementitious material. These kind of cement-based composite material is known as Fiber Reinforced Cementitious Matrices (FRCM) recently used also in combination with synthetic polymeric fibers named PBO. The efficiency of this new confining system has been demonstrated by a large number of com-pression tests on concrete specimens while there are only few experimental researches on the behaviour of large scale specimens under external action able to simul…
Effect of steel collars on the seismic behaviour of granite and heavy stone columns
2013
Granite and heavy stone circular columns could be often find in the cultural heritage among ancient churches and historical buildings in all the Mediterranean area. Their good strength properties allowed to carry great load values, while their bright colours and aesthetical characteristics have been used by a lot of ancient architects to achieve structural solutions with great visual impact. Even if such materials have great compressive strength values, the environmental effects, such as long term effects and thermal loads, could damage the structural members, by cracking them. In this way the slenderness of the column increases, and the presence of an imposed ground motion could be very da…
Occurrence of fumonisins in organic and conventional cereal-based products commercialized in France, Germany and Spain
2013
A fast and effective method for quantitative determination of fumonisins B1 and B2 (FB1 and FB2) in different cereal-based products was developed. Fumonisins were extracted combining a solid liquid extraction (SLE) pre-treatment and immunoaffinity columns (IACs), which were applied for an effective clean-up. Consecutively, high pressure liquid chromatography (HPLC) coupled to hybrid triple quadrupole-linear ion trap mass spectrometer (QTrap®) was used for the separation, detection and quantification of targeted mycotoxins. The analytical method showed acceptable recoveries ranged from 89.7% to 99.1%, as well as a relative standard deviation (%, RSD) lower than 12%. A total of 1250 samples f…
Rapid mycotoxin analysis in human urine: A pilot study
2011
A simple and rapid method effective for quantitative determination of deoxynivalenol (DON), T-2 toxin (T-2), HT-2 toxin (HT-2), zearalenone (ZEN), ochratoxin A (OTA), aflatoxins (AFs) B(1), B(2), G(1) and G(2) and fumonisins FB(1) and FB(2) in urine was developed. The urine was diluted with phosphate buffer solution (PBS) and thoroughly mixed. For clean-up and extraction, the mixture was loaded on a MYCO 6in1 IAC. Hybrid triple quadrupole-linear ion trap mass spectrometer (QTrap) was used for the detection. Extra tools for confirmation of selected mycotoxins in positive samples, Information Dependent Acquisition (IDA) experiments, were also developed. The use of immunoaffinity columns follo…
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…