Search results for "Rc columns"
showing 10 items of 12 documents
Experimental results of RC columns strengthnened with Fiber Reinforced Cementitious Mortars
2012
The structural behaviour of reinforced concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix was investigated. Specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression to investigate the efficiency of a Polypara-phenylene-benzo-bisthiazole (PBO) Fibre Reinforced Cementitious Mortars (FRCM) system in increasing both carrying capacity and ductility. The experimental results show that confinement with PBO fibre produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardening behaviour up to …
Compressive response of substandard steel-jacketed RC columns strengthened under sustained service loads: From the local to the global behavior
2018
Abstract This paper presents an experimental investigation on substandard partially steel jacketed RC columns strengthened under sustained loads and loaded until failure. The aim of the study is to compare the compressive response of preloaded columns with respect to the tests without preload to obtain a more realistic prediction of load-carrying capacity of structural columns after retrofitting under serviceability loads. The influence of the preload level, the delayed contribution of the confining device during the loading process and the time dependent effects are highlighted for the tested specimens. Based on the experimental observations, an analysis-oriented model is proposed for the …
Analytical prediction of ultimate moment and curvature of RC rectangular sections in compression
2013
This paper presents closed form expressions linking the ultimate bearing capacity to the ultimate curvature of rectangular RC sections subjected to axial load and bending moment acting in one of the two symmetry planes of the section. With respect to possible simplified formulations the following effects are also considered: confinement of the concrete, hardening of the longitudinal reinforcement, and presence of reinforcing bars distributed orthogonally to the neutral axis. The formulation is proposed in dimensional terms after a preliminary definition of the geometrical and mechanical parameters governing the structural response of the class of sections considered. The analytical expressi…
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.
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…
A closed form procedure for the design of longitudinal bars in RC sections subjected to axial load and biaxial bending
2020
This paper presents an analytical procedure for the design of the longitudinal reinforcement in reinforced concrete rectangular sections subjected to axial load and biaxial bending moment. The integration of the equilibrium equations is performed in analytical form for the case of uniaxial moment, including the effect of the reinforcement placed on the sides of the section and adopting code-based constitutive laws for steel and concrete. The strength domain of the section is calculated in closed form for the case of only main steel and in simplified form when including the reinforcement disposed on the side. Additionally, a formulation is proposed for the interaction domain of the two compo…