Papers by Keyword: Column

Abstract: Shear failure of column causes the column to have shear reinforcement that cannot withstand shear forces so that it loses of lateral strength quickly. This research aims to see the effect of the configuration with the addition of shear reinforcement in the direction and perpendicular to the direction of the shear force on the capacity of reinforced concrete columns that are loaded with axial and lateral loads. The test was carried out by providing a constant axial load (0.3 P₀) followed by a shear load until the test object failed. The numerical analysis was carried out using software based on the finite element method, namely ATENA Version 5 and GID Version 13.0.1 developed by Cervenka Consulting. This study used reinforced concrete with three variables of shear reinforcement. It can be the normal columns without stirrup reinforcement (S₀P₂), the addition three (3) stirrups in the direction of the shear reinforcement (S₄P₂) and the addition of two (2) stirrups in the direction of the shear reinforcement and one (1) stirrups perpendicular to the shear reinforcement (S₅P₂). After the numerical analysis is carried out, the results are verifies using experimental testing. The numerical analysis and experimental results give the load and deflection relationship results that are almost close. Therefore, the difference in shear loads compared to the experiments results and numerical analysis on columns S₀P₂, S₄P₂, and S₅P₂ is 0.11%, 3.95% and 1.16%, respectively, with a deflection ratio of 4.72%, 37.80% and 9.44%. The pattern of column destruction in the numerical model resembles the destruction pattern of the experimental results, both of which indicate that the column has shear cracks.

Abstract: In analytical form, formulas are obtained for the amplitude of forced harmonic longitudinal vibrations of reinforced concrete and fiber-reinforced concrete columns with fixed edges. In order to verify the proposed approach, columns were simulated in the ANSYS program and calculated by the finite element method. Analysis of the calculations shows that a significant raise in the amplitude of the forced vibrations is observed only in the region of the first resonant frequency. It has been established that the value of the maximum amplitude of the vibrations of the fiber reinforced concrete column is 16% less than that for a reinforced concrete column.

Abstract: Little research has been carried out in validating, fiber reinforced polymer (FRP) concrete strengthened column and the effective using partial wrapping. Also the effect of several parameter on strengthen column using the partial wrapping sheet of desired width and thickness around column have not been found out. To this end, a nonlinear 3D finite element model has been developed in current study for CFRP strengthened reinforced concrete column to simulate the behavior accompanied by the effect of partial wrapping with emphasis on load capacity and failure mode. The finite element simulation of CFRP strengthened RC columns is performed using commercial finite element program ABAQUS. Modelling was conducted on reinforced concrete columns with dimensions of 160 x 250 x 960 mm. The finite element model incorporates the nonlinear material behavior of concrete, bilinear stress-strain curve of steel and linear elastic behavior of CFRP material. The concrete was modeled using a plastic damage model. The performance of the FE model was studied by simulating experimental columns from the literature. The load, and strain of CFRP obtained from the FE study were compared with the corresponding experimental results. The FEM results agreed well with the experiments. In addition, to enhance our understanding of the behavior of strengthened reinforced concrete column capacity using partial wrapping the effect of changing the spacing between the CFRP sheets and number of layers were examined. The increase number of layers and decrease spacing give a higher ultimate load capacity, and delay the failure.

Abstract: Existing masonry columns are often susceptible to cracking due to overloading. Moreover, their fragility under earthquakes’ forces is of particular concern in seismic-prone regions. In order to mitigate these structural deficiencies, Fiber Reinforced Polymers (FRPs) are commonly used for external confinement. Full-jacketing, by means of FRP-wrapping is recognized to be very effective in improving the load bearing capacity and the ductility of masonry columns. Unfortunately, long-term effects seem to be detrimental for the masonry core, since its breathability is obstructed by the polymeric resin. Thus, a discontinuous application of the FRP-confinement appears to be more indicated in stone-masonry columns, allowing the humidity cycles to recur. On the other hand, the discontinuous wrapping negatively affects the confinement effectiveness, since both confined and unconfined masonry regions participate in the bearing capacity. In this sense, the present research is aimed to study the discontinuous confinement of half-scale masonry columns by means of Carbon-FRP strips. Unconfined and confined specimens were tested under uniaxial compression. The CFRP-confinement was studied by investigating the lateral strain in the confined and unconfined portions of the specimens. The results are reported and discussed in the paper in terms of failure modes, axial stress-strain and axial stress versus lateral strain relationships. The outcomes are reasonably convenient for a proper analytical interpretation of the phenomenon.

Abstract: This study proposes steel bar prefabrication technology including V-type supplementary tie and closed hoops for seismic strengthening of deficient columns. The axial concentric behavior of the columns strengthened with proposed approach in the jacket section was examined using five full-scale specimens. Test results showed that the axial strength of the strengthened columns can be estimated conservatively in accordance with the prediction equations of ACI 318-14 approach. The axial ductility of the strengthened columns was 1.4 times as high as that of the existing column. Overall, the proposed technology is effective in enhancing the axial stiffness, strength, and ductility of the deficient columns.

Abstract: The paper describes a comparison of experimental results and theoretical predictions regarding the lateral force-displacement response of built-up battened steel columns including semi-rigid and partial-strength base plate connections. Two specimens, representing samples of columns extracted from an existing industrial building, were fabricated and tested. Different types of both the battens and the base-plate connections characterized the two specimens. Preliminary lateral-loading tests in a range of elastic response, under varying levels of the concomitant axial force, allowed both exploring initial (elastic) stiffness and estimating yield displacements. Subsequently, cyclic lateral-loading tests with a given value of the axial force allowed investigating the restoring force characteristics in case of seismic actions. First, the paper describes and comments on the experimental performance of the two specimens. Second, numerical finite-element model predictions are illustrated and compared with experimental results. Third, based on the experimental results, as well as on the FE model analysis, the study looks for possible extensions and adaptations to current Eurocode 3 prediction models.

Abstract: One of the work cycles of reinforced concrete structures is the state of repair and reconstruction, including the steps of strengthening elements. The traditional types of strengthening of reinforced concrete which are steel and concrete collars and shirts - now are receding into the background. New methods of strengthening with modern materials such as lamellae are increasingly being used. The article deals with the issues related to strengthening the structures made of high-strength concrete using composite polymeric materials.

Abstract: The effectiveness of FRP systems as a confinement technique to strengthen masonry columns has been widely investigated in the last decades. Recently, a new technique, Fabric Reinforced Cementitious Matrix (FRCM), based on the use of fibrous nets embedded in inorganic matrix, has been developed and investigated as a strengthening solution in masonry buildings. Actually, the number of experimental tests on masonry columns confined by using FRCM systems is very limited, especially for real scale specimens. To fill such gap an experimental program aimed at investigating the behaviour of full scale columns made of limestone masonry blocks confined with different FRCM systems has been carried out. The results of four uniaxial compression tests are illustrated and discussed. The used FRCM systems are made with glass and basalt dry nets embedded in a lime-based mortar. The influence of transverse confinement by using internal reinforcement in forms of pultruded GFRP bars has been also investigated. The mechanical properties of the confined specimens resulted increased in terms of load-carrying capacity and ultimate axial strain.

Abstract: Numerical analysis of masonry structures is a complex task requiring deep knowledges about the problematics. This paper deals with concentrically compressed brick masonry column reinforced by fiber reinforced polymer (FRP) wrapping. The experimental research across the world has proved that FRP external sheets are an efficient tool for stabilization or strengthening of masonry structures. A combination of several types of column’s failure were observed during the experimental testing – failure in masonry, rupture of FRP sheet or failure at interface between reinforcement and masonry support. The rupture of sheet occurs close to sharp corners under the assumption of sheets’ perfect overlap. The rounded corners result in an enlargement of the FRP-masonry contact and reduction of the stress concentration. The increasing of an effective area causes a greater influence of FRP wrapping. For all 3D simulations the commercial software package ABAQUS was used and the obtained results are discussed.

Abstract: Any building must ensure safety conditions during the exploitation, at the level of designed exigencies, throughout the entire lifespan. The completion degree of the structural performance requirements, in the given exploitation conditions, results following the assessment of the technical state of the building. This paper presents a case study performed on an industrial “ground floor” type building, with the purpose to assess the exploitation safety level for the constituent structural elements and engineered consolidation measures. The structural reliability solutions have been designed in compliance with the execution possibilities limited by the existing of ventilation tubing , of big dimensions , made in France, of ,,polyester reinforced with glass fiber’’, which is situated along columns of axis A, at 30 cm approximate and the owner cannot to interrupt the technological process during the works.