Influence of High Column Axial Loads in Exterior R/C Beam-Column Joints

Vladimir Guilherme Haach,Ana Lucia Homce De Cresce El Debs,Mounir Khalil El Debs 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.2

Joints are problematic regions to study and to build because they generally present high steel ratio in reduced geometricaldimensions. Column axial load is one among several variables that influence the behavior of the exterior beam-column joints. Thispaper investigates the influence of the column axial load on the reinforced concrete exterior beam-column joints throughexperimental tests and compares the results with some theoretical methods of failure prediction. Three exterior beam-columnconnections, with the same geometrical properties are tested applying different levels of column axial loads. Then, an analysis ofreinforcement strains and cracking pattern of the joints is presented in an attempt to better explain the behavior of the exterior beamcolumnjoints. Design models are applied to the experimental specimens and their results are compared. The present study indicatesthat the column axial loads influence the failure mode and further research on this topic is necessary to ensure more accuracy of thedesign models in the prediction of the ultimate failure load of beam column joints.

Structural behavior of partially encased composite columns under axial loads

Margot F. Pereira,Silvana De Nardin,Ana L.H.C. El Debs 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6

This paper presents the results of experimental and numerical model analyses on partially encased composite columns under concentric loads. The main objective of this study is to evaluate the influence of replacing the conventional longitudinal and transverse steel bars by welded wire mesh on the structural behavior of these members under concentric loads. To achieve these goals experimental tests on four specimens of partially encased composite columns submitted to axial loading were performed and the results were promising in terms of replacing the traditional reinforcement by steel meshes. In addition, a numerical FE model was developed using the software DIANA® with FX+. The experimental results were used to validate the numerical model. Satisfactory agreement between experimental and numerical results was observed in both capacity and deformability of the composite columns. Despite of the simplifying assumptions of perfect bond between steel and concrete, the numerical model adequately represented the columns behavior. A finite element parametric study was performed and parameters including thickness of the steel profile and the concrete and steel strengths were evaluated. The parametrical study results found no significant changes in the partially encased columns behavior due to variations of the steel profile thickness or yield strength. However, significant changes in the post peak behavior were observed when using high strength concrete and these results suggest a change in the failure mode.

Experimental investigation of longitudinal shear behavior for composite floor slab

Marcela N. Kataoka,Juliana T. Friedrich,Ana Lúcia H.C. El Debs 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.3

This paper presents an experimental study on the behavior of composite floor slab comprised by a new steel sheet and concrete slab. The strength of composite slabs depends mainly on the strength of the connection between the steel sheet and concrete, which is denoted by longitudinal shear strength. The composite slabs have three main failures modes, failure by bending, vertical shear failure and longitudinal shear failure. These modes are based on the load <i>versus</i> deflection curves that are obtained in bending tests. The longitudinal shear failure is brittle due to the mechanical connection was not capable of transferring the shear force until the failure by bending occurs. The vertical shear failure is observed in slabs with short span, large heights and high concentrated loads subjected near the supports. In order to analyze the behavior of the composite slab with a new steel sheet, six bending tests were undertaken aiming to provide information on their longitudinal shear strength, and to assess the failure mechanisms of the proposed connections. Two groups of slabs were tested, one with 3000 mm in length and other with 1500 mm in length. The tested composite slabs showed satisfactory composite behavior and longitudinal shear resistance, as good as well, the analysis confirmed that the developed sheet is suitable for use in composite structures without damage to the global behavior.

Shear transfer mechanisms in composite columns: an experimental study

Silvana De Nardin,Ana Lucia H. C. El Debs 국제구조공학회 2007 Steel and Composite Structures, An International J Vol.7 No.5

In the design of concrete filled composite columns, it is assumed that the load transfer between the steel tube and concrete core has to be achieved by the natural bond. However, it is important to investigate the mechanisms of shear transfer due to the possibility of steel-concrete interface separation. This paper deals with the contribution of headed stud bolt shear connectors and angles to improve the shear resistance of the steel-concrete interface using push-out tests. In order to determine the influence of the shear connectors, altogether three specimens of concrete filled composite column were tested: one without mechanical shear connectors, one with four stud bolt shear connectors and one with four angles. The experimental results showed the mechanisms of shear transfer and also the contribution of the angles and stud bolts to the shear resistance and the force transfer capacity.

Study on the behavior of beam-column connection in precast concrete structure

Marcela N. Kataoka,Marcelo A. Ferreira,Ana Lúcia H.C. El Debs 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.1

Due to the increase of the use of precast concrete structures in multistory buildings, this paper deals with the behavior of an specific type of beam-column connection used in this structural system. The connection is composed by concrete corbels, dowels and continuity bars passing through the column. The study was developed based on the experimental and numerical results. In the experimental analysis a full scale specimen was tested and for numerical study, a 3D computational model was created using a finite element analyze (FEA) software, called DIANA. The comparison of the results showed a satisfactory correlation between loading versus displacement curves.

Computer modeling and analytical prediction of shear transfer in reinforced concrete structures

Marcela N. Kataoka,Ana Lúcia H.C. El Debs,Daniel de L. Araújo,Bárbara G. Martins 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.2

This paper presents an evaluation of shear transfer across cracks in reinforced concrete through finite element modelling (FEM) and analytical predictions. The aggregate interlock is one of the mechanisms responsible for the shear transfer between two slip surfaces of a crack; the others are the dowel action, when the reinforcement contributes resisting a parcel of shear displacement (reinforcement), and the uncracked concrete comprised by the shear resistance until the development of the first crack. The aim of this study deals with the development of a 3D numerical model, which describes the behavior of Z-type push-off specimen, in order to determine the properties of interface subjected to direct shear in terms cohesion and friction angle. The numerical model was validated based on experimental data and a parametric study was performed with the variation of the concrete strength. The numerical results were compared with analytical predictions and a new equation was proposed to predict the maximum shear stress in cracked concrete.

An experimental study of connections between I-beams and concrete filled steel tubular columns

Silvana De Nardin,Ana Lucia H. C. El Debs 국제구조공학회 2004 Steel and Composite Structures, An International J Vol.4 No.4

Frame composed of concrete-filled steel tubular columns and I-shaped steel beam has been researched in order to development reasonable connection details. The present paper describes the results of an experimental program in four different connection details. The connection details considered include through-bolt between I-shaped steel beams and concrete-filled steel tubular columns and two details of welded connections. One of the welded connection details is stiffened by angles welded in the interior of the profile wall at the beam flange level. The specimens were tested in a cruciform loading arrangement with variable monotonic loading on the beams and constant compressive load on the column. For through-bolt details, the contribution of friction and bearing were investigated by embedding some of the bolts in the concrete. The results of the tests show that through-bolt connection details are very ductility and the bearing is not important to the behavior of these moment connections. The angles welded in the interior of the profile wall increase the strength and stiffness of the welded connection detail. In addition, the behavior curves of these connections are compared and some interesting conclusions are drawn. The results are summarized for the strength and stiffness of each connection.

Partially encased composite columns using fiber reinforced concrete: experimental study

Margot F. Pereira,Silvana De Nardin,Ana L.H.C. El. Debs 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.6

This paper addresses the results of an experimental study involving 10 partially encased composite columns under concentric and eccentric compressive loads. Parameters such as slenderness ratio, ordinary reinforced concrete and fiber reinforced concrete, load eccentricity and bending axis were investigated. The specimens were tested to investigate the effects of replacing the ordinary reinforced concrete by fiber reinforced concrete on the load capacity and behavior of short and slender composite columns. Various characteristics such as load capacity, axial strains behavior, stiffness, strains on steel and concrete and failure mode are discussed. The main conclusions that may be drawn from all the test results is that the behavior and ultimate load are rather sensitive to the slenderness of the columns and to the eccentricity of loading, specially the bending axis. Experimental results also indicate that replacing the ordinary reinforced concrete by steel fiber reinforced concrete has no considerable effects on the load capacity and behavior of the short and slender columns and the proposed replacement presented very good results.

FE analysis of RC pipes under three-edge-bearing test: Pocket and diameter influence

Marcela Novischi Kataoka,Jefferson Lins da Silva,Luciane Marcela Filizola de Oliveira,Mounir Khalil El Debs 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.4

This paper studies on the behavior of reinforced concrete (RC) pipes used in basic sanitation in the conduction of storm water and sanitary sewer. Pipes with 800 mm and 1200 mm in diameter were analyzed. The 800 mm pipes were built with simple reinforcement and the 1200 mm pipes with double reinforcement. For the two diameters of pipes the presence or absence of the pocket was evaluated, and the denomination of each one is spigot and pocket pipe (SPP) and ogee joint pipe (OJP), respectively. The 3D numerical models reproduce the three-edge-bearing test that provides information about the strength and stiffness of the reinforced concrete pipes. The validation of the computational models was carried out comparing the vertical and horizontal displacements on the springline and crown/invert and it was also evaluated the reinforcement strains and the crack pattern. As a main conclusion, the numerical models represented satisfactorily the behavior of the pipes and can be used in future studies in parametric analysis.

Soil-structure interaction analysis of beams resting on multilayered geosynthetic-reinforced soil

Deb, Kousik Techno-Press 2012 Interaction and multiscale mechanics Vol.5 No.4

In this paper, soil-structure interaction analysis has been presented for beams resting on multilayered geosynthetic-reinforced granular fill-soft soil system. The soft soil and geosynthetic reinforcements are idealized as nonlinear springs and elastic membranes, respectively. The governing differential equations are solved by finite difference technique and the results are presented in non-dimensional form. It is observed from the study that use of geosynthetic reinforcement is not very effective for maximum settlement reduction in case of very rigid beam. Similarly the reinforcements are not effective for shear force reduction if the granular fill has very high shear modulus value. However, multilayered reinforced system is very effective for bending moment and differential settlement reduction.