scholarly journals The method of analysis of a reinforced concrete section under bending in the post-yield range

2013 ◽  
Vol 12 (1) ◽  
pp. 123-130
Author(s):  
Jacek Korentz
Keyword(s):  
Reinforced Concrete ◽  
Analytical Procedure ◽  
Concrete Cover ◽  
Transverse Reinforcement ◽  
Concrete Members ◽  
Extreme Loads ◽  
Concrete Confinement ◽  
The Moment ◽  
The Relationship ◽  
Concrete Section

Predicting the behavior of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquakes plays an important role in assessing maximum stable deformation capacities of framed concrete structures. This paper presents an analytical procedure for analysing the behaviour of a reinforced concrete section under bending in the post-yield range. The following stages of section behaviour are defined as the uncracked; first cracked; yielding; cover crushing; cover spalling; buckling of bars; and limit stages. The relationship between the moment and curvature in these stages, including the effects of concrete confinement, the spalling of the concrete cover, and the inelastic buckling of the reinforced bars, are considered. The results obtained from analytical calculations have are compared to the results obtained from a computer analysis. The presented method makes it possible to estimate the ductility of reinforced concrete members with various longitudinal and transverse reinforcement.

scholarly journals Methods of analysis of a reinforced concrete section under bending with axial force in the post-yield range

2014 ◽  
Vol 13 (3) ◽  
pp. 119-126
Author(s):  
Jacek Korentz
Keyword(s):  
Reinforced Concrete ◽  
Axial Force ◽  
Concrete Cover ◽  
Reinforcing Bars ◽  
Concrete Members ◽  
Extreme Loads ◽  
Concrete Confinement ◽  
The Moment ◽  
The Relationship ◽  
Concrete Section

Predicting the behaviour of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquakes plays an important role in assessing maximum stable deformation capacities of framed concrete structures. This paper presents the analytical procedure for analysing the behaviour of a reinforced concrete section under bending with axial force in the post-yield range. The following stages of section behaviour are defined: the uncracked, first cracked, yielding, cover crushing, cover spalling, buckling of bars and limit stages. The relationship between the moment and curvature in these stages, including the effects of concrete confinement, the spalling of the concrete cover, and the inelastic buckling of the reinforcing bars, is considered. The presented method makes it possible to estimate the ductility of reinforced concrete members with various longitudinal and transverse reinforcement.

Confinement limits for tension lap slices under static loading

1992 ◽  
Vol 19 (3) ◽  
pp. 447-453 ◽  
Author(s):  
T. Rezansoff ◽  
U. S. Konkankar ◽  
Y. C. Fu
Keyword(s):  
Static Loading ◽  
American Concrete Institute ◽  
Concrete Cover ◽  
Transverse Reinforcement ◽  
Lap Splices ◽  
Lap Splice ◽  
Current Limit ◽  
Concrete Confinement ◽  
Bar Diameter ◽  
Concrete Reinforcement

In tension lap splices, the benefit provided to the lap by stirrups placed to intercept longitudinal cracking due to bond splitting action is recognized by the American Concrete Institute code (ACI 318-89) and the design recommendations of ACI Committee 408, on which the American code provisions are partially based. However, a limit exists on the benefit that can be derived from this confinement. In Canada, Canadian Standards Association Standard CAN3 A23.3 M-84 does not directly recognize the confinement benefit provided by stirrups placed along a lap splice. The current study shows that the ACI limit of 1 bar diameter of equivalent concrete cover provided by the transverse reinforcement confinement is too restrictive under static loading. When the concrete cover is small, much larger transverse reinforcement confinement, up to 2-2.5 bar diameters of equivalent concrete cover, can be utilized, in lieu of requiring very long lap lengths. The tests also show that total confinement (actual concrete confinement plus equivalent concrete confinement provided by stirrups) is effective beyond the current limit of 3 main bar diameters, when stirrups are provided. Good performance was found with confinements of 4-4.5 bar diameters, and correspondingly shorter lap splice lengths. Key words: concrete, reinforcement, lap splices, beams, confinement, stirrups, tension, static loading.

scholarly journals Reinforced concrete beams coated with fiberglass-reinforced polymeric profiles as partial substitutes for the transverse reinforcement

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Igor Souza Hoffman ◽  
Jorge Henrique Piva ◽  
Augusto Wanderlind ◽  
Elaine Guglielmi Pavei Antunes
Keyword(s):  
Reinforced Concrete ◽  
Composite Structures ◽  
Mechanical Performance ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymers ◽  
Transverse Reinforcement ◽  
Structural Applications ◽  
The Moment ◽  
The One

abstract: The use of GFRP (Glass Fiber Reinforced Polymers) structural profiles in the construction sector is growing due to their attractive properties, such as high mechanical strength and durability in aggressive environments. With this, it is necessary to conduct studies that deepen the knowledge about the performance of these materials in structural applications. Therefore, this work aims to analyze the mechanical performance of reinforced concrete beams coated with GFRP profiles, in comparison to reinforced concrete beams, by analyzing groups with different spacing between transversal reinforcement. In all groups there was no change in the longitudinal reinforcement, and the D and Q groups were, respectively, made up of transverse reinforcement spaced twice and quadruple the one calculated for the reference beams, and presented the GFRP profiles in their constitution. All beams were tested at four-point bending, and strain gauges were installed in one of the beams of each group studied. The results obtained in the tests showed an increase in strength of 83.67% in the beams of group D, and 79.91% for group Q, in relation to the references. The analysis of longitudinal deformations made it possible to verify increases in stiffness and the moment of cracking in composite beams. Thus, based on this study, the composite structures studied may constitute future solutions for constructions exposed to aggressive environmental conditions, in order to increase their durability and also to contribute to the design of such structural elements with lower reinforcement rates.

Effectiveness of concrete confinement on lap splice performance in concrete beams under reversed inelastic loading

1989 ◽  
Vol 16 (1) ◽  
pp. 36-44
Author(s):  
B. MacKay ◽  
D. Schmidt ◽  
T. Rezansoff
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Transverse Reinforcement ◽  
Cornell University ◽  
Lap Splice ◽  
Concrete Confinement ◽  
Load Cycling

Proposals from Cornell University for seismic design of lap splices, where the strength provided to the lap splice by the concrete confinement is considered insignificant, were evaluated. The concrete confining the splice length is assumed to deteriorate after high-intensity (inelastic) reversed load cycling so that the performance is mainly dependent on the amount of transverse reinforcement provided to confine the lap splice. Lap lengths of 30–40 bar diameters are proposed, along with heavy transverse reinforcement. Longer lap lengths are considered to be less effective. By contrast, for static loading the concrete confining the splice is known to play a major role in transferring load between the bars along the splice.The current program consisted of testing six reinforced concrete beams under fully reversed cycled loading. The three similar beams in each of the two series contained equal stirrup confinement (number of stirrups) along the lap length to satisfy the Cornell University recommendations for seismic loading for the measured reinforcing yield strength, while the splice length was varied. Splices were located in the bottom face of the test beams and were positioned in a region of maximum moment to ensure severe stressing. Each series of specimens exhibited only small strength gains with increasing splice lengths; however, the performance, when evaluated on the basis of the ductility achieved and the hysteretic energy absorbed prior to failure, was superior with long splices. Since the main reinforcement in the test beams was loaded past yielding, large increases in deformation capacity resulted in only small increases in load.Full reversal inelastic load cycling is very detrimental to the concrete that confines the splice region when compared to static (monotonic) loading or one-directional repeated loading to failure. Splice failure loads under reversal loading in the current study were below predicted static strengths for the same beam configurations, and with the longer lap lengths, static failure would have been flexural rather than in the splice. Key words: reinforced concrete, beams, splices (lap), confinement, seismic design, cycled loading, ductility, strength.

Transverse reinforcement effect on cracking behaviour of R.C. members

1983 ◽  
Vol 10 (4) ◽  
pp. 566-581 ◽  
Author(s):  
S. H. Rizkalla ◽  
L. S. Hwang ◽  
M. El Shahawi
Keyword(s):  
Reinforced Concrete ◽  
Uniaxial Tension ◽  
Crack Width ◽  
Crack Spacing ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Reinforcement Effect ◽  
Concrete Members ◽  
Axial Tension ◽  
Final Crack

Two extensive and independent experimental programs have been conducted to study the cracking behaviour of reinforced concrete members subjected to pure tension in the presence of transverse reinforcement. The first program involved the testing of eighteen reinforced concrete segments and was mainly designed to examine the applicability of the existing equations for predicting crack spacings and widths. The segments were reinforced in two directions and loaded in uniaxial tension beyond the yield stress of the steel. The measured average values of the final crack spacings were compared to the values presented by other researchers. Based on this comparison, a simplified and refined expression for prediction of crack spacing is proposed.The second experimental program involved the testing of sixteen reinforced concrete segments, which were divided into two groups with different concrete covers. Within each group, all segments were identical in all parameters, except the spacing of transverse reinforcement. The program was designed to study the influence of transverse reinforcement spacing on crack behaviour. A methodology including proposed expression for predicting the crack spacing in reinforced concrete members subjected to axial tension with variable transverse reinforcement spacing is presented. Keywords: cracking, crack spacing, crack width, membrane forces, reinforced concrete, tension, transverse reinforcement.

Method for Evaluating the Flexural Stiffness Bar of Reinforced Concrete Structures

2013 ◽  
Vol 351-352 ◽  
pp. 67-74
Author(s):  
E. Fenollosa ◽  
Adolfo Alonso-Durá ◽  
V Llopis
Keyword(s):  
Reinforced Concrete ◽  
Structural Design ◽  
Iterative Process ◽  
Bending Moments ◽  
Biaxial Bending ◽  
Concrete Cracking ◽  
Tangent Stiffness Matrix ◽  
Methods Development ◽  
The Moment ◽  
The Relationship

The structural design methods development nowadays allows including the effects of geometric and mechanical nonlinearity of the materials in the analysis itself. The resolution through matrixes methods frequently involves an incremental treatment for load application and a tangent stiffness matrix that bears in mind the nonlinearity. The present paper shows a procedure to evaluate the bar stiffness considering mechanical nonlinearity of materials. For structures of reinforced concrete formed by two materials where each of them has a resistant behavior so different from the other, its appropriated evaluation is, at the same time, necessary and especially complex. The iterative process exposed here provides the equilibrium position of the section to the general case of axial force and biaxial bending taking into account the nonlinear constituent relationships of materials. Once the equilibrium is reached, the relationship between the biaxial moment and the curvature allows the section stiffness module to be derived, from which the bar stiffness will be determined. As an application of the exposed procedure, the iterative process of the equilibrium research in a section of reinforced concrete is showed. At the moment-curvature diagram can be observed the stiffness progressive decreasing as biaxial bending moments are increasing, because of materials nonlinearity stresses and strains and the section inertia reduction produced by concrete cracking.

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