scholarly journals Research on the Estimation Method of the Stiffness Degeneration Index of Reinforced Concrete Members

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yukui Wang ◽  
Zhefeng Liu ◽  
Weijun Yang ◽  
Jian Wang ◽  
Xiao Zheng
Keyword(s):  
Reinforced Concrete ◽  
Estimation Method ◽  
Reinforcement Ratio ◽  
Stiffness Degradation ◽  
Design Parameters ◽  
Transverse Reinforcement ◽  
Degradation Index ◽  
Cumulative Energy ◽  
Concrete Members ◽  
Prediction Reliability

Based on variable amplitude displacement cycle tests of 24 reinforced concrete members with different reinforcement conditions, the stiffness degradation index was proposed to describe the damage. The relationship between the stiffness degradation index, the displacement history, and the cumulative energy dissipation was studied; on this basis, an estimation method for the stiffness degradation index was proposed. By comparing the experimental values and estimated values of the stiffness degradation index, the proposed method provides promising prediction reliability and accuracy. The stiffness degradation index has an effective relationship with the structural design parameters. Based on the stiffness degradation index, the reinforced concrete members can be divided into five performance levels: no damage (DK,k < 0), mild damage (0 < DK,k ≤ 0.3), moderate damage (0.3 < DK,k ≤ 0.7), severe damage (0.7 < DK,k ≤ 0.9), and destruction (0.9 < DK,k ≤ 1), which can provide a good reference for the seismic design of reinforced concrete members. The increase in the transverse reinforcement ratio can significantly reduce the stiffness damage, and the effect is more obvious under the conditions of small ductility. Under the same conditions, the smaller the ductility condition is, the smaller the stiffness damage of the reinforced concrete members will be. Therefore, the control of the ductility condition and the increase in the transverse reinforcement ratio are stable and effective methods for controlling the stiffness damage of reinforced concrete members.

scholarly journals Numerical Sensing of Plastic Hinge Regions in Concrete Beams with Hybrid (FRP and Steel) Bars

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3255 ◽  
Author(s):  
Fang Yuan ◽  
Mengcheng Chen
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Plastic Hinge ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Concrete Members ◽  
Steel Bars ◽  
Hybrid Reinforcement ◽  
Steel Hardening

Fibre-reinforced polymer (FRP)-reinforced concrete members exhibit low ductility due to the linear-elastic behaviour of FRP materials. Concrete members reinforced by hybrid FRP–steel bars can improve strength and ductility simultaneously. In this study, the plastic hinge problem of hybrid FRP–steel reinforced concrete beams was numerically assessed through finite element analysis (FEA). Firstly, a finite element model was proposed to validate the numerical method by comparing the simulation results with the test results. Then, three plastic hinge regions—the rebar yielding zone, concrete crushing zone, and curvature localisation zone—of the hybrid reinforced concrete beams were analysed in detail. Finally, the effects of the main parameters, including the beam aspect ratio, concrete grade, steel yield strength, steel reinforcement ratio, steel hardening modulus, and FRP elastic modulus on the lengths of the three plastic zones, were systematically evaluated through parametric studies. It is determined that the hybrid reinforcement ratio exerts a significant effect on the plastic hinge lengths. The larger the hybrid reinforcement ratio, the larger is the extent of the rebar yielding zone and curvature localisation zone. It is also determined that the beam aspect ratio, concrete compressive strength, and steel hardening ratio exert significant positive effects on the length of the rebar yielding zone.

Cracking behaviour of concrete beams reinforced with fiber reinforced plastic rebars

1996 ◽  
Vol 23 (6) ◽  
pp. 1172-1179 ◽  
Author(s):  
R. Masmoudi ◽  
B. Benmokrane ◽  
O. Chaallal
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Test Results ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Concrete Members ◽  
Reinforced Plastic ◽  
Cracking Pattern

This paper presents the results of an experimental investigation on the cracking behaviour of concrete beams reinforced with fiber reinforced plastic rebars. The effects of reinforcement ratio on the cracking pattern, crack spacing, cracking moment, and crack width are investigated. The test results indicate that the reinforcement ratio has no meaningful effect on the cracking moment, which can be calculated as recommended by the ACI code. Also, the use of the equations adopted by ACI and the European codes for the prediction of crack width of conventionally reinforced concrete members is investigated and due modifications are made. Both relationships show good correlation with the test results; and the prediction of crack width of concrete beams reinforced with these two types of fiber reinforced plastic rebars is now possible. Key words: beam, cracking behaviour, cracking moment, crack width, fiber reinforced plastic, flexure, rebars, reinforced concrete, reinforcement ratio.

Analysis on Flexural Capacity of FRP Reinforced Concrete Members

2012 ◽  
Vol 446-449 ◽  
pp. 98-101
Author(s):  
Chun Xia Li ◽  
Zhi Sheng Ding ◽  
Shi Lin Yan
Keyword(s):  
Reinforced Concrete ◽  
Material Properties ◽  
Failure Modes ◽  
Reinforcement Ratio ◽  
Flexural Capacity ◽  
Steel Reinforced Concrete ◽  
Concrete Members

The balanced reinforcement ratio of FRP-reinforced concrete members and the flexural capacity under two different failure modes (concrete crushing and FRP rupture) are established, based on the analysis on flexural capacity of steel-reinforced concrete members in current concrete code. The effect of material properties on the balanced ratio, the variation of flexural capacity with different reinforcement ratio and a simplified nominal flexural capacity under FRP-rupture failure are derived.

scholarly journals The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

2020 ◽  
Vol 10 (10) ◽  
pp. 3570
Author(s):  
Romualdas Kliukas ◽  
Ona Lukoševičienė ◽  
Arūnas Jaras ◽  
Bronius Jonaitis
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

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 Influence of tensile softening of concrete on crack development and failure in concrete and reinforced concrete beams

2019 ◽  
Vol 68 (1) ◽  
pp. 213-223 ◽  
Author(s):  
Marta Słowik
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Plain Concrete ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Concrete Members ◽  
Cracking Process ◽  
Tensile Softening

In the paper, the own test results were presented. The experimental investigation was focused at determining the cracking and load capacity of beams made of concrete. The beams were characterized by different longitudinal reinforcement ratio from zero — plain concrete beams, through low ratio 0.12% — slightly reinforced concrete beams, middle ratio 0.9% — typical reinforced concrete beams, up to the ratios 1.3% and 1.8% — higher reinforced concrete beams. On the basis of the performed experiments and the results of numerical calculations, the process of crack’s formation and crack’s development in plain concrete, slightly reinforced concrete and reinforced concrete beams with different reinforcement ratio was described. When discussing cracking process in the beams, the contribution of strain softening of tensile concrete in the microcracked zone on the character of beams’ failure was analysed as well. Keywords: civil engineering, concrete and reinforced concrete members, cracking and load capacity.

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.

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