scholarly journals Analysis of Stiffness Reduction Coefficient of Conventionally Reinforced Concrete Coupling Beams on the Bias of Strut-and-Tie Model

2020 ◽  
Vol 13 (5) ◽  
pp. 82-89
Author(s):  
Zhangqi Hu ◽  
◽  
Weirong Lv ◽  
Yusheng Wu ◽  
Miao Zhang
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Ratio ◽  
Longitudinal Reinforcement ◽  
Calculation Methods ◽  
Analysis Model ◽  
Coupling Beams ◽  
Stiffness Reduction ◽  
Depth Ratio ◽  
Study Results ◽  
Reduction Coefficient

Stiffness reduction coefficient of coupling beams (κ) can reflect the stiffness degradation degree at yield and significantly affect the seismic response and the internal force distribution. However, existing calculation methods do not consider the influencing factors comprehensively and have a limited application scope. To effectively predict the stiffness reduction coefficient of conventionally reinforced concrete coupling beams (CCBs), a simplified analysis model was established, and analysis and parameter modification were also implemented. Then, an equation with comprehensive consideration, wide application, and high accuracy was proposed. The proposed equation was verified by comparison with existing test data and calculation methods, and parametric analysis was performed to investigate the independent factors, including the span–depth ratio, longitudinal reinforcement ratio, stirrup ratio and concrete compressive strength. Results show that the independent factors are related to each other, and the span–depth ratio has the greatest influence on the stiffness reduction coefficient of CCBs. Furthermore, κ significantly increases with the longitudinal reinforcement ratio when the coupling beam has a large span–depth ratio, but the stirrup ratio has a bigger role when the span-depth ratio is small. Finally, on the basis of the analysis results, suggestions are made to improve the stiffness reduction coefficient of CCBs. The study results provide a reference for the design and optimization of shear wall and core tube structures.

scholarly journals MODELS OF BAY REINFORCED CONCRETE ELEMENTS RESISTANCE AT ACTION OF CYCLE PERMANENT SIGN HIGH LEVEL FORCES

2018 ◽  
Vol 1 (50) ◽  
pp. 112-123 ◽  
Author(s):  
V. M. Karpiuk ◽  
A. I. Kostiuk ◽  
Yu. A. Somina
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Physical Models ◽  
Cyclic Loads ◽  
Longitudinal Reinforcement ◽  
Calculation Methods ◽  
Cyclic Action ◽  
High Level ◽  
Creep Deformations ◽  
Concrete Elements

The reinforced concrete span beam structures work with small, middle and large shear spans under the action of cyclic loads of high levels is investigated. It is established that researches of physical models development of bending reinforced concrete elements fatigue resistance to the cyclic action of transverse forces and calculation methods on its base are important and advisable due to following features of said load type: the nonlinearity of deformation, damage accumulation in the form of fatigue micro- and macrocracks, fatigue destruction of materials etc. The key expressions of the concrete endurance limits definition (objective strength), longitudinal reinforcement, anchoring of longitudinal reinforcement, which consists the endurance of whole construction are determined. Also the role and the features of influence of vibro-creep deformations on the change mechanics of stress-strain state of concrete and reinforcement of research elements are investigated.

scholarly journals Experimental analysis of steel fiber reinforced concrete beams in shear

2022 ◽  
Vol 15 (3) ◽  
Author(s):  
Aaron Kadima Lukanu Lwa Nzambi ◽  
Dênio Ramam Carvalho de Oliveira ◽  
Marcus Vinicius dos Santos Monteiro ◽  
Luiz Felipe Albuquerque da Silva
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Fiber Addition

Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.

scholarly journals Experimental Study on Shear Capacity of High Strength Reinforcement Concrete Deep Beams with Small Shear Span–Depth Ratio

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1218 ◽  
Author(s):  
Jun-Hong Zhang ◽  
Shu-Shan Li ◽  
Wei Xie ◽  
Yang-Dong Guo
Keyword(s):  
High Strength ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Longitudinal Reinforcement ◽  
Deep Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Diagonal Compression ◽  
Web Reinforcement ◽  
Small Shear

This study aimed to investigate the shear capacity performance for eight deep beams with HTRB600 reinforced high strength concrete under concentrated load to enable a better understanding of the effects of shear span–depth ratio, longitudinal reinforcement ratio, vertical stirrup ratio and in order to improve design procedures. The dimension of eight test specimens is 1600 mm × 200 mm × 600 mm. The effective span to height ratio l0/h is 2.0, the shear span–depth ratio λ is 0.3, 0.6 and 0.9, respectively. In addition, the longitudinal reinforcement ratio ρs is set to 0.67%, 1.05%, 1.27%, and the vertical stirrup ratio is taken to be 0%, 0.25%, 0.33%, 0.5%. Through measuring the strain of steel bar, the strain of concrete and the deflection of mid-span, the characteristics of the full process of shear capacity, the failure mode and the load deflection deformation curve were examined. The test results showed that the failure mode of deep beams with small shear span–depth ratio is diagonal compression failure, which is influenced by the layout and quantity of web reinforcement. The diagonal compression failure could be classified into two forms: crushing-strut and diagonal splitting. With decreasing of shear span–depth ratio and increasing longitudinal reinforcement ratio, the shear capacity of deep beams increases obviously, while the influence of vertical web reinforcement ratio on shear capacity is negligible. Finally, the shear capacity of eight deep beams based on GB 50010-2010 is calculated and compared with the calculation results of ACI 318-14, EN 1992-1-1:2004 and CSA A23.3-04, which are based on strut-and-tie model. The obtained results in this paper show a very good agreement with GB50010-2010 and ACI 318-14, while the results of EN 1992-1-1:2004 and CSA A23.3-04 are approved to be conservative.

scholarly journals Shear capacity of reinforced concrete beams strengthened with web side bonded CFRP sheets

2019 ◽  
Vol 258 ◽  
pp. 04010
Author(s):  
Rendy Thamrin ◽  
Zaidir ◽  
Sabril Haris
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Longitudinal Reinforcement ◽  
Flexural Mode ◽  
Cfrp Sheets ◽  
Reinforced Polymer

The shear capacity of reinforced concrete beams strengthened with web side bonded carbon fiber-reinforced polymer (CFRP) sheets was measured experimentally. Nine reinforced concrete beams without stirrups; three control beams and six beams strengthened with minimal application of web side bonded CFRP sheets, were tested. The test variables were ratio of longitudinal reinforcement (1%, 1.4%, and 2.4%) and angle of application of CFRP sheets (450 and 900). The test results show that reinforced concrete beams strengthened with web side bonded CFRP sheets have higher shear capacity compared to the control beams. Shear capacity of strengthened beams with 450 angle of application of CFRP sheets is similar to that of beams strengthened with 900 angles. Beams with 1% of longitudinal reinforcement ratio failed in flexural mode indicated by concrete crushing in compression zone while beams with higher longitudinal reinforcement ratio (1.4% and 2.4%) failed in brittle mode as indicated by delamination of the concrete cover.

A Method for Calculating Cracking Moment of FRP Reinforced Concrete Beam

2021 ◽  
Vol 896 ◽  
pp. 141-147
Author(s):  
Duy Nguyen Phan
Keyword(s):  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Parametric Study ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Comparison Results ◽  
Study Results ◽  
Frp Reinforcement

This paper presents an analytical method for calculating the cracking moment of concrete beams reinforced with fiber reinforced polymer (FRP) bars, which considers the non-linear behavior of concrete in the tension zone and the contribution of FRP reinforcement. Theoretical cracking moments obtained by the proposed method were verified with the experimental results and the theoretical results calculated according to ACI 440.1R-15. The comparison results show good agreement between theoretical and experimental data. A parametric study on the effect of longitudinal FRP reinforcement ratio and elastic modulus of FRP on the cracking moment of FRP reinforced concrete beams also were done by using the proposed method. The parametric study results show that both longitudinal reinforcement and modulus of elasticity of FRP significantly affect the cracking moment of FRP reinforced concrete beams. Moreover, parametric study results also clarify the weakness of ACI 440.1R-15 in determining the cracking moment of concrete beams reinforced with a large amount of FRP reinforcement ratio and with high modulus of elasticity of FRP.

Parametric Analysis of Shear Behavior of Concrete Beams Reinforced with Continuous FRP Rectangular Spirals

2012 ◽  
Vol 217-219 ◽  
pp. 2435-2439
Author(s):  
Ying Tao Li ◽  
Shi Yong Jiang ◽  
Bing Hong Li ◽  
Qian Hua Shi ◽  
Xian Qi Hu
Keyword(s):  
Parametric Analysis ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Behavior ◽  
Shear Capacity ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Shear Span ◽  
Depth Ratio

An experimental program was carried out by the author to investigate the shear behavior of concrete beams reinforced with continuous FRP rectangular spirals, the main variables considered in the test were the shear reinforcement ratio and the shear span to depth ratio and the longitudinal reinforcement ratio. However, the experimental program is inadequate to gain insight into the shear behavior of the members. First, the quantities of test specimens were too small, only six beams were made and tested, the experimental database was so limited that the resultant analytical results and conclusions may not be sound enough. Second, not all the main factors that have influences on the shear behavior of the members have been treated as variables in the experimental program, such as the effective transverse compression stress and the concrete compression strength, the influences of these two factor on the shear behavior of the members were not clear yet through the experimental study. Considering the insufficient information provided by the experimental investigation, the parametric analysis of the shear behavior of the members was carried out, and a revised rotating-angle softened truss model for the shear analysis of the members was proposed as the analytical tool. Based on the proposed model, the influences of various factors on the shear capacity and shear failure modes of the members were discussed, related nonlinear analysis was carried out using the arithmetic of iteration and step approximation, and several FORTRAN codes were written accordingly. Through the experimental study and the parametric analysis, it is indicated that the shear capacity and the shear failure modes of the members are greatly influenced by three major factors, including the shear reinforcement ratio and the shear span to depth ratio and the effective transverse compression stress. The influences of the concrete compression strength and the longitudinal reinforcement ratio on the shear capacity are not noticeable comparatively. The shear capacity is little affected by the shear span to depth ratio in the case of the shear-tension failure, there is no noticeable correlation between longitudinal reinforcement ratio and the shear failure modes.

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