scholarly journals Mesoscopic Characteristics on Cracks of Three-Point Bending RC Beam with Corroded Reinforcement

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Nan Wu ◽  
Hao Jin ◽  
Qingrong Tian ◽  
Zheng Li
Keyword(s):  
Plastic Strain ◽  
Mechanical Performance ◽  
Lower Boundary ◽  
Concrete Cover ◽  
Rc Beam ◽  
Maximum Deflection ◽  
Rc Beams ◽  
Three Point Bending ◽  
Mesoscopic Models ◽  
Combined Action

The RC beam usually works under the combined action of external loads and corrosion expansion pressures, and the RC beams without corrosion of reinforcements have good mechanical performance. In this study, the mesoscopic models of the three-point bending RC beams with different aggregates, different aggregate contents, and different corrosion expansion pressures were built. The plastic strain and the deflection are analyzed. The results show that the cracks of the RC beam with polygon aggregates are more dispersed than circle aggregates. As the aggregate content increases, the maximum plastic strain and maximum deflection of the RC beam decrease. The aggregate contents increased from 25% to 35%, the maximum plastic strain decreased from 3.4 × 10−3 to 2.1 × 10−3, and the maximum deflection of the lower boundary of the beam decreased from 0.005 m to 0.004 m. Furthermore, the corrosion expansion pressure makes the plastic strain increase in the concrete cover.

Experimental Free Vibration of Damaged RC Beam Models

2019 ◽  
Vol 827 ◽  
pp. 499-504
Author(s):  
R. Capozucca ◽  
E. Magagnini ◽  
M.V. Vecchietti
Keyword(s):  
Free Vibration ◽  
Experimental Tests ◽  
Concrete Cover ◽  
Rc Beam ◽  
Rc Beams ◽  
Response Functions ◽  
Bending Tests ◽  
Damage Degree ◽  
Real Scale ◽  
Theoretical Results

Reinforced Concrete (RC) Beam undamaged and damaged were investigated by free vibration to obtain a variation of frequency values at different degree of damage. Experimental tests were carried out on RC beams in scale and in real scale. The damage of RC beams in real scale was obtained by cracking under static bending tests, while in the case of beam in scale is obtained by notches on the concrete cover with different width. In general, the effects on the dynamic response of diffused damages and of concentrated damages on a section of beam have been experimentally analyzed. The envelope of frequency response functions (FRFs) obtained by dynamic experimental tests was elaborated and the changes of natural frequency values were then correlated to the damage degree of RC beams. The experimental data have been discussed and analyzed by comparison with theoretical results.

scholarly journals Fatigue Stress-Life Model of RC Beams Based on an Accelerated Fatigue Method

2019 ◽  
Vol 4 (2) ◽  
pp. 16
Author(s):  
Eljufout ◽  
Toutanji ◽  
Al-Qaralleh
Keyword(s):  
Cyclic Loading ◽  
Fatigue Testing ◽  
Three Dimensional ◽  
Rc Beam ◽  
Rc Beams ◽  
Testing Methods ◽  
Load Range ◽  
Fatigue Stress ◽  
Life Model ◽  
Prediction Band

Several standard fatigue testing methods are used to determine the fatigue stress-life prediction model (S-N curve) and the endurance limit of Reinforced Concrete (RC) beams, including the application of constant cyclic tension-tension loads at different stress or strain ranges. The standard fatigue testing methods are time-consuming and expensive to perform, as a large number of specimens is needed to obtain valid results. The purpose of this paper is to examine a fatigue stress-life predication model of RC beams that are developed with an accelerated fatigue approach. This approach is based on the hypothesis of linear accumulative damage of the Palmgren–Miner rule, whereby the applied cyclic load range is linearly increased with respect to the number of cycles until the specimen fails. A three-dimensional RC beam was modeled and validated using ANSYS software. Numerical simulations were performed for the RC beam under linearly increased cyclic loading with different initial loading conditions. A fatigue stress-life model was developed that was based on the analyzed data of three specimens. The accelerated fatigue approach has a higher rate of damage accumulations than the standard testing approach. All of the analyzed specimens failed due to an unstable cracking of concrete. The developed fatigue stress-life model fits the upper 95% prediction band of RC beams that were tested under constant amplitude cyclic loading.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

scholarly journals Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

2021 ◽  
Vol 6 (7) ◽  
pp. 97
Author(s):  
Stefanus Adi Kristiawan ◽  
Halwan Alfisa Saifullah ◽  
Agus Supriyadi
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Numerical Study ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Rc Beam ◽  
Shear Span ◽  
Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

Flexural Fatigue Performance of RC Beams Strengthened with Hybrid Fiber Sheets

2012 ◽  
Vol 166-169 ◽  
pp. 1657-1662
Author(s):  
Xu Jun Chen ◽  
Xiao E Zhu ◽  
Zhong Yang ◽  
Mu Xiang Dai
Keyword(s):  
Fatigue Life ◽  
Basalt Fiber ◽  
Reinforced Concrete Beams ◽  
Fatigue Performance ◽  
Rc Beam ◽  
Rc Beams ◽  
Hybrid Fiber ◽  
Cycle Number ◽  
Flexural Fatigue ◽  
Variation Characteristics

Based on the fatigue test for flexural performance of five reinforced concrete beams, the variation characteristics of the crack development, concrete strain, steel strain, fiber strain with the cycle number of the fatigue load were analyzed, and the effect of hybrid fiber sheets and basalt fiber reinforced polymer(BFRP)sheets on flexural fatigue performance of the strengthened beam was studied. The results show that the accumulated damage of RC beams strengthened with hybrid fiber sheets was slowed down significantly, the anti-crack property was much improved, and the fatigue life was greatly prolonged. Compared with the ordinary RC beam and the RC beam strengthened with double BFRP sheets, the fatigue life of RC beams strengthened with hybrid CFRP/BFRP(C/BFRP) sheets and hybrid CFRP/GFRP(C/GFRP) sheets was increased by 291.26%, 298.63% and 10.73%, 13.53%.

scholarly journals MECHANICAL CHARACTERIZATION OF PA 12 AND HDPE PIPES BEFORE AND AFTER AGING IN WATER AT TWO DIFFERENT TEMPERATURES

2021 ◽  
Vol 9 (1) ◽  
pp. 248-256
Author(s):  
J.A. dos Santos ◽  
R.C. Tucunduva ◽  
J.R.M. D’Almeida
Keyword(s):  
High Density Polyethylene ◽  
Mechanical Performance ◽  
High Density ◽  
Effect Of Temperature ◽  
Polyamide 12 ◽  
Polyethylene Pipes ◽  
Before And After ◽  
Different Temperatures ◽  
Deterioration Process ◽  
Combined Action

Polymer pipes are being widely used by many industrial segments. Although not affected by corrosion, the mechanical performance of these pipes can be reduced due to exposure to temperature, UV radiation and by contact with various fluids. Depending on the deterioration process, embrittlement or plasticization may occur, and the service life of the pipe can be severely reduced. In this work, the combined action of temperature and water upon the mechanical performance of polyamide 12 and high-density polyethylene pipes is evaluated. Destructive and non-destructive techniques were used and the performance of both materials was compared. Both polymers were platicized by the effect of water. However, for high density polyethylene the effect of temperature was more relevant than for polyamide. This behavior was attributed to the dependence of the free volume with the markedly different glass transition temperature of the polymers and the temperatures of testing.

scholarly journals Effect of loading rate on flexural behavior of concrete and reinforced concrete beams

2021 ◽  
Vol 15 (3) ◽  
pp. 136-143
Author(s):  
Nguyen Trung Hieu ◽  
Nguyen Van Tuan
Keyword(s):  
Reinforced Concrete ◽  
Loading Rate ◽  
Plain Concrete ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Displacement Curve ◽  
Rc Beams ◽  
Three Point Bending ◽  
Loading Rates ◽  
Hydraulic Servo

The elasto-plastic characteristics of plain concrete are inevitably affected by the loading rate. This paper presents an experimental investigation on the effect of loading rate on flexural behavior of concrete and reinforced concrete (RC) beams, which was carried out with Walter+bai electro-hydraulic servo system. Three-point bending tests on 100 × 100 × 400 mm prismatic concrete samples and 80 × 120 × 1100 mm RC beams with different displacement controlled loading rates of 0.01 mm/min, 0.1 mm/min, and 3 mm/min were imposed. Based on the test results, the effects of loading rates on the load-displacement curve, cracking, and ultimate load-carrying capacities of RC beams were evaluated.

Behavior of Different Corrosion Ratio RC Beams under Fatigue and Monotonic Loads

2010 ◽  
Vol 163-167 ◽  
pp. 3074-3078
Author(s):  
Lei Wang ◽  
Ai Ping Yu ◽  
Bao Chen Liu
Keyword(s):  
Ultimate Load ◽  
Fatigue Loading ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Flexural Stiffness ◽  
Rc Beams ◽  
Reinforced Beams ◽  
Monotonic Loads ◽  
The Impact ◽  
Strength And Ductility

This paper present results and discussions on an experiment study on the impact of corrosion ratio to the RC beams under fatigue and monotonic loads. Seven reinforced beams with the same steel type, concrete cover, steel diameter and ratio were test. The effect of corrosion ratio on flexural stiffness of these RC beams was discussed. Based on fatigue and monotonic test for these beams, the most investigated parameters in this experimental study were distortion, stress distribution, ultimate load of corroded reinforced concrete beams. The results indicate that the effect of corrosion ratio on flexural stiffness of RC beams is very obviously, curvatures of corroded beams increase monotonically with degree of corrosion. Fatigue loading has great impact on the performance of corroded RC beams; it can reduce the ultimate strength and ductility of the beams significantly as corrosion ratio increase.

Shear Failure of Patched Reinforced Concrete Beam without Web Reinforcements

2017 ◽  
Vol 737 ◽  
pp. 441-447 ◽  
Author(s):  
Stefanus Kristiawan ◽  
Agus Supriyadi ◽  
Senot Sangadji ◽  
Hapsara Brian Wicaksono
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Shear Failure ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Patch Repair ◽  
Rc Beam ◽  
Diagonal Crack ◽  
The Web

Degradation of reinforced concrete (RC) element could lead to a reduction of its strength and serviceability. The degradation may be identified in the form of spalling of concrete cover. For the case of RC beam, spalling of concrete cover could occur at the web of the shear span due to corrosion of the web reinfocements. The shear strength of the damaged-RC beam possibly will become less conservative compared to the corresponding flexural strength with a risk of brittle failure. Patch repair could be a choice to recover the size and strength of the damaged-RC beam. This research investigates the shear failure of patched RC beam without web reinforcements with a particular interest to compare the shear failure behaviour of patched RC beam and normal RC beam. The patch repair material used in this research was unsaturated polyester resin (UPR) mortar. The results indicate that the initial diagonal cracks leading to shear failure of patched RC beam occur at a lower level of loading. However, the patched RC beam could carry a greater load before the diagonal crack propagates in length and width causing the beam to fail in shear.

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