scholarly journals The Mechanical Properties of Reinforced Concrete Plate-Girders when Placed Under Repeated Simulated Vehicle Loads

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1831
Author(s):  
Jinquan Zhang ◽  
Pengfei Li ◽  
Yan Mao ◽  
Zhenhua Dong
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Test Beam ◽  
Load Effect ◽  
Plate Girders ◽  
Concrete Plate ◽  
Vehicle Load ◽  
Vehicle Loads

The effect of vehicle loads on reinforced concrete plate-girders was evaluated using the current Chinese specifications. Repeated loading performance tests with loading amplitudes of 77 kN, 97 kN, and 121 kN, which correspond to the standard vehicle load, 1.25 times overload, and 1.6 times overload proportions effect were carried out on three full-scale simply-supported reinforced concrete plate-girders. Our research results indicate that the development of cracks in reinforced concrete beams can be divided into three stages: rapid development, stability, and failure. During the entire process, the strain of steel and concrete did not reach their yield strain. The most severe damage done to the concrete beams was the brittle fractures caused by the fatigue fracturing of the rebar. When in a stable condition, the extent to which the vehicle was overloaded had a significant effect on the fatigue performance of the beam, and the corresponding residual deflection and residual strain increased with the rise in the overload proportion. In addition, as the overload proportion increased, the stiffness degradation and the cumulative damage that occurred under the same loading cycle was more significant. The test beam reached failure after being subjected to 350,000 and 670,000 repeated loading cycles, when the load was 1.6 times and 1.25 times of the standard load effect. With a standard vehicle load effect, the test beam was able to endure 2,000,000 repeated load cycles with no significant degradation in stiffness and bearing capacity.

scholarly journals Experimental Study on Flexural Fatigue Properties of Reinforced Concrete Beams after Salt Freezing

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Jianxi Yang ◽  
Tianmei Zhang ◽  
Quansheng Sun
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Concrete Beams ◽  
Damage Model ◽  
Reinforced Concrete Beams ◽  
Fatigue Properties ◽  
Test Beam ◽  
Residual Deflection ◽  
Freeze Thaw ◽  
Quick Freezing

In order to study the fatigue behavior decay law of reinforced concrete structures in cold region under the action of chlorine salt and freeze-thaw, 150-time water freeze-thaw and salt freeze-thaw cycles of reinforced concrete beams were carried out by the quick freezing method, and then the fatigue properties of the test beams were obtained by the four-point bending fatigue test. The fatigue life of the test beam without freeze-thaw is 1,074,282 times, and the fatigue life of the test beam after freeze-thaw is reduced; the minimum fatigue life of fatigue failure is 493,972. The test results show that the residual deflection of the test beam is similar to the relative dynamic elastic modulus, which accords with the damage and failure mechanism of concrete, and the growth rate of residual deflection accords with the law of the block model. The fatigue damage model of reinforced concrete specimens is established, the nonlinear fitting of the damage model is carried out according to the test data, the fitting correlation coefficient is more than 0.98, which indicates that the model can better reflect the damage degree of concrete, and the method of predicting the life of in-service concrete beam is put forward in combination with the concrete damage model.

Fatigue Life Prediction of Corroded Reinforced Concrete Beams under Repeated Loads

2011 ◽  
Vol 255-260 ◽  
pp. 504-508
Author(s):  
Li Song ◽  
Zhi Wu Yu
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Test Results ◽  
Cycle Fatigue ◽  
Repeated Loads

The behavior of materials under repeated loading has been examined, but extended studies are more and more needed especially for damaged reinforced structures such as bridges, where high-cycle fatigue phenomena and corrosion can be significant. In the present paper, a theoretical model based on fatigue performance of materials and stress analysis for cross-section is proposed in order to analyze the fatigue damage of corroded reinforced concrete beams under repeated loads. Further, fatigue life is predicted by applying this method, and the method is evaluated by test results.

FLEXURAL DUCTILITY OF STRUCTURAL CONCRETE MEMBERS SUBJECTED TO LIMITED CYCLES OF REPEATED LOADING

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Nazar Oukaili ◽  
Mohammed Khattab
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Constant Load ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Structural Concrete ◽  
Concrete Members ◽  
Flexural Ductility ◽  
High Level

For structural concrete members that may expose to serious earthquake, overload or accident impact, the design of ductility must be given the same importance as the flexural strength. The aim of this investigation is to study the change in ductility of structural concrete flexural members during their exposure to limited cycles of repeated loading. Twenty full-scale beam specimens have been fabricated in to two identical groups; each group consisted of ten specimens. The first group was tested under monotonic static loading to failure and regarded as control beams, while the specimens of the second group were subjected to ten cycles of repeated loading with constant load interval, which ranged between 40% and 60% of ultimate load. Specimens in each group were categorized as follows: two traditional reinforced concrete specimens with different intensity of tension reinforcement; three partially prestressed specimens with bonded strands; three partially prestressed specimens with unbonded strands; and two fully prestressed concrete specimens. The main variable, which was considered for all specimens was the partial prestressing ratio (PPR). It was observed that, the ductility of reinforced concrete beams was insignificantly increased during subjecting to limited repeated loading. For fully prestressed and partially prestressed concrete beams with high level of PPR, the ductility was significantly enhanced, while, it was decreased for specimens with small level of PPR.

Application of a Reinforced Self-Compacting Concrete Jacket in Damaged Reinforced Concrete Beams under Monotonic and Repeated Loading

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Constantin E. Chalioris ◽  
Constantin P. Papadopoulos ◽  
Constantin N. Pourzitidis ◽  
Dimitrios Fotis ◽  
Kosmas K. Sideris
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Small Diameter ◽  
Structural Response ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Loading Test ◽  
Flexural Response

This paper presents the findings of an experimental study on the application of a reinforced self-compacting concrete jacketing technique in damaged reinforced concrete beams. Test results of 12 specimens subjected to monotonic loading up to failure or under repeated loading steps prior to total failure are included. First, 6 beams were designed to be shear dominated, constructed by commonly used concrete, were initially tested, damaged, and failed in a brittle manner. Afterwards, the shear-damaged beams were retrofitted using a self-compacting concrete U-formed jacket that consisted of small diameter steel bars and U-formed stirrups in order to increase their shear resistance and potentially to alter their initially observed shear response to a more ductile one. The jacketed beams were retested under the same loading. Test results indicated that the application of reinforced self-compacting concrete jacketing in damaged reinforced concrete beams is a promising rehabilitation technique. All the jacketed beams showed enhanced overall structural response and 35% to 50% increased load bearing capacities. The ultimate shear load of the jacketed beams varied from 39.7 to 42.0 kN, whereas the capacity of the original beams was approximately 30% lower. Further, all the retrofitted specimens exhibited typical flexural response with high values of deflection ductility.

scholarly journals Flexural Behavior of Fiber Reinforced Self-Compacting Rubberized Concrete Beams

2020 ◽  
Vol 26 (2) ◽  
pp. 111-128
Author(s):  
Tamara M. Hasan ◽  
Ahmed S. Ali
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Monotonic Loading ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Repeated Loading ◽  
Fiber Reinforced ◽  
Waste Tire

The massive growth of the automotive industry and the development of vehicles use lead to produce a huge amount of waste tire rubber. Rubber tires are non-biodegradable, resulting in environmental problems such as fire risks. In this search, the flexural behavior of steel fiber reinforced self-compacting concrete (SFRSCC) beams containing different percentages and sizes of waste tire rubbers were studied and compared them with the flexural behavior of SCC and SFRSCC. Micro steel fiber (straight type) with aspect ratio 65 was used in mixes. The replacement of coarse and fine aggregate was 20% and 10% with chip and crumb rubber. Also, the replacement of limestone dust and silica fume was 50%, 25%, and 12% with ground rubber and very fine rubber, respectively. Twelve beams with small-scale (L=1100mm, h = 150mm, b =100mm) were tested under two points loading (monotonic loading). Fresh properties, hardened properties, load-deflection relation, first crack load, ultimate load, and crack width were investigated. Two tested reinforced concrete beams from experimental work were selected as a case study to compare with the results from ABAQUS program (monotonic loading). These two reinforced concrete beams were simulated as a parametric study under repeated loading using this finite element program. The results showed that the flexural behavior of SFRSCC beams containing rubber was acceptable when compared with flexural behavior of SCC and SFRSCC beams (depended on load carrying capacity). Cracks width was decreased with the addition of steel fibers and waste tires rubber.  An acceptable agreement can be shown between the results of numerical analysis and the results obtained from experimental test (monotonic loading). Insignificant ultimate load differences between the results of monotonic loading and repeated loading                                                                                                                                                                                           

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.

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