Bearing Capacity of Beams Strengthened by Common Methods Considering Strain Lag Effect

2012 ◽  
Vol 166-169 ◽  
pp. 1789-1792 ◽  
Author(s):  
Si Meng Liu ◽  
Qing Yang Liu
Keyword(s):  
Bearing Capacity ◽  
Rc Beams ◽  
Critical States ◽  
Loading Process ◽  
Lag Effect ◽  
The World ◽  
Non Linear ◽  
Reinforcing Material

A lot of bridge reinforcement and rehabilitation projects are been implementing throughout China and many countries in the world. However, some fundamental questions still remain unsettled, and this paper addressed one of them, which is the bearing capacity of strengthened beams. We analyzed the loading process of beams after strengthening with strain lag effect, and focused on several critical states. To validate our conclusions, we developed a non-linear FEM program, and compared the data yielded by program with those from reference. We found that for adequate reinforcement RC beams the influence of strain lag effect on the bearing capacity depends on the property of reinforcing material. The conclusion matched with experiment very well.

Study on Bearing Capacity of Beams Strengthened with Section Enlargement Method Considering Secondary Loading Process

2011 ◽  
Vol 368-373 ◽  
pp. 2200-2203 ◽  
Author(s):  
Si Meng Liu ◽  
Ma Sun ◽  
Qing Yang Liu
Keyword(s):  
Theoretical Analysis ◽  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Civil Infrastructure ◽  
Rc Beams ◽  
Loading Process ◽  
Reinforced Beams ◽  
Bridge Strengthening ◽  
Non Linear ◽  
Reinforcement Beam

Bridges are the key components of civil infrastructure. Since decades ago, bridge strengthening and rehabilitation have become popular and their wider applications would be needed in the future. Although much research was carried in this field, some important problems including bearing capacity of reinforced beams didn’t form concordant views in this community. To research influence on bearing capacity of reinforced RC beams, we analyzed the loading process of RC reinforced beams from the beam-loaded-only stage to that of co-working of compound beams (including original beams and their strengthening layers), developed non-linear FEM program to simulate that loading progress, and finally validated the results with data from reference. This paper presents the theoretical analysis, and compares data yielded by program with those of experiment. We found that for adequate reinforcement beam the influence of secondary loading on the ultimate bearing capacity of reinforced beams is very limited. Our finding was confirmed by the experiment and FEM program.

Overcoming “The Third Way” Concept

2006 ◽  
pp. 126-134
Author(s):  
L. Evstigneeva ◽  
R. Evstigneev
Keyword(s):  
Economic Research ◽  
Economic Uncertainty ◽  
Third Way ◽  
The Third ◽  
Linear Approach ◽  
The World ◽  
Non Linear

“The Third Way” concept is still widespread all over the world. Growing socio-economic uncertainty makes the authors revise the concept. In the course of discussion with other authors they introduce a synergetic vision of the problem. That means in the first place changing a linear approach to the economic research for a non-linear one.

Debonding Behaviors of CFRP Strengthened RC Beams with Weak Interfaces

2013 ◽  
Vol 351-352 ◽  
pp. 587-591
Author(s):  
Sen Li ◽  
Xiao Gang Wang ◽  
Xin Gang Zhou
Keyword(s):  
Tensile Strain ◽  
Structural Integrity ◽  
Structural Performance ◽  
Rc Beams ◽  
Test Results ◽  
Weak Interface ◽  
Premature Rupture ◽  
Loading Process ◽  
Interface Effects

Debonding behaviors of CFRP strengthened RC beams were experimentally investigated under the influence of weak interfaces, which are induced either by defective bonding of replaced cover or expansive cracks. Shown by test results, weak interfaces impaired considerably the structural integrity of strengthening systems during loading, and easily led to CFRP debonding failure. U-strips worked effectively in preventing the integral debonding and guarantee the structural performance of flexural sheets. However, local cover delamination in the loading process and premature rupture of flexural CFRP could still take place due to the weak interface effects. Therefore, allowable tensile strain of flexural CFRP should be reduced, and more strict confinement and anchorage measures should be taken in this case.

Comparison of flexural capacity of different hollow slab beams with/without pavement layer reinforced by steel plates

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Long Liu ◽  
Lifeng Wang ◽  
Ziwang Xiao
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Steel Plate ◽  
Plate Thickness ◽  
Experimental Results ◽  
Nonlinear Material ◽  
Finite Element Models ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Content Type

PurposeReinforcement of reinforced concrete (RC) beams in-service have always been an important research field, anchoring steel plate in the bottom of the beams is a kind of common reinforcement methods. In actual engineering, the contribution of pavement layer to the bearing capacity of RC beams is often ignored, which underestimates the bearing capacity and stiffness of RC beams to a certain extent. The purpose of this paper is to study the effect of pavement layer on the RC beams before and after reinforcement.Design/methodology/approachFirst, static load experiments are carried out on three in-service RC hollow slab beams, meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Last, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsThe experimental results showed that pavement layers increase the flexural capacity of hollow slab beams by 16.7%, and contribute to increasing stiffness. Ductility ratio of SPRCB3 and PRCB2 was 30% and 24% lower than that of RCB1, respectively. The results showed that when the steel plate thickness was 1 mm–6 mm, the bearing capacity of the hollow slab beam increased gradually from 2158.0 kN.m to 2656.6 kN.m. As the steel plate thickness continuously increased to 8 mm, the ultimate bearing capacity increased to 2681.0 kN.m. The increased thickness did not cause difference to the bearing capacity, because of concrete crushing at the upper edge.Originality/valueIn this paper, based on the experimental study, the bearing capacity of hollow beam strengthened by steel plate with different thickness is extrapolated by finite element simulation, and its influence on ductility is discussed. This method not only guarantees the accuracy of the bearing capacity evaluation, but also does not require a large number of samples, and has certain economy. The research results provide a basis for the reinforcement design of similar bridges.

Bearing capacity of non-linear metallic spiders used in point supported glass facades

2012 ◽  
Vol 12 (2) ◽  
pp. 191-204 ◽  
Author(s):  
Yuanqing Wang ◽  
Huanxin Yuan ◽  
Yongjiu Shi ◽  
Yu Zou
Keyword(s):  
Bearing Capacity ◽  
Non Linear

scholarly journals Fracture toughness of RC beams on the shear, strengthening by FRCM system

2018 ◽  
Vol 183 ◽  
pp. 02009 ◽  
Author(s):  
Zinoviy Blikharskyy ◽  
Pavlo Vegera ◽  
Rostyslav Vashkevych ◽  
Taras Shnal
Keyword(s):  
Fracture Toughness ◽  
Bearing Capacity ◽  
Shear Failure ◽  
Control Sample ◽  
Variable Parameter ◽  
Rc Beams ◽  
Maximum Width ◽  
Shear Span ◽  
Initial Load ◽  
Inclined Cracks

This research paper present the experimental study of reinforce concrete beams strengthened by FRCM system in the shear area. All samples are without transverse reinforcement at the shear distance. First beams tested as control sample, with shear distance a/d=2. Another three beams tested with strengthening by FRCM system. Variable parameter is the level of initial load, before strengthening. The initial load values were 0, 0.3, 0.5 from carrying capacity of control samples. All RC beams were designed to fail in shear, even strengthened samples. In the result of this research we determined that fracture toughness of RC beams increases with a decrease of span to the effective depth ratio. Results are comparable with the increasing of bearing capacity. The first inclined crack opend in mid-height cross section at the load 50 kN at an angle equal to 450 and it does not depend on the shear span. The maximum width of inclined cracks decrease with decreasing of shear span. The maximum width of inclined cracks decrease with decreasing of the shear span. The maximum values of width of inclined cracks are fixed at the value of 0.55 - 0.85 mm. Using the limit crack opening width as criteria of exhaustion of serviceability (SLS) we saw that about 16 - 29% of bearing capacity still remains before the danger of shear failure of the beam.

scholarly journals СОФІЯ ДЛЯ АВІА

2019 ◽  
pp. 87-96
Author(s):  
А. Л. Свящук
Keyword(s):  
System Theory ◽  
Political System ◽  
Point Of View ◽  
Aircraft Industry ◽  
Philosophical Foundations ◽  
Black Swans ◽  
The World ◽  
Non Linear ◽  
Probabilistic Nature

In the time when the basic formulas and approaches of the aircraft industry are based on the principles of classical science, the nature of the observed phenomena seems non-linear. Such phenomena as turbulence, flutter, buffering, disruption of the air flow can be explained by means of synergetics and system theory in the context of the post-non-classical paradigm. However, a certain contradiction can be observed: non-linear phenomena are explained by linear traditional science. That is why many formulas of aerodynamics and strength have a large empirical part. Therefore, it becomes necessary to revise the philosophical foundations of most approaches and the overall picture of the world as a whole. The use of the concepts of synergetics and system theory allows us to describe more accurately certain phenomena in aviation, which ultimately will lead to the creation of more efficient and safer aircraft. For example, we can design our aircraft not only as a complex system, but also as part of other complex systems, evaluating its effectiveness from the point of view of more ambitious and higher levels, predicting its operation and modernization in the changing conditions of the socio-political system. Moreover, the very nature of engineering creativity based on synergistic approaches will become more efficient and effective by increasing the intensity of aviation thought. Therefore, understanding the role of chance, the effect of emergence will allow us to be prepared for many surprises and black swans and also be wary about our knowledge, assessing their probabilistic nature.

scholarly journals Is our perception of the spread of COVID-19 inherently inaccurate?

2021 ◽  
Author(s):  
Alexander Maier
Keyword(s):  
Decision Making ◽  
Subjective Perception ◽  
Logarithmic Function ◽  
Original Formulation ◽  
Global Crisis ◽  
New Information ◽  
The World ◽  
Non Linear ◽  
The Future ◽  
Linear Nature

One of the most fundamental insights into the nature of our subjective perception of the world around us is that it is not veridical. In other words, we tend to not perceive information about the world around us accurately. Instead, our brains interpret new information through a host of innate and learned mechanisms that can introduce bias and distortions One of the best studied mechanisms that guide – and distort – our perception is the psychophysical Weber-Fechner law. According to this empirically derived, mathematically formulated law we tend to put more emphasis on smaller deviations in size while underestimating larger changes. The original formulation of the Weber-Fechner law takes the shape of a logarithmic function and is commonly applied to somatosensory perception such as the weight of an object. However, later work showed that the Weber-Fechner law can be generalized and describe a large variety of perceived changes in magnitude that even go beyond the sensory domain. Here we investigate the hypothesis that our perception of data associated with the spread of COVID-19 and similar pandemics is governed by the same psychophysical laws. Based on several recently published studies, we demonstrate that the Weber-Fechner law can be shown to directly affect the decision-making of officials in response to this global crisis as well as the greater public at large. We discuss how heightened awareness of the non-linear nature of subjective perception could help alleviate problematic judgements in similar situations in the future.

scholarly journals Experimental and Numerical Study on Ultimate Shear Load Carrying Capacity of Corroded RC Beams

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhanzhan Tang ◽  
Zhixiang He ◽  
Zheng Chen ◽  
Lingkun Chen ◽  
Hanyang Xue ◽  
...  
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Cross Section ◽  
Loss Rate ◽  
Numerical Study ◽  
Rc Beams ◽  
Load Carrying ◽  
Shear Bearing Capacity ◽  
The Cross ◽  
The Impact

For an RC beam, the strength of steel rebar, the bonding strength between the concrete and reinforcement, and the bite action between the aggregates will deteriorate significantly due to corrosion. In the present study, 10 RC beams were designed to study the impact of corrosion on the shear bearing capacity. The mechanism of corrosion for stirrups and longitudinal bars and their effects were analyzed. Based on the existing experimental data, the correlation between the stirrup corrosion factor and the cross section loss rate was obtained. An effective prediction formula on the shear bearing capacity of the corroded RC beams was proposed and validated by the experimental results. Moreover, a numerical analysis approach based on the FE technique was proposed for the prediction of the shear strength. The results show that corrosion of the reinforcements could reduce the shear strength of the RC beams. The corrosion of stirrups can be numerically simulated by the reduction of the cross section. The formulae in the literature are conservative and the predictions are very dispersed, while the predictions by the proposed formula agree very well with the experiment results.

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