Research on Fatigue S-N Curves of Corrosion-Damaged Reinforcement

2006 ◽  
Vol 324-325 ◽  
pp. 607-610 ◽  
Author(s):  
Hong Wei Tang ◽  
Shi Bin Li ◽  
Dong Hai Xie ◽  
Cimian Zhu
Keyword(s):  
Fatigue Tests ◽  
Concrete Bridges ◽  
Fatigue Reliability ◽  
Reinforced Concrete Bridges ◽  
Mass Losses ◽  
Minor Degree ◽  
Residual Fatigue ◽  
Severe Degree ◽  
A Minor ◽  
Define Medium

Three corrosion degrees of reinforcement are chosen in this paper, which are considered to simulate minor, medium and severe degrees of corrosion in this field. A reinforcement mass loss about 5% is used to define a minor degree of corrosion, whereas mass losses about 10% and 20% are used to define medium and severe degree of corrosion, respectively. Fifteen specimens of the three corrosion degrees and seven uncorroded specimens are tested under fatigue. According to the results of the fatigue tests, using stress range as fatigue parameter and 50% as guaranteed probability, the fatigue S-N curves of the four different corrosion degrees of deformed reinforcement adaptable for fatigue reliability evaluation are put forward. These curves provide necessary principle for predicting the residual fatigue lives of aged existing reinforced concrete bridges.

Platelet Incorporation of Labelled Adenosine and Adenosine Diphosphate

1969 ◽  
Vol 22 (02) ◽  
pp. 304-315 ◽  
Author(s):  
E. W Salzman ◽  
T. P Ashford ◽  
D. A Chambers ◽  
Lena L. Neri
Keyword(s):  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Platelet Inhibition ◽  
Electron Microscopic ◽  
Platelet Binding ◽  
Minor Degree ◽  
A Minor ◽  
Plasma Marker ◽  
Electron Microscopic Radioautography ◽  
Simultaneous Assessment

SummaryAfter incubation of platelet-rich plasma with labelled adenosine or ADP, platelet incorporation of radioactivity was assessed. Platelets were rapidly separated for counting by filtration through cellulose acetate Millipore. Inulin-H3 served as a plasma marker, and triple isotope techniques permitted simultaneous assessment of the behavior of the adenine and phosphate moieties of ADP without washing of platelets. In other experiments, electron microscopic radioautography was employed to trace the label after platelet incorporation.The results were consistent with previous reports that ADP is dephosphorylated in plasma and is incorporated by platelets only as a dephosphorylated residue, probably adenosine. The label crossed the platelet membrane and entered the platelet, where it was distributed in platelet granules and the agranular cell sap. Concentration within granules occurred to a minor degree.The results support the hypothesis that platelet aggregation by ADP occurs without a persistent bond of ADP to the platelet. Inhibition of aggregation by adenosine probably depends on a metabolic or transport process rather than on competition between adenosine and ADP for platelet binding sites.

The Effect of Type and Height of Piers on the Seismic Behavior of Reinforced Concrete Bridges

2019 ◽  
Vol 41 ◽  
pp. 79-87 ◽  
Author(s):  
Mohamed Cherif Djemai ◽  
Mahmoud Bensaibi ◽  
Fatma Zohra Halfaya
Keyword(s):  
Reinforced Concrete ◽  
Structural Parameters ◽  
Strong Motion ◽  
Concrete Bridges ◽  
Geometrical Parameters ◽  
Girder Bridges ◽  
Building Research Institute ◽  
Reinforced Concrete Bridges ◽  
Dynamic Analyses ◽  
Strong Motion Database

Bridges are commonly used lifelines; they play an important role in the economic activity of a city or a region and their role can be crucial in a case of a seismic event since they allow the arrival of the first aid. Reinforced concrete (RC) bridges are worldwide used type view their durability, flexibility and economical cost. In fact, their behavior under seismic loading was the aim of various studies. In the present study the effect of two structural parameters i.e. the height and the type of piers of reinforced concrete bridges on seismic response is investigated. For that reason, different multi-span continuous girder bridges models with various geometrical parameters are considered. Then, non-linear dynamic analyses are performed based on two types of piers which are: multiple columns bent and wall piers with varying heights. In this approach, a serie of 40 ground motions records varying from weak to strong events selected from Building Research Institute (BRI) strong motion database are used including uncertainty in the soil and seismic characteristics. Modelling results put most emphasis on the modal periods and responses of the top pier displacements, they show the influence of the considered parameters on the behavior of such structures and their impact on the strength of reinforced concrete bridges.

ON THE EFFECT OF EFFORT REGULATION BY MEANS OF TEMPORARY CONTINUITYIN SPLIT SPAN STRUCTURES OF STEELREINFORCED CONCRETE BRIDGES

2021 ◽  
pp. 58-61
Author(s):  
I.Yu. Belutsky ◽  
◽  
I.V. Lazarev ◽  
Keyword(s):  
Reinforced Concrete ◽  
Bending Moment ◽  
Concrete Bridges ◽  
Stress Rate ◽  
Steel Reinforced Concrete ◽  
Reinforced Concrete Bridges ◽  
Effort Regulation

Abstract. The publication shows the effectiveness of applying the principle of temporary continuity by combining split span structures into acontinuous couplingusing a temporary joint. The method can be viewed as an option for effort regulation, creating abearing capacity reserveinload-bearing constructions within the span structures of bridges. The calculations provided show the effect on stress rate and bending moment in split span structurescombined into a double-spancontinuous coupling by a temporary joint.

An old bridge transformed into a new one: possible, recommendable?

2019 ◽  
Author(s):  
Diego Carro-López ◽  
Ignasi Fernandez ◽  
Natalie Williams Portal
Keyword(s):  
Environmental Issues ◽  
Quality Standards ◽  
Structural Effect ◽  
Coarse Fraction ◽  
Concrete Bridges ◽  
Recycled Aggregates ◽  
Structural Elements ◽  
The Past ◽  
Reinforced Concrete Bridges ◽  
Natural Aggregates

<p>There is an extensive network of reinforced concrete bridges that give service to roads, highways and railways. These structures where constructed with quality standards of the past, and they suffer of severe problems. Now we consider the idea of substituting them with structural elements with much longer service life. However, there is an important question to be addressed in this area: what to do with the existing infrastructure that would be demolished. Even more if we consider environmental issues.</p><p>One good example of this recurrent problem could be found in the case of the Gullspång bridge (Sweden). It was constructed in 1935 and it was severely damaged with corrosion. The administration decided in the 2016 that no further repair would be done and that the bridge would be demolished and a new erected in substitution. A fraction of the concrete from the old bridge was crushed and processed to produce new aggregate. With this aggregate, using the coarse fraction, it was analyzed the structural effect of replacing natural aggregates with these recycled aggregates. The performance of the new structural elements was positive, and it seems that a high percentage of the natural aggregates could be replaced with recycled ones.</p>

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