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Predicting the Service Life of Concrete Bridges Based on Quantitative Research
No full textA new method is proposed that will help predict the remaining service life of concrete bridges based on quantitative deterioration research. It is suggested that for a given degree of damage (stage) and corresponding environmental and bridge design factors, there is only one time value. In that way it is possible to calculate the deterioration rate for given environmental and bridge design factors shared by many different bridges. The method can be used to calculate the key parameters for corrosion deterioration, thereby enabling the prediction of the remaining service life of a bridge using DuraCrete deterioration models
Betona karbonizācijas ietekmes uz dzelzsbetona tiltu kalpošanas laiku Latvijā analīze
No full textKarbonizācijas ietekmes uz dzelzsbetona tiltu kalpošanas laiku analīze tika veikta balstoties uz Latvijā veiktajām tiltu inspekcijām un matemātisko modeli. Veiktā analīze apliecina, ka Latvijā tiltos izmantotajam betonam ir pietiekma karbonizācijas pretestība, lai nodrošinātu kalpošanas laiku 100 gadi, ja minimālā betona aizsargkārta ir 40 mm
Concrete Bridge Deterioration Caused by De-Icing Salts in High Traffic Intensity Road Environment in Latvia
No full textDesign for durability of road infrastructures is becoming increasingly important in view of its large impact on economics. Reinforcement corrosion is the most common cause of concrete deterioration of bridge structures in Latvia. The ingress of chlorides is often considered to be the major threat to durability of concrete structures. During the winter season de-icing salts are spread out on roads to avoid formation of ice and ensure the anti-sliding properties of the road surface. The melting water mixes with de-icing salt and is splashed and sprayed on reinforced concrete pier structures by passing vehicles. Absorbed water with chloride ions initiates and accelerates the reinforcement corrosion process. This paper highlights the results of investing accumulation of chlorides in reinforced concrete bridge piers located near high-intensity roads in Latvia. The chloride contents were determined on different surfaces of reinforced concrete piers. Environmental conditions were analysed and prediction of remaining service life for chloride induced reinforcement corrosion was performed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Concrete Bridge Deterioration Caused by De-Icing Salts in High Traffic Intensity Road Environment in Latvia
No full textDe-icing salts are spread on roads to avoid formation of ice and increase safety on roads during the winter season. De-icing salts, which contain chlorides, initiate and accelerate the corrosion process of reinforcement within the concrete structure. The reinforcement corrosion is the most common reason of reinforced concrete bridge deterioration in Latvia. This paper summarizes the results of several investigations concerning chloride ingress in reinforced concrete bridge structures that are located close to a high intensity roads in Latvia. The amount of chlorides in the concrete cover of different parts of the structures was determined. Road environment has been analyzed and remaining service life predictions for chloride induced reinforcement corrosion have been performed
Dzelzsbetona tiltu kalpošanas laika prognozēšanas metode Latvijai raksturīgā vidē
No full textPētījuma mērķis ir izstrādāt metodi Latvijā esošo dzelzsbetona tiltu kalpošanas laika prognozēšanai, balstoties uz apkārtējās vides un dzelzsbetona tiltu elementu savstarpējās mijiedarbības attīstību. Dzelzsbetona tiltu kalpošanas laika prognozēšanas metode balstās uz apkārtējās vides ietekmes un tiltu elementu konstruktīvo faktoru kvantitātīvas analīzes un pilnveidotas DuraCrete bojājumu attīstības modeļu pielietojuma metodoloģijas. Balstoties uz apkartējās vides meteoroloģijas datiem, izstrādāti apkārtējās vides ietekmes modeļi tiltiem, kuri raksturo dažādu vides faktoru iedarbības daudzumu visā tilta ekspluatācijas laikā. Pētījumā tiek definēti apkārtējās vides un tiltu konstruktīvo faktoru mijiedarbības raksturotāji un to dažādi līmeņi. Kalpošanas laiks tiek prognozēts empīriski, pieņemot, ka pie vienādas apkārtējās vides un tiltu konstruktīvo faktoru mijiedarbības bojājumu attīstība ir nemainīga. Salīdzināti kalpošanas laika prognozēšanas rezultāti, kas iegūti pielietojot izstrādāto metodi, ar eksperimentāli veiktajās izpētēs iegūtajiem rezultātiem. Secināts, ka prognozētais kalpošanas laiks būtiski neatšķiras, ja to vērtības ir mazākas par 100 gadiem
Pretapledojuma sāļu ietekme uz dzelzsbetona tiltu balstu kalpošanas laiku
No full textTo avoid formation of ice on roads de-icing salts are spread during the winter season. The corrosion of the reinforcement in concrete by de-icing salts is one of the major issues concerning the durability of reinforced concrete structures. Reinforced concrete bridge piers have been investigated with the purpose to determine the service life and the amount of damage created by using de-icing salts on roads. The bridge piers have been investigated for chloride ingress during the autumn of 2007. Seven chloride ingress profiles have been obtained and analyzed. The results show that the exposure to chlorides is generally highest for surfaces facing towards the traffic. It has been noted that the position and shape of the bridge piers is of great importance. The surfaces facing towards traffic are in danger to have reinforcement corrosion in coming years. Results for other surfaces show that there won’t be a reinforcement corrosion initated by de-icing salts for current road environment for the remaining service life
Service Life of Two 100 Year Old Concrete Bridges in Latvia
No full textThe earliest reinforced concrete bridges built in Latvia over river Salaca and Gauja were built in 1908 and 1909. 100 years later both are still in service and require only certain maintenance. Bridges were built with intuition of parameters that produces good quality: concrete mix design, choice of shape and installation within formwork. After 100 years in service, both bridge deteriorations could have been avoided, for example, foundation protection for bridge over Salaca and expansion joints for both bridges. The concrete has been vulnerable to carbonation; during the 100 years of exposition the carbonation has reached 40 mm and the main reinforcement. Within this research performed carbonation calculation results show that the inverse effective carbonation resistance of concrete on site is μ=31.45•10-11,σ=5.32•10-11(m5/(s•kgCO2)).For concrete directly exposed to the wetting the weather function value is μ=3.24, σ =0.74. The calculation of carbonation process was modelled by using DuraCrete carbonation model and MonteCarlo simulations at full probabilistic level
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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