The damaging effects of strong ground motions on highway bridges have revealed the limitations of conventional design methods and emphasized the need for innovative design concepts. Although seismic isolation systems have been proven to be an effective method of improving the response of bridges during earthquakes, the performance of base-isolated structures during near-field earthquakes has been questioned in recent years. Near-field earthquakes are characterized by long period and large- velocity pulses. They amplify seismic response of the isolation system since the period of these pulses usually coincides with the period of the isolated structures. This study explores the feasibility and effectiveness of shape memory alloy (SMA)-based isolation systems in order to mitigate the response of bridge structures against near-field ground motions. SMAs have several unique properties that can be exploited in seismic control applications. In this work, uniaxial tensile tests are conducted first to evaluate the degree to which the behavior of SMAs is affected by variations in loading rate and temperature. Then, a neuro-fuzzy model is developed to simulate the superelastic behavior of SMAs. The model is capable of capturing rate- and temperature-dependent material response while it remains simple enough to carry out numerical simulations. Next, parametric studies are conducted to investigate the effectiveness of two SMA-based isolation systems, namely superelastic-friction base isolator (S-FBI) system and SMA/rubber-based (SRB) isolation system. The S-FBI system combines superelastic SMAs with a flat steel-Teflon bearing, whereas the SRB isolation system combines SMAs with a laminated rubber bearing rather than a sliding bearing. Upon evaluating the optimum design parameters for both SMA-based isolation systems, nonlinear time history analyzes with energy balance assessment are conducted to compare their performances. The results show that the S-FBI system has more favorable properties than the SRB isolation system. Next, the performance of the S-FBI systems is compared with that of traditional isolation systems used in practice. In addition, the effect of outside temperature on the seismic response of the S-FBI system is assessed. It is revealed that the S-FBI system can successfully reduce the response of bridges against near-field earthquakes and has excellent re-centering ability.

This diploma thesis is focused on design and assessement of the road bridge in Příbor city, where road I/58 crosses road I/48. There are 3 possible of solution of designed structure which are slab construction, beam construction and prefabricated structure. Each solution includes the design and assessment of individual structures, including drawings and economic evaluation. In conclusion, the three solutions have been evaluated against all of the given criteria.

The subject of Diploma’s thesis is the design of a road bridge on the R1 expressway, at km 1,293 above the road III/51311. The main content is static calculation of supporting structure consisting of four spans. Four studies were processed and the first variant of double-girder monolithic structure was chosen. The range of spans is ranging from 25 m - 30 m. Double-girder consists of two post-tensioned concrete beams and reinforced concrete slab. Static models and load effects are solved in Scia Engineer. Bridge is located in the horizontal curvature, however, compromise was elected (because of small curvature), assessing the upright design. Calculation is made without effects of temperature, wind loads and horizontal forces causing by traffic.

Skador och slitage på brokonstruktioner av betong beror på tösalter, armeringskorrosion och frostcykler i kombination med ökande trafiklaster. Den i särklass vanligaste reparationsåtgärden för dessa typer av skador är att göra en pågjutning. Metoden går ut på att först avlägsna det skadade eller dåliga betongskiktet innan en ny betong pågjuts. För att bedöma hur bra ett pågjutningsarbete är behöver vidhäftningen mellan den nya pågjutningen och gamla betongen fastställas. Den mest använda metoden för detta syfte är s.k. dragprovning som bestämmer draghållfastheten i vidhäftningen. I praktiken är dock vidhäftningens skjuvhållfasthet av större intresse och approximeras därför utifrån draghållfastheten, men med en vridprovning kan fogens skjuvhållfasthet direkt bestämmas. Syftet med examensarbetet är att undersöka vridprovningens reliabilitet för att i framtiden eventuellt kunna bestämma skjuvhållfastheten på ett mer direkt och korrekt sätt. I examensarbetet undersöks vridprovningens reliabilitet för att bestämma skjuvhållfastheten i fogen mellan pågjutning och gammal betong med dragprovningen som referens. Studien omfattar åtta parallellprovningar av drag- och vridprovningar där den lägst uppmätta skjuvhållfastheten jämförs med fogens dimensioneringsvärde enligt EK2. Examensarbetet görs i samband med Spårväg city-projektet vid Sergels torg, Stockholm, i uppdrag från Trafikkontoret i Stockholm och CBI Betonginstitutet. Resultaten från provningarna visade att fogbrott, som är av intresse, var vanligare för dragprovning än vridprovning. Den stora spridningen av mätvärdena var en konsekvens av det låga antalet fogbrott för vridprovningen. Medelvärdet för fogens draghållfasthet på 1,43 MPa tyder på god vidhäftning, men fogens skjuvhållfasthet bestämd med vridprovning visar ett medelvärde på endast 1,61 MPa och understiger det förväntade värdet på ca dubbla draghållfastheten d.v.s. 2,9 MPa. Intressant är att det lägst uppmätta värdet på skjuvhållfastheten på 0,83 MPa var ovanligt lågt, men fortfarande större än dimensioneringsvärdet enligt EK2 på 0,59 MPa. Studien har visat att vridprovningen är en svårtydlig metod för att bestämma skjuvhållfastheten i fogen mellan pågjutning och gammal betong. Anledningen till detta beror främst av tre faktorer, för få antal provningar, den stora spridningen av mätvärden samt de svårtolkade brottmoderna från vridprovningen. Trots detta tros vridprovningen vara en framtida metod för konstruktörer och beställare eftersom metoden är ett bra mätverktyg för att bestämma skjuvhållfastheten för pågjutna betongkonstruktioner som helhet och inte bara i fogen mellan pågjutning och befintlig betong. / Damages and wear on concrete bridges are due to de-icing salt or salt water, reinforcement corrosion and repeated freeze-thaw cycles in combination with increasing traffic loads. The most common repair operation for these types of damages is to remove the deteriorated concrete and replace it with a new concrete overlay. To evaluate how well a bonded concrete overlay is, the bond strength between the new and old concrete has to be determined. The most widely used method for this purpose is the so-called pull off test to determine the tensile bond strength. In practice however the shear bond strength is of greater interest and is therefore approximated on the basis of tensile bond strength, but with a torsion test the shear bond strength can be directly determined. The purpose of this study is to investigate the reliability of the torsion test to determine the shear bond strength in a more direct and accurate manner. The thesis examines the reliability of the torsion test to determine the shear bond strength with the pull off test as a reference. The study includes eight parallel tests of pull off and torsion tests where the lowest measured shear bond strength is compared with the calculated design value of shear bond strength according to EC2. The work is done in connection with the Spårväg city project at Sergels torg, Stockholm, in collaboration with the Traffic Administration Office in Stockholm and CBI, the Swedish Cement and Concrete Research Institute. The results of the tests showed that the failures in the interface between new and old concrete, which are of interest, were more common for pull off tests than torsion tests where only two of the eight test samples showed failure in the interface. The wide scatter of the measured values is a consequence of the low number of failures in the interface. The mean value of the tensile bond strength was 1,43 MPa, which indicates good bond strength. The shear bond strength however made with torsion tests show a mean value of only 1,61 MPa. Lower than the expected value of about twice the tensile bond strength of 2,86 MPa. Interestingly, the lowest measured value of the shear bond strength of 0,83 MPa was unusually low, but still higher than the calculated design value of shear bond strength of 0.59 MPa according to EC2. The study has shown that torsion test is a difficult method for determining the shear strength of the bond between the new and old concrete. The reason for this is mainly due to three factors, the low number of tests, the large scatter of values, and the difficulty to interpret failures of the test samples. Despite this the torsion test seems to be a future method for structural engineers and contractors as a tool to determine shear strength for repaired concrete structures in general and not only the shear bond strength.

Ingenieurbauwerke sind zentrale Elemente der technischen Infrastruktur eines Landes. Ihr sicheres Funktionieren ist von entscheidender Bedeutung für die Daseinsvorsorge und die wirtschaftliche Entwicklung. In den letzten Jahren sind vor allem die bestehenden Brückenbauwerke in den Fokus der öffentlichen Aufmerksamkeit geraten. Zum einen wird nach langen Erklärungsbemühungen der Bauverwaltungen nun auch seitens der Politik endlich wahrgenommen, dass sich der Zustand der Bauwerke in den vergangenen Jahrzehnten merklich verschlechtert hat. Zum anderen sorgen die jüngsten unplanmäßigen Brückensperrungen auf Autobahnen und Eisenbahnstrecken für Verkehrsinfarkte und heftige Verspätungen. Die Bundesrepublik Deutschland verfügt über einen Bestand von ca. 40.000 Brücken auf Bundesfernstraßen mit einer Gesamtfläche von ca. 32 Millionen Quadratmetern. Der überwiegende Teil dieser Bauwerke besteht aus Stahlbeton und Spannbeton. Hinzu kommen ca. 26.000 Eisenbahnbrücken mit einer Gesamtbrückenfläche von ca. 9 Millionen Quadratmetern, ebenfalls weitgehend in Massivbauweise. Mit einem durchschnittlichen Preis von 3.500 €/m² für Straßenbrücken und von 10.000 €/m² für Eisenbahnbrücken hätten diese Bauwerke einen Wiederbeschaffungsneuwert von etwa 200 Milliarden Euro, was etwa 25 % der gesamten jährlichen Steuereinnahmen von Bund und Ländern entspricht. Hinzu kommen nochmals etwa 70.000 Brückenbauwerke im kommunalen Bestand. Der Brückenbestand Deutschlands stellt damit ein riesiges Anlagevermögen dar. Ihn vollständig zu erneuern würde erhebliche Aufwendungen verursachen. Deshalb kommt der kontinuierlichen Instandhaltung und Sanierung der Brückenbauwerke eine entscheidende Bedeutung zu.

Im Zusammenhang mit Sanierungsmaßnahmen an bestehenden Brückentragwerken muss auch der Zustand ihrer Lager bewertet werden. Im Falle historischer Brückenlagertechnik bleiben hierbei oft Fragen unbeantwortet, zum Beispiel zu den Möglichkeiten einer zerstörungsfreien Beurteilung des Lagerwerkstoffs. Am Beispiel des ab etwa 1880 zunehmend für Lager verwendeten Werkstoffs Stahlguss – früher zumeist Stahlformguss – verfolgt der Beitrag den Ansatz, die mittels Spektralanalyse ermittelte Werkstoffrezeptur als Ausgangspunkt für zentrale Aussagen zur Werkstofffestigkeit zu nutzen. Der Artikel erläutert die Methodik, diskutiert Ergebnisse des Vorgehens und zeigt eine interessante Option für eine quasi zerstörungsfreie Werkstoffuntersuchung auf.

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The thesis deals with design and static assessment of the steel railway bridge with a span 36,6 m. The bridge is located on the two-track corridor line Košice - Púchov. It consists of two bridge structures connected by a longitudinal expansion joint. The main construction consists of four solid welded beams mounted on steel calotte bearings. The bridge deck is the top with a tub for the track bed, which is continuous at the site of the bridge. Bridging the bridge is secured by a track bed and a horizontal and lateral truss bracing. On both sides of the bridge are pedestrian walkways with a width of 1,5 m.