This master thesis is focused for design, respectively for creating counterproposal of existing structure of Motorway Bridge located at D1 motorway between Jánovce and Jablonov in district Levoča in Slovakia. This bridge is over a local road. The main aim of this thesis is design, analysis and assessment of bearing elements of bridge deck. For purposes of this thesis was created three variants of bridge deck. Detailed analysis was performed on bearing construction from post-tensioned precast beam with monolithing concrete slab. Two mathematic models were used for analysis of chosen variant. First model was spatial 3D shell construction. The purpose of this model was determinate cross spreading line of other constant load and live load. Second, flat 2D model, was for determination creep and shrinkage appeared from long-term load. These effects were observed in at advanced defined time nodes. Outcomes from upper mentioned model were used from design and assessment of bearing elements of bridge deck, design prestressed reinforcement cables and concrete reinforcement rods.

The purpose of this research was to develop a new index for concrete bridge deck management in Utah. Data were collected in the summer of 2005 from 15 concrete bridge decks in the vicinity of Salt Lake City. The decks ranged from 2 to 21 years in age and were all constructed using epoxy-coated rebar. Visual inspection, sounding, Schmidt hammer testing, half-cell potential testing, and chloride concentration testing were performed on six 6-ft by 6-ft test areas randomly distributed within the single lane closed to traffic on each deck, and testing protocols followed American Society for Testing and Materials standards to the extent possible. Collected data were analyzed using statistics, and age, cover, and half-cell potential were ultimately selected for inclusion in a new Utah Bridge Deck Index (UBDI); these variables effectively reflect chloride-induced corrosion mechanisms active on Utah bridge decks, are highly correlated to delamination distresses, and are relatively easy to measure compared to chloride concentration. At the request of Utah Department of Transportation (UDOT) personnel, the UBDI equation was structured around a deduct system using a 100-point scale similar to the sufficiency rating system, in which a perfect bridge deck receives a score of 100. Coefficients were selected based largely on the judgment of the researchers and the UDOT personnel involved in the research, and threshold values for maintenance, rehabilitation, and replacement (MR&R) options were specified to be the same as those associated with the standard sufficiency ratings. The UBDI and corresponding MR&R recommendation were then provided for each of the bridge decks tested in this research; nine of the decks are recommended for preventive treatment, and six are recommended for rehabilitation. In addition, the possibility of treatment applications was considered, leading to required adjustments in the UBDI calculation; the treatment options that were considered include an epoxy seal, an HPC overlay, and an asphalt membrane overlay. Four case scenarios were developed to demonstrate the response of the revised UBDI equation to these treatments. Finally, as aids for UDOT personnel implementing this research, charts were created to facilitate rapid determination of the required number of half-cell potential and concrete cover measurements for different levels of reliability and tolerance. The UBDI developed in this research is recommended for implementation by UDOT personnel as a tool for optimizing the timing of MR&R treatments on concrete bridge decks similar to those evaluated in this project. In measuring cover and half-cell potential values, UDOT personnel should utilize the sampling guidelines presented in this report to ensure adequate characterization of each deck. Furthermore, to facilitate the inclusion of treatment effects in the UBDI, UDOT personnel should establish a policy of recording the types and dates of all MR&R treatments applied to bridge decks. As performance data are collected for specific treatments over time, the treatment lives proposed in this research for epoxy seals, HPC overlays, and asphalt membrane overlays should be revised as needed, and information for other treatments may be added. In addition, to maximize the predictive capabilities of the UBDI, more accurate relationships between half-cell potential values and deck age should be developed for estimating future deck condition.

The objectives of this research were to investigate the sensitivity of two-prong and fourprong resistivity measurements to certain operator-controlled variables and to conduct a direct comparison of the sensitivity of two-prong and four-prong resistivity measurements to certain concrete material variables. Four full-factorial experiments were designed for this research. In the experimentation on operator-controlled variables with two-prong resistivity testing, main effects that are both statistically significant and practically important include hole depth and surface water. In the experimentation on operator-controlled variables with four-prong resistivity testing, probe position, surface water, and prong spacing are all neither statistically significant nor practically important. This high degree of unexplained variation may be of concern to practitioners. In the experimentation on concrete material variables with two-prong and four-prong resistivity testing, main effects that are both statistically significant and practically important include chloride concentration and temperature, both of which exhibit inverse relationships with resistivity. These research findings support several important recommendations for resistivity testing. Operators of the two-prong resistivity device should use an accurately positioned drill stop to ensure that the prepared holes are consistently the correct depth, and they should expect to obtain different values depending on the presence of surface water on the deck surface. Operators considering use of the four-prong resistivity device should not expect the measurements to be sensitive to probe position with respect to rebar, presence of surface water, or prong spacing for conditions similar to those investigated in this research. Operators interested in monitoring resistivity values over time to ascertain material changes in a bridge deck should develop protocols for measuring concrete temperature in the field and subsequently normalizing resistivity measurements to a standard temperature.

Numerous methods have been developed to measure corrosion potential relating to chloride infiltration in concrete, including an emerging application of electrochemical impedance spectroscopy (EIS). EIS involves measurements of electrical impedance to evaluate the corrosion potential of steel reinforcement in concrete. With EIS, current is injected vertically into the concrete bridge deck between the surface and the embedded reinforcing steel, usually the top mat, to evaluate the degree to which the reinforcing steel is protected from chloride infiltration by the entire bridge deck system. The objectives of this research were to 1) investigate the sensitivity of EIS measurements obtained at various frequencies to specific deck properties, 2) recommend a particular frequency or range in frequency at which impedance measurements can differentiate among various levels of corrosion protection for reinforcing steel in concrete bridge decks, and 3) compare impedance values measured at the recommended frequency(ies) to more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. This research involved impedance testing of 25 concrete slabs, divided into five sets. The effects of sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, chloride concentration, and epoxy coating condition on individual impedance measurements were evaluated. For the controlled laboratory experiments, sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, and epoxy coating condition were shown to have a statistically significant effect on impedance measurements, with p-values less than 0.05. The statistical analyses indicated that impedance testing in the frequency range of approximately 100 Hz to 1 kHz would be expected to provide the best data about the degree to which the reinforcing steel is protected from chloride infiltration by a bridge deck system. In this frequency range, a high level of differentiation among levels of corrosion protection is expected, and a high speed of data collection is also possible. For the uncontrolled laboratory experiments, a single frequency of 200 Hz was selected for impedance testing. Statistical analyses were performed to compare impedance with more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. Longitudinal and transverse cover, dry and wet resistivity, dry and wet half-cell potential, dry linear polarization, and chloride concentration were determined to be correlated with impedance, with p-values less than 0.15.

The objectives of this research were to 1) monitor in-situ moisture and diffusivity for both conventional concrete and concrete containing pre-wetted lightweight fine aggregate (LWFA), 2) compare deck performance in terms of early-age cracking, compressive strength, and chloride ingress, and 3) compare concrete properties in terms of compressive strength, chloride permeability, elastic modulus, and water content in the laboratory using cylinders cast in the field at the time of deck construction. The research involved field and laboratory evaluations of four newly constructed bridge decks located in northern Utah, two constructed using conventional concrete and two constructed using pre-wetted LWFA to promote internal curing. Data from sensors embedded in the concrete decks indicate that the moisture content of the internally cured concrete was consistently 1.5 to 4 percentage points higher than the moisture content of the conventional concrete for the first 6 months following deck construction. By 1 year, however, the internally cured concrete showed little difference in moisture content compared to the conventional concrete. While the internally cured concrete decks had a higher average moisture content, the electrical conductivity values were not consistently higher than those measured on the conventional concrete decks during the first approximately 8 to 10 months. However, after 8 to 10 months, both internally cured concrete decks exhibited higher electrical conductivity values than those measured on the conventional concrete decks. Laboratory compressive strength data indicate that, for the first 6 months following deck construction, the two concrete mixtures exhibited very similar strength gain characteristics. However, at 1 year, the conventional concrete was stronger by an average of 12.9 percent, or nearly 900 psi, than the internally cured concrete. In rapid chloride permeability testing, the internally cured concrete consistently passed between 13.1 and 17.5 percent less current than that passed by the conventional concrete. Laboratory free-free resonant testing at 1 year showed that the modulus of the internally cured concrete was 3.9 percent lower, on average, than that of the conventional concrete. For the tested specimens, the moisture content of the internally cured concrete was 0.5 percentage points higher, on average, than that of the conventional concrete. In the field, Schmidt rebound hammer testing showed that the internally cured concrete was neither consistently stronger nor weaker than the conventional concrete. On average, the internally cured concrete exhibited higher chloride concentrations than the conventional concrete. On average, the conventional concrete bridge decks had 4.6, 21.5, and 2.8 times more cracking than the internally cured concrete decks at 5 months, 8 months, and 1 year, respectively. At 1 year, very distinctive reflection cracks from the joints between the underlying pre-cast half-deck panels were observed on all of the decks.

The objective of this research was to investigate the effects of twisted steel micro rebar (TSMR) fibers on 1) the mechanical properties of concrete used in bridge deck construction and 2) the early cracking behavior of concrete bridge decks. This research involved the evaluation of four newly constructed bridge decks through a series of laboratory and field tests. At each location, one deck was constructed using a conventional concrete mixture without TSMR, and one was constructed using the same conventional concrete mixture with an addition of 40 lb of TSMR per cubic yard of concrete. Regarding laboratory testing, the conventional and TSMR beam specimens exhibited similar average changes in height after 4 months of shrinkage testing. The electrical impedance measurements did not indicate a notable difference between specimens comprising concrete with TSMR and those comprising conventional concrete. Although no notable difference in behavior between conventional and TSMR specimens was apparent before initial cracking, the toughness of the TSMR specimens was substantially greater than that of the conventional concrete specimens. Regarding field testing, sensors installed in the bridge decks indicated that the addition of TSMR does not affect internal concrete temperature, moisture content, or electrical conductivity. The average Schmidt rebound number varied little between the TSMR decks and conventional decks; therefore, the stiffness of the TSMR concrete was very similar to that of conventional concrete. Distress surveys showed that the conventional decks exhibited notably more cracking than the TSMR decks. The TSMR fibers exhibited the ability to limit both crack density and crack width. For all of the decks, chloride concentrations increased every year as a result of the use of deicing salts on the bridge decks during winter. However, the chloride concentrations for samples collected over cracked concrete increased more rapidly than those for samples collected over non-cracked concrete. Although TSMR fibers themselves do not directly affect the rate at which chloride ions penetrated cracked or non-cracked concrete, the fibers do prevent cracking, which, in turn, limits the penetration of chloride ions into the decks. Therefore, the use of TSMR would be expected to decrease the area of a bridge deck affected by cracking and subsequent chloride-induced corrosion damage and thereby increase the service life of the bridge deck.

New railway lines are continuously being constructed and existing lines are upgraded. Hence, there is a need for research directed towards efficient design of the supporting structures. Increasingly advanced calculation methods can be motivated, especially in projects where huge savings can be obtained from verifying that existing structures can safely support increased axle loads and higher speeds. This thesis treats the dynamic response of bridges under freight and passenger train loads. The main focus is the idealisation of the train load and its implications for the evaluation of the vertical bridge deck acceleration. To ensure the running safety of train traffic at high speeds the European design codes set a limit on the vertical bridge deck acceleration. By considering the train–bridge interaction, that is, to model the train as rigid bodies on suspension units instead of constant moving forces, a reduction in bridge response can be obtained. The amount of reduction in bridge deck acceleration is typically between 5 and 20% for bridges with a span up to 30 m. The reduction can be higher for certain train–bridge systems and can be important also for bridge spans over 30 m. This thesis aims at clarifying for which system parameter combinations the effect of train–bridge interaction is important. To this end, a thorough literature survey has been performed on studies in train–track–bridge dynamics. The governing parameters in 2D train–bridge systems have been further studied through a parameter screening procedure. The two-level factorial methodology was applied to study the effect of parameter variations as well as the joint effect from simultaneous changes in several parameters. The effect of the choice of load model was thus set in relation to the effect of other parameter variations. The results show that resonance can arise from freight train traffic within realistic speed ranges (&lt; 150 km/h). At these resonance peaks, the reduction in bridge response from a train–bridge interaction model can be considerable. From the screening of key parameters it can furthermore be concluded that the amount of reduction obtained with a train–bridge interaction model depends on several system parameters, both for freight and passenger train loads. In line with the European design code’s guidelines for dynamic assessment of bridges under passenger trains an additional amount of damping can be introduced as a simplified way of taking into account the reduction from train–bridge interaction. The amount of additional damping is today given as function of solely the bridge span length, which is a rough simplification. The work presented in this thesis supports the need for a refined definition of the additional damping. / Nya järnvägslinjer byggs kontinuerligt och befintliga linjer uppgraderas. Det finns därför ett behov av forskning inriktad på effektiv design av de bärande konstruktionerna. Alltmer avancerade beräkningsmetoder kan vara motiverade, särskilt i projekt där stora besparingar kan erhållas från att verifiera att befintliga konstruktioner kan bära ökade axellaster och högre hastigheter. Föreliggande avhandling behandlar broars dynamiska respons under belastning av gods- och passagerartåg. Huvudfokus är att studera modelleringsalternativ för tåglasten och vilka konsekvenser de har för utvärderingen av brobanans vertikala acceleration. För att garantera trafiksäkerhet vid höga tåghastigheter definierar de europeiska normerna en maximalt tillåten vertikal acceleration i brobanan. Genom att beakta tåg-bro-interaktion, där tågkomponenterna modelleras som avfjädrade stela kroppar istället för konstanta punktlaster, kan en minskning av brons respons erhållas. Reduktionen av brobanans acceleration är typiskt mellan 5 och 20% för broar med en spännvidd på upp till 30 m. Minskningen kan vara högre för vissa tåg-brosystem och kan vara viktigt också för spännvidder över 30 m. Denna avhandling syftar till att klargöra för vilka kombinationer av tåg-broparametrar effekten av tåg-bro-interaktion är viktig. I detta syfte har en omfattande litteraturstudie genomförts inom området tåg-spår-brodynamik. De styrande parametrarna i 2D tåg-brosystem har studerats vidare i en parameterstudie. Två-nivå faktorförsök har tillämpats för att studera effekten av parametervariationer samt den ytterligare effekten av samtidiga förändringar i flera parametrar. Effekten av valet av lastmodell sattes därmed i relation till effekten av andra parametervariationer. Resultaten visar att resonans kan uppstå från godstrafik inom ett realistiskt hastighetsintervall (&lt; 150 km/h). Vid dessa resonanstoppar kan en betydande minskning av broresponsen erhållas med en tåg-bro-interaktionsmodell. Från studien av nyckelparametrar kan man vidare dra slutsatsen att reduktionen som erhålls med en tåg-bro-interaktionsmodell beror på flera systemparametrar, både för gods- och passargerartåg. Enligt de europeiska normernas rekommendationer för dynamisk kontroll av broar för passagerartrafik kan en ökad brodämpning introduceras som ett förenklat sätt att ta hänsyn till minskningen från tåg-bro-interaktion. Mängden tilläggsdämpning anges idag som en funktion av enbart brons spännvidd, vilket är en grov förenkling. Det arbete som presenteras i denna avhandling visar på behovet av en förbättrad definition av tilläggsdämpningen. / <p>QC 20140429</p>

Chloride-induced deterioration of concrete bridge decks can be described in terms of three phases: 1) initiation of rebar corrosion, 2) rust formation and development of deck damage, and 3) accelerated deck damage towards structural failure. The first objective of this research was to investigate relationships among chloride concentration at the top mat of reinforcing steel, deck age, cover depth, and occurrence of delamination for concrete bridge decks with selected surface treatments and rebar types. Relating these factors can help establish greater understanding about the duration of each phase of the deterioration process. A second objective of this research was to investigate the relationship between chloride concentrations that develop between the bars and those that develop directly above the bars in the top mat of reinforcing steel to better understand the effects of the presence of reinforcing steel on diffusion of chloride ions through the concrete matrix.Data collected from 48 concrete bridge decks in Utah were used to address both of the objectives stated for this research. Surface treatment types included bare concrete, thin-bonded polymer overlays, and asphalt overlays, and rebar types included uncoated and epoxy-coated rebar. Regarding the first objective, baseline relationships between chloride concentration, deck age, and cover depth were developed for all three deck types. The results show that, as deck age increases, chloride concentration also increases and that chloride concentrations are much higher for shallower concrete depths than for deeper concrete depths. Based on these relationships, the duration of the first phase of the deterioration process was estimated using the critical chloride threshold of 2.0 lb Cl-/yd3 of concrete. For decks with asphalt or polymer overlays, development of clear relationships between chloride concentration, deck age, and cover depth required consideration of treatment time. The data show that chloride concentrations for decks that had an overlay applied 10 or more years after construction are higher than those for decks that had an asphalt overlay applied immediately after construction. Relevant to determining the duration of the second phase of the deterioration process, the relationship between delamination occurrence and chloride concentration for bare concrete bridge decks was developed. In general, the results show that the occurrence of delamination increases with increasing chloride concentration. Estimated durations of the second phase of the deterioration process were then determined using a chloride concentration threshold of 4.0 lb Cl-/yd3 of concrete for each of the same combinations of surface treatment and cover depth used for determining durations of the first phase of the deterioration process. Regarding the performance of epoxy-coated bar, the data clearly demonstrate the benefit of epoxy coatings on reinforcing steel for the purpose of significantly delaying the onset of chloride-induced delamination in concrete bridge decks. The relationship between the ratio of chloride concentrations directly above and between steel reinforcing bars and deck age was then developed. The results show that, as deck age increases, the average ratio of chloride concentrations directly above and between the bars asymptotically decreases from above 1.5 toward 1.0, which is reached at a deck age of approximately 30 years. Given that increasing deck age generally corresponds to increasing chloride concentration, which would in turn eventually lead to similar chloride concentrations directly above and between bars as the concrete pore water within the cover depth approached chloride saturation, this observed relationship is consistent with theory.

No description available.

Orthotropic steel deck has been widely used over the decades especially on long-span bridges due to its light weight and fast construction. However fatigue cracking problems on the welds have been observed in many countries. Rib-to-deck welds need special care since they are directly under wheel loads, which cause large local stress variations and stress reversals. Currently the only requirement by AASHTO bridge code is that the rib-to-deck welds need to be fabricated as one-sided partial penetration welds with minimum penetration of 80% into the rib wall thickness. However considering the thin rib plate thickness, it is very difficult to achieve this penetration without a "melt-through" or "blow-through" defect. Large cost has been caused for the repair. However recent research has found that the fatigue performance of the rib-to-deck weld is not directly related to its penetration. Other factors contribute to the fatigue performance as well. Therefore, alternative requirements which are more cost-effective and rational are desired. The objective of this research is to provide recommendations to the design and fabrication of rib-to-deck welds by investigating their fatigue performance with different weld dimensions, penetrations, and welding processes. Fatigue tests were performed to 95 full-scale single-rib deck segments in 8 specimen series fabricated with different welding processes and root gap openness. Specimens were tested under cyclic loads till failure. Three failure modes were observed on both weld toes and the weld root. Test results showed that the fatigue performance was more affected by other factors such as failure mode, R-ratio and root gap openness, rather than the weld penetration. The failure cycles were recorded for the following S-N curve analysis. Finite element analysis was performed to determine the stress state on the fatigue cracking locations. Special considerations were made for the application of hot-spot stress methodology, which post-processes the FEA results to calculate the stress values at cracking locations with the structural configuration taken into account. The hot-spot stress range values were derived and adjusted accounting for the fabrication and test error. Hot-spot S-N curves were established for each specimen series. Statistical analyses were performed to study in depth the effect of weld dimensions and test scenarios. Multiple linear regression (MLR) was performed to investigate the effects of different weld dimensions; and multi-way analysis of covariance (Multi-way ANCOVA) for the effects of specimen series, failure mode, R-ratio and weld root gap. It was found that the weld toe size was more relevant to the fatigue performance, other than the weld penetration. The failure mode and R-ratio were very influential on the fatigue performance. Recommendations to the weld geometry were proposed based on the MLR model fitting. S-N data were re-categorized based on ANCOVA results and the lower-bound S-N curve was established. AASHTO C curve was recommended for the deck design. / Master of Science