Extracting bridge frequencies from dynamic responses of two passing vehicles

A conventional way to identify bridge frequencies is utilizing vibration data measured directly from the bridge. A drawback with this approach is that the deployment and maintenance of the vibration sensors are generally costly and time-consuming. One of the solutions is in a drive-by approach utilizing vehicle vibrations while the vehicle passes over the bridge. In this approach, however, the vehicle vibration includes the effect of road surface roughness, which makes it difficult to extract the bridge modal properties. This study aims to examine subtracting signals of two trailers towed by a vehicle to reduce the effect of road surface roughness. A simplified vehicle-bridge interaction model is used in the numerical simulation; the vehicle - trailer and bridge system are modeled as a coupled model. In addition, a laboratory experiment is carried out to verify results of the simulation and examine feasibility of the damage detection by the drive-by method.

Investigating Feasibility of Drive-by Bridge Monitoring by Laboratory Experiments

A potentially powerful drive-by bridge inspection approach was proposed to inspect bridge conditions utilizing the vibrations of a test vehicle while it passes over the target bridge. This approach suffers from the effect of roadway surface roughness and two solutions were proposed in previous studies: one is to subtract the responses of two vehicles (time-domain method) before spectral analysis and the other one is to subtract the spectrum of one vehicle from that of the other (frequency-domain method). Although the two methods were verified theoretically and numerically, their practical effectiveness is still an open question.Furthermore, whether the outcome spectra processed by those methods could be used to detect potential bridge damage is of our interests. In this study, a laboratory experiment was carried out with a test tractor-trailer system and a scaled bridge. It was observed that, first, for practical applications, it would be preferable to apply the frequency-domain method, avoiding the need to meet a strict requirement in synchronizing the responses of the two trailers in time domain; second, the statistical pattern of the processed spectra in a specific frequency band could be an effective anomaly indicator incorporated in drive-by inspection methods.

Monitoring and model updating of an FRP pedestrian truss bridge

This paper presents the results of a real bridge field experiment, carried out on a fiber reinforced polymer (FRP) pedestrian truss bridge of which nodes are reinforced with stainless steel plates. The aim of this paper is to identify the dynamic parameters of this bridge by using both conventional techniques and a model updating algorithm. In the field experiment, the bridge was instrumented with accelerometers at a number of locations on the bridge deck, recording both vertical and transverse vibrations. It was excited via jump tests at particular locations along its span and the resulting acceleration signals are used to identify dynamic parameters, such as the bridge mode shape, natural frequency and damping constant. Pedestrianinduced vibrations are also measured and utilized to identify dynamic parameters of the bridge. For a complete analysis of the bridge, a numerical model of the FRP bridge is created whose properties are calibrated utilizing a model updating algorithm. Comparable frequencies and mode shapes to those from the experiment were obtained by the FE models considering the reinforcement by increasing elastic modulus at every node of the bridge by stainless steel plate. Moreover, considering boundary conditions at both ends as fixed in the model resulted in modal properties comparable/similar to those from the experiment. This study also demonstrated that the effect of reinforcement and boundary conditions must be properly considered in an FE model to analyze real behavior of the FRP bridge.

Evaluation and Testing of a Lightweight Fine Aggregate Concrete Bridge Deck in Buchanan County, Iowa, TR-648, 2016

Internal curing is a relatively new technique being used to promote hydration of Portland cement concretes. The fundamental concept is to provide reservoirs of water within the matrix such that the water does not increase the initial water/cementitious materials ratio to the mixture, but is available to help continue hydration once the system starts to dry out. The reservoirs used in the US are typically in the form of lightweight fine aggregate (LWFA) that is saturated prior to batching. Considerable work has been conducted both in the laboratory and in the field to confirm that this approach is fundamentally sound and yet practical for construction purposes. A number of bridge decks have been successfully constructed around the US, including one in Iowa in 2013. It is reported that inclusion of about 20% to 30% LWFA will not only improve strength development and potential durability, but, more importantly, will significantly reduce shrinking, thus reducing cracking risk. The aim of this work was to investigate the feasibility of such an approach in a bridge deck.

Can the European Union build a bridge over troubled waters? An analysis of the politicised and depoliticised legal approach between the European Union and Cyprus

The Cyprus dispute accurately portrays the evolution of the conflict from ‘warfare to lawfare’ enriched in politics; this research has proven that the Cyprus problem has been and will continue to be one of the most judicialised disputes across the globe. Notwithstanding the ‘normalisation’ of affairs between the two ethno-religious groups on the island since the division in 1974, the Republic of Cyprus’ (RoC) European Union (EU) membership in 2004 failed to catalyse reunification and terminate the legal, political and economic isolation of the Turkish Cypriot community. So the question is; why is it that the powerful legal order of the EU continuously fails to tame the tiny troublesome island of Cyprus? This is a thesis on the interrelationship of the EU legal order and the Cyprus problem. A literal and depoliticised interpretation of EU law has been maintained throughout the EU’s dealings with Cyprus, hence, pre-accession and post-accession. The research has brought to light that this literal interpretation of EU law vis-à-vis Cyprus has in actual fact deepened the division on the island. Pessimists outnumber optimists so far as resolving this problem is concerned, and rightly so if you look back over the last forty years of failed attempts to do just that, a diplomatic combat zone scattered with the bones of numerous mediators. This thesis will discuss how the decisions of the EU institutions, its Member States and specifically of the European Court of Justice, despite conforming to the EU legal order, have managed to disregard the principle of equality on the divided island and thus prevent the promised upgrade of the status of the Turkish Cypriot community since 2004. Indeed, whether a positive or negative reading of the Union’s position towards the Cyprus problem is adopted, the case remains valid for an organisation based on the rule of law to maintain legitimacy, democracy, clarity and equality to the decisions of its institutions. Overall, the aim of this research is to establish a link between the lack of success of the Union to build a bridge over troubled waters and the right of self-determination of the Turkish Cypriot community. The only way left for the EU to help resolve the Cyprus problem is to aim to broker a deal between the two Cypriot communities which will permit the recognition of the Turkish Republic of Northern Cyprus (TRNC) or at least the ‘Taiwanisation’ of Northern Cyprus. Albeit, there are many studies that address the impact of the EU on the conflict or the RoC, which represents the government that has monopolised EU accession, the argument advanced in this thesis is that despite the alleged Europeanisation of the Turkish Cypriot community, they are habitually disregarded because of the EU’s current legal framework and the Union’s lack of conflict transformation strategy vis-à-vis the island. Since the self-declared TRNC is not recognised and EU law is suspended in northern Cyprus in accordance with Protocol No 10 on Cyprus of the Act of Accession 2003, the Turkish-Cypriots represent an idiomatic partner of Brussels but the relations between the two resemble the experience of EU enlargement: the EU’s relevance to the community has been based on the prospects for EU accession (via reunification) and assistance towards preparation for potential EU integration through financial and technical aid. Undeniably, the pre-accession and postaccession strategy of Brussels in Cyprus has worsened the Cyprus problem and hindered the peace process. The time has come for the international community to formally acknowledge the existence of the TRNC.

Clinton Multimodal (U. S. 30 Mississippi River Bridge) Study, 2003

The purpose of this memorandum is to document the benefit-cost analysis of the river crossing concept alternatives described in the "Concept Alternatives Technical Memo." Benefit-cost studies are designed to measure, in dollars, the potential positive or negative impacts of large-scale construction projects. The concept alternatives analyzed include improvements to the Union Pacific Railroad (UPRR) River Crossing and the U.S. Highway 30 (U.S. 30) River Crossing.

State-of-the-Art Methods for Design of Integral Bridge Abutments, HR-227, 1981

The routine use of integral abutments to tie bridge superstructures to foundation piling began in this country about 30 years ago. Kansas, Missouri, Ohio, North Dakota, and Tennessee were some of the early users. This method of construction has steadily grown more popular. Today more than half of the state highway agencies have developed design criteria for bridges without expansion joint devices.

Neuroscience and education: prime time to build the bridge

As neuroscience gains social traction and entices media attention, the notion that education has much to benefit from brain research becomes increasingly popular. However, it has been argued that the fundamental bridge toward education is cognitive psychology, not neuroscience. We discuss four specific cases in which neuroscience synergizes with other disciplines to serve education, ranging from very general physiological aspects of human learning such as nutrition, exercise and sleep, to brain architectures that shape the way we acquire language and reading, and neuroscience tools that increasingly allow the early detection of cognitive deficits, especially in preverbal infants. Neuroscience methods, tools and theoretical frameworks have broadened our understanding of the mind in a way that is highly relevant to educational practice. Although the bridge’s cement is still fresh, we argue why it is prime time to march over it.

The Keokuk & Hamilton Bridge : Keokuk, Iowa - Hamilton, Illinois, 1982

The Keokuk & Hamilton Bridge is one of three remaining in Iowa that were designed by Ralph Modjeski, one of this country's premier early 20th century bridge engineers. The eleven-span, double-deck steel superstructure was built in 1915-1916 on piers retained from an earlier (1869-1871) structure, to meet greater loading requirements from railroads that operated across the Mississippi at this point.

Upgrading Bridge Rails on Low-Volume Roads in Iowa, TR-679, 2016

Building on previous research, the goal of this project was to identify significant influencing factors for the Iowa Department of Transportation (DOT) to consider in future updates of its Instructional Memorandum (I.M.) 3.213, which provides guidelines for determining the need for traffic barriers (guardrail and bridge rail) at secondary roadway bridges—specifically, factors that might be significant for the bridge rail rating system component of I.M. 3.213. A literature review was conducted of policies and guidelines in other states and, specifically, of studies related to traffic barrier safety countermeasures at bridges in several states. In addition, a safety impact study was conducted to evaluate possible non-driver-related behavior characteristics of crashes on secondary road structures in Iowa using road data, structure data, and crash data from 2004 to 2013. Statistical models (negative binomial regression) were used to determine which factors were significant in terms of crash volume and crash severity. The study found that crashes are somewhat more frequent on or at bridges possessing certain characteristics—traffic volume greater than 400 vehicles per day (vpd) (paved) or greater than 50 vpd (unpaved), bridge length greater than 150 ft (paved) or greater than 35 ft (unpaved), bridge width narrower than its approach (paved) or narrower than 20 ft (unpaved), and bridges older than 25 years (both paved and unpaved). No specific roadway or bridge characteristic was found to contribute to more serious crashes. The study also confirmed previous research findings that crashes with bridges on secondary roads are rare, low-severity events. Although the findings of the study support the need for appropriate use of bridge rails, it concludes that prescriptive guidelines for bridge rail use on secondary roads may not be necessary, given the limited crash expectancy and lack of differences in crash expectancy among the various combinations of explanatory characteristics.

BEHAVIOR OF FIBER REINFORCED POLYMER COMPOSITE PILES WITH ELLIPTICAL CROSS SECTIONS IN INTEGRAL ABUTMENT BRIDGE FOUNDATIONS

Every year in the US and other cold-climate countries considerable amount of money is spent to restore structural damages in conventional bridges resulting from (or “caused by”) salt corrosion in bridge expansion joints. Frequent usage of deicing salt in conventional bridges with expansion joints results in corrosion and other damages to the expansion joints, steel girders, stiffeners, concrete rebar, and any structural steel members in the abutments. The best way to prevent these damages is to eliminate the expansion joints at the abutment and elsewhere and make the entire bridge abutment and deck a continuous monolithic structural system. This type of bridge is called Integral Abutment Bridge which is now widely used in the US and other cold-climate countries. In order to provide lateral flexibility, the entire abutment is constructed on piles. Piles used in integral abutments should have enough capacity in the perpendicular direction to support the vertical forces. In addition, piles should be able to withstand corrosive environments near the surface of the ground and maintain their performance during the lifespan of the bridge. Fiber Reinforced Polymer (FRP) piles are a new type of pile that can not only accommodate large displacements, but can also resist corrosion significantly better than traditional steel or concrete piles. The use of FRP piles extends the life of the pile which in turn extends the life of the bridge. This dissertation studies FRP piles with elliptical shapes. The elliptical shapes can simultaneously provide flexibility and stiffness in two perpendicular axes. The elliptical shapes can be made using the filament winding method which is a less expensive method of manufacturing compared to the pultrusion or other manufacturing methods. In this dissertation a new way is introduced to construct the desired elliptical shapes with the filament winding method. Pile specifications such as dimensions, number of layers, fiber orientation angles, material, and soil stiffness are defined as parameters and the effects of each parameter on the pile stresses and pile failure have been studied. The ANSYS software has been used to model the composite materials. More than 14,000 nonlinear finite element pile models have been created, each slightly different from the others. The outputs of analyses have been used to draw curves. Optimum values of the parameters have been defined using generated curves. The best approaches to find optimum shape, angle of fibers and types of composite material have been discussed.

Training civic bridge builders: Outcomes of community leadership development programs

As rural communities experience rapid economic, demographic, and political change, program interventions that focus on the development of community leadership capacity could be valuable. Community leadership development programs have been deployed in rural U.S. communities for the past 30 years by university extension units, chambers of commerce, and other nonprofit foundations. Prior research on program outcomes has largely focused on trainees’ self-reported change in individual leadership knowledge, skills, and attitudes. However, postindustrial leadership theories suggest that leadership in the community relies not on individuals but on social relationships that develop across groups akin to social bridging. The purpose of this study is to extend and strengthen prior evaluative research on community leadership development programs by examining program effects on opportunities to develop bridging social capital using more rigorous methods. Data from a quasi-experimental study of rural community leaders (n = 768) in six states are used to isolate unique program effects on individual changes in both cognitive and behavioral community leadership outcomes. Regression modeling shows that participation in community leadership development programs is associated with increased leadership development in knowledge, skills, attitudes, and behaviors that are a catalyst for social bridging. The community capitals framework is used to show that program participants are significantly more likely to broaden their span of involvement across community capital asset areas over time compared to non-participants. Data on specific program structure elements show that skills training may be important for cognitive outcomes while community development learning and group projects are important for changes in organizational behavior. Suggestions for community leadership program practitioners are presented.

Neuroscience and education: prime time to build the bridge

As neuroscience gains social traction and entices media attention, the notion that education has much to benefit from brain research becomes increasingly popular. However, it has been argued that the fundamental bridge toward education is cognitive psychology, not neuroscience. We discuss four specific cases in which neuroscience synergizes with other disciplines to serve education, ranging from very general physiological aspects of human learning such as nutrition, exercise and sleep, to brain architectures that shape the way we acquire language and reading, and neuroscience tools that increasingly allow the early detection of cognitive deficits, especially in preverbal infants. Neuroscience methods, tools and theoretical frameworks have broadened our understanding of the mind in a way that is highly relevant to educational practice. Although the bridge’s cement is still fresh, we argue why it is prime time to march over it.

Analyzing the effect of connecting horizontal tidal stream turbines on the pier of a sea established bridge

In this thesis, producing ability of electricity by horizontal tidal current turbines and installing possibility of these turbines on bridge's piers in the marine environments has been studied to reduce primary implementation costs and make the plan, economical. To do this and to study its feasibility, the exerted forces from installing horizontal tidal current turbines were compared with the forces applied to the bridge structure during designing process (given in the Standards). Then, the allowable ranges of the overloading which is tolerable by the piers of the bridge were obtained. Accordingly, it is resulted that for installing these turbines, the piers of the existing bridges are required to be strengthened. Because of increasing usage of renewable powers and as a suggestion, the exerted forces from installing turbine for loading coefficients of different Standards are given. Finally as an example, preliminary designing of a horizontal tidal current turbine was carried out for Gesham Channel and the forces exerted from turbine to the bridge's pier were calculated for the future usage in order to create a test site of real dimensions.