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O trabalho tem por objetivo o estudo teórico e experimental de pontes protendidas de madeira para pequenos vãos utilizando madeiras de reflorestamento. Para esta finalidade foram avaliados os parâmetros elásticos destas madeiras e o efeito da presença de juntas de topo na rigidez longitudinal do tabuleiro da ponte. A metodologia utilizada para obter os parâmetros elásticos é a experimentação em laboratório de placas ortotrópicas submetidas à torção. Os efeitos das juntas de topo foi verificado em ensaio de modelo reduzido e comparado a uma simulação numérica em computador utilizando o programa AnSYS 5.2 de elementos finitos, módulo Shell, com propriedades ortotrópicas. Finalmente é proposto um critério de dimensionamento para estas estruturas a partir dos resultados experimentais obtidos e de disposições de códigos internacionais. / The aim of this work is the theoretical and experimental study of prestressed timber bridges to small spans using reforestation species. To this purpose elastics characteristics are analysed as well the butt joint effects on timber deck stiffeness. The experimental methodology was used to find the elastics characteristics is torsional tests in orthotropic plates. The butt joints effects was made in a reduced model and the results compared with a computer numerical analysis using the software AnSYS 5.2, shell module, with ortotropic characteristics. Finally, a design criteria was proposed to these structures using the experimental results obtained and the international codes recomendations.

Masonry arch bridges still play an important role in the transportation infrastructure today in the United Kingdom. Previous research has mainly focused on the load carrying capacity in the span direction. The three dimensional behaviour is often investigated by simplifying into two dimensions with modified arch parameters but these simplified analyses cannot represent all aspects of behaviour. Spandrel wall failure in some railway masonry arch bridges has raised concerns recently, and this is one aspect which cannot be modelled in two dimensions. This thesis presents a research which attempts to model the interaction behaviour between arch, backfill and spandrel wall with the aim of representing the three dimensional nature of real bridges. It mainly focuses on the spandrel wall defects under increasing load, including crack development across the wall and longitudinal cracks in the arch barrel underneath spandrel wall. Experimental results from the laboratory tests on engineering blue brick and a hydraulic premixed mortar as well as brickwork masonry specimens are presented. Numerical analysis was initially performed on these brickwork masonry specimens for validation. Three dimensional FE models were proposed for both small and large scale bridges. The general behaviour of the small scale bridge under rolling load and large scale bridge under increasing load were studied. Reasonable agreement between the FE analyses and experimental results from previous literature was obtained, indicating the model validated for small masonry specimens could be scaled up to full-scale bridges. A series of computer models were constructed to investigate the relationship between a range of geometric and material parameters and the lateral behaviour of arch bridges. The backfill depth and spandrel wall thickness have greatest impact on both bridge strength and lateral behaviour. The fill properties also have an importance influence on the load carrying capacity. This provides an indication of which bridge should be more closely monitored for spandrel wall defects. Separate FE models was constructed to simulate existing longitudinal cracks found in the arch barrel for old bridges and the influence of strengthening of spandrel wall with tie bars. The general behaviour under a concentrated load is studied and discussed. It has been demonstrated that it is possible to effectively model the three dimension behaviour of masonry arch bridges and in particular, spandrel wall failures.

This paper investigates the application of tuned mass damper (TMD) systems to bridge pier systems for structural impact damage mitigation and thus reduce the risk of collapses. A bridge superstructure and substructures are designed in accordance with The American Association of State Highway and Transportation Officials (AASHTO) specifications. A variety of vessel collision forces are obtained from collision testing of a scaled reinforced concrete pier. The optimal parameters of TMD systems are then determined such that the drift and displacement of the bridge superstructure are minimized for various impact scenarios. The structural impact mitigation performance of the pier equipped with the proposed optimal TMD system is compared with five different TMD systems employing the benchmark TMD optimal parameters. The uncontrolled responses are used as a baseline. It was demonstrated from the extensive simulations that the control effectiveness of the proposed TMD system was 25% better than all of the existing TMD models in reducing structure responses.

With the majority of bridges in the country aging, over capacity and costly to rehabilitate or replace, it is essential that engineers refine their inspection and evaluation techniques. Over the past 130 years the information gathering techniques and methods used by engineers to inspect bridges have changed little. All of the available methods rely on one technique, visual inspection. In addition, over the past 40 years individual bridge inspectors have gone from being information gathers to being solely responsible for the condition rating of bridges they inspect. The reliance on the visual abilities of a single individual to determine the health of a particular bridge has led to inconsistent and sometimes erroneous results. In an effort to provide bridge inspectors and engineers with more reliable inspection and evaluation techniques, this thesis will detail the case for development of a new inspection tool, and the assembly and use of one new tool called Fringe Interferometry

The cost and effort of modelling existing bridges from point clouds currently outweighs the perceived benefits of the resulting model. The time required for generating a geometric Bridge Information Model, a holistic data model which has recently become known as a "Digital Twin", of an existing bridge from Point Cloud Data is roughly ten times greater than laser scanning it. There is a pressing need to automate this process. This is particularly true for the highway infrastructure sector because Bridge Digital Twin Generation is an efficient means for documenting bridge condition data. Based on a two-year inspection cycle, there is a need for at least 315,000 bridge inspections per annum across the United States and the United Kingdom. This explains why there is a huge market demand for less labour-intensive bridge documentation techniques that can efficiently boost bridge management productivity. Previous research has achieved the automatic generation of surface primitives combined with rule-based classification to create labelled cuboids and cylinders from point clouds. While existing methods work well in synthetic datasets or simplified cases, they encounter huge challenges when dealing with real-world bridge point clouds, which are often unevenly distributed and suffer from occlusions. In addition, real bridge topology is much more complicated than idealized cases. Real bridge geometries are defined with curved horizontal alignments, and varying vertical elevations and cross-sections. These characteristics increase the modelling difficulties, which is why none of the existing methods can handle reliably. The objective of this PhD research is to devise, implement, and benchmark a novel framework that can reasonably generate labelled geometric object models of constructed bridges comprising concrete elements in an established data format (i.e. Industry Foundation Classes). This objective is achieved by answering the following research questions: (1) how to effectively detect reinforced concrete bridge components in Point Cloud Data? And (2) how to effectively fit 3D solid models in the format of Industry Foundation Classes to the detected point clusters? The proposed framework employs bridge engineering knowledge that mimics the intelligence of human modellers to detect and model reinforced concrete bridge objects in point clouds. This framework directly extracts structural bridge components and then models them without generating low-level shape primitives. Experimental results suggest that the proposed framework can perform quickly and reliably with complex and incomplete real-world bridge point clouds encounter occlusions and unevenly distributed points. The results of experiments on ten real-world bridge point clouds indicate that the framework achieves an overall micro-average detection F1-score of 98.4%, an average modelling accuracy of (C2C) ̅_Auto 7.05 cm, and the average modelling time of merely 37.8 seconds. Compared to the laborious and time-consuming manual practice, the proposed framework can realize a direct time-savings of 95.8%. This is the first framework of its kind to achieve such high and reliable performance of geometric digital twin generation of existing bridges. Contributions. This PhD research provides the unprecedented ability to rapidly model geometric bridge concrete elements, based on quantitative measurements. This is a huge leap over the current practice of Bridge Digital Twin Generation, which performs this operation manually. The presented research activities will create the foundations for generating meaningful digital twins of existing bridges that can be used over the whole lifecycle of a bridge. As a result, the knowledge created in this PhD research will enable the future development of novel, automated applications for real-time condition assessment and retrofit engineering.

Every two-bridge knot or link is characterized by a rational number p/q, and has a fundamental group which has a simple presentation with only two generators and one relator. The relator has a form that gives rise to a formula for the Alexander polynomial of the knot or link in terms of p and q [15]. Every two-bridge knot or link also has a corresponding “up down” graph in terms of p and q. This graph is analyzed combinatorially to prove several properties of the Alexander polynomial. The number of two-bridge knots and links of a given crossing number are also counted.

The Utah Transportation Center (UTC), in partnership with the Mountain Plains Consortium (MPC), sponsored a study to investigate the differences in prestress losses and temperature gradients in a concrete deck bulb tee girder bridge. The Millville Bridge was built as an access point to the Ridgeline High School in Millville, Utah. The bridge was built in 2016 and presently supports two lanes of traffic. Changes in prestress were measured with a total of 16 vibrating wire strain gauges located at four cross-sections. Temperature gradients were measured with a total of 50 thermocouples located at five cross-section locations, four of which were shared locations with the vibrating wire strain gauges. These instruments were placed at the mid-span and end of an exterior and center girder to effectively measure the bridge response in one quarter of the bridge superstructure. These instruments were placed in the precast plant and tied to the reinforcing steel before the concrete was poured. The prestress loss recordings were initiated before the prestressing strands were released. The thermocouple data for Girder 1 began to be recorded before the initial casting of the girder concrete. The thermocouple data for Girder 5 was not recorded during casting and curing of the girder concrete, but was started before the curing blanket was removed in the casting yard. All data was recorded until February 29, 2016. Prestress losses at the girder mid-span and temperature gradients were compared with code recommended values according to the AASHTO bridge design specifications.

Fiber reinforced polymer (FRP) deck has some significant advantages compared to concrete deck in use of bridges, such as light self-weight, high stiffness and strength, good durability and easy to install. FRP deck has already been used in some bridge rehabilitation and short span bridges. But for widely used in bridges, FRP deck bridges still need further research. Currently many research efforts focus on the filed tests of FRP deck bridges. Compared to field tests, Finite element analysis also has great advantages, such as low cost and convenient to conduct. Therefore, in this thesis finite element analysis is conducted by ABAQUS on the Boyer Bridge in Pennsylvania. The finite element model is verified by the static field test result. Then a simplified moving truck load is applied on the bridge model in order to analyze the dynamic responses of the FRP deck bridge, including the displacements and stress of each girder at the middle span. The dynamic effect is shown by comparing the dynamic responses and the static responses of the bridge. The connection between the FRP deck and girder is very important to the behavior of the bridge. In this thesis shear studs serve to connect the FRP deck and girder. This thesis also analyzes the effect of shear studs to the dynamic responses of the bridge by changing the number of the shear studs.