Interruption of railway traffic creates important financial losses for the transportation utilities and society at large. At this moment, to limit this impact, the CN uses emergency girders stored around their territory to decrease the time to transport the materials to the site. However, this method is difficult to put in place and bypass of the traffic is not possible everywhere. The development of a portable railway bridge is interesting for this purpose. This structure has to be transported, erected and in services within 48h. This type of bridge should also be adjustable in length to allow reusing of the existing bearings, piers and abutments (5 to 28m of span). Between the steel superstructure possibilities, three solutions have been chosen: (a) plate girder, (b) through girder and (c) through truss. The geometry and the construction method are the particularities to consider. After those conceptions, the three alternatives have been analyzed as a function of many criteria. The number of bolts, the quantity of material and the dimension of the prefabricated sections were considered to determine the best solution for this kind of utilization.

Traditionally, prestressed concrete girder bridges are limited to 150 ft span lengths in Texas due to restrictions on handling and transportation. An effective way of increasing span lengths of precast, prestressed concrete girder bridges is demonstrated using splicing technique. In spliced girder bridges, precast girder segments are transported in shorter segments for handling and transportation and then spliced together to form long-span continuous bridges. Different methods are explored for construction of spliced girder bridges. Two application examples are developed to demonstrate the design of continuous prestressed concrete spliced girder bridges for both shored and partially shored methods of construction. A three-span bridge having a span configuration of 190-240-190 ft is considered for both examples. Advantages and dis-advantages of each method of construction are discussed. Construction issues that should be considered in the design are highlighted. The results of this study indicate that span lengths up to 240 ft are achievable using standard Tx70 girders with the help of splicing techniques. A parametric study is performed to further explore the design space of spliced girder bridges. The results of the parametric study, along with critical design issues that were identified, are highlighted and related recommendations are provided. The results of this study will be of significant interest to bridge engineers and researchers for guidance in implementing spliced girder bridges in Texas and other states.

Glue laminated wood deck systems are commonly used for bridge decks on girder bridge systems. These decks are usually covered with a hot-mix asphalt wearing surface in conjunction with a bituminized fabric sheet waterproofing membrane. Often cracks occur in the asphalt at the intersection of two adjacent deck panels which limits the useful life of the wear surface, provides a poor riding surface and potentially allows moisture to flow to wooden bridge components. The purpose of this study was to investigate the structural behavior of asphalt/wood/membrane deck systems. This was accomplished experimentally by determining the deflection of bridge deck panels with respect to each other under simulated truck loading. A classical linear analysis model and a finite element analysis model were developed for the deck panel deflections. These analytical results were compared to the experimental results and a value of approximately 0.05 in for the interpanel differential deflection was determined to be a reasonable, conservative value for the typical configuration considered. This deflection was then used to load various asphalt/membrane/ wood configurations to investigate the effectiveness of the arrangement with regards to resisting hot-mix asphalt cracking. It was found that when subjected to repeated deflections of 0.05 in, the following experimental composite bridge deck performed best in terms of reduced cracking: 1) hot-mix asphalt base layer applied directly onto the glulam deck panel; 2) waterproofing membrane placed on the base layer of asphalt; 3) hot-mix asphalt surface layer placed on the waterproofing membrane. / Master of Science

The UK has a long history in the railway industry with a large number of railway assets. Railway bridges form one of the major asset groups with more than 35,000 bridges. The majority of the bridge population are old being constructed over 100 years ago. Many of the bridges were not designed to meet the current network demand. With an expected increasing rate of deterioration due to the increasing traffic loads and intensities, the management authorities are faced with the difficult task of keeping the bridge in an acceptable condition with the constraint budget and minimum service disruptions. Modelling tools with higher complexity are required to model the degradation of assets and the effects of different maintenance strategies, in order to support the management decision making process. This research aims to address the deficiencies of the current bridge condition systems and bridge models reported in the literature and to demonstrate a complete modelling approach to bridge asset management. The degradation process of a bridge element is studied using the historical maintenance data where previous maintenance actions were triggered by a certain type of defects. Two bridge models are then developed accounting for the degradation distributions, service and inspection frequency, repair delay time and different repair strategies. The models provide a mean of predicting the asset future condition as well as investigating the effects of different maintenance strategies will have on a particular asset. The first model is a continuous-time Markov bridge model and is considered more complex than other models in the literature, the model demonstrates the advantages of the Markov modelling technique as well as highlighting its limitations. The second bridge model presented a novel Petri-Net modelling approach to bridge asset modelling. This stochastic modelling technique allows much more detail modelling of bridge components, considering: non-constant deterioration rates; protective coating modelling; limits of the number of repairs can be carried out; and the flexibility of the model allows easily extension to the model or the number of components modelled. By applying the two models on the same asset, a comparison can be made and the results further confirm the validations and improvements of the presented Petri-Net approach. Finally, optimisation technique (Genetic Algorithm) is applied to the bridge models to find the optimum maintenance strategies in which the objectives are to minimise the whole life cycle cost whist maximising the asset average condition. A hybrid optimisation that takes advantage of both bridge models, resulting in a significant time saving, is also presented.

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