River bridges get damaged or even collapse because of various reasons, such as development of adverse hydraulic conditions during severe floods, disastrous earthquakes, deficiencies in structural and geotechnical design, material deficiencies, or other unexpected external factors. Failure of service at vital lifelines, bridges, can lead to loss of several lives and properties, traffic disruption, and/or deficiencies in daily usage. Existing structures should be monitored periodically for decision-making and necessary protective works should be implemented to increase the safety. Types of items to be inspected would be categorized as structural, geotechnical, hydraulic, and status of materials. Requirement for periodic inspections and the ways of handling these activities are discussed within the framework of aforementioned aspects with special reference to the current situation of river bridges in Turkey and current practices in USA. An algorithm, composed of sets of checklists, is proposed. In such an algorithm, rank-based prioritization of events is identified. The evaluation and interpretation are displayed with the help of a few case studies, selected among several river bridges around Ankara.

Accelerated bridge construction methods are being progressively used to construct and replace bridges in North America. Unlike traditional bridge construction methods, accelerated bridge construction methods allow bridges to be built in a shortened period of time on the construction site. These methods reduce the road closure time and the traffic disruption that are associated with bridge construction. One of these methods is carried out by prefabricating the bridge elements offsite and then assembling them onsite in a time-efficient way to build the bridge. This construction method can be used to build steel-precast composite bridges, where steel plate girders are connected to full-depth precast concrete deck panels. For the expeditious construction of composite bridges, a proper shear connection detail is needed to develop composite action between the steel plate girders and the precast concrete deck panels. This research project investigated two types of shear connection that would accelerate the construction of steel-precast composite bridges. First, finite element analysis was used to study the behaviour of composite bridge girders with panel end connections. The girders were analyzed for their load-displacement behaviour, cross-sectional stress and strain profile, and connection force distributions. Secondly, experimental push tests were conducted to study the load-slip behaviour of bolted connections. The effects of steel-concrete interface condition, bolt diameter and bolt tension on the shear capacity of bolted connections were analyzed. Based on the finite element analysis results, it is concluded that the panel end connected girder exhibited strong composite action at service and ultimate load. The level of composite action decreased slightly when the panel end connection stiffness was reduced by a factor of ten. Based on the experimental results, it is concluded that the total shear capacity of the bolted connection is the sum of the friction resistance and the bolt dowel action resistance. The friction resistance of the connection depends on the interface condition and the bolt clamping force. An analytical model that can predict the ultimate shear capacity of bolted connections has been developed and recommended. The proposed model is shown to give reliable predictions of the experimental results. It should be noted that bolted connections exhibit good structural redundancy because the bolt fracture failures do not happen simultaneously.

Vehicle collisions with bridge piers can result in significant damage to the support pier and potentially lead to catastrophic failure of the whole structure. The Nation’s aging infrastructure suggests that many structures no longer meet current design standards, placing many bridge susceptible to failure if subjected to an extreme loading event. This research aims to study the structural response of reinforced concrete bridge piers subjected to vehicle collisions. A sensitivity analysis is conducted to observe the causes of shear and bending failures of bridge piers subjected to vehicle collision. Parameters, such as pier diameter, transverse reinforcement spacing, vehicle impact velocity, pile cap height, and multi-pier configuration, are investigated in this study. The finite element code LS-DYNA is utilized to simulate and analyze the vehicle collisions to obtain accurate and detailed results. The vehicle models offered by the National Crash Analysis Center and the National Transportation Research Center, Inc. are used to conduct this research. The finite element modeling controls and material properties are validated by conducting an impact drop hammer experiment. The bridge pier collision models are validated by comparing vehicle damage and impact forces with published research results. Conservation of energy is also checked to assure stability within the impact simulation. A sensitivity analysis suggests that different pier parameters have a profound effect on failure modes and distribution of impact forces. Piers with large stiffness result in high impact forces, low lateral displacements, and high resistance to shear forces and bending moments. A performance-based analysis shows that bridge piers can be designed using damage ratios associated with particular damage states.

There are approximately 4000 railway bridges in Sweden and a common construction type is the short span concrete trough bridge. With the current standards the load distribution through ballast is assumed to be uniformly distributed with a distribution slope of 2:1 according to the Swedish Administration of Transport or 4:1 according to Eurocode 1. Previous research shows that there are a lot of factors that affects the load distribution through the ballast and that the distribution rarely is uniform. Different load patterns on bridges can result in different responses in the structure and it is possible that a more optimized evaluation of the loads could reduce the internal stresses in the bridge. There are gaps in the current literature regarding the structural response to different load patterns on reinforced concretetrough bridges and this master thesis aims to further the research in this area. This report will consist of a literature study where load distribution in ballast is researched in order to find what different load distributions are common and how different parameters affects the load distribution through the ballast. Further, a non-linear FE-model of a typical trough bridge in Sweden that was located in Lautajokki will be developed using ATENA Science. The model will be complete with ballast, sleepers and rails and will be calibrated using the results from a previous full-scale test on the Lautajokki bridge. Four more models will be developed without ballast, sleepers and ballast where the load distribution instead is modelled directly on top of the slab of the bridge. These models will be compared to the model with ballast, sleepers and rail (called the Full model) to see what load distribution that is the closest to reality and how the behavior of the bridge changes depending on the assumed load distribution. The parameters that will be tested and compared during this master thesis is the maximum load capacity, the stiffness, the crack patterns, the stresses in the reinforcement, the moments and shear forces. The load distributions that are tested in this thesis is the Swedish standard, TDOK 2013:0267 (Trafikverket, 2019), the European standard Eurocode 1 (CEN-1991, 2003), a load distribution that is theoretical according to research done by Andersson (2020) (called Realistic load case), and one where the load is assumed to be partially uniformly distributed under the rail seats under a sleeper according to AREMA (2010) (called Partially distributed). The results showed that the realistic load case was the one that was the closest to the Full model since it was the closest load distribution to the Full model for the stiffness of the bridge, the maximum load capacity, the max stress in the reinforcement and the average shear force in the bridge. The only parameters where it was not the closest was for the maximum strain in the concrete and for the average moment in the bridge. This load distribution is however not realistic to use for designing bridges since the pressure distribution is so unnecessarily complex. When it comes to the Swedish standard it also followed the behavior of the Full model closely, it had capacities that were generally larger compared to the Full model, the only exception was the max axle load where it had 1.5% lower capacity. The Swedish standard was also the second closest to the Full model in all tested parameters except for the stiffness. Furthest from the Full model was the load distribution after Eurocode 1 which had the furthest values from the Full model in every tested parameter except for the average moment distribution in the bridge. Eurocode 1 also had lower capacities compared to the Full model for every tested parameterwhich means that this model probably underestimates the capacity of the bridge. The stiffness of this model was however one of the closest to the Full model. The Partially distributed load case had higher capacities compared to the Full model in every measurement. It also had a stiffness that was the stiffest for every measuring point compared to any other load case. This model can probably overestimate the capacity of the bridge. Since non-linear analyses takes a long time to perform linear analyses are more often used to design structures. To test how big the differences are between non-linear and linear analyses all load distribution models will also be run with linear elastic materials to compare the two FEM methods. The comparison between the non-linear analysis and the linear analysis showed that the linear elastic analyses give larger extreme values for both the moments and shear forces which is reassuring since this means that these values are on the safe side. The one exception is the transversal moments for the slab were the moments at the connection to the beam was greater for the non-linear analyses compared to the linear one

The objective of the research presented in this thesis was to study and optimize the transverse deck reinforcement for a skewed concrete bridge deck supported by Hybrid Composite Beams (HCB's).  An HCB consists of a Glass Fiber Reinforced Polymer outer shell, a concrete arch, and high strength seven wire steel strands running along the bottom to tie the ends of the concrete arch together.  The remaining space within the shell is filled with foam.  The concrete arch does not need to be cast until the beam is in place, making the HCB very light during shipping.  This lowers construction costs and time since more beams can be transported per truck and smaller cranes can be used.  HCB's are quite flexible, so AASHTO LRFD's design model for bridge decks, as a one-way slab continuous over rigid supports, might not apply well to the HCB's deck design. A skewed three HCB girder bridge with a reinforced concrete deck and end diaphragms was built in the laboratory at Virginia Tech.  Concentrated loads were applied at locations chosen to maximize the negative and positive moments in the deck in the transverse direction.  The tests revealed that the transverse reinforcement was more than adequate under service loads. An Abaqus model was created to further study the behavior of the bridge and to help create future design recommendations.  The model revealed that the HCB bridge was behaving more like a stiffened plate at the middle section of the bridge, indicating that the flexibility of the girders needed to be considered. / Master of Science

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A set of experimental tests were performed at Virginia Tech to investigate transverse joints and blockouts on full depth concrete bridge deck panels. The joints were designed on a deck replacement project for a rural three span continuous steel girder bridge in Virginia. Two cast-in-place and four post-tensioned joints were designed and tested in cyclical loading. Each joint was tested on a full scale two girder setup in negative bending with a simulated HS-20 vehicle. The blockouts were built as hollow concrete rings filled with grout and left to shrink under ambient conditions. Thirteen combinations of different surface conditions and grouts were designed to test the bond strength between the materials. The strain profile, cracking patterns, and ponding results were measured for all specimens. A finite element analysis was performed and calibrated with the laboratory results. The cast-in-place joints and the two post-tensioned joints with 1.15 MPa (167 psi) of initial stress experienced cracking and leaked water by the end of the tests. The two post-tensioned joints with 2.34 MPa (340 psi) initial stress kept the deck near a tensile stress of 1.5√(𝑓'c) and performed the best. These transverse joints did not leak water, did not have full depth cracking, and maintained a nearly linear strain distribution throughout the design life. Full depth deck panel may be effectively used on continuous bridges if a sufficient amount of post-tensioning force is applied to the transverse joints. The finite element model provides a design tool to estimate the post-tensioning force needed to keep the tensile stresses below the cracking limit. The blockouts with a roughened surface or an epoxy and a grout equivalent to Five Star Highway Patch grout had the highest bond stresses, did not leak water, and had smaller cracks at the grout-concrete interface than the control samples. A minimum bond strength of 2.5√(𝑓'c) was maintained for all of the specimens with a grout equivalent to Five Star Highway Patch. A pea gravel additive in the grout reduced shrinkage and reduced the bond strength. The finite element model provides a design tool to estimate cracking at the grout-surface interface. / Ph. D.