This thesis is concerned with the seismic design of bridge piers. Particular attention is given to lifeline bridges with reinforced concrete hollow columns. Development of an analytical model to predict the stress-strain behaviour of reinforcing steel under dynamic cyclic loading is presented. Model predictions agreed well with previous tests on mild and high strength steel specimens. A generalised stress-strain model for plain or confined concrete under dynamic cyclic axial compression loading is presented. To verify the model, axial compression tests were carried out on 15 circular columns with spiral reinforcement, 16 rectangular walls and five square columns with rectilinear hoops. Theoretical predictions compared well with the experimental behaviour of the near full size specimens. A ductile design methodology for lifeline bridges is presented. Inelastic response spectra for "maximum credible" earthquake motions were derived for structures with concrete columns. These design spectra can be used to assess ductility demand of column hinges. Using the steel and concrete stress-strain models, a theoretical model is developed to predict the lateral load-deformation behaviour, and thus ductility capability, of reinforced concrete columns under axial load and cyclic flexure. Design charts are prepared to enable the rotational capacity of columns with confined concrete to be assessed. Finally, an experimental investigation into the seismic performance of ductile hollow reinforced concrete columns is described. Four specimens, 40 percent full size, containing different amountsof confining steel in the plastic hinge zone were subjected to a constant axial load and cyclic lateral displacements. An assessment of the effect of axial load and the amount of confining steel on the rotational capacity of the plastic hinge is made. The specimens performed satisfactorily, obtaining member ductilities between 6 and 8, without any significant strength degradation under cyclic loading. Predictions from the proposed lateral load- deformation model are found to compare well with the experimental results.

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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.

Yes / River dynamics and sediment transport play an important role in river bed morphology. Building a bridge pier along the river alters the cross-section of the river and causes the change in flow processes. These changes are mainly responsible for pier scour. In this paper, the usage of collars to reduce scour around circular piers has been investigated. The collars with different diameters and depth positions have been studied using previous data and additional data collected in the present study to assess their effectiveness in reducing scour. Using a wide range of measured data, an empirical equation to compute the maximum scour depth around the circular piers in the presence of collars has been proposed. The proposed equation has been validated and proven to be applicable to a wide range of pier layouts. It has been found that the maximum efficiency can be achieved by fixing the collar at bed level and adopting a collar diameter 1.5–2.5 times of pier diameter.

Real-time structural health monitoring is a well established tool for post-earthquake damage estimation. A key component in the monitoring campaign is the approach used for processing the data from the structural health monitoring system. There is a large body of literature on signal processing approaches aimed at identifying ground-motion induced damage in civil engineering structures. This dissertation expands on a specific subgroup of processing approaches dealing with the identification of damage induced high-frequency transients in the monitoring data. The underlying intuition guiding the current research can be formulated in the following hypothesis - the time difference between the occurrence of a high-frequency transient and the closest deformation extremum forward in time is proportional to the degree of damage. A mathematical deduction is provided in support of the above hypothesis followed by a set of shaking table tests. For the purposes of this research two shaking table tests of reinforced concrete bridge piers were performed. Data from a shaking table test performed by another research group was also analyzed. The cases in which the proposed procedure could find a practical application are examined along with the present limitations.

It is an important task that design engineers in practice predict the local scour around bridge piers as accurately as possible because excessive local scour around bridge piers unbalance and demolish the bridges. Many equations have been proposed previously by various researchers, based on their experimental findings, but no general method has been developed so far due to the complexity of the topic. In the present study two new bridge pier groups were employed to investigate the inclination effect of the most upstream and downstream piers on the local scours around all piers. Total of 72 experiments have been conducted with 3 inclination angles, one of which representing the vertical case, each experiment lasting 6 hours, under uniform flow and clear-water conditions for a range of water depths and flow velocities on the uniform bed material. It is clearly observed and measured that the amount of local scour reduces substantially by the effect of inclination in the group piers, especially the reduction in the scour around the most upstream pier is found notable. Based on the experimental data, regression analyses are made and an empirical scour depth equation is developed for each individual pier in the pier groups studied. Comparisons with the similar studies performed by other researchers have been made and the results discussed.

Many river bridges fail or are seriously damaged due to excessive local scouring around piers and abutments. To protect a bridge from scour-induced failure, it should be designed properly against excessive scouring and its scour criticality should be checked regularly throughout the service life to take prompt action. The Federal Highway Administration of United States (FHWA) developed a program, HYRISK, as a basis for evaluation of existing scour failure risk of a bridge. It provides implementation of a risk-based model, which is used to calculate the annual risk of scour failure of a bridge or series of bridges in monetary values. A case study is carried out for a bridge crossing Fol Creek in Black Sea Region (close to Vakfikebir), for the illustration of this software. Besides, hydraulic analysis and scour depth computations of the bridge are carried out via HEC-RAS program. Also, a study is carried out to recommend scour countermeasures that can be applied to the aforementioned bridge.

For a bridge engineer, it is very important to estimate the maximum scour depth around the piers as accurately as possible, in order to design the footing safely. Many experimental studies have been performed by several investigators until now, in order to obtain information about scouring mechanism. The aim of this experimental study is to examine the effect of inclination of the dual bridge piers on scour depth. The experiments have been conducted with dual pier models under clear-water conditions, for various uniform flow depths. Scour depths had been measured at four different points around the piers / namely upstream and downstream faces of both piers. Dimensional and non-dimensional scour curves have been developed and presented to show the temporal variation of scour depth. The depths of local scour around inclined piers have been observed to be smaller than the scour depths around vertical piers.

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