Life Cycle Assessment (LCA) is the globally the most recognised method for quantifying theimpact the a product or service has on the environment through its whole life-span. Theconstruction sector plays a key role in the depletion of the natural resources and the energyconsumption on the planet. Thus it is fundamental that an environmental assessment tool likeLCA should be in close cooperation with the construction process.This thesis focuses on the environmental impact of bridge abutments, and can be divided in twoparts.The rst one focuses on enhancing the automated design in the construction eld. A Python codeis created that focuses on creating the geometry of any type of bridge abutment and conductingthe calculations for the required concrete and reinforcement. The process is attempted to becomecompletely automated.The second part introduces three alternative designs for a bridge abutment that attempt to havethe same structural properties and cooperate successfully with the superstructure, while at thesame time utilize as little material as possible. The possible reduction in material is quantiedin environmental terms after an environmental impact assessment is performed.The results show that dierent designs can have a great impact on the reduction on the materialconsumption and on the impact that the whole structure has on the environment. The resultsin this study might provide the designers with valuable motivation and guidelines to achievehigher sustainability standards in the future.

Numerical analyses of two different geotechnical problems, namely a bridge abutment and a geosynthetic reinforced embankment are presented in this thesis. Settlement, bearing capacity and slope stability are the major factors that need to be considered in the design of a foundation near a sloped fill. In this thesis, the behaviour of a small scale model footing located near the shoulder of a sloped fill was investigated numerically. Single and multiple layers of geogrid were used to reinforce the sloped fill, and their effects on the load-deformation behaviour and bearing capacity of the footing were explored. The analyses showed 80%, 168%, 295% and 375% maximum improvement in the ultimate bearing capacity with 1, 2, 3 and 4 reinforcement layers respectively. This maximum improvement depends on the embedment depths of the reinforcement layers below the foundation and the suggested optimal depths are discussed. Typically, greatest improvement in ultimate bearing capacity with a single layer of reinforcement was obtained when the reinforcement was at a depth between 0.50 and 0.75 times the foundation width. Similarly, highest ultimate bearing capacity with 2 reinforcement layers was predicted when the spacing between them was 1.0 times the width of the foundation. However, higher settlement was estimated at failure for the reinforced sloped fill than the unreinforced one. The second problem investigated was the three-dimensional (3D) analysis of Sackville embankment, a geosynthetic reinforced embankment on soft soil. Previous analyses using two-dimensional (2D) numerical modelling of Sackville embankment indicated potential 3D effects affecting the performance of this embankment. Therefore, 3D analysis incorporating geometric variations of Sackville embankment foundation soil, anisotropic model for fluid flow, mobilization of geotextile stresses in minor direction and the boundary effects (lateral directions) were taken into account in this analysis. The predicted performance of Sackville embankment were compared with the field data and the previously reported 2D analysis results in terms of vertical and horizontal displacements and excess pore pressures in the foundation soil, and geotextile stresses, strains and displacements. Better overall predictions of the Sackville embankment performance was obtained from this 3D analysis than the previous analysis reported in the literature.

Deterministic scour prediction equations for bridge abutments do not involve uncertainties coming from scouring parameters and they only consider effects of hydraulic parameters. However, in order to safely design bridge abutments, treatment of these uncertainties and evaluation of possible risks are required. Two artificial neural network (ANN) models are constructed to describe scouring phenomenon using the parameters of two different equations. The equation to be used in the reliability analysis is then determined according to ANN modeling results. To conduct reliability analysis, Monte Carlo simulation technique is used in which different distributions and coefficients of variations are used for random variables to examine their effects on reliability. It is observed that probability distributions of governing variables have no impact on reliability. However, coefficients of variations of these variables influence reliability.

The passive force-deflection relationship for abutment walls is important for bridges subjected to thermal expansion and seismic forces, but no test results have been available for skewed abutments. To determine the influence of skew angle on the development of passive force, lab tests were performed on a wall with skew angles of 0º, 15º, 30º, and 45º. The wall was 1.26 m wide and 0.61 m high and the backfill consisted of dense compacted sand. As the skew angle increased, the passive force decreased substantially with a reduction of 50% at a skew of 30º. An adjustment factor was developed to account for the reduced capacity as a function of skew angle. The shape of the passive force-deflection curve leading to the peak force transitioned from a hyperbolic shape to a more bilinear shape as the skew angle increased. However, the horizontal displacement necessary to develop the peak passive force was typically 2 to 3.5% of the wall height. In all cases, the passive force decreased after the peak value, which would be expected for dense sand; however, at higher skew angles the drop in resistance was more abrupt than at lower skew angles. The residual passive force was typically about 35 to 45% lower relative to the peak force. Lateral movement was minimal due to shear resistance which typically exceeded the applied shear force. Computer models based on the log-spiral method, with apparent cohesion for matric suction, were able to match the measured force for the no skew case as well as the force for skewed cases when the proposed adjustment factor was used.

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force versus backwall deflection relationship. Current design codes make no allowances for skew effects on the development of the passive force. However, small-scale experimental results and available numerical models indicate that there is a significant reduction in peak passive force as skew angle increases for plane-strain cases. To further explore this issue large-scale field tests were conducted at skew angles of 0°, 15°, and 30° with unconfined backfill geometry. The abutment backwall was 11 feet (3.35-m) wide by 5.5 feet (1.68-m) high, and backfill material consisted of dense compacted sand. The peak passive force for the 15° and 30° tests was found to be 73% and 58%, respectively, of the peak passive force for the 0° test which is in good agreement with the small-scale laboratory tests and numerical model results. However, the small differences may suggest that backfill properties (e.g. geometry and density) may have some slight effect on the reduction in peak passive force with respect to skew angle. Longitudinal displacement of the backfill at the peak passive force was found to be approximately 3% of the backfill height for all field tests and is consistent with previously reported values for large-scale passive force-deflection tests, though skew angle may slightly reduce the deflection necessary to reach backfill failure. The backfill failure mechanism appears to transition from a log spiral type failure mechanism where Prandtl and Rankine failure zones develop at low skew angles, to a failure mechanism where a Prandtl failure zone does not develop as skew angle increases.

This analysis is an expansion of research done by Rollin Hotchkiss during his Ph.D work. The research uses fluid flow, sediment transport, and perturbation theory to predict where scour will occur in a variable-width channel. The resulting equations also determine equilibrium scour depth based upon the stream bed elevation derived from a dimensionless bed slope equation. Hotchkiss perturbed the width of the channel using a second order Taylor Series perturbation but neglected second order terms. The present work follows the same procedures as Hotchkiss but maintains the second order terms. The primary purpose is to examine how the additional terms impact the final equilibrium scour depth and location results. The results of this research show a slight variation from the previous work. With respect to a hypothetical case, there was not a significant amount of change, thereby verifying that scour migrates downstream with an increase in discharge. Interestingly, the comparison shows a slight increase in sediment discharge through the test reach analyzed. Supplementary to previous research, values of scour depth and location in terms of distance from the start of channel-width perturbation are provided; at the lowest discharge maximum scour occurs 4% of a wavelength upstream of the narrowest portion, and at the highest discharge maximum scour occurs at the narrowest point. Additionally, a one-dimensional HEC-RAS sediment transport model and a two- dimensional SRH flow model were compared to the analytical results. Results show that the model output of the HEC-RAS model and the SRH model adequately approximate the analytical model studied. Specifically, the results verify that maximum scour depth transitions downstream as discharge increases.

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force-deflection relationship for the abutment wall. Current design codes make no allowance for skew effects on passive force; however, large scale field tests indicate that there is a substantial reduction in peak passive force as skew angle increases. A reduction in passive force also reduces the transverse shear resistance on the abutment. The purpose of this study is to validate three-dimensional model using PLAXIS 3D, against large scale test results performed at Brigham Young University and to develop a set of calibrated finite element models. The model set could be used to evaluate the variation in passive resistance with skew angle for various abutment geometries and backfill types. Initially, the finite element model was calibrated using the results from a suite of field tests where the backfill material consisted of dense compacted sand. Results were available for skew angles of 0, 15, 30 and 45°. Numerical model results were compared with measured passive force-deflection curves, ground surface heave and displacement contours, longitudinal displacements, and failure plane geometry. Soil properties were defined by laboratory testing and in-situ direct shear tests on the compacted fill. Soil properties and mesh geometries were primarily calibrated based on the zero skew test results. The results were particularly sensitive to the soil friction angle, wall friction angle, angle of dilatancy, soil stiffness and lateral restraint of the abutment backwall movement. Reasonable agreement between measured and computed response was obtained in all cases confirming numerically that passive force decreases as skew angle increases Additional analyses were then performed for abutments with different soil boundaries.

Correct understanding of passive force behavior is particularly key to lateral evaluations of bridges because plastic deformation of soil backfill is vital to dissipation of earthquake energy and thermally-induced stresses in abutments. Only recently have studies investigated the effects of skew on passive force. Numerical modeling and a handful of skewed abutment tests performed in sand backfill have found reduced passive force with increasing skew, but previous to this study no skewed tests had been performed in gravel or Geosynthetic Reinforced Soil (GRS) backfills. The goal of this study was to better understand passive force behavior in non-skewed and skewed abutments with gravel and GRS backfills. Prior to this study, passive pressures in a GRS integrated approach had not been investigated. Gravel backfills also lack extensive passive force tests.Large-scale testing was performed with non-skewed and 30° skewed abutment configurations. Two tests were performed at each skew angle, one with unconfined gravel backfill and one with GRS backfill, for a total of four tests. The test abutment backwall was 11 ft (3.35 m) wide, non-skewed, and 5.5 ft (1.68 m) high and loaded laterally into the backfill. However, due to actuator loading constraints, all tests except the non-skewed unconfined gravel test were performed to a backfill height of 3.5 ft (1.07 m). The passive force results for the unconfined gravel test was scaled to a 3.5 ft (1.07 m) height for comparison.Test results in both sets of backfills confirmed previous findings that there is significant reduction in passive force with skewed abutment configurations. The reduction factor was 0.58 for the gravel backfill and 0.63 for the GRS backfill, compared to the predicted reduction factor of 0.53 for a 30° skew. These results are within the scatter of previous skewed testing, but could indicate that slightly higher reduction factors may be applicable for gravel backfills. Both backfills exhibited greater passive strength than sand backfills due to increased internal friction angle and unit weight. The GRS backfill had reduced initial stiffness and only reached 79% to 87% of the passive force developed by the unreinforced gravel backfill. This reduction was considered to be a result of reduced interface friction due to the geotextile. Additionally, the GRS behaved more linearly than unreinforced soil. This backfill elasticity is favorable in the GRS-Integrated Bridge System (GRS-IBS) abutment configuration because it allows thermal movement without developing excessive induced stresses in the bridge superstructure.

The effects of seismic forces and thermal expansion on bridge performance necessitate an accurate understanding of the relationship between passive force and backwall deflection. In past case studies, skewed bridges exhibited significantly more damage than non-skewed bridges. These findings prompted studies involving numerical modeling, lab-scale tests, and large-scale tests that each showed a dramatic reduction in passive force with increased skew. Using these results, a correlation was developed between peak passive force and backwall skew angle. The majority of these tests had length to height ratios of 2.0; however, for several abutments in the field, the length to height ratio might be considerably higher than 2.0. This change in geometry could potentially affect the validity of the previously found passive force reduction correlation. To explore this issue, laterally loaded, large-scale pile cap tests were performed with densely compacted sand at a length of 11 ft (3.35 m) and a height of 3 ft (0.91 m), resulting in a length to height ratio of 3.7. The backwall interface was adjusted to fit three various skew angles including: 0°, 15° and 30°. The behavior of both the pile cap and adjacent soil backfill were monitored under these conditions. The peak passive force for the 15° and 30° tests were found to be 71% and 45%, respectively, of the peak passive force for the 0° skew test. These findings are relatively consistent with previously performed tests. Passive forces peaked at deflections between 2% and 5% of the backwall height, decreasing with skew angle. All skews exhibited a log spiral failure plane that transitioned into a linear plane. These results also agreed with previously reported values for large-scale passive force-deflection tests. Rotation of the pile cap was detected in the direction opposite to the skew. Higher pressures were found to be on both corners of the pile cap than in the middle portion, as is suggested by the elastic theory.

Skewed bridges have exhibited poorer performance during lateral earthquake loading in comparison to non-skewed bridges (Apirakvorapinit et al. 2012; Elnashai et al. 2010). Results from numerical modeling by Shamsabadi et al. (2006), small-scale laboratory tests by Rollins and Jessee (2012), and several large-scale tests performed by Rollins et al. at Brigham Young University (Franke 2013; Marsh 2013; Palmer 2013; Smith 2014; Frederickson 2015) led to the proposal of a reduction curve used to determine a passive force skew reduction factor depending on abutment skew angle (Shamsabadi and Rollins 2014). In all previous tests, a uniform longitudinal load has been applied to the simulated bridge abutment. During seismic events, however, it is unlikely that bridge abutments would experience pure longitudinal loading. Rather, an inclined loading situation would be expected, causing rotation of the abutment backwall into the backfill. In this study, a large-scale test was performed where inclined loading was applied to a 30° skewed bridge abutment with sand backfill and compared to a baseline test with uniform loading and a non-skewed abutment. The impact of rotational force on the passive resistance of the backfill and the skew adjust factor was then evaluated. It was determined that inclined loading does not have a significant effect on the passive force skew reduction factor. However, the reduction factor was somewhat higher than predicted by the proposed reduction curve from Shamsabadi and Rollins 2014. This can be explained by a reduction in the effective skew angle caused by the friction between the side walls and the back wall. The inclined loading did not change the amount of movement required to mobilize passive resistance with ultimate passive force developing for displacements equal to 3 to 6% of the wall height. The rotation of the pile cap due to inclined loading produced higher earth pressure on the obtuse side of the skew wedge, as was expected.These findings largely resolve the concern that inclined loading situations during an earthquake may render the proposed passive force skew reduction curve invalid. We suggest that the proposed reduction curve remains accurate during inclined loading and should be implemented in current codes and practices to properly account for skew angle in bridge design.