Long Term Behavior Of Integral Abutment Bridges

Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To expand their applicability, studies were implemented to define limitations supported by rational analysis rather than simply engineering judgment. Previous research investigations have resulted in larger length limits and an overall better understanding of these structures. However, questions still remain regarding IA behavior; specifically questions regarding long-term behavior and effects of skew. To better define the behavior of these structures, a study was implemented to specifically investigate the long term behavior of IA bridges. First, a field monitoring program was implemented to observe and understand the in-service behavior of three integral abutment bridges. The results of the field investigation were used to develop and calibrate analytical models that adequately capture the long-term behavior. Second, a single-span, quarter-scale integral abutment bridge was constructed and tested to provide insight on the behavior of highly skewed structures. From the acquired knowledge from both the field and laboratory investigations, a parametric analysis was conducted to characterize the effects of a broad range of parameters on the behavior of integral abutment bridges. This study develops an improved understanding of the overall behavior of IA bridges. Based on the results of this study, modified length and skew limitations for integral abutment bridge are proposed. In addition, modeling recommendations and guidelines have been developed to aid designers and facilitate the increased use of integral abutment bridges.

Integral abutment bridges, a type of jointless bridge, are the construction option of choice when designing highway bridges in many parts of the country. Rather than providing an expansion joint to separate the substructure from the superstructure to account to volumetric strains, an integral abutment bridge is constructed so the superstructure and substructure are continuous. The abutment is supported by a single row of piles which must account for the longitudinal movement previously accommodated by the joints. The primary advantage of an integral abutment bridge is that it is jointless (expansion joints are eliminated) and thus reduces both upfront and overall life-cycle costs. In addition to other benefits provided by integral construction, the reduction in overall cost has led to INDOT requiring all new structures within certain geometric limitation be integral. These geometric limitations, traditionally based on engineering judgment, have been modified over time based as investigations have revealed more about the behavior of integral abutment bridges. While there has been a considerable amount of research and investigation conducted on the behavior of integral abutment bridges, information is limited on both long-term behavior and the effects of highly skewed structures. Because there is a great desire for the application of these structures to be expanded, this research serves to expand the understanding of the behavior of integral abutment structures. Additionally, updated geometric limitations are recommended along with design recommendations and recommended analysis procedures for properly modeling integral abutment behavior.

intermediate length bridges. Integral abutment construction eliminates joints and bearings which reduce long-term maintenance costs. However, in the absence of joints and bearings, the bridge abutments and foundations must be able to accommodate lateral movements from thermal expansion and contraction of the superstructure and from seismic events. Previous research has focused on the response to thermal expansion and contraction. The current research examines the response of integral abutment bridges to seismic loading. A field investigation was conducted to examine the response of an integral abutment to lateral loading from thermal expansion and contraction. The results were used to calibrate analytical bridge models used to estimate displacements of the abutment during design seismic events. A laboratory investigation was conducted to estimate the lateral displacement capacity of the abutment based on the performance of the abutment-pile connection. Results of the field, analytical, and laboratory investigations were used to evaluate allowable bridge lengths based on seismic performance. Finally, design recommendations are provided to enhance the seismic performance of integral abutment bridges.

Integral abutment bridges have been used in the United States for decades. By eliminating expensive expansion joints, the piles supporting the end bent accommodate the total thermal movement of the bridge. Currently, integral bridges are designed based upon experience, and a rational design specification has not been developed. Furthermore, the interaction of the abutment, pile, and soil remains uncertain. A better understanding regarding the behavior of this system is needed. The objective of this research is to evaluate the behavior of the integral abutment-pile system and evaluate any limitations of its use. To achieve this objective, two phases of research were conducted. The first phase was a field study that investigated the in-service pile behavior of four integral abutment bridges. The second phase was an experimental study that was used to evaluate the capability of piles typically used in integral abutment bridges. Nine low-cycle, large amplitude lateral displacement pile tests were conducted. Throughout both phases, analytical investigations were also conducted. To develop simplified modeling techniques that sufficiently account for soil-pile interaction, the piles supporting abutments were analytically modeled and calibrated based on the field and experimental results. A parametric study was also performed with variables including pile type, pile orientation, axial load, pile length, and soil type. The results of these phases were evaluated and design recommendations were developed based on these results. Overall, the design recommendations provide for an extension in the length limits often used for integral bridges. The extension of these limits can result in a reduction in bridge construction and maintenance costs for a large number of structures that cannot currently be built using this structural system.

Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability contains lectures and papers presented at the Eleventh International Conference on Bridge Maintenance, Safety and Management (IABMAS 2022, Barcelona, Spain, 11–15 July, 2022). This e-book contains the full papers of 322 contributions presented at IABMAS 2022, including the T.Y. Lin Lecture, 4 Keynote Lectures, and 317 technical papers from 36 countries all around the world. The contributions deal with the state-of-the-art as well as emerging concepts and innovative applications related to the main aspects of safety, maintenance, management, life-cycle, resilience, sustainability and technological innovations of bridges. Major topics include: advanced bridge design, construction and maintenance approaches, safety, reliability and risk evaluation, life-cycle management, life-cycle, resilience, sustainability, standardization, analytical models, bridge management systems, service life prediction, structural health monitoring, non-destructive testing and field testing, robustness and redundancy, durability enhancement, repair and rehabilitation, fatigue and corrosion, extreme loads, needs of bridge owners, whole life costing and investment for the future, financial planning and application of information and computer technology, big data analysis and artificial intelligence for bridges, among others. This volume provides both an up-to-date overview of the field of bridge engineering and significant contributions to the process of making more rational decisions on bridge safety, maintenance, management, life-cycle, resilience and sustainability of bridges for the purpose of enhancing the welfare of society. The volume serves as a valuable reference to all concerned with and/or involved in bridge structure and infrastructure systems, including students, researchers and practitioners from all areas of bridge engineering.

This report presents the results of a pilot study on the seismic behavior and response of steel bridges with integral abutments. Analytical investigations were conducted on computational models of steel bridges with integral abutments to determine their seismic behavior as a system and to develop seismic design guidelines. The effect of the superstructure flexibility due to inadequate embedment length was investigated using 3D finite element models. This flexibility, modeled as translational and rotational springs, proved to have significant effect on the overall bridge dynamic characteristics in terms of periods and critical mode shapes. Lateral and longitudinal load paths and the seismic response were investigated using modal pushover and nonlinear time history analyses. A limited investigation on the effect of skew was conducted on a single-span integral abutment bridge. A procedure for incorporating the system level damping due to the yielding and inelastic responses of various components was proposed for use in the seismic analysis. Based on the analytical investigations and available experimental research, guidelines for the seismic analysis and design of integral abutment bridges were developed.

This report presents the details of the first integral abutment bridge in the state of Iowa that utilized precast, prestressed concrete piles in the abutment. The bridge, which was constructed in Tama County in 2000, consists of a 110 ft. long, 30 ft. wide, single-span PC girder superstructure with a left-side-ahead 20 degree skew angle. The bridge was instrumented with a variety of strain gages, displacement sensors, and thermocouples to monitor and help in the assessment of structural behavior. The results of this monitoring are presented, and recommendations are made for future application of precast, prestressed concrete piles in integral abutment bridges.