Integral Abutment Bridges Research Articles

Seismic Soil Structure Interaction for Integral Abutment Bridges: a Review

In an integral abutment bridge (IAB), the superstructure and the abutment are constructed monolithically at their junction without the presence of any bearing or expansion joint. This leads to a significant reduction in the maintenance cost of the bridge. However, integral connection at deck-abutment junction causes a significant change in the bridge behavior under thermal loading and earthquake shaking as the superstructure (along with bridge deck and girders), abutment, foundation, wingwall, and approach slab may act like a single unit. Different countries and the respective Highway Agencies have adopted different guidelines for design and construction of IABs. Though many advancement in construction of IAB have been made, still there are many aspects which require additional attention. The aim of the present paper is to review the past studies on seismic behavior of IABs performed in the last three decades incorporating seismic soil-structure interaction. A few features are also highlighted which need to be addressed through further studies.

CASE STUDY OF 3D SEISMIC PUSHOVER ANALYSIS OF INTEGRAL ABUTMENT BRIDGE

Integral abutment bridges (IABs) have a continuous deck monolithically encased into abutment stem, and typically using single row of piles to carry vertical loads and accommodate longitudinal thermal deformation. Except for smooth pavement and low maintenance cost, IABs have also outperformed conventional seat-type abutment bridges in seismic performance due to increased redundancy, higher damping, and smaller displacements. However, lack of information on their seismic design and performance may have discouraged their use in high seismic zones. In this study, current research and implementation of IABs are comprehensively reviewed. IABs with steel-concrete girders provided by NYDOT are chosen for intensive seismic case study. Three-dimensional finite element models of IABs for nonlinear seismic analysis are elaborated to capture the behavior of components of superstructure, abutment stem, piles, backfill, etc. Pushover analyses are carried out to obtain the capacity curves. Through parametric studies, the effects of bearing are outlined. Conclusions and some recommendations are made for seismic evaluation and design practice of IABs.

Response of full-height frame integral abutments subjected to seismic motions

As a new type of bridge, integral bridges can significantly reduce long-term maintenance costs, and their application is encouraged in many countries. However, there is great uncertainty regarding the dynamic performance of full-height integral abutments during earthquakes. This paper presents the findings from a dynamic numerical simulation on a typical full-height frame integral bridge abutment. The influences of peak acceleration, bridge deck length, and abutment height are investigated. The effect of a mitigation method, i.e., installation of a compressible layer behind the abutment, is also discussed. The results highlight the effect of the rigid connection between the deck and the integral abutment, which will transfer the very large inertial force of the bridge deck to the abutment top and cause strong dynamic interaction between the abutment and the backfill. The traditional Mononobe-Okabe method adopted in current bridge abutment design codes cannot provide a reasonable prediction as to the dynamic earth pressure behind integral abutments, leading to unsafe designs. Although a compressible layer can reduce the dynamic earth pressure, the deformation and bending moments of the abutment will increase as a result of the much lower restraint provided by the compressible layer during earthquakes.

Behavior of Integral Frame Abutment Bridges Due to Cyclic Thermal Loading: Nonlinear Finite-Element Analysis

AbstractThis paper presents a finite-element (FE) study of the behavior of integral frame abutment bridges under alternate cycles of expansion and contraction of the bridge due to seasonal temperat...

SEISMIC BEHAVIOUR OF NOVEL INTEGRAL ABUTMENT BRIDGES

Integral abutment bridges (IABs) are becoming rather common due to the durability problems of bearings and expansion joints. Monolithic connections between the deck and sub-structure allow, on one side, to increase the structure redundancy and reduce the maintenance costs. However, from the other side, soil-structure effects are also introduced due to the interactions between the abutment and the backfill and between the pile and soil induced by thermal variations, long-term effects (creep and shrinkage) and dynamic loads, such as earthquakes. Several authors have investigated the soil-structure interaction for IABs both theoretically and experimentally, but there is still a lack of common line guidelines and codes. After a literature review of the main studies regarding the seismic response of IABs, this paper introduces some recent contributions given by investigators in this field. In particular, the following topics are discussed: (a) an experimental study on an innovative deck to pier/abutment joint; (b) the possibility of using prestressed concrete or ultra-high performance piles in IABs; (c) a pile isolation technique based on a pre-hole filled with damping materials; and (d) a research project supported by European Union inside the Horizon 2020 SERA project on the seismic behaviour of novel integral abutment bridges. The paper clearly demonstrates the potential applications of the proposed technologies for IABs built in seismic zones.

Response of integral abutment bridges under a sequence of thermal loading and seismic shaking

This article investigates the response of Integral Abutment Bridges (IAB) when subjected to a sequence of seasonal thermal loading of the deck followed by ground seismic shaking in the longitudinal direction. Particular emphasis is placed on the effect of pre-seismic thermal Soil-Structure Interaction (SSI) on the seismic performance of the IAB, as well as on the ability of various backfills configurations, to minimize the unfavorable SSI effects. A series of two-dimensional numerical analyses were performed for this purpose, on a complete backfill-integral bridge-foundation soil system, subjected to seasonal cyclic thermal loading of the deck, followed by ground seismic shaking, employing ABAQUS. Various backfill configurations were investigated, including conventional dense cohesionless backfills, mechanically stabilized backfills and backfills isolated by means of compressive inclusions. The responses of the investigated configurations, in terms of backfill deformations and earth pressures, and bridge resultants and displacements, were compared with each other, as well as with relevant predictions from analyses, where the pre-seismic thermal SSI effects were neglected. The effects of pre-seismic thermal SSI on the seismic response of the coupled IAB-soil system were more evident in cases of conventional backfills, while they were almost negligible in case of IAB with mechanically stabilized backfills and isolated abutments. Along these lines, reasonable assumptions should be made in the seismic analysis of IAB with conventional sand backfills, to account for pre-seismic thermal SSI effects. On the contrary, the analysis of the SSI effects, caused by thermal and seismic loading, can be disaggregated in cases of IAB with isolated backfills.

Discrete element model study into effects of particle shape on backfill response to cyclic loading behind an integral bridge abutment

The discrete element method, implemented in a modular GPU based framework that supports polyhedral shaped particles (Blaze-DEM), was used to investigate effects of particle shape on backfill response behind integral bridge abutments during temperature-induced displacement cycles. The rate and magnitude of horizontal stress build-up were found to be strongly related to particle sphericity. The stress build-up in particles of high sphericity was gradual and related to densification extending relatively far from the abutment. With increasing angularities, densification was localised near the abutment, but larger and more rapid stress build-up occurred, supported by particle reorientation and interlock developing further away.

Numerical modelling of integral abutment bridges under seasonal thermal cycles

Interest in integral abutment bridges (IABs) from the industry has increased in recent years. IABs are robust bridges without joints and bearings and hence they are durable and virtually maintenance free; moreover, the resulting cost-saving associated with their construction is significant, a fact that makes IABs appealing to agencies, contractors and consultants. However, their use in long-span bridges is limited by the complex soil–structure interaction. Thermal movements, horizontal loads and dynamic actions are transferred directly to the backfill soil, leading to settlements, ratcheting effects, high earth pressures and deterioration of the backfill soil. The longer the integral bridge the greater the challenge, as movements are increased. This paper provides an extended review of the techniques used in the international literature and in practice to alleviate the interaction between a bridge abutment and the backfill. Subsequently, the performance of an innovative isolation system for IABs using recycled tyres as a compressible inclusion is studied using detailed numerical models of a representative three-span IAB. The proposed isolation scheme was found to be an effective and sustainable method to isolate the structure from the backfill soil, reducing the pressures experienced by the abutments and the residual vertical displacements of the backfill soil.

Lateral stress profiles on integral bridge abutments

Integral bridges have become established as a viable structural form in many countries for reducing maintenance liability and increasing the robustness of structures. The advent of new design guidance associated with the Eurocodes provides an opportunity to review the design of these structures. Research indicates that peak stresses due to bridge expansion continually increase with cycles and in theory may reach a fully passive state. However, this may not happen in practice during a bridge's life. A numerical model has been developed and calibrated against test data, enabling predictions of the development of lateral stresses acting on a full-height frame integral abutment during its life, both in terms of magnitude and distribution down the wall. Design guidance is shown to be appropriate for bridges up to 60 m long, but to be unconservative for longer bridges. The effect of applying daily cycles of movement rather than just annual cycles has also been investigated.

STUB TYPE INTEGRAL ABUTMENT – BACKFILL SOIL RELATIONSHIP

Integral bridges have become one of the most common types of joint-less bridge construction, certainly over the last three decades. Simple integral abutments, such as stub-type abutments supported by piling, have been found to perform well and recommended for widespread use. Cost-effective system in terms of construction, maintenance and longevity becomes their principal advantages, derived from the elimination of expansion joints and bearings. Elimination of joints from bridges creates a significant soil-structure interaction behind the abutment. A 2D finite element analysis was performed on a typical integral abutment bridge using OASYS SAFE to investigate the complex interactions that exist between the stub-type integral abutment bridge and the backfill soil. Where possible, these results were validated with existing field data. The results from this analysis are believed to help answer two of the most debated issues with respect to stub-type integral abutment bridge-soil interaction analyses. Firstly, it is clear, and now possible, that a reliably accurate soil constitutive model is used in the analysis/design. The Mohr-Coulomb soil model was found to realistically represent the soil behaviour. Secondly, the research may suggest that cyclic movements / loads may not significantly influence the overall behaviour of integral abutment bridges especially in a small daily temperature changes.

Insights into the Effect of Spatial Variability of Recorded Earthquake Ground Motion on the Response of a Bridge Structure

ABSTRACTWith the aim of evaluating the effect of spatial variability of recorded ground motions on spatially extended structures, we present a numerical study on the linear and nonlinear response of an idealized integral-abutment bridge, subject to the 2004 Parkfield recordings at the UPSAR array. The results show that spatial variability of recorded motion may present features which are poorly predictable by standard coherency approaches and this may have a considerable impact even on a regular, 300-m long structure on homogenous stiff soil conditions, leading to localized increase or decrease of engineering demands parameters up to a factor of about 50%.

Seismic modeling of integral abutment bridges in Illinois

Integral abutment bridges (IABs) are a common bridge type used in modern design and construction to prevent damage at the abutment seat from water, dirt, or deicing chemicals penetrating through a compromised expansion joint. Elimination of expansion joints in IABs leads to complex soil-structure-interaction limit states involving the IAB abutment and surrounding soil, as well as unique overall bridge behavior in comparison to non-IABs. Despite this different behavior, there is a lack of studies investigating overall bridge performance of IABs when subjected to seismic loads. Existing seismic IAB studies have typically investigated individual components, such as the interaction between abutment piles and soil or the behavior of superstructure-abutment connections, but the comprehensive behavior of all IAB components when subjected to an earthquake has not been evaluated in an integrated fashion. This study details an IAB model developed for dynamic analysis that simultaneously considers contributions from all critical IAB components. The seismic response of two IABs, one with steel plate girders and another with precast prestressed concrete girders, is evaluated at the design-level shaking using the developed model. The design-level shaking is provided by 20 ground motions, for a 1000-year return period hazard-level, developed for the southern Illinois city of Cairo. Results demonstrate the ability of the IAB model to capture key features of bridge seismic behavior, and they provide a framework for bridge engineers to understand IAB earthquake response and limit states, as well as support recommendations for IAB seismic design in Illinois concerning side retainer anchor bolt size and pier column size.

Numerical Analysis of the Behavior of an IPM Bridge According to Super-Structure and Sub-Structure Properties

A bridge with an integrated and pile-bent abutment with a mechanically stabilized earth-wall (IPM) was developed by separating earth pressure from the abutment to overcome the problems typically faced by integral abutment bridges. Also, the IPM bridge removes expansion joints and bearing by integrating the super-structure and the abutment and does not need many piles because it separates the earth pressure from backfills. Therefore, it is superior in cost, durability, and maintainability to traditional bridges and is sustainable due to using less material. A numerical analysis was conducted to ascertain the behavior of the IPM bridge according to its super-structural and sub-structural characteristics. Based on the analysis results, the behaviors of the IPM bridge are as follows: The bending moments ( M y ) of the pre-stressed concrete (PSC) girder and the steel-plate girder of the bridge were influenced by the presence of the time-dependent loads. The contraction behavior in the PSC girder is largely due to the time-dependent loads, whereas the expansion behavior in the steel-plate girder is large due to its greater thermal expansion coefficient and temperature range compared with those of the PSC girder. In general, the suggested bridge length limit for PSC girders in both the integral abutment bridge and the IPM bridge is larger than that in a steel bridge. This needs to be reviewed again with consideration of the long-term and seasonal behaviors.

Durable transition structure for long integral abutment bridges

The construction of integral abutment bridges is becoming more common. Since these bridge structures have no expansion joints or bearings, it is possible to build low‐maintenance and long‐lasting structures. The length of most existing integral abutment bridges does not exceed 20 m, but larger lengths are also increasingly being implemented. Structures up to approximately 70 m are considered to be unproblematic. In longer integral abutment bridges, problems often occur in regard to surface cracks and settlements behind the abutments. To address these challenges, intensive research work has been conducted. A new jointless roadway transition structure for long integral abutment bridges has been developed at the Institute of Structural Engineering of TU Wien. The design principle of the new transition structure is based on the distribution of the deformations, which occur in the bridge due to temperature changes, shrinkage, creep, and external loading, over a longer area behind the abutment. Because the deformations are distributed, it is possible to build a seamless pavement structure across the expansion joint, from the bridge to the embankment. The Research Center for Road Engineering, TU Wien, has developed a special multilayer bituminous pavement structure just for this purpose. Based on the design considerations for the transition structure, a full‐scale prototype was built. The prototype was tested at various construction stages to obtain relevant data for practical use.

A design approach of integral-abutment steel girder bridges for maintenance

Integral abutment bridges (IABs) have no joint across the length of bridge and are therefore also known as jointless bridges. IABs have many advantages, such as structural integrity, efficiency, and stability. More importantly, IABs have proven to be have both low maintenance and construction costs. However, due to the restraints at both ends of the girder due to the absence of a gap (joint), special design considerations are required. For example, while replacing the deck slabs to extend the service life of the IAB, the buckling strength of the steel girder without a deck slab could be much smaller than the case with deck slab in place. With no deck slab, the addition of thermal expansion in the steel girders generates passive earth pressure from the abutment and if the applied axial force is greater than the buckling strength of the steel girders, buckling failure can occur. In this study, numerical simulations were performed to estimate the buckling strength of typical steel girders in IABs. The effects of girder length, the width of flange and thickness of flange, imperfection due to fabrication and construction errors on the buckling strengths of multiple and single girders in IABs are studied. The effect of girder spacing, span length ratio (for a three span girder) and self-weight effects on the buckling strength are also studied. For estimation of the reaction force of the abutment generated by the passive earth pressure of the soil, BA 42/96 (2003), PennDOT DM4 (2015) and the LTI proposed equations (2009) were used and the results obtained are compared with the buckling strength of the steel girders. Using the selected design equations and the results obtained from the numerical analysis, equations for preventing the buckling failure of steel girders during deck replacement for maintenance are presented.

Soil behaviour around the stub abutment of an integral bridge and buried piles in the contraction state

The change in the deck length under temperature load affects the upper part of integral bridge abutments and causes abutments rotation. The deck contraction makes the abutment move away from the backfill and causes a failure wedge. To prevent the failure wedge, a new method has been proposed. In this method, the inhibition of integral bridges under contraction is done by cables connected from each abutment to the buried piles outside the bridge along the abutments. In the analysis, the behaviour of soil around the abutment and buried piles is an important parameter which has a great influence on the results. In this paper, the soil behaviour around a laterally loaded stub abutment and buried piles was studied on laboratory stub abutment models using the PIV (particle image velocimetry) method. The PIV analysis was carried out to obtain the deformation pattern and shear strains of the soil around the stub abutment and buried piles. The effects of piles number and soil – pile interaction on the soil deformation pattern were investigated. The results showed that the use of buried piles connected by the cable avoided creating a failure wedge in the backfill.

Finite element modelling and seismic behaviour of integral abutment bridges considering soil–structure interaction

A comprehensive non-linear finite element (FE) model of integral abutment bridges (IABs) is presented to facilitate the analysis of such bridges using commercial software, especially under seismic loading. The presented model is capable of capturing non-linearity in both the structure and soil, in addition to considering far-field soil response. The model is simple enough to be used for practical purposes. On the other hand, many aspects of seismic behaviour of IABs are unclear, due to complicated soil–structure interaction. Using the presented model, a parametric study is performed to identify the effects of bridge length, abutment type and soil type on seismic behaviour of IABs. Non-linear direct integration FE analyses are performed on the IAB models. The results of the parametric analyses demonstrate the importance of non-linear modelling of soil and pile in capturing a realistic seismic response of IABs.

Behavior of integral abutment bridge with partially protruded piles

This study presents structural and parametric analyses on the behavior of an integrated and pile-bent abutment with mechanically stabilized earth wall (IPM) bridge. The IPM bridge is an integral abutment bridge (IAB) with partially protruded piles, which excludes earth pressure by means of a mechanically stabilized earth wall developed by the authors. The results of the analysis indicate that the IPM bridge, as any other IAB, is influenced to a large extent by temperature and time-dependent loads. When these loads are applied, the stress on a pile in the IPM bridge decreases as the displacement of the pile top increases, because the piles protrude from the ground surface and no soil reaction is generated on the protruded pile. Because the length of an IAB is restricted by the forces acting on its piles, the IPM bridge is an effective alternative to extend its length.

A Study of Structural Behavior Rationality and Load Carrying-capacity Evaluation of Integral Abutment Bridge

A Study of Structural Behavior Rationality and Load Carrying-capacity Evaluation of Integral Abutment Bridge

Nonlinear Finite-Element Analysis of Integral Abutment Bridges due to Cyclic Thermal Changes

Nonlinear Finite-Element Analysis of Integral Abutment Bridges due to Cyclic Thermal Changes