Full-scale shake table investigation of bridge abutment lateral earth pressure

Wilson, Patrick; Elgamal, Ahmed

doi:10.5459/bnzsee.42.1.39-46

Cited by 12 publications

(5 citation statements)

References 11 publications

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“…Test 2: Field water conditions [27] Another ambiguous point in the formulation of the 'Hyperbolic Gap Material' is the use of the empirically defined Rf parameter (Equation 1), whose value may vary significantly from case to case. For instance, [6] suggest a value range of 0.75 -0.95, while [29] fitted their experimental results to Equation 1 with Rf = 0.7. The fact that other research works introduced modified versions of Equation 1 resulting in a different range of empirically defined Rf values (e.g., Shamsabadi et al [1] recommend values from 0.94 to 0.98 for their closed-form relationship) may also cause confusion.…”

Section: Formulation Of the Proposed Modelmentioning

confidence: 92%

Modelling of the Full-Range Response of Abutment-Backfill Systems

Mikes,

Kappos

2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Over the last decades, the findings of numerous analytical studies, experiments and in-situ observations have highlighted the importance of the deck-abutment-backfill interaction on the seismic response of bridges. These findings have allowed various research groups to develop closed-form relationships that describe the nonlinear behaviour of the abutment-backfill system. Such relationships have been broadly used in research, reflected in modern seismic codes and guidelines, and incorporated in nonlinear analysis software. However, the behaviour of the abutment-backfill systems after the attainment of peak strength has been neither studied to a sufficient extent from the analysis point of view nor included in the constitutive models of widely used nonlinear analysis software packages, such as Open-Sees, even though large-scale tests have captured this critical phase of the response. The softening region of the response of the backfill has been addressed by some hardening/softening plasticity models that are not appropriate when simpler approaches (like Winkler springs) are used. Notably, the estimation of the abutment-backfill response at any level of seismic intensity is necessary for an appropriate fragility analysis of a bridge since the abutment-backfill component is almost always considered to affect at least some aspects of the bridge response and its failure is one of the possible failure modes that should be accounted for. In the above context, the main aim of the work presented herein is to propose an extended version of the 'Hyperbolic Gap' OpenSees material, the so-called 'Hyperbolic Gap Softening' material, which allows the user to define a set of parameters that describe the softening branch of the backbone curve of an abutment-backfill system. In addition to tests of the new model using a simple configuration, results of response history analyses of a case study bridge with different abutment-backfill properties are also reported, with a view to verifying the applicability of the proposed model and investigating the importance of capturing the post-peak abutment-backfill behaviour on the estimation of the response of a bridge.

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Section: Formulation Of the Proposed Modelmentioning

confidence: 92%

Modelling of the Full-Range Response of Abutment-Backfill Systems

Mikes,

Kappos

2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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“…Subsequent studies 7,8 used multilinear models for modeling backfills where the initial stiffness and ultimate deformation of sandy and clayey backfills were assumed to be within 115.00–288.00 kN/cm/m, and 6–10% of the backwall height, respectively. Further experimental and theoretical studies also led to the use of hyperbolic curves to model backfills, 9–12 some of which were applied in preliminary bridge‐fragility feasibility analyses 13 . Current Caltrans guidelines 14 retain the approximate bilinear form, but now specify a unit‐width stiffness value of 287 kN/cm/m and truncation pressure value of 0.24 MPa, along with wall‐height scaling rules, for modeling the passive resistance of abutment backfills meeting current material standards.…”

Section: Introductionmentioning

confidence: 99%

Influence of abutment straight backwall fracture on the seismic response of bridges

Zheng

Yang

Xie

et al. 2021

Earthq Engng Struct Dyn

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Field reconnaissance reports reveal the seismic vulnerability of bridge abutment foundations. To reduce the time and cost of postearthquake repair, modern seismic design specifications allow abutment backwalls to fracture before the supporting abutment foundations reach their maximum strength. This design strategy enables abutment backwalls to function as a fuse, thus protecting the abutment foundations from experiencing excessive forces and damage. This paper introduces a new abutment modeling scheme to capture the shear fracture mechanism of straight backwalls in seat abutments. To this end, a backwall connection spring is developed and incorporated into a spring system that simulates the behavior of various abutment components. The importance of considering the backwall fracture is examined by reviewing conventional modeling methodologies for abutments and building companion numerical models. Static pushover and incremental dynamic analyses (IDAs) were conducted for two bridges (single‐ and two‐span) modeled by both the proposed and conventional abutment modeling schemes. Moreover, component‐level fragility curves are developed using IDA results. The comparisons show that the conventional abutment modeling schemes significantly overestimate abutment foundation damage and underestimate the likelihood of deck unseating, column damage, and bearing displacement in the passive direction. Conversely, the proposed modeling scheme is able to capture the essential seismic responses of various components in seat abutment bridges. The consideration of backwall fracture in the modeling of abutment components enables a more rational seismic response assessment of bridges with backwalls, which are likely to be damaged during earthquakes, particularly for bridges which are seismically designed to protect abutment foundations.

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“…Experimental investigations of SSI with a focus on the potentially beneficial/detrimental role of integral abutments on seismic response are rare. Quarter scale two‐span and four‐span bridge models were tested at the University of Nevada at Reno, 51 while shaking table tests exploring the abutment contribution to the dynamic bridge response were conducted at the University of California in San Diego 52 …”

Section: Introductionmentioning

confidence: 99%

Integral abutment bridges: Investigation of seismic soil‐structure interaction effects by shaking table testing

Fiorentino

Cengiz

Luca

et al. 2020

Earthq Engng Struct Dyn

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In recent years there has been renewed interest on integral abutment bridges (IABs), mainly due to their low construction and maintenance cost. Owing to the monolithic connection between deck and abutments, there is strong soil‐structure interaction between the bridge and the backfill under both thermal action and earthquake shaking. Although some of the regions where IABs are adopted qualify as highly seismic, there is limited knowledge as to their dynamic behaviour and vulnerability under strong ground shaking. To develop a better understanding on the seismic behaviour of IABs, an extensive experimental campaign involving over 75 shaking table tests and 4800 time histories of recorded data, was carried out at EQUALS Laboratory, University of Bristol, under the auspices of EU‐sponsored SERA project (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The tests were conducted on a 5 m long shear stack mounted on a 3 m × 3 m 6‐DOF earthquake simulator, focusing on interaction effects between a scaled bridge model, abutments, foundation piles and backfill soil. The study aims at (a) developing new scaling procedures for physical modelling of IABs, (b) investigating experimentally the potential benefits of adding compressible inclusions (CIs) between the abutment and the backfill and (c) exploring the influence of different types of connection between the abutment and the pile foundation. Results indicate that the CI reduces the accelerations on the bridge deck and the settlements in the backfill, while disconnecting piles from the cap decreases bending near the pile head.

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Full-scale shake table investigation of bridge abutment lateral earth pressure

Cited by 12 publications

References 11 publications

Modelling of the Full-Range Response of Abutment-Backfill Systems

Modelling of the Full-Range Response of Abutment-Backfill Systems

Influence of abutment straight backwall fracture on the seismic response of bridges

Integral abutment bridges: Investigation of seismic soil‐structure interaction effects by shaking table testing

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