Athanasios Agalianos

Last Name

Agalianos

First Name

Athanasios

ORCID

0000-0003-3057-1261

Organisational unit

09569 - Anastasopoulos, Ioannis / Anastasopoulos, Ioannis

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Publications 1 - 10 of 27

Simplified method for real-time seismic damage assessment of motorway bridges: Transverse direction - Accounting for abutment stoppers
Sakellariadis, Lampros; Agalianos, Athanasios; Anastasopoulos, Ioannis (2018)
Earthquake Engineering & Structural Dynamics
Strike-slip faulting and interaction with structures: a combined numerical and experimental study
Agalianos, Athanasios (2021)
Numerical analysis of surface foundation subjected to strike–slip faulting: model boundaries, pre-softening volumetric response, parametric study
Agalianos, Athanasios; Anastasopoulos, Ioannis (2021)
Soil Dynamics and Earthquake Engineering
The paper investigates strike-slip fault rupture propagation through dense sand and its interaction with surface foundations, employing 3D finite element (FE) modelling. Two soil constitutive models (implemented in Abaqus through user subroutines) are employed for this purpose: (i) a recently developed simple yet efficient model with a Mohr–Coulomb yield criterion, which incorporates post-yield isotropic frictional hardening and softening (MC–HS model); and (ii) the basic version of the more sophisticated hypoplastic model for sand. Both models are calibrated on the basis of monotonic triaxial compression tests (and an additional oedometer test for the hypoplastic model), conducted as part of this study. The numerical predictions are comparatively assessed against centrifuge model test results. In accord with the centrifuge model tests, the free-field analyses with the MC-HS model reveal a complex fault pattern at the ground surface, consisting of Riedel (R) shears. These are the surficial manifestation of complex 3D structures of helicoidal geometry, attributed to the spatial variation of shear stresses within the overburden soil due to the imposed bedrock offset. The development of R shears is primarily controlled by the pre-softening volumetric soil response in monotonic compression and soil dilation. The latter is underestimated by the basic hypoplastic model, thus predicting the formation of a single straight shear band instead of R shears. A parametric study is conducted employing the validated MC-HS model, exploring fault rupture–soil–foundation interaction. Foundation response is shown to be sensitive to the surficial fault pattern (R shears vs. single fault trace), but the mechanism (rotational vs. translational) and foundation distress are not affected to the same extent. A two-step design strategy is outlined, requiring a free-field analysis to capture the surficial fault pattern, followed by a minimum of four interaction analyses, varying the fault-normal and fault-parallel foundation location.
Comparative Assessment of Two Rocking Isolation Techniques for a Motorway Overpass Bridge
Agalianos, Athanasios; Psychari, Antonia; Vassiliou, Michalis F.; et al. (2017)
Frontiers in Built Environment
Rocking isolation of structures is evolving as an alternative design concept in earthquake engineering. The present paper investigates the seismic performance of an actual overpass bridge of the Attiki Odos motorway (Athens, Greece), employing two different concepts of rocking isolation: (a) rocking of the piers on the foundation (rocking piers); and (b) rocking of the pier and foundation assembly (rocking footings) on the soil. The examined bridge is an asymmetric 5-span system having a continuous deck and founded on surface foundations on a deep clay layer. The seismic performance of the two rocking-isolated bridges is comparatively assessed to the existing bridge, which is conventionally designed according to current seismic design codes. To that end, 3D numerical models of the bridge–foundation–abutment–soil system are developed, and both static pushover and non-linear dynamic time history analyses are performed. For the latter, an ensemble of 20 records (10 ground motions of 2 perpendicular components each) that exceed the design level are selected. The conventional system collapses in 5/10 of the (intentionally severe) examined seismic excitations. The rocking piers design alternative survives in 8/10 of the cases examined, with negligible residual deformations. The safety margins of the rocking footings design concept are even larger, as it survives in all cases examined. Both rocking isolation concepts are proven to offer increased levels of seismic resilience, reducing the probability of collapse and the degree of structural damage. Nevertheless, in the rocking piers design alternative high stress concentrations at the rotation pole (pier base) are developed, indicating the need for a special design of the pier ends. This is not the case for the rocking footings concept, which however is subject to increased residual settlements but no residual rotations.
Slab foundations subjected to strike-slip faulting on dense sand: a combined experimental and numerical study
Agalianos, Athanasios; Korre, Evangelia; Anastasopoulos, Ioannis; et al. (2022)
Proceedings - ICONHIC 2022
Seismic Performance of a Rocking Isolated Overpass Bridge
Psychari, Antonia; Agalianos, Athanasios; Vassiliou, Michalis F.; et al. (2017)
Proceedings of the 3rd International Conference on Performance-based Design in Earthquake Geotechnical Engineering
Cost‐effective analysis technique for the design of bridges against strike‐slip faulting
Agalianos, Athanasios; Sieber, Max; Anastasopoulos, Ioannis (2020)
Earthquake Engineering & Structural Dynamics
The paper studies the performance of a typical overpass bridge, with continuous deck and monolithic pier‐deck connections, subjected to strike‐slip faulting. A three‐dimensional (3D) finite element (FE) model of the entire bridge–foundation–abutment–soil system is developed, accounting for soil, structure and geometric nonlinearities. Soil behaviour is simulated with a thoroughly validated strain softening constitutive model. The concrete damaged plasticity (CDP) model is implemented for piers, accounting for the interaction between axial force N , bending moment M , shear force Q and torsion T (NMQT ); the model is validated against experimental results from the literature. The location of the fault rupture is parametrically investigated, confirming the vulnerability of indeterminate structural systems to large tectonic deformation. The deck is shown to sustain both in‐plane and out‐of‐plane bending moments, as well as torsion; the piers are subjected to biaxial bending, shear and torsion. The response is highly dependent on the location of the fault rupture, emphasizing the need to develop cost‐effective modelling techniques. Four such techniques are developed (with and without decoupling) and comparatively assessed using the detailed 3D FE model as benchmark. The best prediction is achieved by a coupled model, which includes the bridge superstructure, detailed 3D modelling of the soil‐foundation system only for the pier directly affected by the fault, and nonlinear springs representing the foundations of all other piers. The proposed technique offers a computationally efficient means to parametrically analyse long multispan bridges subjected to faulting, for which full 3D FE modelling is impractical.
Experimental study of the interaction of shallow foundations with an emerging strike-slip fault rupture
Agalianos, Athanasios; Korre, Evangelia; Abdoun, Tarek H.; et al. (2020)
4th European Conference on Physical Modelling in Geotechnics
Real-Time Seismic Damage Assessment of Various Bridge Types Using a Nonlinear Three-Stage Least Squares Approach
Androutselis, Thomas; Sarwar, Tawfiq; Eker, Ugur; et al. (2020)
Journal of Infrastructure Systems
Simplified method for the assessment of the seismic response of motorway bridges: longitudinal direction—accounting for abutment stoppers
Agalianos, Athanasios; Sakellariadis, Lampros; Anastasopoulos, Ioannis (2017)
Bulletin of Earthquake Engineering

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Athanasios Agalianos

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