Publications by Andronikos Skiadopoulos

Modelling and Experimental Investigation of Ductile Crack Initiation in Welded Connections with Bevelled Backing Bars and Inelastic Panel Zones

Dimitrios Lignos, Andronikos Skiadopoulos

In pre-qualified welded connections, current design and fabrication rules that were formulated after the 1994 Northridge earthquake necessitate high-notch toughness weld requirements and rigorous treatment in the weld backing bar region, including the back ...

Springer Science and Business Media Deutschland GmbH2024

Beam-column joint structure

Dimitrios Lignos, Andronikos Skiadopoulos

A beam-column joint structure (1) including: a column (11) and an I-beam (212) with a pair of beam flanges (216) of the I-beam joined directly to joint plates (16) of the column main body via a welded section (218); wherein at the intersect position (P1), ...

2024

Towards instability-free welded moment connections

Dimitrios Lignos, Andronikos Skiadopoulos

In capacity-designed steel moment resisting frames (MRFs), inelastic deformations are mostly concentrated in the steel beams and the column fixed ends of the first story, while the participation of the panel zones in energy dissipation is limited. In such ...

2023

Full-Scale Experiments of Cyclically Loaded Welded Moment Connections with Highly Dissipative Panel Zones and Simplified Weld Details

Dimitrios Lignos, Andronikos Skiadopoulos

This paper presents the experimental results of two welded unreinforced flange-welded web (WUF-W) beam-to-column connections that defy the current design paradigm of prequalified welded connections. The proposed WUF-W connections feature customized beveled ...

2023

Geometric tolerances of welded connections with inelastic panel zones

Dimitrios Lignos, Andronikos Skiadopoulos, Ce Wen

Prequalified beam-to-column connections in steel moment resisting frames usually concentrate inelastic deformations in the steel beam ends. As such, nonlinear geo-metric instabilities (i.e., local buckling) may occur in these regions at modest lateral drif ...

Ernst & Sohn2023

Database of Residual Stress Measurements on Hot-rolled Wide Flange Steel Cross Sections

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Andronikos Skiadopoulos

Data_info.csv: Database of 'Residual Stress Measurements on Hot-rolled Wide Flange Steel Cross Sections' including cross-sectional and material characteristics as well as information relevant to ploting the residual stress distributions. Distributions.zip: ...

Zenodo2023

Experimental Investigation of Instability-Free Welded Moment Connections With Simplified Weld Details

Dimitrios Lignos, Andronikos Skiadopoulos

In capacity designed steel moment resisting frames, inelastic deformations are mostly concentrated in the steel beams and the column fixed ends of the first story. This design concept limits the participation of the column web’s panel zone in the energy di ...

2023

Proposed residual stress model for hot‐rolled wide flange steel cross sections

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Andronikos Skiadopoulos

Residual stresses in hot-rolled wide flange steel cross sections may lead to premature yielding, accelerated corrosion and brittle fracture of steel members. The above phenomena lead to a loss of a steel member's stiffness and resistance under mechanical l ...

Ernst & Sohn2023

Surrogate modelling for seismic collapse risk assessment of steel moment resisting frames

Dimitrios Lignos, Andronikos Skiadopoulos, Nenad Bijelic

With the overall goal of reducing the numerical burden of uncertainty quantification involved in seismic risk assessments, this paper examines opportunities for assessment of seismic collapse capacity and risk using data-driven surrogates as a complement t ...

2023

Experiments and proposed model for residual stresses in hot-rolled wide flange shapes

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Andronikos Skiadopoulos

This paper proposes a new residual stress model for hot-rolled wide flange steel cross sections. For this purpose, a dataset of 85 residual stress measurements is first assembled. The dataset is comprised of prior measurements available in the literature t ...

2023

Proposed Panel Zone Model for Beam-To-Column Joints in Steel Moment Resisting Frames

Dimitrios Lignos, Ahmed Mohamed Ahmed Elkady, Andronikos Skiadopoulos

In capacity designed steel moment resisting frames (MRFs), beam-to-column joints (i.e., panel zones) are designed to remain elastic. To potentially exploit the beneficial aspects of the stable panel zone hysteretic response in shear, a robust panel zone mo ...

2023

Hysteretic behaviour of welded connections with highly inelastic panel zones

Dimitrios Lignos, Andronikos Skiadopoulos

The current practice in capacity-designed steel moment resisting frames (MRFs) worldwide allows for limitedshear yielding in the column web panel zone. As such, inelastic deformations concentrate near the beam ends, thereby leading to flexural stre ...

Ernst & Sohn2023

Experimental Evaluation and Modeling of Residual Stress Distributions for Hot-Rolled Wide Flange Steel Members

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Andronikos Skiadopoulos

Local and member instability modes in structural steel members are influenced by initial geometric imperfections and residual stresses among other parameters. The robustness of stability-related design provisions and finite element modeling procedures of s ...

2023

Welded moment connections with highly dissipative panel zones for enhanced seismic performance of steel moment frames

Andronikos Skiadopoulos

Research conducted after the 1994 Northridge earthquake in the U.S. and the 1995 Kobe earthquake in Japan led to the development of today's pre-qualified beam-to-column connections for capacity-designed steel moment resisting frames (MRFs). Welded moment c ...

EPFL2022

Seismic stability of steel moment resisting frames with inelastic panel zones

Dimitrios Lignos, Andronikos Skiadopoulos

This paper summarizes preliminary findings of nonlinear simulations aiming to quantify the seismic demands of codecompliant steel MRFs with variable panel zone targeted shear distortions, 𝛾!. The probability of beam fractures is explicitly considered in th ...

Earthquake Engineering Research Institute2022

Proposed Backing Bar Detail in Welded Beam-to-Column Connections for Seismic Applications

Dimitrios Lignos, Andronikos Skiadopoulos

The use of prequalified welded unreinforced flange-welded web (WUF-W) beam-to-column connections in capacity-designed steel moment-resisting frames necessitates the removal of the weld backing bar at the bottom beam flange-to-column flange groove welded po ...

ASCE-AMER SOC CIVIL ENGINEERS2022

Seismic demands of steel moment resisting frames with inelastic beam-to-column web panel zones

Dimitrios Lignos, Andronikos Skiadopoulos

This paper intends to provide quantitative seismic response characteristics of steel moment resisting frames (MRFs) with inelastic beam-to-column panel zone joints. Two modeling approaches are proposed for this purpose along with a methodology to consider ...

WILEY2022

Development of Inelastic Panel Zone Database

Dimitrios Lignos, Andronikos Skiadopoulos

This data paper reviews the experimental research on fully restrained beam-to-column connections for steel moment-resisting frames (MRFs) over the last 50 years worldwide and presents an experimental database consisting of 100 tests with an emphasis on tho ...

2021

Proposed Panel Zone Model for Seismic Design of Steel Moment-Resisting Frames

Dimitrios Lignos, Ahmed Mohamed Ahmed Elkady, Andronikos Skiadopoulos

This paper proposes a new mechanics-based model for the seismic design of beam-to-column panel zone joints in steel moment-resisting frames. The model is based on realistic shear stress distributions retrieved from continuum finite element (CFE) analyses o ...

ASCE-AMER SOC CIVIL ENGINEERS2021