Publications by Hiroyuki Inamasu

Dissipative Embedded Column Bases for Enhanced Seismic Performance of Steel Moment Resisting Frames

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

This paper presents an innovative design concept for embedded column base (ECB) connections. The developed ECB connection achieves a non-degrading hysteretic response. In the proposed ECB connections, the dissipative zone is shifted into the embedded porti ...

EEME2023

Seismic performance of steel columns interacting with embedded column bases while exhibiting inelastic deformations

Dimitrios Lignos, Hiroyuki Inamasu

Observations from past earthquakes indicate that embedded column bases (ECBs) in steel moment resisting frames (MRFs) exhibited inelastic deformations while they were designed to be non-dissipative. Consequently, the amount of inelastic damage concentrated ...

ELSEVIER SCI LTD2022

Full-scale testing of European steel beams with reduced beam section under reversed cyclic loading

Dimitrios Lignos, Hiroyuki Inamasu

Steel beams with reduced beam section (RBS) are often used as part of prequalified connections in seismic regions. However, RBS connections are not as common in Europe. Reasons relate to easiness in fabrication, which requires on-site welding, and the seis ...

Springer Nature2022

Finite element modeling and behavior of dissipative embedded column base connections under cyclic loading

Dimitrios Lignos, Hiroyuki Inamasu

This paper explores, by means of continuum finite element (CFE) analysis, a recently developed concept that promotes controlled inelastic energy dissipation within the embedded portion of column base connections rather than in steel columns of conventional ...

ELSEVIER SCI LTD2022

Development and Experimental Validation of Dissipative Embedded Column Base Connections for Enhanced Seismic Performance of Steel Moment-Resisting Frames

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

This paper proposes a novel embedded column base (ECB) connection that defies the current paradigm in capacity-designed steel moment-resisting frames (MRFs) where column bases have been traditionally considered as nondissipative. In the proposed concept, a ...

2022

Development of dissipative embedded columns base connections for mitigating column axial shortening

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

This paper proposes an innovative design concept for embedded column base (ECB) connections featuring wide flange steel columns. The developed ECB connection achieves a non-degrading hysteretic response up to lateral drift demands associated with low proba ...

Springer Nature2022

Seismic design of non-dissipative embedded column base connections

Dimitrios Lignos, Hiroyuki Inamasu

Embedded Column Base (ECB) connections in seismically resistant steel moment frames are commonly designed to be stronger than the connected column, to protect them from inelastic actions. This relies on estimation of demands induced by the column and the s ...

2021

Full-scale testing of naturally buckling steel braces and evaluation of partially rib-strengthened sections to cumulative damage

Hiroyuki Inamasu

Naturally buckling steel braces (NBBs) have been recently developed by the authors and co-workers to improve the buckling performance and energy dissipation capacity of braced framed structures. In NBBs, a low-yield-point steel (LYS) channel and a high-str ...

ELSEVIER SCI LTD2021

Anchor-yield exposed column bases for minimizing residual deformations in seismic-resistant steel moment frames

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

This paper explores the concept of dissipative exposed column base connections by means of anchor rod yielding. This concept aims at enhancing the seismic performance of low-rise steel moment-resisting frames (MRFs). A mechanics-based model is proposed tha ...

2021

Development of Dissipative Steel Column-Base Connections for Steel Moment-Resisting Frames under Seismic Loading

Hiroyuki Inamasu

In capacity-designed steel moment resisting frames (MRFs), column base connections feature a strong-base/weak-column design philosophy. Prior studies on fixed-end wide flange steel columns featuring seismically compact cross sections subjected to coupled a ...

EPFL2021

An explicit model for exposed column base connections and its parameter sensitivity

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

Exposed column bases are the connection type most often employed in low to mid-rise steel moment resisting frames. Design typically follows idealized conditions for their boundaries, i.e. either pinned or fixed. In truth, the bases' behavior falls between ...

2019

Seismic Stability of Wide-Flange Steel Columns Interacting with Embedded Column Base Connections

Dimitrios Lignos, Hiroyuki Inamasu

The rotational flexibility of column base connections is commonly assumed to be detrimental to the seismic response of steel moment-resisting frames (MRFs) because it increases story drift demands and promotes soft-story formation by lowering the point of ...

2019

Concepts to minimize earthquake-induced column axial shortening in steel moment-resisting frames

Dimitrios Lignos, Hiroyuki Inamasu

Capacity-designed steel moment-resisting frames (MRFs) dissipate the seismic action through inelastic flexural yielding of protected zones located at the beam ends and the first story column bottom end. During low-probability of occurrence seismic events, ...

2019

Exposed Column Base Connections for Minimizing Earthquake-induced Residual Deformations in Steel Moment-Resisting Framess

Albano António De Abreu E Presa De Castro E Sousa, Dimitrios Lignos, Hiroyuki Inamasu

This paper proposes a new exposed column base (XCB) design concept for steel moment-resisting frames (MRFs) that promotes anchor rod yielding rather than plastic hinging at the bottom of the first story columns. A mechanics-based numerical model is first d ...

2019

Influence of embedded steel column base strength on earthquake-induced residual deformations

Dimitrios Lignos, Hiroyuki Inamasu

Recent experiments on steel columns under multi-axis cyclic loading suggest that a steel column may experience appreciable axial shortening due to local buckling. Reconnaissance reports from recent earthquakes indicate that a number of embedded column base ...

2018

Self-Centering Rocking Composite Frame Using Double-Skin Concrete-Filled Steel Tube Columns and Energy-Dissipating Fuses in Multiple Locations

Hiroyuki Inamasu

2018

Effect of Column Base Flexibility on Earthquake-Induced Residual Deformations of Steel Columns

Dimitrios Lignos, Hiroyuki Inamasu

Post-earthquake residual deformations often control decisions regarding potential demolition of earthquake-damaged buildings. While residual deformations are typically assumed to be lateral, the column residual axial shortening has similar implications for ...

Trans Tech Publications Ltd2018

Effect of Column Base Flexibility on the Hysteretic Response of Wide Flange Steel Columns

Dimitrios Lignos, Hiroyuki Inamasu

Recent experiments on wide flange steel columns subjected to multi-axial cyclic loading underscore the influence of the member end boundary conditions on strength and stiffness deterioration due to coupling of local and lateral torsional buckling. Field ob ...

2017

The seismic stability and ductility of steel columns interacting with concrete footings

Dimitrios Lignos, Hiroyuki Inamasu

First-story columns in steel moment resisting frames are subjected to various forms of geometric instabilities during earthquakes. These instabilities have the potential to seriously compromise structural performance, and expedite structural collapse. In t ...

American Institute of Steel Construction2017

Gusset Plate Connections for Naturally Buckling Braces

Hiroyuki Inamasu

A naturally buckling brace (NBB) is a steel brace that consists of a high-strength and low-yielding steel channel arranged in parallel with eccentricity acting along the brace length. To enhance the feasibility of NBB fabrication, three connecting design d ...

American Society of Civil Engineers2017