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arxiv: 1907.10263 · v1 · pith:XAVJKN6Jnew · submitted 2019-07-24 · ⚛️ physics.geo-ph

Seismic performance of an infilled moment-resisting steel frame during the 2016 Central Italy Earthquake

Phan Hoang Nam , Fabrizio Paolacci , Phuong Hoa Hoang This is my paper

Pith reviewed 2026-05-24 16:53 UTC · model grok-4.3

classification ⚛️ physics.geo-ph
keywords seismic performanceinfilled steel framemasonry infillCentral Italy earthquakenonlinear analysisdamage patternmoment-resisting frameOpenSees
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The pith

Nonlinear analyses of a 3D model show how masonry infills affected the seismic response of a steel frame damaged in the 2016 Central Italy earthquake.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper examines a moment-resisting steel frame building in Amatrice that suffered damage in the 2016 Central Italy earthquake sequence. Researchers created a three-dimensional model in OpenSees software, representing beams and columns with nonlinear hinges and masonry infills as diagonal struts with hysteretic behavior. They ran nonlinear static and dynamic analyses on both the bare frame and the infilled version. The results match the actual damage observed after the event and indicate that the infills played a key role in the building's seismic performance. This work demonstrates the importance of including infill effects when assessing earthquake damage to such structures.

Core claim

The three-dimensional model of the infilled moment-resisting steel frame, with infills idealized as diagonal struts, reproduces the damage pattern surveyed after the 2016 Central Italy earthquake through nonlinear static and dynamic analyses, and demonstrates the significant effect of the masonry infill on the overall seismic response compared to the bare frame.

What carries the argument

The 3D OpenSees model using nonlinear hinge elements for beams and columns and nonlinear hysteretic diagonal struts for infills, which enables comparison of bare and infilled frame responses to confirm observed damage.

Load-bearing premise

The model of the building and the idealization of infills as diagonal struts accurately capture the real structure's behavior during the earthquake.

What would settle it

If the damage locations and severity predicted by the nonlinear analyses do not match the surveyed damage in the actual building in Amatrice.

Figures

Figures reproduced from arXiv: 1907.10263 by Fabrizio Paolacci, Phan Hoang Nam, Phuong Hoa Hoang.

Figure 2
Figure 2. Figure 2: Macro-modelling of masonry infill through equivalent struts Since FE models are generally unfit for practice-oriented analyses of the seismic response of steel frames, several macro-models were proposed and are currently available in the scientific literature to simulate the global seismic response of masonry infilled steel frames (Asteris et al. 2011). Such models are generally based on the assumption of … view at source ↗
Figure 3
Figure 3. Figure 3: Force-displacement curve according to the model by Panagiotakos and Fardis (1996) The initial shear stiffness 𝑅0of the uncracked panel can be defined as follows: 𝑅0 = 𝐺4𝑡4𝑙4/ℎ4 (1) where 𝐺4 is the shear modulus of the masonry infill obtained in diagonal-compression tests while 𝑡4, 𝑙4 and ℎ4 are the thickness, the length and the height of the masonry wall. Then, the load value at the onset of cracking, name… view at source ↗
Figure 9
Figure 9. Figure 9: Axial force – displacement of the representative infill panels in the floors 4. CONCLUSIONS The paper presents a numerical assessment of the structural performance of a case steel MRF building located in Amatrice, Central Italy, which suffered extensive structural and non-structural damage during the recent swarm of events. Refined numerical models of the existing steel building are developed with and with… view at source ↗
Figure 7
Figure 7. Figure 7: Time history data in terms of total base shear [PITH_FULL_IMAGE:figures/full_fig_p005_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Peak interstory drift along with the building height The local behavior of the infill panels on three floors is shown in [PITH_FULL_IMAGE:figures/full_fig_p005_8.png] view at source ↗
read the original abstract

A sequence of earthquakes occurred between the end of August 2016 and the end of October 2016 in Central Italy causing significant damage and major disruption in a wide area. The sequence of events is composed of five events with magnitude between Mw 5.5 to 6.5. As a consequence, numerous residential buildings in the affected area was not particularly resistant to the shaking, resulting in the collapse and heavy damage. With a particular focus on masonry infilled steel frames, this paper evaluates the seismic performance of an infilled moment-resisting steel frame located in Amatrice, Central Italy, which suffered significant damage during the August 2016 Central Italy earthquake. The aim is to investigate the effect of the masonry infill to the seismic performance of the building. The three-dimensional (3D) frame building is modeled using the Opensees software, where the beam and column elements are modeled by using a nonlinear hinge model and the infill is idealized as diagonal struts with nonlinear hysteretic behavior. Nonlinear static and dynamic analyses are performed for both bare and infill frames in order to assess the effect of the masonry infill on the overall seismic response and confirm the actual damage pattern surveyed in the aftermath of the 2016 Central Italy earthquake of the case study.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 3 minor

Summary. The manuscript examines the seismic behavior of a masonry-infilled steel moment-resisting frame in Amatrice that sustained damage in the August 2016 Central Italy earthquake. The 3D structure is modeled in OpenSees with nonlinear plastic hinges for beams and columns and equivalent diagonal struts possessing nonlinear hysteretic rules for the infills. Nonlinear static pushover and dynamic time-history analyses are performed on both the bare and infilled configurations to quantify the effect of the masonry infill on global response and to reproduce the damage pattern documented by post-event surveys.

Significance. If the strut and hinge parameters can be shown to be robustly constrained by the survey data and the damage match is demonstrated quantitatively rather than qualitatively, the study would supply a useful case-history illustration of infill-frame interaction under recorded near-field motions. The work is otherwise incremental; it applies standard OpenSees modeling techniques to a single real building without introducing new constitutive models or generalizable design rules.

major comments (3)
  1. [Modeling section (infill idealization)] Modeling section (infill idealization): the claim that the analyses 'confirm the actual damage pattern' rests on the fidelity of the diagonal-strut hysteretic parameters, yet no quantitative mapping is supplied from the post-earthquake survey measurements (masonry compressive strength, panel dimensions, observed crack patterns) to the strut strength, stiffness, or degradation rules. Without this mapping or a sensitivity study, the damage match is non-unique and cannot be used to isolate the infill contribution.
  2. [Results section (comparison with survey)] Results section (comparison with survey): the manuscript states that the nonlinear analyses reproduce the surveyed damage, but presents neither element-by-element damage indices, interstory drift profiles at the recorded ground-motion intensities, nor a table contrasting predicted versus observed damage states. A purely visual or narrative match is insufficient to support the central claim.
  3. [Ground-motion input] Ground-motion input: the dynamic analyses employ the 2016 records, but the manuscript does not specify which stations, components, or scaling/selection criteria were used, nor whether the records were applied to the bare and infilled models at the same intensity. This omission directly affects the reliability of the infill-effect assessment.
minor comments (3)
  1. [Abstract] Abstract, line 3: 'numerous residential buildings in the affected area was not particularly resistant' contains a subject-verb agreement error.
  2. [Modeling section] The paper would benefit from a brief table listing the key mechanical properties assigned to the struts and hinges together with their literature or survey sources.
  3. [Figures] Figure captions should explicitly state whether the plotted curves correspond to the bare or infilled model.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive comments. We agree that additional quantitative details are needed to support the central claims and will revise the manuscript accordingly. Point-by-point responses follow.

read point-by-point responses

  1. Referee: Modeling section (infill idealization): the claim that the analyses 'confirm the actual damage pattern' rests on the fidelity of the diagonal-strut hysteretic parameters, yet no quantitative mapping is supplied from the post-earthquake survey measurements (masonry compressive strength, panel dimensions, observed crack patterns) to the strut strength, stiffness, or degradation rules. Without this mapping or a sensitivity study, the damage match is non-unique and cannot be used to isolate the infill contribution.

    Authors: We agree that the current version lacks an explicit quantitative mapping and sensitivity analysis. In the revised manuscript we will add a dedicated subsection deriving the strut strength, initial stiffness, and hysteretic degradation parameters directly from the post-event survey values (masonry compressive strength, panel geometry, and observed crack patterns). We will also include a sensitivity study on the principal strut parameters to demonstrate robustness of the damage match and to better isolate the infill contribution. revision: yes

  2. Referee: Results section (comparison with survey): the manuscript states that the nonlinear analyses reproduce the surveyed damage, but presents neither element-by-element damage indices, interstory drift profiles at the recorded ground-motion intensities, nor a table contrasting predicted versus observed damage states. A purely visual or narrative match is insufficient to support the central claim.

    Authors: We acknowledge that a purely visual comparison is insufficient. The revised manuscript will include (i) interstory drift profiles extracted from the time-history analyses at the recorded intensities, (ii) element-level damage indices for beams, columns, and infill struts, and (iii) a table that directly contrasts predicted versus observed damage states for each structural element. These additions will provide the quantitative validation requested. revision: yes

  3. Referee: Ground-motion input: the dynamic analyses employ the 2016 records, but the manuscript does not specify which stations, components, or scaling/selection criteria were used, nor whether the records were applied to the bare and infilled models at the same intensity. This omission directly affects the reliability of the infill-effect assessment.

    Authors: We will expand the ground-motion section to list the specific recording stations and components, describe the selection and scaling procedure, and explicitly state that identical records and intensity measures were applied to both the bare-frame and infilled-frame models. This clarification will ensure the infill-effect comparison is reproducible and reliable. revision: yes

Circularity Check

0 steps flagged

No circularity; external ground motions and surveyed damage serve as independent benchmarks

full rationale

The paper constructs a 3D OpenSees model using nonlinear beam/column hinges and diagonal strut idealizations for infill, then subjects it to recorded 2016 Central Italy ground motions. Simulated damage states are compared to post-event survey observations. Neither the model parameters nor the hysteretic rules are stated to be fitted to the target damage pattern; the comparison is presented as validation against external data. No self-citation chain, self-definitional equations, or renaming of fitted outputs as predictions appears in the derivation. The analysis chain therefore remains open to falsification by the independent survey record.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

Only the abstract is available, so the full set of modeling parameters and assumptions cannot be audited. The paper relies on standard assumptions in seismic modeling software.

free parameters (2)
  • strut properties
    Nonlinear hysteretic parameters for infill struts likely fitted or chosen based on typical values.
  • hinge model parameters
    Nonlinear hinge properties for beams and columns.
axioms (2)
  • domain assumption Nonlinear hinge model for beams and columns accurately captures plastic behavior.
    Invoked in the modeling section of the abstract.
  • domain assumption Diagonal strut model represents masonry infill behavior.
    Idealization used for infill.

pith-pipeline@v0.9.0 · 5767 in / 1173 out tokens · 30985 ms · 2026-05-24T16:53:50.549244+00:00 · methodology

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Reference graph

Works this paper leans on

14 extracted references · 14 canonical work pages

  1. [1]

    Construction Publisher ISBN 978-604-82-2518-6 ID No./ pp. … Seismic performance of an infilled moment-resisting steel frame during the 2016 Central Italy Earthquake Phan Hoang Nam1,2,*, Fabrizio Paolacci1, Phuong Hoa Hoang2 1Department of Engineering, Roma Tre University, Rome, Italy 2Faculty of Road and Bridge Engineering, The University of Danang – Univ...

    work page 2016

  2. [2]

    The first main shock on August 24th, 2016 was of moment magnitude Mw 6.0 and occurred at a depth of 4 km

    INTRODUCTION The 2016-2017 Central Italy earthquakes consisted of several moderately-high magnitude earthquakes between moment magnitudes Mw 5.5 and 6.5. The first main shock on August 24th, 2016 was of moment magnitude Mw 6.0 and occurred at a depth of 4 km. The epicenter of the August’s shock was located in the North-East area of the province of Rieti; ...

    work page 2016

  3. [3]

    These events caused a total of 299 fatalities, 386 injured and about 4800 homeless (Fiorentino et al

    The particular event had an epicenter 5 km from Norcia, overlaying the northern part of the fault activated by the earthquake of August 24th. These events caused a total of 299 fatalities, 386 injured and about 4800 homeless (Fiorentino et al. 2018). Most of the victims were in the areas of Amatrice, Accumoli, and Arquata del Tronto. In these municipaliti...

    work page 2018

  4. [4]

    DESCRIPTION OF CASE STUDY The sample steel frame is a two-story building located in Amatrice, Central Italy. It was built in the early 90’s according to the 1996 Italian seismic code and consists of a basement, the ground floor, and two upper stories alongside a shorter top story that serves as a penthouse. The building plan layout is trapezoidal; it is 2...

    work page 1996

  5. [5]

    At the end of the entire seismic sequence, the building experienced evidently permanent deformation along its longer direction

    The sample building after the 2016-2017 Central Italy earthquakes After the 24 August event, the building mainly suffered major cracks in the brick infill panels, with only small local flange instabilities observed at the top of two front columns of the ground floor. At the end of the entire seismic sequence, the building experienced evidently permanent d...

    work page 2016

  6. [6]

    Preliminary finite element analyses of the building confirmed that the fundamental period of the structure is approximately equal to 0.56 s (Di Sarno et al. 2017). This was an uncoupled translational mode along the long side, which was mainly attributed to the orientation of the steel columns with their strong axes aligned with the short side of the build...

    work page 2017

  7. [7]

    Macro-modelling of masonry infill through equivalent struts Since FE models are generally unfit for practice-oriented analyses of the seismic response of steel frames, several macro-models were proposed and are currently available in the scientific literature to simulate the global seismic response of masonry infilled steel frames (Asteris et al. 2011). S...

    work page 2011

  8. [8]

    … equivalent struts proposed by Panagiotakos and Fardis (1996) is presented

    Construction Publisher ISBN 978-604-82-2518-6 ID No./ pp. … equivalent struts proposed by Panagiotakos and Fardis (1996) is presented. The skeleton curve is step-wise linear in shape to describe the compression-only behavior of the strut. In particular, the model is characterized by the following stress states (see Fig. 3): - initial elastic behavior; - p...

    work page 1996

  9. [9]

    Force-displacement curve according to the model by Panagiotakos and Fardis (1996) The initial shear stiffness 𝑅0of the uncracked panel can be defined as follows: 𝑅0 = 𝐺4𝑡4𝑙4/ℎ4 (1) where 𝐺4 is the shear modulus of the masonry infill obtained in diagonal-compression tests while 𝑡4, 𝑙4 and ℎ4 are the thickness, the length and the height of the masonry wall....

    work page 1996

  10. [10]

    Construction Publisher ISBN 978-604-82-2518-6 ID No./ pp. … are evaluated from the geometric and mechanical properties of the masonry infills through the model by Panagiotakos and Fardis (1996), while the ones on the response envelope in tension are assumed equal to zero. The floor plan and front elevation views of the model are shown in Fig

    work page 1996

  11. [11]

    The infill panel on the ground floor is still in the elastic range of the behavior, and the one on the third floor reaches the cracking strength

    The most damaged infills are clearly located on the first floor of the building, where a large value of the interstory drift observed. The infill panel on the ground floor is still in the elastic range of the behavior, and the one on the third floor reaches the cracking strength. This result fits closely the observed response of the real building after th...

    work page 2016

  12. [12]

    Refined numerical models of the existing steel building are developed with and without considering the effect of the perimeter masonry infill

    CONCLUSIONS The paper presents a numerical assessment of the structural performance of a case steel MRF building located in Amatrice, Central Italy, which suffered extensive structural and non-structural damage during the recent swarm of events. Refined numerical models of the existing steel building are developed with and without considering the effect o...

    work page 2016

  13. [13]

    Proceedings of the 11th National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Los Angeles, CA

    The 2016 Central Italy earthquakes sequence: observations of incremental building damage. Proceedings of the 11th National Conference in Earthquake Engineering, Earthquake Engineering Research Institute, Los Angeles, CA

    work page 2016

  14. [14]

    Bulletin of Earthquake Engineering, 16(3), 1399-1423

    Damage patterns in the town of Amatrice after August 24th 2016 Central Italy earthquakes. Bulletin of Earthquake Engineering, 16(3), 1399-1423. McKenna, F., Fenves, G. L., and Scott, M. H

    work page 2016