Seismic Fragility for a Masonry-Infilled RC (MIRC) Building Subjected to Liquefaction

Round 1

Reviewer 1 Report

1. More information on the liquefaction induced mechanisms are required. What damages have been experienced in the past earthquakes?

2. Improve reference list.

• Rasulo, A., Pelle, A., Lavorato, D., Fiorentino, G., Nuti, C., Briseghella, B. (2020). Finite element analysis of reinforced concrete bridge piers including a flexure-shear interaction model. Applied Sciences, 10(7), 2209.
• Drobiec, Ł., Jasiński, R., Mazur, W., & Rybraczyk, T. (2020). Numerical Verification of Interaction between Masonry with Precast Reinforced Lintel Made of AAC and Reinforced Concrete Confining Elements. Applied Sciences, 10(16), 5446.
• Modoni, G., Spacagna, R. L., Paolella, L., Salvatore, E., Rasulo, A., & Martelli, L. (2019, June). Liquefaction risk assessment: Lesson learned from a case study. In Proc., 7th Int. Conf. on Earthquake Geotechnical Engineering. Boca Raton, FL: CRC Press, Taylor and Francis Group.
• Chiaradonna, A., Bilotta, E., d’Onofrio, A., Flora, A., & Silvestri, F. (2018). A simplified procedure for evaluating post-seismic settlements in liquefiable soils. In Geotechnical Earthquake Engineering and Soil Dynamics V: Liquefaction Triggering, Consequences, and Mitigation (pp. 51-59). Reston, VA: American Society of Civil Engineers.

Author Response

Many thanks for time devoted to the review and your observations. Please consider the developed part of the introduction were your suggestions helped to improve the paper.

1. More information on the liquefaction induced mechanisms are required. What damages have been experienced in the past earthquakes?

 

Please check how the introduction was expanded, following your suggestion.

 

2. Improve reference list.

• Rasulo, A., Pelle, A., Lavorato, D., Fiorentino, G., Nuti, C., Briseghella, B. (2020). Finite element analysis of reinforced concrete bridge piers including a flexure-shear interaction model. Applied Sciences, 10(7), 2209.
• Drobiec, Ł., Jasiński, R., Mazur, W., & Rybraczyk, T. (2020). Numerical Verification of Interaction between Masonry with Precast Reinforced Lintel Made of AAC and Reinforced Concrete Confining Elements. Applied Sciences, 10(16), 5446.
• Modoni, G., Spacagna, R. L., Paolella, L., Salvatore, E., Rasulo, A., & Martelli, L. (2019, June). Liquefaction risk assessment: Lesson learned from a case study. In Proc., 7th Int. Conf. on Earthquake Geotechnical Engineering. Boca Raton, FL: CRC Press, Taylor and Francis Group.
• Chiaradonna, A., Bilotta, E., d’Onofrio, A., Flora, A., & Silvestri, F. (2018). A simplified procedure for evaluating post-seismic settlements in liquefiable soils. In Geotechnical Earthquake Engineering and Soil Dynamics V: Liquefaction Triggering, Consequences, and Mitigation (pp. 51-59). Reston, VA: American Society of Civil Engineers.

Please check that these contributions have been added.

Reviewer 2 Report

The article addresses the problem of evaluating the response for an infilled reinforced concrete structure, considering the soil-structure interaction and the effect induced by the earthquake on the possible liquefaction of the soils. 

Despite the topic is interesting, some assumptions made by the author makes the results for this case study unrealistic. It is strongly recommended to address the following observations:

• Rows 25-72: In the paragraph entitled background, a number of papers dealing with the problem of soil-structure interaction and liquefaction are collected. However, it is often difficult to read and results to be a mere listing of bibliographic sources. A complete revision of this part is recommended; in particular, it is suggested to try grouping the bibliographic sources providing a more organic and meaningful view by evidencing the main contribution of each work.
• A real introduction in which the main contribution of this work with respect to previous ones is missing. In addition to the description of existing papers, it is recommended to add what is lacking in previous works, and which is the contribution of this paper.
• Rows 102-116: This article addresses the generation of fragility curves for an infilled reinforced concrete structure. However, the simulated structure is characterized by very large spans (8 and 10m). This makes this type of structure unrealistic for Italian standards. Please, comment this observation.
• Furthermore, the behavior of infill panels is assumed to be linear. This is allowed when the seismic intensity is very low, as infill panels cracks for very low interstory drift values. During the generation of fragility curves this modeling aspect cannot be neglected since it will produce unrealistic results. It is strongly recommended to modify the model.
• Row 184. The author declares the adoption of the Incremental dynamic analysis with a PGA step of 0.1g between 0 and 1.0g. However, in figure 10 and 13, the ln(PGA) points should be aligned along vertical lines. Why this not occurs?
• Row 234: Drift limits used for the analysis are extracted from the Hazus manual. However, it is not specified for which type these curves are proposed. To the reviewer’s memory, these limits are not provided for infilled RC structures. So which values were selected? Please, justify.
• Rows 286-293: In this part of the paper, it is suggested to compare the curves obtained with those proposed in reference [25]. However, the fragility curves generated in [25] represent the response of bare reinforced concrete structures. Thus, the proposed comparison is not very realistic, also due to different criteria adopted to define the attainment of different damage states. Please, clarify in the text the differences between fragilities obtained in [25].
• It would be interesting to model the structure without considering the interaction with the soil and liquefaction to highlight the importance of considering the SSI.
• The method adopted for generating fragility curves is the one generally used for CLOUD analysis, in which earthquakes are applied without scaling. However, the regression model in the log-log plane (called probabilistic seismic demand model), allows to derive the parameters of the fragility curve by adopting appropriate limits (e.g. in terms of interstory drifts), but assumes a single beta parameter (see also [25]) . Why is beta variable?
• The author declares to propose a probabilistic framework. However, the fragility curves, to be representative, need to take into account not only the dispersion due to the record-to-record variability, but also the dispersion relative to the model (intra-model variability) and that relative to the definition of the damage states. The author should addredd this issue.
• The author neglects the effect of vertical earthquakes during the analysis. However, when addressing the problem of liquefaction of soils, this component could be important. The author should justify this assumption.
• Figure 13. The regression curve seems not fitting well the data, despite the high R2. Which method was adopted to derive the coefficients for the regression curve?

Author Response

Many thanks for time devoted to the review and your observations. Please consider the following answers to your questions.

Please see the attached file.

Regards

Author Response File: Author Response.docx

Reviewer 3 Report

This research investigates the liquefaction-induced damages in masonry-infilled RC frames. The FE-based computational model is proposed to perform structural simulations. However, the submitted work seems to be a continuation study of the author, which is prepared with little effort and mostly relying on his earlier studies. The article does not include any new information or up-to-date validation procedures. Hence, I do not recommend publishing the article. 

Author Response

Many thanks for time devoted to the review and your observations. Please consider the developed part of the introduction were the novelties are described.

Round 2

Reviewer 2 Report

The article can be accepted in the current form.

However, some concerns remain about the modeling of infill panels. In particular, the problem of interaction between frame and infill walls depends on the model adopted to simulate the infill wall behavior, as demonstrated in:

Gaetani d’Aragona, M., Polese, M., & Prota, A. (2021). Effect of Masonry Infill Constitutive Law on the Global Response of Infilled RC Buildings. Buildings, 11(2), 57.

Further, I suggest to the author, to add as a comment to the text that due to the complexity of the problem and the computational burden required to complete the analyses, generally simplified models are employed to account for the nonlinear behavior of the superstructure: as an example

Lu, Y., Hajirasouliha, I., & Marshall, A. M. (2016). Performance-based seismic design of flexible-base multi-storey buildings considering soil–structure interaction. Engineering Structures, 108, 90-103.

Gaetani d'Aragona, M., Polese, M., Di Ludovico, M., & Prota, A. (2021). The use of Stick‐IT model for the prediction of direct economic losses. Earthquake Engineering & Structural Dynamics, 50(7), 1884-1907.

Gaetani d'Aragona, M., Polese, M., & Prota, A. (2020). Stick-IT: A simplified model for rapid estimation of IDR and PFA for existing low-rise symmetric infilled RC building typologies. Engineering Structures, 223, 111182.

Author Response

Many thanks for time and attention devoted to the paper, please consider the new version that includes your suggestions.

Regards

Reviewer 3 Report

The author improved the article and make clear where the specific contribution are. Hence, the current form is much better for the readers. Several minor issues are given below.

1-In section-3, the author highlight the new developments regarding the probabilistic approaches in the seismic assessment however, do not cite the most recent studies. Please consider to give reference the following works: 

doi.org/10.1016/j.engstruct.2021.112115;doi.org/10.1016/j.engstruct.2021.112095; doi.org/10.1016/j.engstruct.2021.112620 ;doi.org/10.1016/j.engstruct.2016.10.013

2-It is better to say "to save computational time", instead of "to safe computational time".

3- In the conclusion part, the author may want to write rather than "nonlinear mechanism", it would be more appropriate to say "more sophisticated material models and computational modeling strategies". 

Author Response

Many thanks for time and attention devoted to the paper, please consider the new version that includes your suggestions.

Regards