Review Reports
by
- Vincent Baumann 1,*,
- Lucas Adélaïde 2 and
- Pierre Argoul 2,3
Reviewer 1: Anonymous Reviewer 2: Anonymous Reviewer 3: Georgios E. Stavroulakis Reviewer 4: Anonymous Reviewer 5: Anonymous
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe main contribution of this work is related to the experimental study of the crowd effect (up to 97 people) on event floors from the perspective of human-structure interaction. The authors evaluated several cases, such as passive people, walking, bobbing, and jumping. As practical results, floor accelerations, impact coefficients, and Fourier coefficient curves and equations for jumps from experimental tests are presented. In addition, to estimate the contribution of human damping to the structure, a TMD model was considered, which is compatible with other works in the literature. Therefore, this work can help engineers to better account for the effect of human-structure interaction in design practice.
However, for the paper to be considered for publication, the authors should improve the explanation of the methods used, the discussions of the analyses (by comparing the human comfort criteria evaluated in situ with those in the literature) and the figure captions (some figures have labels and acronyms in French). The decimal separator should be standardised between figures and text (commas are being used in figures and full stops in text). Revision of the English text is recommended.
The comments are as follows:
2 Experimental protocol
2.1 Prototype design and construction
Page 3, line 93: “without participating in the structural system”. It should be “without participating as stiffness in the structural system”.
2.2 Sensors
Page 5 (Figure 6b): Justify the positioning of the accelerometer on the back of the neck.
2.3. Experimental protocol and rough results
2.3.1. Phase 1: Modal Characterisation of the prototype with and without dampers
Page 6, lines 151-155: Specify the sampling rate, filters, cut-off frequency and decimation used.
Page 6, lines 151-155: Concerning the excitation force provided by the shaker, what is the sweep frequency range? What type of signal is used? What is the excitation amplitude?
2.3.2. Phase 2: Tests with fully instrumented active groups: training and calibration
Page 6, lines 161-166: Are the results of this phase in the paper? If not, please reference them accordingly.
2.3.2. Phase 3: Crowd testing
Page 6, line 172: It is unclear which tests (3 tests) the authors are referring to.
Page 6, lines 175-180: How many people were used in each test?
Page 7, line 188: Indicate the natural frequency of the structure in the text. Define ‘fr’, ‘h’.
Page 7, lines 192-193: “therefore seem to observe a shift in the natural frequency which would be due to the contribution to the modal mass of the crowd in contact.” What is the percentage change in the frequency of the empty structure?
Page 9, Figures 11 and 12: In Figures 11 and 12, what do ‘AA’ and ‘AS’ mean, respectively?
Page 9: How do the acceleration results in Figures 11 and 12 compare to the human comfort criteria in standards and design guidelines?
3 Results
3.1. Characterisation of crowd-structure interaction
3.1.1. Influence of music on crowd action
Page 11, Figure 14: Indicate the name of the test and the number of people in the figure caption.
3.1.2. Influence of floor’s vibration on crowd action
Page 12: Are these comfort limits based on the individual assessment of participants? How do these limits compare to those established in design guides [AISC (2016), SCI P354 (2009)] and authors in the literature? It would be interesting if these limits were indicated in Figures 11 and 12.
3.1.3. Jumping coordination of individuals as a function of the size of the group
Page 13: Add the reference for equation 3.
Page 13: Explain Figure 16 in more detail. The labels for the X and Y axes are missing. Describe the labels for the curves and points in the caption for Figure 16: what is ‘Puissance (μα1+2σα1)’?
Page 14, lines 349-356: Was there a difference in the Fourier coefficients when comparing the tests without a damper and with a damper? Please explain it.
3.2. Characterisation of damping
3.2.1. Specific damping of the structure
Page 15, subsection 3.2.1: It should be “Damping ratio” rather than “Specific damping”
Page 15, lines 365-369: This paragraph needs to be explained/detailed in much greater depth.
Page 15: Detail the captions in Figure 17. What does ‘AD’ mean?
Page 16: In the caption for Figure 20, which curve is with damping and which is without damping? The acronyms should correspond in English.
3.2.2. Equivalent damping of a static crowd
Page 17, lines 421-424: It is necessary to cite authors who have used the TMD approach for human-structure interaction.
Page 18, Table 3: Why was FRF 03_250 mg chosen?
3.2.3. Equivalent damping of an active crowd (walking, bobbing or jumping)
Page 20, lines 483-488: It should be noted that, as jumping activity induces greater acceleration, the criterion of human comfort cannot be met on adjacent floors for passive persons.
- Discussion
Page 21: The SCI P354 guide considers up to the third harmonic for the ULS (see item 8.1.2 and example D.3 Design for rhythmic activity). It is important to make this counterpoint in the text, especially for rhythmic impact activities.
Page 21, line 523: It is necessary to mention the cut-off frequency of other codes. For example, SCI P354 considers 8.4 Hz for rhythmic activities.
Page 22, lines 558-560: This paragraph needs further clarification. It is unclear how fatigue is accounted for according to reference 25.
- Conclusion
Page 22: What are realistic damping values to be used in a design?
Author Response
Dear Reviewer,
Thank you for your detailed review.
Please find attached our responses to your comments.
Kind regards,
The Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper investigates vibration of a lab structure while excited by a number of people acting in different ways (e.g., bouncing, jumping). The conclusions derived are not new (and not general since they come from a specific experiment) and are already discussed in the dedicated literature. Literature review at the beginning of the paper is indeed very limited and poor. Authors are invited to investigate in more detail related papers available in the literature.
Author Response
Dear Reviewer,
Thank you for your review.
Please find attached our responses to your comments.
Kind regards,
The Authors
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper reports on a very interesting experiment. Sufficient information is given for people who want to reproduce results or continue research. Basic information from model structure (like eigenvalues, eigenmodes, damping estimate) can be presented in more details, supported by suitable computational tools.
Author Response
Dear Reviewer,
Thank you for your review.
Please find attached our responses to your comments.
Kind regards,
The Authors
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors1.Section 2.2 lists many devices and systems (accelerometers, displacement sensors, fiber optic sensors, data acquisition systems, force plates, IMUs, cameras), but the paper does not provide the necessary acquisition/processing parameters for replication. Please add a dedicated table (e.g., “Instrumentation & Acquisition Parameters”) including, at minimum: (1) sampling frequencies for each subsystem; anti-aliasing; synchronization/time alignment across systems; (2) sensor ranges, mounting, coordinate axes; calibration steps; (3) filtering (type, cutoff), windowing, signal conditioning, how peak/RMS are defined; (4) modal identification method(s) and settings used in Phase 1 tests (5) This is essential because later results and comparisons rely on response magnitudes and frequency-domain interpretation.
2. The coordination coefficient formulation and its fitted power-law behavior are presented as a key contribution, but the fitting procedure is not sufficiently documented. In the text, the number of points per group size is mentioned, and weighting choices are stated but not justified. Please add: (1) number of trials per N, inclusion/exclusion rules, and variability (mean ± SD or CI); (2) explicit fit method (OLS/WLS/robust), objective function, and rationale for weights; (3) confidence intervals for fitted parameters, not only R^2; (4) consistent legend language (Figure 16 currently includes non-English items such as “Puissance”) .Without this, the reported exponents and conclusions about harmonic coordination can be interpreted as ad hoc.
3. Several figures/captions use comma decimal separators (e.g., “3,4 m/s²”), which is inconsistent with the journal’s English formatting norms. All decimals should use periods. Additionally, figure references around the acceleration results show ambiguity between test series labels (“G” vs “H”) and figure numbering/captions. Please: (1) enforce a single standard for numbers and units; (2) ensure all figure legends/captions are in English; (3) ensure each figure unambiguously corresponds to one dataset (tests G/H) and that the text references match the correct figure.
4.The equivalent damping discussion is important, but the manuscript needs clearer articulation of assumptions and boundaries. In particular: (1) if a fixed human-body damping ratio and frequency are adopted from literature, justify their applicability and discuss sensitivity (you already note dependence on excitation conditions elsewhere); (2) Table 7 includes “estimated ranges” and references to large crowd estimates (“714 people* estimate…based on reference floor”). The scaling/mapping method must be explicitly described (how reference-floor properties are translated to the prototype: modal mass, frequency, mode shape, density, excitation characteristics).
5. The current data availability wording indicates a repository identifier and “please contact the author”, which is not sufficiently transparent. Please revise to include: (1) a full, persistent repository citation (DOI or stable link in the final submission); (2) exactly what is available (raw/processed time series, metadata, scripts); (3) any restrictions (especially video/participant data) and what anonymized derivative datasets can be shared.
Author Response
Dear Reviewer,
Thank your for your detailed review.
Please find attached our responses to your comments.
Kind regards,
The Authors
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsSee comments in the attached file.
Comments for author File: Comments.pdf
Author Response
Dear Reviewer,
Thank you for your review.
Please find attached our responses to your comments.
Kind regards,
Vincent Baumann
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAs the authors have addressed the comments, the paper can be accepted for publication. Before that, I recommend two minor revisions:
-Author's responses 25 and 30 should be included in the text. Response number 30 should preferably be placed in the conclusion.
Author Response
Dear Reviewer,
Please find atached our responses to you comments.
Kind regards,
The Authors
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThank you so much for your efforts. All the concerns which I had listed the authors had figured out.
Author Response
Dear Reviewer,
Please find attached our responses to your comments.
Kind regards,
The Authors
Author Response File: Author Response.pdf