Seismic Behavior of a Bridge with New Composite Tall Piers under Near-Fault Ground Motion Conditions

Round 1

Reviewer 1 Report

GENERAL COMMENT

The work presents a new solution for tall piers to resist near-fault ground motions. In particular, the new design proposes four concrete-filled steel tubular columns and energy dissipating mild steel plates.

The work is well organized and presented. The structure is clear and the results concise. However, further explanations on the numerical results would be suggested.

The level of English is good, although some parts require further revision and typos correction.

DETAILED COMMENTS

Introduction:

The section is too long and focuses mainly on the design of tall piers. The reviewer suggests to reduce the introduction section on tall piers to few paragraphs, and then focus on design improvements towards seismic excitations and especially near-fault ground motions.

The last paragraph of the introduction is rather written as an abstract, so it would be advised to revise it.

Section 2 line 191: “…mitigate the seismic damage” should be corrected with “mitigates”.

Figure 1: it is not clear which views are these (top, side?).

Section 2 line 201: correct “apparent” with “visible”.

Section 3.1: the symbol for the span arrangements should be an “x” rather than a “+”. Moreover, the definitions of “GPZ(II)3DX and 3SX are missing. Also Q345 and LYP100 should be explained in the text.

Figure 3: the views (top, side) should be clearly marked.

Section 4 line 288: the symbol φ should be changed to Φ.

Section 4 line 292: Mises should be corrected to Von Mises.

Section 5.1: the following terms need to be clarified for the reader: B31, *rebar, S4R, “tie” command.

Section 5.2: more details on the results of the modal analyses would be appreciated, especially describing Figure 5.

Section 5.3: please include the reference for PEER database.

Section 5.4: it is useless to have 4 digit for values of curvature with an order of magnitude of 10^-4. Please revise. Moreover, wasn’t it the value of yield stress of 100 MPa? Why is it 345? Please specify. From Figure 6 it appears clearly that under some earthquake intensities the displacement on the new design is higher than the prototype one. The authors should explain this aspect, as it suggests that the prototype works better than the new one under some ground motions.

Table 7: what is the meaning of the table? It should either be described in the text or removed, as it reproduces the same information of Figure 8.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

if possible it could be interesting and increase the quality of the paper a deeper description of the finite element models introduced (i.e. some informations about the materials properties, if the modelling procedure was validated etc.).

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

In the Reviewer opinion the research paper entitled “Seismic Behavior of the Bridge with CFST Column and Mild Steel Plate Composite Tall Piers under Near-Fault Ground Motions” is good.

The objectives of this study are to put forward an innovative design concept of a tall pier system and its application in tall-pier bridges. The concept of the innovative tall pier system is derived from the principle of earthquake-resilient structures, and is to improve the seismic performances of the tall-pier bridges under strong near-fault ground motions. The proposed tall pier system has a box section and is composed of four concrete-filled steel tubular (CFST) columns and energy dissipating mild steel plates (EDMSPs). Both static analysis and nonlinear time history analysis of both the bridges with the new composite tall piers and conventional RC tall piers under the near-fault velocity pulse-type ground motions were conducted in Midas Civil2019 and ABAQUS. The results show that: under the design-based earthquake (DBE), the CFST columns and connecting steel beams remain elastic in the bridge with the new composite tall piers, while the damage is found in the replaceable EDMSPs which help dissipate the seismic input energy. It is concluded that the bridge with the new composite tall piers is seismic resilient under near-fault ground motions.

Some comments which greatly enhance the understanding of the paper and its value are presented below. Specific issues that require further consideration are:

1. The title of the manuscript is matched to its content but it is too long.
2. In the Reviewer’s opinion, the current state of knowledge relating to the manuscript topic has been presented, but the author's contribution and novelty are not enough emphasized.
3. In the Reviewer’s opinion, the bibliography, comprising 39 references, is rather representative.
4. An analysis of the manuscript content and the References shows that the manuscript under review constitutes a summary of the Author(s) achievements in the field. However, the introduction needs more attention.
5. Conclusion needs to be more revised.
6. In the Reviewer’s opinion the manuscript should be published in the journal after minor revision.

Author Response

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Author Response File: Author Response.doc