Experimental Study of Steel Reinforced Concrete (SRC) Joints

The article treats an   interesting issue related to the steel reinforced concrete joints. Such issue   is of practical interest especially for seismic zones and the industry   working with reinforced concrete technology. The authors have carried out   different experiments which have been summarized in the presented manuscript.   The article provides much relevant information but its presentability   requires additional effort by the authors. It is suggested that this   manuscript, based on its current form should be improved in terms of a   literature review, set-up explanation and results presentations. Also, the   English is not adequate hence it requires professional editing.

The manuscript fulfills   the scope of the journal. In this regard, the paper deserves the attention of   the editorial board. However, for the sake of clarity, the submitted   manuscript may be considered for publication only after the authors raise the   following comments and carry out a significant revision of their manuscript.

Specific Comments

Point 1: •   The title should not end with a full stop (.).

Response 1: The comment has been taken into account.

Point 2: •   The abstract is poorly constructed where the fluently and the main goal of   the research is missing. It is recommended to provide a new abstract, highly   improved compared to this version.

Response 2: We agree with the   comment. The summary has been improved.

Point 3: •   The authors use SRC the abbreviation of “Steel reinforced concrete”, which in   the text is used mixed, both the full name and the abbreviation are used   simultaneously. It is not the correct way of writing. Only the abbreviation   or the full length should be used, up to the choice of the authors. Important   is to introduce each notation used in the text.

Response 3: You are right. The mistake has been corrected.

Point 4: •   The introduction does present a low-quality literature review. The   introduction to the main critical issues of the studied topic and the   contribution of the article or is missing or is not correctly addressed. In   some cases, the references are not adequate, like e.g. “This research found   it necessary to perform numerical simulations of three specimens [20].”. How   it comes that the authors refer to the current research, and then they cite   an article? This is misleading. It is recommended that the introduction   should be reviewed.

Response 4: The phrase has been eliminate.

Point 5: •   The methodology is not adequately clear. Why have the authors chosen this specimen   of the joint? Why are the authors referring to the corner joint? In Figure 1,   the highlighted joints are not comparable, for the T-joint (up) is not the   same as the rotated T-joint (left), because the seismic loads are not applied   as described in the image.

Response 5: This specimen of the joint has been chosen as it is a conventional   solution and has dimensions capable of being tested in the available gantry.

Point 6: •   Figure 2 is not very clear, a better image with explicative notes is   necessary.

Response 6: Figure 2 has been   improved and included a photo to improve its understanding.
 
 

Point 7: •   Figure 3 is not correct because the horizontal loads are not equal for both   stories. It is better to show the moments in the frame parametrically to have   an idea of which would be the most vulnerable (loaded) joints. The arched   arrows of the moments are not correctly displayed, and they are not   necessary.

Response 7: Figure 3 of difficult   understanding has been eliminated.

Point 8: Figure 5 should be explained better. Why is this scheme used to load the   joint and to which node (joint) it resembles during an earthquake? Why did   the authors work with absorbed energy? Also, other parameters are crucial for   the safety of the structure and an optimal design; hence a better   justification is expected by the authors.

Response 8: The diagram of the   figure has been used as it is the test capable of being carried out with our   gantry. Comparing the different results with energy absorbed allows us to   demonstrate that our test is valid and allows us to know the numerical   difference between different constructive solutions. The energy absorbed is a   quantitative parameter that allows to compare the ductility of the different specimens.
 
 

Point 9: • Figure 7 seems the setup of the experiment of the joint not for   assessing the material properties as the authors claim in the last row of the   first paragraph of section 3.

Response 9: We agree with the comment.

Point 10: • Section 3 provides much unuseful information instead of providing   crucial information about the setup. It is recommended to avoid trivial   sentences and statements. A better explanation of the specimens is necessary.  

Response 10: Section 3 has been   improved as indicated by the reviewer.

Point 11: • What do   the authors refer to: “loads were introduced as a displacement imposed,”   because previously was introduced a loading machine, with the maximum load of   300kN?

Response 11: It refers to the   way to introduce the load. It can be introduced as load or displacement,   being the case of displacement imposed the option to know the ultimate   ductility of the specimens. Only the elastic analysis can be performed with   the load.

Point 12: • What   does it mean: “As the latter weighed less than the former, the solution with   IPN was more economical with proportional mechanical characteristics”? Is it   a correct sentence?

Response 12: Refers to the weight of the metal section. With the same weight, the   behavior is similar.
 
 

Point 13: • The authors say: “The maximum load that each specimen was able to   support was a form of relevant data, but the maximum deflection that it was   able to reach and the ultimate load corresponding to that deflection were   more relevant.” What is the difference between the maximum load and the   ultimate load? Do the authors agree that this statement is not scientifically   correct?

Response 13: The phrase has   been rewritten to be scientifically correct. The maximum arrow reached and   the final load provide very interesting data to know the ductility of the   structure.

  Point 14: • The last   part of section 4, is quite confusing due to the utilization of non-standard   terminology, like: “The plastic moment of the steel cross-section was   calculated from the plastic strength module and the steel tension”;   “section’s last strength”; “pre-breakage phase” etc.

Response 14: The comment has been taken into account.
 
  Point 15: • The authors   say: “The ultimate breakage of the beam could not be achieved despite the   large deformations obtained since the plastic deformation of the steel   section was very large (Figure 10B).” while Figure 10B shows a total failure.   How that? What do the authors refer?

Response 15: Figure 10B shows a   significant bending of the metal section, of 45 °, without reaching breakage.   This allows that in the mixed structures the efforts are redistributed before   the collapse of the structure.
 
 

Point 16: • The displayed graphs in figure 11 and 12 are not clear to distinguish   each case. It is better to display each graph with different colors and   different line style.

Response 16: The comment has been taken into account.

  Point 17: • Why the   authors had another specimen P07, a and b? What the difference and what is   the point?

Response 17: The difference is   that the P07a break was not the knot, but in the transition zone between the   metal section and the reinforced concrete section. To know the different   behavior between reinforced concrete structures reinforced in all their bars   with metal sections and others in which only the knots are reinforced, it is very important to ensure that the plastic kneecap does not appear in the   transition zone between the metal section and the section of reinforced   concrete.
 
  Point 18: • The   result presented in Figure 15, is quite trivial when comparing the sections   with or without steel beams. P05 has a considerable load capacity compared   with other sections and needs some additional comments. The shape of P04,   P06, and P07 are similar, and that needs some comments too.

Response 18: Section P05 is designed of reinforced concrete with an armor with an elastic resistance   similar to those of specimen P04. The lower ductility and the decrease in   resistance in the plastic section can be checked.
  Section P04, P06 and P07, with the embedded metal section, have a similar   behavior with greater ductility than reinforced concrete. The metallic section   provides a greater capacity of absorption of energy and a greater ductility.

  Point 19: • The   authors say: “The results of using the conventional test frame with a   loading–unloading cycle are similar to those conducted with more complex   frames in which loads have been applied with the reverse sense,” but it is   fully true if you conduct both tests and compare the results. Such an   experiment is not carried out hence the statement is not correct.

Response 19: The phrase has been modified.
 
 

Point 20: • The conclusions may require additional review also based on the   previous comments.

•                       • English is far from   perfect and requires professional editing.

•                       • Protruding- is not the   correct term.

•                       • Which is the meaning of   “dents” in the text?

Response 20: The indicated errors have been eliminated. English has been improved.   The article was sent to the specialized review of the publisher, as shown by   the quality certificate. If you considers it appropriate, we send it again.
Dent refers to bucking flange and the mistake have been modified.

Point 21: Final Statement

Response 21: Thank you for your comments. All your annotations have been taken.

I have improved, in general, the scientific language.

Thank you very much for your kind attention.

Best regards,

Isaac Montava Belda