Cyclic Evaluation of Exterior Beam-to-Column Connections for Intelligent Accelerated Construction of Industrial Facilities

Round 1

Reviewer 1 Report

The authors evaluated three large-scale exterior beam-column joints that were fabricated and tested under lateral load up to a 4.0% drift ratio. The paper presents valuable information about the behavior of fabricated RC joints and can publish in the current version but the English language and style require a minor spell check.

Author Response

Thank the Reviewer for these constructive comments. The language and writing style have been thoroughly revised, as highlighted in red in the revised manuscript. Thank you.

Reviewer 2 Report

In paper, the Cyclic Evaluation of Exterior Beam-to-Column Connections were investigated. Two types of connectors were studied. Cyclic behaviour of beam - column joints are important in seizmic regions.

Could you provide more details for movement of crane between working positions?

Author Response

Thank the reviewer for the meaningful comments and the interest in this device. But regrettably, this device is in the patent application stage. We look forward to describing how it works in more detail in our future publications. Thanks!

Reviewer 3 Report

In this study, the authors performed the experimental study of three large-scale exterior beam-to-column connections. Two anchorage forms, namely, the mechanical splices and the grouted sleeves, were adopted and compared with the monolithically cast specimen. Test results showed that the specimen using the grouted sleeves had similar seismic performance to that of the cast-in-place specimen, whereas the specimen using the mechanical splices presented significant post-peak deterioration under positive beam bending moments. In general, the contents are interesting and well written, and the figures are plotted with great efforts by the authors. The paper is recommended for publication, and a few questions are required to be well handled.

1. The authors performed the experimental assessment of precast concrete joints, which is a great work. The introduction section can be further improved to the literature, and the reviewer suggests to focus more on the short comings of the existing references. The following papers related can be included into the Intro and contents. 10.1016/j.jobe.2022.104904

2. The hysteresis curves for LZ1 and LZ3 are ideal with great energy dissipation capacity. As for LZ2, it seems like a brittle failure. Is it an accidental case or experimental error? As the mechanical coupler is also one of the choices in the bar connections for precast structures.

3. Although the failure of the precast connection using mechanical couplers was not expected, can the authors give some explanations or give some design suggestions to avoid the phenomenon in the further research?

4. For 3.5. Drift contributions, how to differentiate between the elastic and plastic flexural deformation in experiments? Because the obtained displacement data are commonly a combination of elastic and plastic deformation.

Author Response

•  Response to question 1: 

Thank the reviewer for these relevant comments. We have improved the introduction section and pointed out that for practical reasons, we did not choose a new type of precast connections proposed in previous literature, but chose relatively traditional steel bar connection methods for comparison. The literature mentioned by the reviewer is useful and has been included in the revised manuscript. Than you!

•  Response to question 2: 

Thank the reviewer for this important comment. We agree that the mechanical coupler is also the common choice for bar connections in precast structures. But as our post-test tensile experiments show, the tensile properties of ordinary threaded couplers are indeed sensitive to the tightness of the reinforcement. A slightly improper operation will lead to a substantial decline in seismic performance of connections. This was also observed in French et al.’s study [14]. Therefore, we believe that this is not an accidental phenomenon, and hope that this phenomenon can arouse the attention of the engineering community.

•  Response to question 3: 

Thank the reviewer for this constructive comment. In hindsight, we have found in our tests that if the steel bar is not tightened into the mechanical coupler, the tensile strength can be reduced by up to half. French et al. [14] recommended that tapered-threaded couplers be more reliable than ordinary threaded couplers. In the future, it is necessary to conduct more in-depth research on characterizing the tensile performance of ordinary threaded couplers under large inelastic cyclic deformations, which has been pointed out in the conclusion.

•  Response to question 4: 

We feel sorry that we misled the reviewer. In fact, the elastic deformation of the beam refers to the bending deformation outside the plastic hinge zone, while the plastic deformation of the beam refers to the bending deformation inside the plastic hinge zone. We have rephrased these descriptions. Thank you very much!

Reviewer 4 Report

This paper presented the test of different beam column connection methods is useful and practical. The test method adopted is technical sound but not innovative. This paper is well-written and the test results are clearly presented. The findings of unsatisfactory ductility performance of mechanical couplers are important for engineers. In short, this paper can be accepted for publication in Buildings.

Author Response

Thank the reviewer for these encouraging comments.