Development of Multi-Tee-Type Precast Concrete Slabs with Insulating Materials for Structural Safety at the Construction Stage

Round 1

Reviewer 1 Report

General comments

This article aims at showing the efficiency of a clip-type shear reinforcement for the dapped end of precast slabs. A comparison with another Z-type of shear reinforcement is proposed.

This article is globally well-written and the technological contribution is certain. However the scientific contribution is more uncertain. I can't discern any scientific locks and I invite the authors to better highlight their scientific contribution (may be by carrying a probabilistic analysis of your results)

 

Questions

• page 1 line 19-20 : replace the text Ptest/Pm = 1.20-1.40 by a sentence. Actually, at this moment of the reading, reader does not know the meaning of Pm,P test.
• line 59-60 : Please, give examples of special care taken to design the dapped end (in the literature or guides)
• line 107 : You should add parameters 'a' and 'd' in figures 2.
• Figure 4 : you should add pictures to figures 4d.
• line 127 : please write "Two prestressed strands..."
• line 128 : write "A D16 nonprestressed reinforcing bar..."
• line 200 parameter fy is not present in equation (1). You should replace fs by fy (indicating that flexural yielding of the PC slab is associated to yielding of nonprestressed reinforcement)
• equation (3) : you should indicate what is f'c (concrete compressive strength)
• Table 2 should be moved at the end of section 2.4 (just before the beginning of section 3)
• line 239 : you should detail what is 'ineffective' shear reinforcement vs 'effective'.
• line 231 below table 2 replace 'smallest' by 'highest'
• Table 2, please replace 'Vn-end' by 'Vn-dap' (also in line 234)
• lines 248, 250, 253. Please replace 'Pv-end' by 'Pv-dap'.
• line 260. Is this information about the variability of f'c used ? You should think about considering variability of the parameters in your article. It will confer it a better scientific angle.
• Figure 9 : Is this figure actually useful ?
• line 322 : It is not clear for me why you used the word "safely" in the sentence "the flexural strength ... can be safely predicted". Are you able to give a level of reliability to this assertion ?
• Figure 10 : the differences between the figures (a) to (d) is not clear. what is the meaning of "strand at center" or "strand at right line",etc.
• Figure 12 : ZS-12.8. Are you able to explain why curves in the (C) region are very different from the others ?

Author Response

The authors appreciate the comments and suggestions on the paper. The paper was thoroughly revised in accordance with the reviewer’s comments. Please see the attached word file, which contains the replies to the reviewer’s comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article presents an experimental study on the behaviour of precast reinforced concrete hollow core slab subjected to flexural loads. The aim was to investigate the contribution of two types of shear reinforcements (i.e. Z or clip shape) in the dapped end of the slab system. In general, the article reads well. It has a careful description of the initial considerations, methodology (theoretical assumptions and test procedures) and discussion of results; all complemented with helpful diagrams and photos. The higher efficiency of the anchorage of clip shape shear reinforcement in relation to the Z shape reinforcement has been demonstrated in terms of anchorage.

 

The following comments are suggested for consideration of the authors:

 

1. Figure 2(b) would benefit from the indication of theta as the angle between the reinforcing steel and the member axis, as defined later in line 222.
2. In line 262, it is stated that three coupon tests of reinforcing bars were tested. Would this refer to three coupon tests for each diameter or three coupons of each reinforcing bars diameters were tested (i.e. D10, D13, D16)?
3. I wonder if similar crack distribution has been observed in the internal and webs and dapped ends. Please comment on that.

 

Author Response

The authors appreciate the comments and suggestions on the paper. The paper was thoroughly revised in accordance with the reviewer’s comments. Please see the attached word file, which contains the replies to the reviewer’s comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

The submitted article “applsci-1088503” entitled: “Development of Multi-Tee-Type Precast Concrete Slabs with Insulating Materials for Structural Safety at the Construction Stage” is an original experimental contribution to the study non-conventional, special “clip-type” shear reinforcement at the shear-critical region of dapped ends of multi-tee Precast Concrete (PC) slabs. A well-planned test program of simply supported PC slabs subjected to monotonic loading is performed, well-presented and adequately discussed. An important aspect is the consideration of structural safety at the construction stage of the tested PC slab specimens with “Z-type” and the proposed “clip-type” shear reinforcement. Test results include load versus deflection curves, failure modes, strength ratios and shear-reinforcement strains. It is an interesting and novel topic. Manuscript is well-structured presenting valuable test results and concluding to useful remarks for researchers and engineering community. For all the aforementioned reasons I believe that this research is definitely worthy of publishing. There are a few minor issues that are suggested to be considered based on the following comments which are raised for Authors’ reference:

 

1. Test results are presented in a clear manner. However, a table summarizing the detailed experimental results illustrated in Figures 7 and 12 would be very useful.

 

2. The onset and the propagation of the shear diagonal cracking in the shear-critical area of the tested PC slabs is an important parameter that influences the overall response and the failure mode of the tested specimens and could justify, till a point, the different results between the specimens with “Z-type” and the proposed “clip-type” shear reinforcement. Thus, the load at this stage (first diagonal crack) would be useful to be reported.

 

3. In introduction, the tasks and the research significance of the study are clearly defined. The literature review seems also very informative. A suggestion that could further improve the motivation and the novelty of this research is to consider some additional “special type” non-conventional shear reinforcement such as the application of continuous spirals. In this direction, the following relevant experimental works concerning the shear response of reinforced concrete beams could be considered and, therefore, are suggested for Authors’ reference (order by date):

• Shear capacity of RC rectangular beams with continuous spiral transversal reinforcement, WIT Transactions on Modelling and Simulation 2005.
• Shear tests of reinforced concrete beams with continuous rectangular spiral reinforcement, Construction and Building Materials 2013.
• Nonlinear finite element study on the improvement of shear capacity in reinforced concrete T-Section beams by an alternative diagonal shear reinforcement, Engineering Structures 2016.

 

Author Response

The authors appreciate the comments and suggestions on the paper. The paper was thoroughly revised in accordance with the reviewer’s comments. Please see the attached word file, which contains the replies to the reviewer’s comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The replies done to my comments are acceptable.

This submission reaches the standard of Applied Sciences journal.