Role of Subgrade Reaction Modulus in Soil-Foundation-Structure Interaction in Concrete Buildings

Round 1

Reviewer 1 Report

In this manuscript, the role of subgrade reaction modulus in soil-foundation-structure interaction in concrete buildings was investigated. An equation was provided to simplify considering SSI effects in foundation design which may be useful for civil engineers. Specific comments are presented below.

1. Did the author consider the radiation damping of the foundation under the seismic action?
2. What is amplitude and duration time of the earthquake loads in Type 1? How to enforce the earthquake loads?
3. What do the dead and live load mean?
4. Introduce the version of ANSYS used in this manuscript.
5. Please add the unit in Figure 5 and 6.
6. Interface element has an important effect on the results. The authors should review the interface element, the following reference is recommended.“Xue B, Du X, Wang J, Yu X. A Scaled Boundary Finite-Element Method with B-Differentiable Equations for 3D Frictional Contact Problems. Fractal and Fractional. 2022; 6(3):133.”

Author Response

Reviewer 1:

In this manuscript, the role of subgrade reaction modulus in soil-foundation-structure interaction in concrete buildings was investigated. An equation was provided to simplify considering SSI effects in foundation design which may be useful for civil engineers. Specific comments are presented below.

1. Did the author consider the radiation damping of the foundation under the seismic action?

Reply: Thank you for your insightful comments. Revised version of the manuscript was uploaded and changes have been highlighted in the text. The amount of radiation damping induces by dynamic soil-foundation structure (SFS) interaction while we used linear static analyses in all analyses and the purpose of these analyses were to calculate the time-independent behavior of a structure against different loads.

1. What is amplitude and duration time of the earthquake loads in Type 1? How to enforce the earthquake loads?

Reply: The earthquake loads considered as an inertia acceleration with value  in buildings’ width and length directions.

1. What do the dead and live load mean?

Reply: Dead load are materials loads such as beams load, columns load, shear walls load and slabs load. In fact they are gravitational loads and live loads are equal to normal live load which should be considered for each floor which were assigned as pressure load with value of 200 Kg/m² in each floor and 150 Kg/m² in top floor.

1. Introduce the version of ANSYS used in this manuscript.

Reply: In this manuscript, ANSYS 11 and 19 were used.

1. Please add the unit in Figure 5 and 6.

Reply: All the units in all these figures are meter and were added in figures and mentioned in the text.

1. Interface element has an important effect on the results. The authors should review the interface element, the following reference is recommended.“Xue B, Du X, Wang J, Yu X. A Scaled Boundary Finite-Element Method with B-Differentiable Equations for 3D Frictional Contact Problems. Fractal and Fractional. 2022; 6(3):133.”

Reply: CONTA173 element was used in these analyses to represent contact and sliding between 3-D target surfaces and a deformable surface defined by this element. The element is applicable to 3-D structural and coupled-field contact analyses. It can be used for both pair-based contact and general contact. This element is located on the surfaces of 3-D solid or shell elements.

Reviewer 2 Report

In section 2 and “Fig. 1” are not shown the sizes of columns, beams, slabs, walls, infills, story height. The soil or seismic parameters and materials characteristics (concrete class, reinforcement area, and diameter) are also missing.

Can be provided in section 3, some data about the time required for building modelling by using the ETABS and ANSYS software’s? Is the equation 2 feasible to be used for design of any type of structures as an alternative to DFEM? Are there any limitations imposed? If it is possible, it would be interesting to discuss the differences between the methods used for evaluation of soil-structure interaction. Are there similar differences as were obtained in case of buildings with different story highlighted in Table 1?

It was shown that a variable value of “subgrade reaction modulus” may offer economic advantages in term of material consumption. Even so please can you compare the results obtained in these simulations with the results obtained by other scientific researchers, to highlight better the elements of originality?

In section 4 the “further research” may be presented.

Please complete some data related to the patent (patent number, title, year).

Author Response

In section 2 and “Fig. 1” are not shown the sizes of columns, beams, slabs, walls, infills, story height. The soil or seismic parameters and materials characteristics (concrete class, reinforcement area, and diameter) are also missing.

Reply: We appreciate the reviewer for the insightful comments and ideas. All the beams and columns are rectangular shape and each story has 3m height. Beams, columns and shear walls are concrete with isotropic materials such as  where Ex and  are Modulus of Elasticity and Poisson’s ration respectively. Ceilings, material properties are . Table 1 shows the details of used sections, Sh-W is represent of shear walls in this table.

Table 1. Sections’ details of 6, 8 and 10-story buildings

Can be provided in section 3, some data about the time required for building modelling by using the ETABS and ANSYS software’s? Is the equation 2 feasible to be used for design of any type of structures as an alternative to DFEM? Are there any limitations imposed? If it is possible, it would be interesting to discuss the differences between the methods used for evaluation of soil-structure interaction. Are there similar differences as were obtained in case of buildings with different story highlighted in Table 1?

Reply: This method can be used for concrete buildings but for steel buildings, it should be considered in future studies. With this method, the weight of the required reinforcement of foundation would be near 1/3. In addition, when the number of stories are increased the weight of the required reinforcement of foundation will be reduced more.

It was shown that a variable value of “subgrade reaction modulus” may offer economic advantages in term of material consumption. Even so please can you compare the results obtained in these simulations with the results obtained by other scientific researchers, to highlight better the elements of originality?

Reply: There is a correlation between soil modulus of elasticity and subgrade reaction modulus. There are some different methods to assign different value of Ks in foundation design such as ATC FEMA273 Code (FEMA, F., 273, NEHRP guidelines for the siesmic rehabilitation of buildings; FEMA 274. Federal Emergency Management Agency, 1996).

In section 4 the “further research” may be presented.

Please complete some data related to the patent (patent number, title, year).

Reply: There isn’t any registered patent for this study.

Round 2

Reviewer 1 Report

This manuscript can be published in present form.

Author Response

We appreciate the reviewer for the insightful comments. 

Reviewer 2 Report

Thanks to the authors for the answers and for the changes made. Some future research directions would be interesting to present at the end of the article.

Author Response

Thank you so much for your previous comments, which helped improving the manuscript. This suggested method can be used for concrete buildings but for steel buildings, it should be considered in future studies. In addition, all of our analyses were deterministic, while role of uncertainty in soil parameters could be considered by probabilistic analyses. Lines 256-258 were added.