Study on the Stress Performance of an Incompletely Prefabricated Profile Steel Reactive Powder Concrete Column in High-Rise Modular Buildings

Round 1

Reviewer 1 Report

The paper investigates the stressing performance of incompletely prefabricated steel reactive powder concrete (PSRPC) columns and establishes the calculation method for PSRPC columns. The study examines the effects of the strength grade and steel content of reactive powder concrete (RPC) on the axial compression performance of PSRPC columns and the effects of the steel content and eccentricity on the eccentricity performance of PSRPC columns.

The study also analyses the damage morphology of the specimens and the load-displacement and strain relationships, investigates the damage mechanism and the main factors influencing the compressive load capacity of the PSRPC columns.

However, it is pointed out that the higher the RPC strength, the higher the component strength. Is there a suitable RPC strength value so that this new component meets both ductility and strength requirements. At the same time, the member becomes brittle. This problem needs to be described in detail, otherwise the new component may not have practical application significance. The following questions need to be considered before acceptance:

1. The value of RPC combined with practical application should be considered in more detail.

2. The reason why RPC is added to brittle components can be detail.

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Author Response

Thank you for your review of our paper. We have answered each of your points below.

Q1.[The value of RPC combined with practical application should be considered in more detail.]

R: Reactive Powder Concrete (RPC) is an advanced structural material known for its exceptional properties, including ultra-high strength, high toughness, and excellent durability. It offers several advantages when used in structural design, such as reducing the weight of structures, enhancing structural durability, and lowering maintenance costs over time.

Due to the unique characteristics of RPC, its constitutive relationship differs from that of conventional concrete. The constitutive relation defines the relationship between stress and strain in a material and is crucial for conducting nonlinear finite element analysis and developing design theories for RPC structures.

RPC's formulation principles, which involve specific ratios of cement, fine powders, silica fume, steel fibers, and superplasticizers, result in distinct mechanical behavior. The high-density packing of fine particles and the use of steel fibers contribute to RPC's remarkable strength and toughness. Therefore, the constitutive relationship for conventional concrete cannot be directly applied to RPC materials.

To accurately analyze and design RPC structures, it is necessary to develop specialized constitutive models tailored to RPC's unique characteristics. These models consider factors such as the stress-strain response, strain rate effects, confinement effects, and the influence of steel fibers on the mechanical properties of RPC. Researchers and engineers have been working on developing such constitutive models and conducting experimental studies to validate their accuracy.

By accurately capturing the behavior of RPC materials through appropriate constitutive relationships,

Q2.[The reason why RPC is added to brittle components can be detail.]

R:

Reactive Powder Concrete (RPC) and steel can be combined to create strong and durable structures. Here are some key aspects to consider when using RPC and steel together:

1. Composite Construction: RPC can be reinforced with steel fibers or combined with traditional steel reinforcement to form composite elements. Steel reinforcement provides additional tensile strength and ductility to the RPC, while RPC enhances the compressive strength and durability of the composite structure. This combination can result in efficient load-bearing capacity and improved crack resistance.

2. Connections and Joints: Steel is often used for structural connections and joints in RPC structures. Steel bolts, brackets, or welds can effectively connect RPC components, ensuring stability and load transfer between different elements. Proper connection design is crucial to achieve the desired structural performance and integrity.

3. Hybrid Systems: RPC and steel can be used in combination to create hybrid structural systems. For example, steel frames or trusses can be combined with RPC elements, such as beams or columns, to optimize the design for specific load requirements. This approach leverages the strength and stiffness of steel with the enhanced durability and crack resistance of RPC.

4. Strengthening and Rehabilitation: Steel reinforcement or external steel elements can be utilized to strengthen and rehabilitate existing structures. RPC can be applied as a protective layer or overlay on the steel-reinforced surfaces, providing increased durability and improved resistance to corrosion, abrasion, and environmental factors.

5. Lightweight Design: RPC's high strength and ductility allow for the design of lighter structures. By combining RPC with steel elements, such as lightweight steel framing or trusses, it is possible to achieve lighter and more efficient structural systems. This can lead to cost savings, reduced foundation requirements, and faster construction.

It's worth noting that the design and implementation of RPC and steel combinations require careful consideration of factors such as compatibility, compatibility, and load transfer mechanisms. Engineering expertise and analysis are crucial to ensuring the optimal integration of these materials in a specific project.

Overall, the combination of RPC and steel offers the potential for high-performance structures with enhanced strength, durability, and efficiency. The specific application and design approach will depend on project requirements, structural demands, and cost considerations.

Reviewer 2 Report

Review comments to applsci-2436961

Overall this paper is sound and the investigation is fair. But I still have some major comments about the design methods used. 

Comment 1: The stress-strain distribution diagram shown in Fig. 16a and 16b, is valid only if the bonding between the steel and concrete is sufficient. As the tested samples failed in large cracks (Figs. 4 and 5), this reviewer is not sure if the used stress-strain diagram is valid for this design approach. 

Comment 2: Please include the design example for demonstration. It will help the industries to follow. 

Author Response

Thank you for your review of our paper. We have answered each of your points below.

Q1.The stress-strain distribution diagram shown in Fig. 16a and 16b, is valid only if the bonding between the steel and concrete is sufficient. As the tested samples failed in large cracks (Figs. 4 and 5), this reviewer is not sure if the used stress-strain diagram is valid for this design approach.

R： Thanks a lot for reminding us of this important point. We quite agree with your comment. We have noted the errors in the details of the article and made corrections

Q2.Please include the design example for demonstration. It will help the industries to follow. 

R：Thanks a lot for reminding us of this important point. We quite agree with your comment. We have noted the errors in the details of the article and made corrections

 

Round 2

Reviewer 1 Report

I am happy with the correction