Complete EPC Prefabricated Project Case Study: Shanghai Minhang New City MHC10204 Unit 19A-03A

1. Project Overview

The Shanghai Minhang New City MHC10204 Unit 19A-03A plot project is managed by Shanghai Shenhai Cultural Investment Co., Ltd. Shanghai Electric Research Concrete Building Technology Group Co., Ltd. provides prefabricated consulting and design services, while Changzhou Concrete Building Technology Co., Ltd. supplies the prefabricated components. The project site is located in Minhang District, Shanghai, bordered by Qishen Road to the east, the land red line to the west, Xiuwen Road to the south, and Guihua Road to the north. The total building area covers 62,706 square meters, featuring a frame shear wall structural system.

The project includes four types of prefabricated components: integrated decorative prefabricated exterior walls, prefabricated composite beams, prefabricated composite panels, and prefabricated air conditioning panels. The goal is to achieve 100% prefabricated building coverage with a minimum single prefabrication rate of 30%.

2. Key Features of EPC Implementation

(1) Planning Phase

During the planning phase, the floor layout must consider component division, simplification, and modularization. The selection of prefabricated component types should balance production efficiency and construction costs effectively.

(2) Expansion and Construction Drawing Stage

This stage involves two main areas: architecture and mechanical & electrical engineering. The architectural aspect is divided into facade and structural elements.

For the facade, prefabricated exterior wall panels should have a maximum dimension of 3.3 meters in one direction to facilitate handling and installation.

The structural components are categorized as cast-in-place columns, composite beams, and composite panels:

• Cast-in-place columns: When positioning and reducing column cross-sections, consider the impact on composite beam specifications. The recommended clear spacing between longitudinal bars in columns connected to prefabricated beams is at least 100 mm. Also, provide positioning details for column longitudinal bars connected to prefabricated beams.
• Composite beams: Beam layout should consider floor slab specifications. Avoid diagonal steel bars protruding from prefabricated surfaces. It’s advisable to extend waist reinforcement beyond the prefabricated surface. Partial truncation of bottom reinforcement at supports is recommended where stress permits. Steel bars entering supports should be limited to one or two rows, preferably just one. A minimum spacing of 50 mm between steel bars is recommended; if mechanical splices or anchoring plates are used, spacing must meet relevant standards.
• Composite panels: The bottom bar spacing in composite floor slabs should be multiples of 50 mm.

Regarding mechanical and electrical installations, three main guidelines apply:

• No reserved holes or embedded parts should be located at prefabricated component joints. For example, junction boxes on floor slabs or wall panels should avoid joints, as should pipelines passing through these elements and embedded parts for pipe supports or hangers.
• Avoid installing complex electrical facilities, such as equipotential boxes or strong and weak current boxes, directly on prefabricated components.
• For pipelines passing through beams, ensure the casing top is at least 50 mm below the floor slab bottom.

(3) Deepening Design Phase

This phase involves two key processes: confirming reserved pre-embedded points and preparing detailed drawings.

• Reserved and embedded points confirmation includes:

• Door and window frame nodes and materials
• Mechanical and electrical embedding principles and materials
• Railing nodes and materials
• Construction materials for reserved and embedded elements (e.g., tower crane wall supports, elevator wall supports, construction layout holes, formwork reinforcement)
• Lightning protection grounding nodes and materials

3. Project Highlights and Challenges

(1) Artistic Concrete Veneer Integrated Prefabricated Exterior Walls

Located at the intersection of Qishen Road and Xiuwen Road, this landmark project in Xinzhuang Town demands a high-quality facade. The integrated prefabricated exterior walls feature artistic concrete veneer with clear textures and smooth lines, offering significant advantages over traditional coatings in aesthetic appeal.

The exterior wall panels incorporate integrated decorative elements made using silicone molds with coarse and fine patterns. This molding technique creates smooth line textures, delivering a dynamic and elegant facade effect. Renderings for buildings 1# and 2# are illustrated in Figure 2.

Decorative Prefabricated Exterior Wall Installation

The prefabricated exterior wall panels measure approximately 1.5 to 3.0 meters wide, 4.5 to 6.0 meters tall, and 120 mm thick. Due to transportation height limits and the need to protect finished surfaces, panels are stacked and transported in a side-standing position. This requires an additional flipping process during installation compared to standard panels.

Given the integrated finish, protecting the exterior surface during flipping posed significant challenges. Three flipping methods were explored:

1. Sand Pit Flipping: Excavating a 4.0m x 7.0m pit, 1.0m deep, filled with 800 mm of fine sand at the yard edge for panel flipping.
2. Tire Flipping: Creating a tire flipping area at the yard edge with coarse fiber fabric laid over tires to maintain cleanliness and increase friction. On-site construction is shown in Figure 3.
3. Flipping Machine: Using a specialized flipping device where panels are placed on a flipping platform before lifting.

After comprehensive comparison and field tests, the sand pit method was ruled out due to site constraints, and the flipping machine was deemed too costly and risky. Therefore, the tire flipping method was selected as the optimal solution.

(3) Waterproofing of Decorative Prefabricated Exterior Walls

Using BIM models in design, the project adopts a combination of structural and material waterproofing techniques. Strict on-site controls ensure 100% water testing for wall panel joints and achieve complete waterproofing compliance.

(4) Application of BIM Technology

BIM technology is employed throughout the consulting and detailed design phases of prefabricated components. This 3D modeling approach enhances clarity and visualization, simplifies collision detection between nodes, and improves the accuracy of component information.

4. Conclusion

The understanding of prefabricated building concepts during architectural design critically affects resource efficiency in subsequent design, production, and construction stages. Shanghai Electric Research Concrete Construction Technology Group Co., Ltd. engaged at the early scheme stage and applied lean design principles throughout project execution. This approach minimized changes during prefabricated assembly production and construction, significantly reducing resource waste.

By integrating production and assembly processes with a design-centered approach, the project effectively controls costs while optimizing efficiency.

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