The Fully Prefabricated Reinforced Concrete Assembled Integral Shear Wall Structure (NPC) system—referred to hereafter as the NPC system—is an innovative construction method designed to enhance structural efficiency and quality.
Principle of the NPC System
The NPC system, or Industrial Prefabricated Reinforced Concrete Assembly Integrated Structure Technology, involves prefabricating vertical shear walls and columns, while beams and slabs are stacked horizontally on-site. Vertical connection nodes are linked using slurry anchors, and horizontal-to-vertical connections are secured with reserved steel bars that are stacked and cast in place. This process forms a cohesive overall structural system.
Key Features of the NPC System
1. Components are factory-manufactured, ensuring consistent product quality and integrated finishing. The visible surfaces meet the standards of plain concrete.
2. Exterior wall panels include prefabricated decorative surface layers and insulation, reducing on-site finishing work and enhancing project quality.
3. Window frames are embedded during prefabrication, preventing common issues such as water leakage from outer windows.
4. The use of reusable materials for site templates and support systems is reduced to 20% compared to traditional cast-in-place methods.
5. Construction time is shortened, labor requirements are decreased, and workers’ physical strain is minimized.
6. On-site work is reduced, lowering dust and noise pollution, which benefits environmental sustainability.
Overview of Pilot Projects
One notable pilot project is Building 33 in Haimen Zhongnan Century City, Nantong City. This structure features one underground floor and ten above-ground floors, reaching 32.5 meters in height with a total construction area of 4,556 square meters. It employs a shear wall structural system where foundations and basement shear walls use cast-in-place reinforced concrete, while upper shear walls, beams, slabs, and stairs utilize the prefabricated NPC system.
Conclusion
1. The NPC system incorporates cast-in-place treatment at key nodes and floor slabs, which enhances overall structural integrity and matches the performance of traditional cast-in-place structures. It successfully integrates architectural components with HVAC, plumbing, electrical, and other building systems, achieving seamless coordination and optimized performance without compromising safety.
2. Further detailed research is needed to refine construction methods for the NPC system. For example, reinforcing beams and columns requires full-section connections at stress points or nodes. The system replaces traditional 135-degree hooked stirrups with high-strength welded closed stirrups for improved strength.
3. Accelerated development is essential in production technology, application research, standards preparation, personnel training, and pilot project implementation. Emphasis should be placed on advancing application technologies and updating standard specifications, along with fostering collaborations between universities and enterprises to promote building industrialization in China.
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