Housing Prefabricated Beam Standard

The relevant standards for housing prefabricated beams are primarily reflected in the 'Technical Standard for Prestressed Prefabricated Concrete Frame Structures.' This standard, which came into effect on April 1, 2025, covers the entire process of design, fabrication, construction, and acceptance.

Scope of Application and Structural Forms

This standard applies to prestressed prefabricated concrete frame structures in areas with seismic fortification intensities of 9 degrees or less, including structural forms where frame beams and columns are prefabricated components connected through post-tensioned prestressing. Such structures combine factory-prefabricated components with on-site assembly, significantly shortening construction periods and reducing construction pollution, aligning with modern trends in building industrialization.

Classification and Seismic Requirements

Based on seismic performance, prefabricated beam technology is classified into three categories:

• Class I and II Prestressed Frames: Suitable for areas with seismic intensities of 8 degrees or less, covering frame structures, frame-shear wall structures, and frame-core tube structures. These frames balance structural stiffness and ductility by optimizing the configuration of prestressed reinforcement, meeting seismic demands in low- to moderate-intensity regions.
• Class III Prestressed Frames: Applicable to frame structures in areas with seismic intensities of 9 degrees or less, employing higher-strength prestressed reinforcement and stricter node connection designs to ensure structural stability under high-intensity earthquakes.

Design Conditions and Load-Bearing Capacity

The standard requires that the design of prefabricated beams consider four working conditions:

• Persistent Conditions (e.g., long-term load effects): Use basic combinations of actions to ensure the load-bearing capacity of the structure during normal use.
• Transient Conditions (e.g., loads during construction): Also use basic combinations, focusing on verifying the stability of temporary support systems.
• Accidental Conditions (e.g., fire, explosion): Use accidental combinations, reducing the impact of extreme events on the structure through redundant design.
• Seismic Conditions: Use seismic combinations, combined with structural dynamics analysis, to ensure that beam-column joints do not undergo brittle failure under seismic action.

Technical System Background and Development

Prefabricated beam technology falls under the category of prefabricated assembly construction, with advantages including:

• Industrialized Production: Components are standardized and fabricated in factories, ensuring high quality controllability.
• Construction Efficiency: On-site assembly reduces wet work, shortening construction periods by 30%–50%.
• Environmental Protection: Reduces construction waste and dust pollution, meeting green building requirements. China's prefabricated concrete technology originated in the 1950s, initially applied in factory and residential construction. It experienced a resurgence in the 21st century due to environmental demands, with companies like Vanke widely applying it in practical projects, driving technological iteration and standard refinement.

For further information on construction techniques, advantages and disadvantages, or specific application scenarios, refer to the comparative analysis between cast-in-place and prefabricated beams.