Prefabricated Panel House Reinforcement Case

There are mainly two types of reinforcement cases for prefabricated panel houses: reinforcement of old rural prefabricated panel houses and reinforcement of a project on the Bund in Shanghai.

Reinforcement of Old Rural Prefabricated Panel Houses

• Using I-beams as crossbeams: Use I-beams as the main frame of the house, and determine the density of placement according to the size of the selected profile. For example, if 20 steel is selected, place three pieces to form a cross with the panels. Erect I-beam columns at both ends for support, and fix the columns to the walls. In rural areas, many prefabricated panels are 4 meters long, and the distance between the two walls of a room is 3.75 meters. Adding steel as crossbeams in the middle can greatly enhance the hardness of the prefabricated panels. This method is relatively simple in construction, low in cost, and can effectively improve the stability of the house structure.
• Adding a layer of concrete on the prefabricated panels: First, remove a prefabricated panel in the middle to serve as a crossbeam. Add a vertical beam on the crossbeam to form a cross-beam, and then add another floor slab to increase the thickness of the floor slab. The cross-beam form makes the beams and the floor slab an integral whole, enhancing the structural strength. However, the walls still need to be reinforced with this method because many old houses have brick walls without columns, and the walls are aged over time. Columns are required to reduce the pressure of the floor slab on the walls. This method is more robust than steel reinforcement but has a higher cost, and the columns and beams are more visible, which may affect the appearance of the house.

Reinforcement of a Project on the Bund in Shanghai

• Project overview: The project is located on the Bund in Shanghai and was completed in 1982. It was originally a non-seismic-resistant reinforced concrete frame-shear wall structure. The floor system adopted an assembled monolithic floor system combining pre-turned basket beams, prestressed hollow slabs, and monolithic casting layers. It was originally used for office purposes and is now being renovated into a high-end hotel.
• Main reinforcement ideas: Reduce the self-weight and adopt dry construction methods and simple construction reinforcement methods. For example, use light steel keel partitions or lightweight aerated blocks for interior partitions; use steel supports to improve the structural stiffness to meet the current seismic code requirements; retain the prefabricated floor slabs as much as possible to reduce the workload of structural demolition and renovation and improve economic efficiency.
• Reinforcement of prefabricated panels:
  • Hole opening and reinforcement at the mid-span of the panel: The original reinforcement of the prefabricated panel is one cold-drawn longitudinal bar with a diameter of 14 mm per rib. The most unfavorable situation for hole opening is to break one longitudinal bar. Carbon fiber reinforcement is carried out according to the principle of equal bending capacity.
  • Hole opening and reinforcement at the panel support: Hole opening at the panel support weakens the shear capacity of the panel. The reinforcement method is to infuse high-strength grouting material into the holes of the original hollow slab within the perimeter range of the hole opening to compensate for the weakening of the panel's cross-section caused by the hole opening.
  • Reinforcement of the prefabricated panel due to increased load: Due to the increase in load, the bending moment at the mid-span of the panel increases. Carbon fiber reinforcement is carried out according to the principle of compensating for the bending capacity.