Adding Columns and Beams to Prefabricated Slab Houses

The reinforcement of prefabricated slab houses by adding columns and beams can be carried out through the following three main methods:

1. Using I-beams as cross beams This method uses I-beams as the main frame of the house for reinforcement, and the layout density needs to be determined according to the selected profile specifications. For example, when using No. 20 I-beams, three steel members can be placed parallel below the prefabricated slabs (crossing the slabs in a '+' shape), and I-beam columns can be set vertically at both ends as supports. The columns need to be fixed to the walls through chemical bolts or welding to form a stable frame structure. This plan can significantly improve the flexural rigidity of the prefabricated slabs and is especially suitable for the renovation of rooms with large spans. It should be noted that the connection strength between the steel members and the walls needs to meet the design load requirements to avoid local stress concentration leading to wall cracking.

2. Adding a concrete layer on the prefabricated slabs and setting up '+' cross beams By pouring a concrete layer on the surface of the original prefabricated slabs to increase the floor thickness and simultaneously transforming the structural system. The specific operations include: partially removing a prefabricated slab to form a cross-beam space, adding vertical longitudinal beams on the cross beams to form a '+' cross-beam system, and finally pouring a new floor to make the beams and slabs form a whole. This plan can effectively disperse the loads, but the walls need to be reinforced simultaneously: old brick walls are prone to deformation due to the lack of column support and long-term pressure from the floor, so reinforced concrete construction columns need to be added at key positions to transfer the floor loads to the foundation through the columns and reduce the burden on the walls. This method is suitable for house renovations where the floor height allows, and strict control of the concrete pouring quality and curing period is required.

3. Adding ring beams and construction columns For two-story brick-concrete prefabricated slab houses in rural areas, the combined reinforcement of ring beams and construction columns is a key measure:

• Ring beam system: Setting middle and upper ring beams in the middle and upper parts of the house can enhance the overall rigidity of the building and effectively resist horizontal loads such as earthquakes; the bottom ground beam serves as a fixed foundation for the walls and can prevent structural damage caused by uneven settlement.
• Construction column system: Construction columns are set at stress concentration positions such as wall intersections and staircases, and are connected to the walls through steel bars to form a whole. The construction columns need to be provided with tie bars connected to the walls every 500mm along the height of the house to ensure a continuous load transfer path. This plan needs to be combined with wall reinforcement measures, such as using steel wire mesh mortar surfaces to enhance the shear resistance of brick walls, forming a 'beam-column-wall' collaborative structural system.

Implementation points: All reinforcement plans need to be calculated and reviewed by structural engineers to ensure reliable connections between the newly added components and the original structure; the wall plaster layers should be removed to the surface of the brick masonry before construction to ensure the bonding quality between the reinforcement materials and the base layer; after renovation, load tests should be carried out to verify the structural safety.