Beam Addition Renovation for Prefabricated Slab Houses

Prefabricated slab houses can undergo beam addition renovation to achieve structural reinforcement through methods such as 'wall-to-beam conversion', but a scientific plan must be formulated based on the house's safety rating. The specific implementation should follow the following principles and steps:

I. Determining the House's Safety Rating is a Prerequisite for Renovation According to the 'Standards for the Appraisal of Dangerous Houses', prefabricated slab houses must be appraised by a Class A inspection agency to determine their safety rating:

1. Class C Houses (partial load-bearing structures with insufficient bearing capacity): If the cost of reinforcement does not exceed 50% of the reconstruction cost, reinforcement renovation should be prioritized. For example, a prefabricated slab building from the 1980s in Jiaxing, Zhejiang, faced the risk of fracture and saved on reconstruction costs through reinforcement renovation.
2. Class D Houses (overall structural damage, accounting for less than 4%): They must be immediately evacuated and demolished for reconstruction, with any reinforcement attempts prohibited.

II. The Core Goal of Reinforcement Renovation is to Enhance Integrity Prefabricated slab houses are prone to issues such as floor slab fractures and wall cracks due to weak structural connections. Renovation should enhance structural synergy through the following methods:

1. Carbon Fiber Sheet Reinforcement: For cases where the flexural bearing capacity of floor slabs or beams is insufficient, high-strength carbon fiber sheets are adhered to the surface of the components to improve their performance using their tensile strength. This method is convenient for construction and causes minimal damage to the original structure.
2. Steel Plate Bonding Reinforcement: Steel plates are bonded at key locations such as slab-wall junctions and beam-column joints to form a composite load-bearing system with structural adhesive, addressing issues of insufficient joint connection strength.
3. Rebar Planting Reinforcement: By drilling holes, cleaning them, injecting rebar planting adhesive, and implanting rebars, ring beams or structural columns are added to form a spatial frame structure, significantly improving the house's seismic performance.

III. Renovation Must Strictly Adhere to Technical Specifications

1. Professional Appraisal First: A structural safety appraisal must be completed by a Class A qualified inspection agency to clarify the location, extent, and cause of damage, providing a basis for plan formulation.
2. Targeted Plan Design: Reinforcement methods should be selected based on the appraisal results. For example, if floor slab fractures are caused by insufficient bearing capacity, carbon fiber sheet reinforcement can be prioritized; if joint connection fails, steel plate bonding reinforcement is required.
3. Construction Process Control: Reinforcement materials must comply with national standards, and construction techniques must strictly adhere to specifications. For example, the depth of rebar planting must meet design requirements, and carbon fiber sheet adhesion must ensure no voids.

IV. Typical Cases Verify Feasibility A renovation project of a prefabricated slab building in Jiaxing, Zhejiang, showed that after reinforcing the floor slab with carbon fiber sheets and adding structural columns through rebar planting, the house's bearing capacity increased by more than 30%, and the cost was only 40% of reconstruction, verifying the effectiveness of scientific reinforcement.