Reinforcement of Prefabricated Panels on Roof

There are several common methods for reinforcing prefabricated panels on roofs, which can be selected based on actual load requirements and construction conditions:

1. Carbon Fiber Adhesive Reinforcement Method When the load increase on the prefabricated panels is relatively small (such as adding only lightweight equipment or local loads), reinforcement can be achieved by adhering carbon fiber sheets to the bottom of the hollow panels. Carbon fiber materials are characterized by high strength, light weight, and corrosion resistance. By adhering them to the panel bottom with specialized structural adhesives, the flexural bearing capacity of the panels can be effectively enhanced. During construction, it is essential to ensure that the panel bottom surface is flat and clean. After adhesion, curing should be carried out according to specifications to avoid early load-induced damage. This method offers a short construction period and minimal damage to the original structure, but it has relatively high costs and is suitable for scenarios with small load increments.

2. Steel Beam Addition Reinforcement Method If the load increase is significant or there is a need to change the structural load-bearing mode, steel beams can be added beneath the panels. The steel beams are fixed to the supports at both ends of the prefabricated panels using chemical anchors or expansion bolts, forming a 'beam-panel' composite system. The newly added steel beams can share part of the load, altering the simple flexural state of the original hollow panels and significantly improving the overall structural stiffness. During construction, attention should be paid to the reliability of the connection between the steel beams and the prefabricated panels to avoid local stress concentration leading to damage. This method is suitable for scenarios with large spans or significant load changes, but it requires occupying a certain amount of indoor clear height and involves professional welding or bolt installation.

3. Casting Reinforced Concrete Composite Layer Method This is the most fundamental and effective reinforcement method, suitable for most prefabricated panel structures requiring enhanced load-bearing capacity. The specific steps are as follows:

• Surface Preparation: Thoroughly clean the top surface of the prefabricated panels to remove dust and oil, exposing the coarse aggregate surface. If necessary, perform roughening treatment to enhance the bond between the new and old concrete.
• Reinforcement Mesh Installation: Arrange a reinforcement mesh with a diameter of 6mm at intervals of 20cm×20cm. The reinforcement intersections should be firmly tied, and connected to the original reinforcement in the prefabricated panels through short reinforcement welding or rebar planting.
• Concrete Pouring: Use fine aggregate concrete with a grade not lower than C25 (with a maximum aggregate size of ≤15mm) for layered pouring. The thickness should be controlled between 5-8cm, and the concrete should be vibrated densely and then surface-finished.
• Curing: After pouring, cover and maintain moisture for at least 14 days to avoid early shrinkage cracks. This method significantly enhances the flexural and shear capacities of the prefabricated panels by increasing the structural section height and reinforcement ratio. The construction process is mature, and the cost is moderate, but attention should be paid to controlling the thickness of the composite layer to avoid adding excessive self-weight.

Selection Recommendations:

• For small load increases, prioritize carbon fiber adhesion.
• For large spans or sudden load changes, choose steel beam addition reinforcement.
• When comprehensive load-bearing capacity enhancement is required and conditions permit, prioritize the composite layer method. Before construction, a professional institution should be commissioned to conduct structural testing, determine the reinforcement plan based on calculation results, and have it implemented by a qualified unit.