Flat Roof Cement Prefabricated Lifting

For the lifting of cement prefabricated components on flat roofs, reference can be made to the construction plan for gantry cranes for cement house trellises, which organically integrates prefabricated concrete houses, lightweight decorative or supporting structures, and gantry cranes. The specific process is as follows:

Foundation Preparation

The floor or roof of the cement house must undergo rigorous structural calculations to ensure it can bear the loads of the gantry crane and the trellis (or cement prefabricated components). Usually, embedded parts or track slots are reserved in the prefabricated concrete components to provide connection points for fixing the gantry crane tracks or components later. For old house renovation projects, the original cement house structure needs to be reinforced to meet the requirements of the additional loads. The accuracy of structural calculations directly affects construction safety and must be completed and reported by a professional engineer.

Selection and Installation of Gantry Cranes

Select a gantry crane with an appropriate tonnage based on the weight, size, and lifting height of the trellis or cement prefabricated components. Prioritize lightweight designs to reduce pressure on the cement house structure. There are two methods for laying the walking tracks of the gantry crane:

1. Dedicated Beam Laying: Add dedicated steel or concrete beams on top of the cement house as track support structures;
2. Main Beam Integration: Directly integrate the tracks with the main beams of the trellis or cement prefabricated components to simplify the structure and save space.
   Track installation must ensure a levelness error of no more than ±2mm/m; otherwise, it will cause the gantry crane to run sluggishly or the components to shift during lifting.

Lifting of Trellises or Cement Prefabricated Components

1. Prefabrication Stage: Prefabricate the trellis or cement components in sections at the factory, strictly controlling dimensional tolerances to the millimeter level to ensure assembly accuracy later.
2. On-site Assembly: After transporting the prefabricated components to the site, complete the overall assembly on the ground to reduce the risk of high-altitude operations.
3. Lifting and Positioning: Use the gantry crane to lift the assembled components to the predetermined position and fix them to the embedded parts through bolting or welding. During the lifting process, the levelness of the components must be monitored in real-time to avoid uneven structural loading due to tilting.

Construction Precision and Key Points for Old House Renovation

This plan requires extremely high design and construction precision, especially the dimensional tolerances of the cement house prefabricated components must be strictly controlled; otherwise, the gantry crane tracks will not align smoothly. In old house renovations, if the original structure is intact, a lightweight gantry crane can be added after reinforcement to achieve rapid installation of roof components. However, the structural load-bearing capacity must be evaluated in advance, and a special reinforcement plan must be formulated.