Lifting Deflected Slab

Location: The 5th Settlement, Cairo, Egypt

2024

Year of completion

Support then lift the deflected slab 20cm in order to return it to its original height.

Lifted Slab Area:

150 Sq.M

Lifted Slab Weight:

300 Tons

Project Owner

Contracting Company, Egypt

Added Value to the Customer:

· Provide the best economic solution which saves time and money.

· Full detailed load calculations and specific lifting points.

· Flexible adaptation to high loads and considering the sensitive situation to avoid cracks for the existed slabs during the lifting process.

· Providing safe working areas and smooth access to all areas of operations by following all safety requirements during the stages of the work.

· Preparing a detailed work methodology that represents the work steps according to the bridge drawings and loads.

Engineering Concept:

In the shopping center project, a deflection of 20 cm occurred for the slabs on two floors due to premature removal of formwork and non-casting of the boring strip. 300-tons is the overall weight of each deflected slab.

Fast Track Solution:

Solution was applied in three phases:

Phase 1: Back Propping System

· By using the Shorbrace system under each deflected slab, and in addition to one more floor underneath. We placed the system spacing and grid sizes according to detailed loads calculations and approved drawings by consultant.

Phase 2: Steel Structure Support System

· In between the back propping system, we installed a steel structure system consisting of hot-rolled sections and assembled as a frame system.

· It helped as additional support for the slab as well as a lifting points to support the heavy lifting jacks and provide forces equilibrium.

Phase 3: Lifting Process

· According to our calculations and design, we needed 24 lifting points using 20 tons capacity jacks.

· To begin the process of lifting the 1^st slab, we placed each jack at its own lifting point on the steel structure support system, then carefully began the lifting and blocking process.

· We repeated the same process continuously until we reached the desired height, which returned the deflected slab to its correct position. It was necessary to monitor the edge of the slab to ensure that nothing more than hairline cracks occurred.

· When we finished lifting the 1^st slab, we waited for the main contractor to pour the boring stripe in addition to the consultant's recommended days for the concrete to reach the appropriate strength.

· After that, we lift the slab to a very slight height, so that we can remove the supports and blocks that were placed there. Also, the steel structure and the back propping of the 1^st slab were removed as well.

· Again, for the 2^nd slab, we repeated the exact same mentioned process.