Basement Roof Side Beam Openings

Background The basement structure of the project has been completed in the early stage, and the electromechanical installation unit proposed to increase the demand for basement drainage pipes. According to the requirements of the design change order, it is necessary to open holes on the side beams of the basement roof and add 7 new casings. The central elevation of the newly added drainage pipe is 1.80m, the maximum diameter of the casing is 250mm, and the size of the side beam of the basement roof is 500mmX1400mm. The construction technology of the side beam opening in the basement of this project not only requires the reinforcement of the concrete structure, but also ensures the anti-seepage of the side beam.

The traditional method of opening holes in frame beams is to open holes in the back of the beams, and the concrete beams need to be chiseled and then poured again. This method is complicated in process, long in construction period and highly destructive to the structure. To this end, the project technicians have carefully studied and applied the bonding steel reinforcement technology in the construction of the side beam opening, and the effect is good.

The inner and outer sides of the beam are reinforced with bonded steel, and the casing is welded with the bonded steel. This scheme not only ensures the firmness of the outer wall reinforcement, but also enhances the impermeability, and the construction is simple and the construction period is short.

Set up a basement roof backfill excavation, a positioning and lay-out, determine the opening and drilling area, a water drill to open a hole, an artificial air pick to chisel a casing and a waterstop to install and fix. A mold, grouting, bonding with steel, reinforcement, maintenance, and removal of the top frame.

Advantages of bonding steel reinforcement technology in side beam openings

The project innovatively applies the bonding steel reinforcement technology in the side beam openings to meet the technical requirements of structural reinforcement and waterproofing, avoid the impact of the joint between the casing and the structural wall panel on the waterproofing, and ensure the waterproofing quality. The specific advantages are as follows.

1) Reduce the workload of chiseling and reduce the damage to the original structure

In the original reinforcement scheme, columns and beams were required to be added on both sides of the inner and outer sides of the opening, and the chiseling of the original structure required a large amount of work, which would cause greater structural damage. However, after the bonding steel reinforcement technology is adopted, the opening of the chisel is relatively small, and the steel bars within the opening range outside the casing are retained, and the retained steel bars are all treated with U-shaped steel reinforcement welding. This scheme has minimal damage to the original structure.

2) Easy to operate in narrow space, saving cost and shortening construction period

The original reinforcement plan required tying steel bars, supporting formwork, pouring concrete, and curing. The inner space of the side beams of the basement roof was narrow, the working surface was small, and the construction was difficult. After the application of the bonding steel reinforcement technology, the shaped steel plate can be processed in advance, and bolts can be used to anchor to the designated position after the completion of the previous process, and the grouting material and epoxy resin harden quickly, and the curing cycle is short. Compared with the original reinforcement scheme, the construction process is reduced and the construction period is greatly shortened.

3) Waterproof effect is better

The use of bonded steel reinforcement technology, the casing and the water-stop steel plate are fully welded, and the casing and the original structure are poured with 95% C45 grouting material and 5% epoxy resin, which has the advantages of good integrity and firm connection between the old and new structures151. Bonded steel reinforcement technology has strong applicability and technical safety.

This project solves the problems of opening reinforcement of the existing structure and water-stopping of the rear opening by innovatively combining the reinforcement of the bonded steel with the installation of the casing. It not only ensures the structural safety of the rear extension hole, but also effectively solves the problem that the rear extension casing is easy to leak.