The lowest bid

In order to successfully win the bid for some project leaders, the overall quotation is far below the market level. Under the circumstance that the budget is greatly reduced, it is easy to have errors in reinforcement design, disordered reinforcement construction procedures, poor reinforcement materials, and unqualified reinforcement procedures. After reinforcement, the expected effect cannot be achieved, and even the original components are damaged during the reinforcement process. After reinforcement, new safety hazards arise, so they have to be dismantled and rebuilt.

Construction unit unqualified

Under normal circumstances, structural reinforcement projects require a team with special qualifications to be responsible for the construction. However, in the actual operation process, through layers of subcontracting and subcontracting, the final task fell to the construction team without qualifications or poor professionalism. Due to the inability to meet high technical requirements, especially the handling of some special technologies, it is easy to make the reinforcement effect invalid and leave safety hazards.

Construction is not in line with reality

The on-site construction personnel only constructed according to the drawings and ignored the actual problems on the site. Although the construction was completed in accordance with the relevant specifications and process requirements, the newly discovered diseases of the original structure on the site were not dealt with, resulting in defects after reinforcement and transformation.

No overall calculation

Because the reinforcement and reconstruction design did not do the whole experience calculation, the reinforced part of the building was too strong, and the unreinforced part was weak, the building as a whole could not work in harmony, nor did it meet the requirements of seismic bearing capacity. Therefore, it is suggested that the overall calculation and design of the reinforced and reconstructed buildings should be done.

Stiffness requirements not considered

Without considering the rigidity requirements, new damage will be caused due to insufficient rigidity and large deformation after reinforcement and reconstruction. Especially for some structural transformations, such as the insufficient beam height when the joist is pulled out of the column, and the continuous beam plate has become a simply supported beam plate when the partial beam plate is removed, it is very dangerous to remove it without considering the structural reinforcement.

Indiscriminate use of reinforcement methods

There is a lack of scientific research and calculation in the selection of reinforcement methods, and sticking to steel and carbon fiber is regarded as a cure for all diseases. Even sticking multiple layers, just want to compensate the strength, but do not understand what is the super-reinforced beam-slab structure and its failure mechanism, nor do they understand that the shear force transmission of the pasted section is related to the bonding strength of the beam-slab itself, resulting in hidden dangers still exist after reinforcement.

The construction process is chaotic

For example, in the design of transforming a brick-concrete structure into an inner frame, the practice of adding foundations and beams, slabs and columns first, and then removing the inner walls and layers of boards is not adopted. Instead, the inner walls and slabs were first demolished during construction, resulting in instability of the outer walls. Although temporary supports were added, the supports would affect the construction space and deformation would be inevitable, which would lead to the existence of unsafe factors in the reconstruction construction.

Weld break adhesive

Mainly reflected in the outsourcing steel reinforcement method. When the outer steel is used for reinforcement, the outer steel is pasted with adhesive and then welded, which causes the adhesive to be burned out by welding, or the adhesive is not paid attention to, and the unqualified glue is used, and cement mortar is used instead of glue.

Without anchoring measures

For example, when bonding steel reinforcement, it is believed that the effect of bonding steel glue is not added for bolt anchoring, or the surface of the substrate and the steel are not treated, resulting in a greatly reduced bonding effect. It is even involved in the failure of the steel plate bonding, separation and chipping, resulting in new hidden dangers or sudden damage during the use of the structure.

Insufficient curing time

In order to seize the construction period, when the adhesive is not fully cured, subsequent reinforcement is carried out, resulting in the failure of the reinforcement effect. Or the season, room temperature and other factors are not considered when calculating the curing time, and the time judgment is wrong, resulting in irreversible consequences.