Seismic strengthening of existing building

Project Overview:

The building covers an area of 635 square meters, with a total of 6 layers on the ground (originally designed for 5 layers). There is no underground layer. The total area of the original design is 3310 square meters. A layer of reinforced concrete sandwich (floor elevation is 3.200) is added around 2000. The total building area is 3990.05 square meters. The building is a reinforced concrete frame structure with a total height of 22.27 meters and an elevator room with a height of 3.5 meters.

Problems 

Leakage of tendons in the cantilever beam and slab

Partial floor slabs through cracks

Solution

Regardless of the effect of earthquakes, beam and column reinforcements meet the requirements. Owners should plan to organize routine maintenance and repairs, including: rust removal at floors and beams should be preceded by rust removal, then surface treatment (such as repair with polymer mortar). For severe corrosion of reinforcing steel parts, FRP wrap should be used for reinforced. Part of the floor through the cracks for structural cracks, it is recommended to use grouting reinforcement treatment.

When considering the role of seismic forces, the following reinforcement measures need to be added:

(1) Considering that the building is a Class C building, the construction time is long, and the original structure is not earthquake-resistant. According to the test results, it is necessary to comprehensively strengthen the earthquake resistance, improve its anti-seismic capacity, and ensure its seismic safety;

(2) Some column reinforcements do not meet the current regulatory requirements. It is recommended to use the extended section method or stick steel method for column reinforcement. For walls with insufficient wall seismic capacity, reinforcement measures such as reinforced concrete plywood or double-faced wire mesh mortar are recommended.

(3) For the lack of anti-seismic measures, such as eccentricity, rigid-to-heavy ratio, stiffness ratio, displacement angle between layers, displacement ratio, etc., which do not meet the current specification requirements, targeted reinforcement shall be carried out, and it is recommended to add intercolumn bracing, seismic wall or damping. Or measures such as increasing the cross-section of the column to enhance the seismic load-bearing capacity of the building;

(4) Part of the column axial pressure ratio is greater than 0.85, does not meet the current regulatory requirements, it is recommended to use the extended column section method for column reinforcement;

(5) For the beam end and the top of the column without the stirrups encryption area, it is recommended to use sticking steel or paste carbon fiber cloth for beam and column reinforcement;