Seismic strengthening of existing buildings

Project overview

The existing building is built in 2006, the main body is divided into two parts, the south section is on the ground, the archaize modeling, the ridge height 5.6m, the cast-in-place frame structure, the roof structure of the roof to achieve the archaize modeling, and the part is considered in the temporary building in the planning red line.

The northern section is one and a half floors underground, with two storey buildings on the ground. The eaves are 4.6m high and the ridge height is 8.3m. The cast-in-place shear wall structure is adopted, and the seismic grade is two. The roof adopts hard mountain purlin, and the sloping roof is 120 thick reinforced concrete slab.

Due to the transfer of property right and the change of use function, the owner intends to make a large renovation of the whole building structure and adopt a new house decoration scheme. In this reinforcement, the building is transformed from office room to a high end club. The use of the building is changed, the structure layout and load are greatly changed, and the general reinforcement is strengthened. Compared with the retrofit design, the transformation project has the following characteristics:

1. seismic performance of the original structure is "incongenitally deficient": the seismic performance of the original structure has not been able to meet the specification requirements, and the whole seismic strengthening is needed.

2. The new decoration scheme is inconsistent with the original structure, so the number of shear walls removed is large, resulting in a large number of original vertical load-bearing components missing.

3. When the shear wall is dismantled, the span of the beam used for underpinning is larger, the maximum span is 10m, and the owner has strict requirements on the room clearance. The common underpinning beam can not meet the requirements. Therefore, the external prestressing reinforcement technology is used to reduce the beam height.
   

The main features of the project are the demolition of reinforced concrete walls, new concrete beams, columns, shear walls, the reinforcement of the original frame beams, and the reinforcement of the original structure. The connection between the prestressed underpinning beam and the underpinning beam end and the original structure is the key content of the reinforcement design.

Seismic reinforcement ideas

1. Overall reinforcement: due to the wide scope of the transformation of the project, it is necessary to improve the overall seismic performance of the structure, take effective measures to reinforce the structure, optimize the force transmission, meet the requirements of the structural rules and meet the requirements of stiffness and ductility.

2. Strengthening of important nodes: the reinforcement of nodes is very important in the overall seismic reinforcement. It is an important connection between components and components, and should pay special attention to the reinforcement effect of the joints.
   

Seismic reinforcement method

1. the original shear wall structure has been demolished in a wide range because of the new decoration scheme used by the owner, and the original structure is replaced by the external prestressed reinforcement section beam. The vertical force and the force principle of the reinforced structure are basically the same as the original structure.

2. according to the identification conclusion, the thickness of the floor slab is small and the concrete carbonization problem exists. It is suggested that the floor plate be bonded with carbon fiber fabric at the bottom of the slab and the slab surface is strengthened with the superimposed layer to improve the durability and bearing capacity of the floor.

   
   

3. Due to the dismantling of shear walls, the seismic bearing capacity of some frame beams is not satisfied with the requirements of current norms. It is suggested that the reinforcement method of the steel plate is adopted to strengthen the frame beam.

4. The original shear wall structure has been demolished in a large scope. In order to improve the stiffness and bearing capacity of the structure, a method of adding shear walls locally is adopted. For new shear walls and frame beams and columns, rebar planting and other measures can be reliably connected with the original structure to enhance the overall seismic capacity.