Shanghai Exhibition Center Reinforcement

Structural overview and retrofit design

The main part of the central hall of the Shanghai Exhibition Center is made of reinforced concrete arch structure composed of 13 large arches with a span of 30m and a height of 19.5m. The thickness of the concrete roof slab is 80mm, and a large arch is used as a fulcrum to form a one-way thin arched steel shell concrete slab with a span of 6m. Due to the quality of the early construction and the sun and rain in the past 50 years, a large number of honeycomb and hemp surfaces appeared on the concrete surface of the arched roof panel. There is a crack running through the arch section on the top surface of the roof panel. Several cracks with different lengths, the width of the crack is 0.1-0.2mm.

Due to the lower design and construction standards in the early days, the bearing capacity of arched roof slabs is lower than the current standards. The arched roof slab is simplified into a one-way continuous multi-span slab, which is calculated by the PKPM program. The main rib reinforcement of the roof slab is lower than the current seismic design standard by about 30%.

Considering the stress characteristics of the roof slab, the positive and negative bending moments of the roof slab are all reinforced with carbon fiber cloth.

In the reinforcement design, the carbon fiber cloth is converted into the amount of steel bars according to the strength, and calculated according to the same method as the calculation of the bending resistance of the reinforced concrete members. The limit state method is used to calculate the limit state of the bearing capacity and the normal use limit state. Carbon fiber cloth is pasted along the direction of the main reinforcement with insufficient strength of the steel-reinforced concrete structure. The specific measures are as follows: On the bottom of the arched roof slab, along the vertical arch beam direction, paste a layer of carbon fiber cloth with a width of 200mm and a spacing of 500mm on the bottom of each span, and the length is the net distance between the arch beams. Along the arch beam curve direction, a layer of 200mm wide carbon fiber cloth is pasted on the midline of the arch bottom of each span

On the top of the arched roof slab perpendicular to the direction of the arch beam, with the arch beam as the center line, paste a layer of carbon fiber cloth of 250mm × 3500mm with a spacing of 1000mm to each arch beam. At the same time, a layer of long carbon fiber cloth with a width of 250mm and a distance of 1000mm is pasted, and the short carbon fiber cloth with the vault is not staggered. Paste a layer of carbon fiber cloth at the center line of the arch plate along the arch beam curve. It adopts Horse UD200 carbon fiber cloth, the thickness of the fabric is 0.111mm, the width is 300mm, and the surface density is 200g. Main technical indicators: the tensile strength is 3800 MPa, the tensile modulus is 230 GPa, and the elongation is 1.6%.

Advantage of carbon fiber strengthening for Shanghai Exhibition Center

From the point of view of mechanical performance, Horse carbon fiber cloth has high tensile strength and fatigue performance, which is suitable for the reinforcement of most concrete beams, slabs, and walls of the Shanghai Exhibition Center.

From the point of view of material characteristics, Horse carbon fiber is used as a flexible coiled material, which can be used to bypass various pipeline facilities and penetrate walls and holes according to needs at the construction site. Construction can be carried out in elevator shafts and staircases in narrow spaces. It can also be superimposed into any shape to reinforce the structure of complex shapes.

From the perspective of practical application, Horse carbon fiber reinforced concrete technology avoids the disadvantages of other reinforcement methods such as increasing the size of the structure, reducing the building space, increasing the weight, long construction period, and poor corrosion resistance. To the greatest extent, the original building layout of the exhibition center is guaranteed, and the vision of this overhaul and renovation is reflected.

In terms of engineering control, Horse's carbon fiber reinforced concrete technology is to achieve the purpose of reinforcement by sticking carbon fiber cloth on the outside of the concrete structure and through the joint force of the two.

In terms of technical economy, compared with the traditional reinforcement technology, Horse carbon fiber reinforced concrete technology has good economic performance. On the surface, the material price of carbon fiber cloth is relatively higher, but when it is actually used in the reinforcement project, its comprehensive cost is lower.

Summary

The Shanghai Exhibition Center's reinforcement and overhaul project is the largest restoration project in Shanghai's historical protective buildings. The arched roof slab of the central hall of the exhibition center adopts carbon fiber reinforcement technology, which effectively improves the bearing capacity and structural durability of the original arched roof slab.