A Railway Station Roof Space Truss Structure Hoisting Technology
- 1 Overview of Construction Engineering
This project is located next to Fengshen Avenue, Huadu District, Guangzhou City. The project name is China Railway First Bureau Group Co., Ltd. Guangzhou Rail Transit Line 9 Qishan Depot Construction II Standard Steel space frame Frame, Double-layer Profiled Steel Plate Thermal Insulation Roof and Lighting Belt Roofing Project. Steel space frame area: 28673m2. The details are as follows: the application library is a composite library with a reinforced concrete frame bent structure, the roof is a steel space frame and the projected area is 27455m2. The construction material shed and the car shed are single-single stories, the roof is a steel space frame structure, and the projected area is 1218m2. The roof space frames are all square pyramid space frames with bolted ball joints and are supported by the bottom chord. The rod material is mainly NQ235B, and the bolt ball is 45# steel.
1.2 Overview of steel structure engineering
The steel structure part of this project is mainly used for the roof steel mesh frame of the warehouse combination warehouse and the construction material shed and the car shed. The projection of the roof space frame of the combined warehouse is about 279.675 meters at the longest point and 132 meters at the widest point, the elevation of the column top is 7.2 meters, and the lower chord elevation of the space frame. This e maximum span of the roof space frame is 25.4 meters, and the column spacing is 18N. Structural joints are set on axes 9 to 10 to divide the roof space frame into two parts. The construction material shed and car shed space frame is about 43. parameters meters wide, 30 meters wide, 6.95 meters above the space frame column, and has a projected area of 1218 square meters. There are expansion joints at the 3-axis position with a width of 700mm. The roof steel mesh frame mainly uses the combined warehouse roof steel mesh frame and the construction material shed and the car shed. The space frame is mainly in the form of a positive four-cornered bolt ball and is supported by the lower chord, and the lower chord of the space frame ported on the top of the reinforced concrete column through the bearing ball joint.
The type of space frame is bol same, the lower elevation space frame meters, the height of the space frame itheouwithout ~ 2.3m, the lower chord of the space frame is horizontal, and the upper chord is a regular curved surface to find a slope. The space frame size of the space frame is 3m×3m, the elevation of the highest point of the space frame is 9.8m, the maximum span of the space frame is 25.4m, and the column net size of the space frame support column is 18m×25.4m.
2.1 Construction site layout
To ensure the To of the steel mesh frame, the mesh frame components must be processed in the processing plant. Assemble the bolted ball space frame on site. To effectively ensure the construction order and construction progress, the driving route and the stacking of components must be reasonably arranged.
1. Site leveling: Before the space frame construction starts, the civil engineering unit shall be responsible for backfilling and leveling the site in the plant. 2. Site treatment: Before the construction of the steel structure, the backfill soil is first treated, which can ensure that the 16-ton truck crane can travel to the site.
2. Protection of floor piles: To prevent the damage to the floor piles caused by the walking of trucks, gravel or ballast is laid above the pile heads of the floor piles.
3. Site treatment between the foundation caps: backfill and level, without water accumulation. To ensure the safety of crane hoisting, the foundation caps must be compacted and compacted.
4. The space frame is installed by the method of block hoisting + cantilever method, and the floor of the site needs to meet the requirements of heavy trucks and small cars.
3 block hoisting process
Usually, it is difficult to use the overall hoisting method for construction due to the relatively large size, complex structure, and heavy quality of the space frame structure and is greatly restricted by the on-site construction site. At this time, the complete space frame structure is often divided into several parts. The sub-section is the hoisting unit of the space frame Then assemble the hoisting unit on the flat ground according to the construction plan, and then press Shi-r Jl are. Lift in sequence. Then hoist the hoisting unit to the design position, and then connect the scattered hoisting units into a whoholerough the supplementary rod or the connecting rod. This construction method is called the block hoisting method.
4. Construction technology of space frame cantilever method
4.1 Introduction of cantilever hoisting
The high-altitude bulk method is to first set up an assembly bracket on the ground, then use a crane to hoist the space frame components to the design position in the air, and finally assemble them on the bracket. Its scope of application is the construction of hollow ball joints, bolted ball joints, or bolted space frames in narrow spaces. The high-altitude bulk method is divided into two types: the full-support method (full scaffolding method) and the cantilever method.
4.2 Process principle
The advantage of using high altitude is that for the roof as a whole, especially for large-scale public facilities such as gymnasiums, due to the large area and corresponding weight, it is not conducive to ground assembly. Helps reduce installation costs. The installation sequence should be determined according to the structural form of the space frame, the type of support, the stress characteristics of the structure, the small unit of the rods, the boundary conditions of temporary stability, the performance of construction machinery, and the site conditions.
5. Engineering application
The construction plan and technical measures of the roof space frame cantilever method of this project are as follows:
1. After the initial space frame is hoisted in blocks, according to the space frame installation sequence, use a 16t truck crane to hoist the small assembled units assembled on the ground to the installation position for expansion and installation one by one.
2. During the installation process of high-altitude cantilevered bulk, every time 2 to 3 space frameframinstalledtalledd, temporary support is immediately set at the center of the lower chord. The support is made of ①180X6 steel pipe, which is used to control the deflection of the space frame and to advance the space frame after the temporary transition. During the installation, check at any time during the installation process that the nodes are not tightened, the space frame is bent downward, the rods are bent, the elevation, axis, etc., it is strictly forbidden to install forcibly. 3. The top of the temporary support frame is equipped with a mechanical jack, which is used to adjust and control the elevation and deflection of the reticulated shell.
