ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
The main structure of an office building in Chengdu is a steel frame supporting tube system, which is divided into three parts: core tube, inner tube (with bracing system inside) and outer frame. The total plane size of outer frame is 51 m x 51 M. The structure is about 200 meters high, 5 underground floors and 40 above ground floors. The total steel diaphragm used in the project is 36,000 tons. There are four steel columns in the core of the project, with the specifications of 900 x 900 x 90; 20 steel columns in the inner tube, with the specifications of 1300 x 900 x 60 (four corner columns) and 900 x 900 x 60 in the box; 32 steel columns in the outer tube with the specifications of 800 x 800 x 60 in the box; a total of 56 steel columns in a construction unit are vertical when the main structure of the construction unit is 1.1 meters above ground. Recurrent measurement of straightness deviation, installation status and problems are shown in Fig. 1. It is found that there are deviations in different degrees of steel columns. Among them, the vertical deviation of 44 steel columns exceeds the permissible range of the Code for Acceptance and Acceptance of Construction Quality of Steel Structural Engineering (GB50205-2001). The maximum deviation is 38 mm, and some steel columns appear twisting deviation at two angles.
In order to install the project smoothly above the ground, measures must be taken to correct the deviation of the steel column. 3. The selection of the rectification scheme is based on the deviation degree of the steel column verticality and the installation status. After many rounds of discussion, two schemes, progressive and one-time rectification, are basically determined. The progressive rectification scheme is based on the deviation of steel columns, and it corrects each steel column step by step in the allowable deviation range until the steel column is completely located at the axis position. One-time rectification is to rectify the upper section of steel column at + 1.1m once and reinforce the joints at the joints of the upper and lower sections of steel columns. To achieve the purpose of rectifying deviation. Through careful analysis, detailed implementation rules 3.1 are formulated for the two schemes respectively. Gradual rectification takes A6-AL axle steel column as an example. The column body at + 1.1m is 15 mm northward and 19 mm eastward. Therefore, the vertical deviation of the column should be adjusted from two axis directions. Before adjusting the vertical deviation, the positioning axis of the steel column should be adjusted first.
According to the requirements of the code, the relative horizontal displacement difference between the top central line of a single section of steel column and the bottom central line of the column can be divided into two directions: X and Y. The allowable deviation value is less than h/1000 and less than 10 mm (h is the length of a single section of steel column). After subdividing each section of steel column at this location with steel column + 1.1 m or more, the first section of steel column is 4.9 m high, the second section is 5 m high, and each section above is 9.2 M. The steel column shifts 19 mm eastward and 15 mm northward along A6-AL axis. Therefore, it is determined that the steel column above 1.1 m should be adjusted four times. + The first section of column above 1.1m is adjusted 4 mm to the West and 4 mm to the south in installation; the second section is adjusted 5 mm to the West and 5 mm to the south in installation; the third section is adjusted 7 mm to the West and 6 mm to the south in installation; the fourth section is corrected 4 MR to the West in installation, and the following matters should be noted: 1. When making steel column, steel should be marked by steel punching in advance on the four sides of the bottom of the column. The center line of the column; (2) The positioning axis of the last section of the column is not allowed to use the positioning axis of the next section of the column, which should be directed from the axis of the control network to the high altitude to ensure the installation standard of each section of the column and avoid excessive error accumulation; (3) The two theodolites placed in the radial direction are used to observe the steel column during the correction process, as shown in Figure 2; (4) During the correction process, in the inclined side of the column, the axis is adjusted by the jack. After adjusting the steel column to the pre-control value, tighten the high-strength bolt of the temporary connection ear plate (the bolt hole of the temporary connection ear plate should be 4 m larger than the bolt diameter, and use the bolt hole to enlarge the error of - 1 ~ + 5 mm to adjust the manufacturing error of the steel column), as shown in Figure 3. _According to the control value of the rectification of each steel column, the length of the steel beam should be compensated or reduced in the manufacturing process; _When installing the steel beam, the upper beam should be installed first, and then installed. Install.