ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
3.4.2. Installation of truss in frame 1. The span of truss in middle 4 axes of frame is large. The total height of assembled scaffolding from 35 stories to the lower chord of truss is 264 meters. The total height of scaffolding splicing outside Zuyuan Hall is 8 meters. See Fig. 9. In order to avoid the local stress on the floor, the contact area between the floor and the floor is added, and the hot I20a steel is used under the bottom of the load-bearing scaffold under the splicing points of each section of the truss. At the same time, in order to improve the overall stability of the scaffolding, the scaffolding at Zuyuan Hall, i.e. each floor of the scaffolding is connected with the structural steel column by a cross-stalk 2. The scaffolding at the lower chord splicing fulcrum of the truss is adjusted by jacks and sleepers. At the same time, the horizontal hoop is hung. Fig. 1, 2010, the installation of the lower chord of the Pangu Grand View Truss in Beijing is shown in Fig. 3, in order to transfer the installation error to the frame. To ensure that the frame and the external truss can be better connected, we determined that the frame truss should start from the A14 axis. During installation, the trusses at the intermediate AG and AF are installed first, and then the other six-segment trusses are installed symmetrically after the rigid structure is formed.
Taking AF and AG as examples, the installation sequence is as follows: (1) installing the fourth truss of AF and AG axes installing the second truss between the fourth truss installing the third truss of AF and AG axes installing the second truss between the second truss of the third truss installing the second truss of AF and AG axes installing the second truss of the second truss of the second truss after primary school. Secondary truss installation of the first section of AF and AG axes installation of secondary truss between the first section of two trusses 9 installation of the connection beam and support between F and AG trusses. When the two trusses are corrected and welded to form rigid joints, the next symmetrical installation of adjacent trusses 11 is the installation sequence diagram of overhanging trusses. The installation principle of overhanging trusses is 3.4.3 for the steel structure of super high-rise office buildings, and 3.4.3 for overhanging trusses. The installation principle of overhanging trusses is to adopt the installation method of overhead piecewise splicing and extending progressively. When each segment truss is installed, it moves symmetrically from the middle to the two ends. After the first segment of the truss is the first segment to form a rigid joint, the second segment is installed, so that the splicing proceeds step by step until the installation is completed.
Considering the shortage of factory site, the whole installation process must be organized in strict accordance with this order, from component production, supply, assembly, hoisting, correction and welding sequence are organized in accordance with this principle. In order to reduce the workload on site, the main and secondary trusses in 11 counties are assembled in whole silk. In order to meet the transportation requirements, the factories are divided into blocks and pre-assembled, and then transported to the site. The construction layout of the cantilever truss is shown in Fig. 12. The calculation and analysis of the lifting weight of each section of the cantilever truss are carried out. The main truss of the cantilever part is lifted in whole sections. The sections of the 32 sections of the main truss can be directly lifted and positioned by the North Tower from a single machine on the ground of the North Field. The measures taken during hoisting are (1) before silk hoisting, the safety ropes and operating platforms at all hoisting operation points of the main truss are set on the ground [including walking safety ropes, operating platforms for pulling wind ropes and inverted chains, girth welding of wind ropes, cage climbing ladder for installing secondary trusses, safety ropes for removing horizontal nets, etc.) Figure 12 shows the safety ropes for hoisting trusses. Installation plane layout (2), cantilevered main truss on the ground for flat assembly, silk hooking needs to use 50 tons of car crane to turn over in the air, and 20 tons of inverted chain to adjust the slope of the upper chord of the main truss (3), in the main truss butt to set up anti-downward moving resistance plate, in order to avoid the southern end of each section of the suspended main truss in place due to self-weight (4), vertical. The cable wind rope in the direction is stable as shown in Fig. 13. In the horizontal direction, the rigid support is made of scaffolding steel pipe and connected between the two main trusses. The end of each main chord is provided with rigid support.