ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
(2) Internal threading scheme of steel castings. Internal threads are used for steel castings, and both ends of steel tie rods are connected by threads. Advantages: small size of joints, beautiful structural form and shortcomings: difficult installation, tension is not easy to control, structural size is not easy to guarantee, and the quality of internal threads in steel castings is not easy to control. From the above comparison, it can be seen that the design scheme of using external threads in steel cable-stayed joints has an impact on the construction effect, but it is easier to meet the construction needs. In order to solve the shortcoming that the joint length of this scheme is slightly larger, we further optimize the outer arc of the steel sleeve to reduce the visual sense of abruptness. The optimized scheme has been affirmed by the architect. It is relatively rare to use the 3.3.2 installation technology in the lower chord of the beam-string system with the steel tie-rod structure, which is usually cable structure. In this paper, we have carried out a detailed process study on the installation of the structure. Through the research, we found that the following points should be paid attention to: first, the location of tension joints must be determined beforehand; secondly, the upper chord beam must be relaxed during installation; secondly, the sequence of installation of steel tie rods must be considered; and thirdly, the threaded stroke must be fully prepared according to the above points in advance, and then according to each key point. Point out the installation work.
Firstly, the location of tensioned joints should be determined. Considering the uniformity of tension, the layout of tensioned tooling and the ease of operation, the other joints of tensioned joints fixed in the middle of the beam string are used as the connection joints. The second step is to install, first to relax the upper chord beam, the upper chord beam is a box beam, the shape of a strong structure has a certain rigidity. On the assembly frame, we choose the middle point of the upper chord beam, divide it into four points and use four 20 ton oil pumps to evenly top it up to 40mm, so that the Steel Trunnion plate of the two sides of the tug pin can move inward, and improve the installation operability, then set the installation sequence. According to the fact that the tension node is located in the middle of the lower chord group, the tension node is the threaded stroke control node, so the threaded direction of the node is opposite, while the threaded direction of other joints is the same. Because of this thread connection mode, the installation sequence must be considered as a whole, and can not be installed arbitrarily. Through the research, we decided to install the rods in the order of 1-2-3-4-5-6. Firstly, the connecting nodes were installed, then the pin joints were installed, and finally the tensioning joints were installed.
After considering the installation sequence, it is necessary to determine the screw stroke installation is to consider the deflection distance of the straight web rod to ensure that the verticality of the straight web rod meets the acceptance requirements after tension. According to the previous description, we initially determined the deflection value, and then installed the steel drawbar in sequence, and connected the steel castings with the steel drawbar with the steel sleeve of the special wrench. After installation, the middle web rod is kept perpendicular to the ground, and the installation of the steel tie rod is completed. 3.3.3 Prestress control technology according to the requirements of the design drawings, the pretension of the beam string is only to meet the establishment of the structural system, while ensuring the size of the arch, the applied value of the prestress is not limited. Therefore, in preparation, we decided to take structural deformation as the main factor and stress application as the supplementary tension scheme (1) First of all, structural reset, after the installation of steel tie rod, relax 20 tons of oil pump, so that the roof truss reset. After the roof truss is restored, the position of the roof truss body, straight belly, steel tension and steel castings is checked by electronic total station, which does not meet the initial tension requirements. After the adjustment, all structural constraints are relaxed. The roof truss is lifted 50 mm by 50 ton oil pump at both ends, so that the two supporting points can be reached. (2) Next, the tension device is installed to connect the oil. Before stretching, the connecting sleeve is adjusted accurately to ensure that the initial length of the lower chord steel tie rod of the steel frame is controlled within a certain range.
(1) Tension construction, synchronous graded tension, slow loading, to ensure that the tension displacement and connection sleeve rotation follow-up synchronization. Three to five tension adjustments were made by the tension equipment. Deformation measurement and data acquisition were carried out synchronously to observe the change of the arch size of the beam string. According to the measured data, the tension coordinated adjustment is carried out in time. When the arch of the beam string reaches the predetermined value, the tension is stopped and the tension is completed.