ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
Through calculation and analysis, the stress distribution of each joint coincides with the theoretical analysis, and the structure of the joint meets the need of stress. Fourth, truss processing first uses Xsteel or AUTOCAD software to establish three-dimensional wire frame model, then through data conversion, uses six-axis NC intersection cutting machine to cut, steel pipe blanking, cutting at one time. Rod bending is based on the curvature of the truss chord to bend the steel pipe. After the culm is cut on the intersection surface, the cold bending CNC pipe bending is used for the initial processing (garden 12). In the process of bending, the suitable die is selected according to the radius and bending radius. Elastic deformation should be considered when bending. The radius of bending curvature should be enlarged appropriately according to the experience data, and manual correction should be adopted when necessary. Fifth, the selection of the construction scheme for the installation of truss 5.1 The Pavilion is a single-storey structure composed of concrete filled steel tubular columns and steel truss roofs. The roof is composed of 11 trusses of different lengths. The longest truss is about 90 meters, the shortest truss is about 57 meters, and the supporting column page elevation of the truss is 14 meters.
The shape of the truss is inverted triangular shuttle, and the weight of the single truss is about 34 tons. Except for the mountain truss at both ends, the other nine trusses are prestressed on the lower chord. Because the truss length is longer (the longest is 90 meters) and the height is higher (the highest is 7 meters), it is difficult to install the truss. In the process of installation, how to ensure the stability of the truss and the control of deformation are very important. At the same time, the tension and control of prestressing force are also the key points to ensure the safety of the structure. After comparing various schemes, considering the above factors, the truss is constructed by the high-altitude assembly method of the movable frame. 5.2 Accuracy control of sliding frame proves that the accuracy of sliding frame is the key to ensure the assembly accuracy. Firstly, the position of truss nodes on the assembly frame is determined by the data obtained from computer lofting, and the relative position of the control points of the frame is measured by total station, and the assembly of components is started after the determination of the accuracy. The welding shrinkage should be considered in advance for the length and position of assembly rod. The tyre frame is equipped with adjusting device to ensure that there is a certain adjustment allowance of 5.3 longitudinal truss installation. The longitudinal truss is hoisted in stages. The principle of truss sectioning is one section from each column.
Firstly, the sectional truss is assembled in the assembly site, and then the installation position is transported by flat car. The truck crane or the track silk are directly hoisted and positioned. Longitudinal truss silk loading is synchronized with steel column silk loading. In order to ensure the accuracy of truss installation, accurate measurement must be carried out to ensure the accuracy of the position. Prestressed cables are made of unbonded prestressing strand harness with 7 Q5 steel strand specification, 1860 Mpa tensile strength and P-film outsourcing. Anchors are made of low-stress anti-loosening clip anchorage project, and the prestressing tension is made by one-time local adjustment. The construction process of the sheet stress cable can be roughly divided into a. Strand cutting: length L = length of steel pipe inside + working length 800-900mm at each end of the tension end) Strand penetrates into the lower chord steel pipe, the strand is connected with the strand harness through a special traction head, and a strand penetrated first is used as traction and guidance. C. Strand threading: dynamic traction by winder, pre-drawing. The stress cable passes through the bottom chord of the steel pipe from the orifice of one end of the steel pipe. After the cable penetrates, the anchors at both ends are installed to be tensioned by the prestressing cable and slipped by the scaffold after the anchor is sealed.
D. The haunting tension: the tension supervisor chooses 250 tons and 150 tons of jacks. The actual tension force should be determined according to the internal force analysis, and zero displacement under dead load can be achieved by displacement control. The tension procedure of the prestressing cable is 0.3 con (initial reading)0.650 c0n (intermediate reading) 10cn (final reading). Anti-loosening clamp anchor is used at both ends of the cable body. Anti-loosening splint anchor is a new type of pre-stressed truss truss, which is composed of anchor plate, anti-loosening splint, cover plate to prevent splint loosening and protective cover structure. It has better mechanical performance and better economy. In the design process of this project, the main joints of the structure are theoretically analyzed and the structural requirements are fully considered. At the same time, the construction method of truss, especially the tension of prestressing force, is checked under various working conditions, which provides a reference for the application of similar engineering after achieving good results.