ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
The verticality of webs of beam string has a great influence on the construction effect after the completion of the project. When setting the inspection standard, the architect put forward that the vertical deviation of webs should not exceed 10 mm. In actual manufacture, because the lower chord of beam is tension structure, one stroke of thread tension is 10 mm, which puts forward a very high requirement for the installation of webs. In reference D, we calculate the prestress value first by calculating the score, then use ProE software to install the structure virtually and determine the theoretical travel value. In actual process operation, I revise the deviation of the theoretical value and add a negative tolerance as the pre-bias value for the installation of the belly cane. The actual point is fixed. The lower flange fulcrum first deflects the pre-tensioning stroke in the opposite direction according to the theoretical value, and then deflects a certain value according to the allowable deviation value to meet the requirements of the verticality of the pre-tensioned belly rod. In the first installation, we doubled the allowance of the deviation correction value. After pre-tensioning, the vertical deviation of the abdominal tract was measured to be 7 mm, which was successful.
With experience, we can adjust the correction value of deviation, and the verticality of the web rod installed behind can be controlled to (+5mmd). Pre-assembly is a direct and effective method for interface coordination between segments. In the process preparation stage, we decided to adopt the pre-assembly scheme to solve the problem of interface coordination. However, in preparation, we noticed that the roof truss structure is large in size and heavy in weight. Considering the manufacturing conditions and construction progress, it is almost impossible to pre-assemble the five segments. We optimize the scheme, divide the five segments into 11 sub-segments, and then imitate the pre-assembly method of the bridge. Each three segments are divided into a group, which is divided into 1-3, 3-5 and 59-11 groups for pre-assembly. Through such pre-assembly method, which is from big to small and from difficult to easy, the cooperation problem of sub-interface is well solved. (2) The difficult point of the sectional manufacturing of column connection is the spatial location of special-shaped steel castings. From the view of roof truss structure system, the branch steel column is connected under the section, and pin joint is used to locate the roof truss.
Therefore, the axis of the hole and the axis of the main beam of the corresponding joint cast steel are not simply parallel or vertical, but a space angle. When two steel castings are located in one section at the same time, the installation measures must be carefully considered to ensure that the branch branch branch can penetrate into two steel casting holes at the same time. After the structural modeling of this part by computer, it is considered that the correct location of the branch branch branch branch can not be determined by the conventional hole location method. Even if the electronic total station is used, the accuracy of the patch can not be guaranteed because the reflection point is located in the center of the eye hole, so it is difficult to use digital positioning. In this case, another method must be found to solve the positioning problem of special-shaped steel castings. Through a thorough study of the model characteristics, we noticed that the special-shaped steel casting base is just part of the lower flange of the roof truss beam, and the longitudinal and transverse axes of its base plane are consistent with the longitudinal and transverse axes of the roof truss beam. We wondered if we could change the base point and use the steel casting base to locate it. If we could, we could solve this problem by simple drawing method.
After continuous investigation, we decided to adopt the method of base plane positioning to determine the base plane of steel castings as the structural datum, including the manufacture of steel castings, the processing of all sides, borehole drilling, and the marking inspection. In this way, the location of the hole can be guaranteed as long as the base plane is positioned accurately during the installation of steel castings. When installing, the vertical and horizontal axis of the base plane corresponds to the axis and latitude of the roof truss beam, and the base plane datum point is used as the positioning datum point to locate and install, which is simple and convenient. From the results of the overall installation of the structure, the installation error is within the allowable range. Relevant to manufacturing.