Application of BIM technology in the construction of special-shaped space frame ball joints (Part 1)

The characteristics of steel structure construction are usually long construction period, large number of parts, complex manufacturing process and high design error. During the construction of the project, there are very strict requirements on the overall accuracy of the construction. In order to complete high-quality steel structure construction tasks, various advanced technologies including BIM technology have begun to be applied to structural construction. Technology application has advantages in information sharing, dynamic visualization, etc. It can provide structural construction services more intelligently, and its application value is more prominent.

1、Definition of BIM technology

For BIM technology, it generally includes two aspects, one is the information model, and the other is the digital model. As far as the information model is concerned, it generally runs through the entire life cycle of a building with the help of computer information technology, specifically including architectural design and construction, which is conducive to all-round management. Based on the further development of science and technology, BIM technology has been widely used, including the application in the design stage and construction stage. As early as the 1970s, there was a definition of BIM technology. With the help of computer technology, a series of information models included in construction project management were summarized, such as geometric characteristics and functions, and all information models were classified into a single information model. At the same time, in order to further ensure the management of construction projects, in this single model, information such as construction progress and cost are also combined. With the advancement of science and technology, BIM technology has become more and more perfect. After that, various definitions have also been produced. The introduction of BIM technology in construction projects can build a corresponding digital information model, which involves the management process of all aspects of the construction.

2、Application advantages of BIM technology

Introducing BIM technology to participate in the management of engineering project construction can not only realize the sharing of engineering data and key construction node information among various departments, but also use the shared data to comprehensively manage the progress of project implementation and the expected cost of the project . Project management based on this method can not only solve the disadvantages of the traditional management model, but also realize the macro, real-time and dynamic monitoring of the whole process of project implementation, and realize the comprehensive improvement of the project management and control level. At the same time, BIM technology has the advantages of visualization, collaboration, and simulation. The construction party can use the building structure information model to fit the engineering quantity parameters before construction, and display the three-dimensional and four-dimensional renderings of the construction project by matching the construction design drawings. In this way, more accurate node construction reference information is provided for workers, and basic data is provided as a support for the good and orderly cooperation between various departments.

3、Application of BIM technology in the construction of special-shaped space frame ball joints

3.1、Application process and step description

(1) Establish a high-precision space frame model, and carry out high-precision detailed modeling of the steel space frame according to the BIM industry LOD400 standard.

(2) The space frame model is divided reasonably, combined with the characteristics of the building, and considering the comprehensive factors such as the weight of the block division, the overall size, the installation height, and the cost performance of the machine, the space frame of the main steel structure is divided into several areas.

(3) Convert the coordinates of the center of the sphere for processing. In the BIM model, each space frame is proposed separately, and the model is adjusted in an inverted horizontal manner to facilitate processing, and the relative coordinates of the sphere center in the new form of the single space frame are collected.

(4) Establish a processing control network, pour cushion concrete in the planned processing area to ensure the smoothness of the processing area, pop up the processing control network on the cushion, and provide technical and safety disclosure to personnel through BIM animation before assembly.

(5) Fabrication of the tire frame The vertical direction of the assembled tire frame is supported by circular tubes, and the length is determined according to the on-site lofting of the space frame radian; if the vertical support is greater than 2m, set up a diagonal brace, and the angle between the vertical support and the vertical support is not less than 30 degrees.

(6) Stick 4 measurement reflective stickers on each solder ball. Stick the reflective stickers on the installation position of the space frame ball, facing inward and downward, to facilitate construction measurement.

(7) Review the relative coordinates of the center of the ball. During the assembly stage, multiple rounds of precision adjustments are carried out to control the size deviation of the single assembly within 5mm.

(8) After correcting, the connecting rods are welded.

(9) Flaw detection of welding points, derusting and anti-corrosion after passing the test. In the BIM model, place a single space frame according to the model position, collect the coordinates of the center of the ball at the installation position of the space frame, set the origin of measurement through the software model, and select the space frame ball to view Attributes to get the theoretical radius and theoretical construction sphere center coordinates of each space frame sphere. Establish a construction measurement control network: The construction accuracy of each part of the structural system of this project directly affects the installation error accuracy of the next process, so it must be implemented in strict accordance with the measurement plan during the on-site assembly and fabrication to the hoisting process. Measure the hoisting space frame ball center reflective sticker group; input the measured values of any 4 points on the surface of the ball into the algorithm applet: input the measured values of 4 points on the spherical surface to get the existing coordinate position of the center of the ball.