Methods Study Of Virtual Trial Assembly Of Steel Structure

There are two ways for trial assembly of steel structures:virtual trial assembly and physic trial assembly. At present, most domestic construction projects apply the physic trial assembly, which is highly reliable while the cost is huge. Compared with the physic trial assembly, virtual trial assembly can save costs to a great extent and shorten the construction period, which is particularly true when the project is large and complex or in poor construction conditions. In recent years, with the development of computer technology and the worldwide conduction of related researches, the virtual trial assembly technology has reached higher maturity and reliability than before; practical construction applications has gradually increased with a great application prospects.Therefore, this paper presents experimental study of virtual trial assembly based on digital industrial photogrammetry. The experiment measures structural elements by applying digital industrial photogrammetry software system TRITOP, then virtually assembles these structural elements by using Generalized Procrustes Analysis (GPA) or Extended Orthogonal Procrustes Analysis (EOPA),methods of virtual trial assembly, based on Procrustes analysis.The experiment result shows that transforming the local coordinate system of elements by applying methods of EOPA can obtain a optimized local coordinate system. Taking advantages of this local coordinate system, computer can identify measurement of elements. Virtual trial assembling the elements by EOPA can furnish less discrepancies between the actual coordinates with the theoretic coordinates and meet the requirements of virtual trial assembly. Virtual trial assembling the element by GPA can furnish less discrepancies among the pairs of corresponding points in various elements. Further analysis shows that, in order to obtain good results of GPA, the program of virtual trial assembly must limit the cycle index of GPA. or else the discrepancies among the actual coordinates and the theoretic coordinates would be bigger than requirements, as well as the discrepancies among the pairs of corresponding points in various elements decrease. Taking advantages of further adjustment of weight coefficient of individual elements that didn’t meet the requirements of assembly, these ones can meet the requirements.