INVESTIGATION OF THE EXACT SEQUENTIAL CONSTRUCTION ANALYSIS IN COMPARISON WITH THE CONVENTIONAL ANALYSIS AND THE APPROXIMATE CFM METHOD

Nowadays, in common structure analyses, dead and live loads of all oors are applied instantaneously. In fact, it is assumed that the structure does not bear any load before the end of construction. This assumption could be valid for lateral loads or the dead loads of subsequently installed components, but it is unsuitable for the dead loads of the structural members and oor because these types of loads are gradually applied to the previously constructed members during the progress of construction, which depends on technology and construction planning. According to the sequence of construction, structural members are added to stages as the building construction proceeds; therefore, their dead load is carried by the part of the structure completed during their installation stage. Hence, it is clear that the distribution of displacements and stresses in the constructed part of the structure at any stage does not depend on the sizes, properties, or the presence of members composing the remainder of the structure. In this procedure the deformations of the lower stories are already taken place under the self weight of their oors even before the upper oors are built. Hereupon, in each stage of construction, the newly- built members are installed on the previously deformed members of the structure, and the nal deformation of structure is the cumulative outcome of deformations in construction of each story until the completion of the nal stage of construction. Ignoring the eect of sequence of construction may lead to seriously incorrect analysis results, particularly at the upper oors of the building. In this paper, the exact method of sequential construction analysis has been investigated, and also the manual method of calculating the elastic sequential analysis has been studied in order to have the sucient knowledge of how the software works. To comprehend the necessity of sequential construction analysis, the outcomes are eventually compared with the conventional analysis and simulation methods of the real behavior of the structure, compatible with the real construction schedule such as CFM method. A 21-story steel structure has been chosen as a case study to achieve the aforementioned purpose of this paper.