Investigation Of Load-carrying Behavior And Finite Element Modal Analysis Of Prestressed Portal Frame

Portal frame structure is widely used in the field of light-weight steel structure buildings for its obvious advantages over the traditional structure in the construction period and applicability. Current control steel dosage mainly focus on adapting cuniform portal frame according to the internal force of sections. As the economic index of the ordinary long span solid abdomen type portal rigid frame will drop along with the span increasing, a new type of way is presented in this paper, which is fixing up horizontal prestressed cables at the joints between beams and columns. The situation of internal force in the structure is improved because of the applied prestress. Partial components are unloaded. The traditional calculation mode is modified, some proposals are provided for the design and the scientific construction method of steel structure.Perstress is applied to the portal frame according to the cable method. Stiffness matrix of variable cross-section is deduced and the related program which is based on finite element principle and Matlab language is given. This program is used to analyze and calculate. The stress performance of the pre-stressed portal frame is researched under different parameters, such as initial tension of the cable, cross-section of the cable, span of the frame, slope gradient of the frame and so on. The variation law of internal force and deformation in the prestressed portal frame is obtained. The model analysis of the prestressed portal frame is carried out using the theory of vibration and the APDL language of ANSYS. The emphasis is laid on researching the influence on the mode of the prestressed portal frame which is caused by the factors such as height of the columns, gradient, span and so on. Natural vibration character of the structure is researched and then the theoretical calculation basis for the harmonic response analysis, transient dynamic analysis and spectral analysis of the engineering structure is provided.The comparison between ordinary portal frame and prestressed portal frame is carried out both in the research on bearing performance and modal analysis with finite element method, a corresponding design proposal is also presented in this paper. Therefore, this paper can be used as an useful reference for the project design.