Abstract:In order to investigate the overall stability of I-shaped stainless steel member under axial compression load, the nonlinear finite element analysis of the stainless steel members subjected to axial compression load was performed by ANSYS software. By comparing the numerical results with the experimental results, the accuracy of the finite element model was verified. The effects of initial geometric imperfections, section residual stress, material mechanical properties, and section width-thickness ratio and slenderness ratio on the overall stability of the members were parametrically analyzed by means of the validated finite element analysis. According to the comparison, it can be seen that the material mechanical properties and slenderness ratio of the members are the key influential factors. Based on the parameter analysis, a new three-segment formula for calculating the overall stability coefficient was proposed by data fitting. The proposed three-segment formula can accurately predict the overall stability bearing capacity for I-shaped stainless steel member under axial compression load.

Abstract:Numerical simulation was used to analyze the mechanical property of steel beam based on membrane effect. The stress distribution of the beam was given and compared with those of steel box-beam and steel H-beam. The results show that, with the same span and mass, the new beam has higher bearing capacity, and with the increase of the span, under rational design, the superiority of the bearing capacity is more evident.

Abstract:The calculation methods of overall stability for HM and HW-shaped steel beams under uniform load on the upper flange and concentrated load on the lower flange are not included in current steel structure code. According to the results obtained with energy theory, with the impact of deformation before buckling on flexural-torsional buckling considered, the critical moment formula of biax-symmetrical HM and HW-beams was derived under the load mentioned above, and the effects of the load scale factor on critical moment were also summarized in this paper. The finite element method was used to verify the moment formula. When the load scale factor was less than 3，the result difference between the finite element method and the theoretical method was within 5%. In addition, the coefficient formula of equivalent critical bending moment for the steel beams under the same loading was put forward. The maximum error of this coefficient formula was less than 8% and the average error was about 3%.

Abstract:Based on probability and mathematical statistics, a new method was proposed by analyzing the information of measured geometric position deviation of selected joints and by using truncated Gaussian distribution model to simulate the distribution of the geometric position of unmeasured joints.With the Monte-Carlo method, a group of stability factors was obtained, and the critical stability factor was determined with the probability theory.Furthermore, the critical stability factor calculation flow chart of existing reticulated shells was given.By taking a Kiewit single layer reticulated shell as an example, the feasibility of this method was verified.

Abstract:The calculation methods of the overall stability of I-section steel beams, under loading both on upper and lower flanges, are not contained in current steel structure code. Energy method was used to derive the critical moment formula of biaxial symmetry I-beams under the loading mentioned above, and the effects of the load scale factor on the critical moment were also summarized. The finite element method was used to verify the moment formula. The results of the finite-element calculation were consistent with the theoretical results when the load scale factor was less than 3. In addition, through computational analysis, the formula of the equivalent critical bending moment coefficient for the I-section steel beams under the same loading was put forward. This formula has a preferable calculation accuracy.