The Stress States Analysis Of Solid Web Steel Arch Structure

With elegant structure and reasonable stress, arch structure is widely used in civil engineering. It can transfer the vertical load to the support in the form of axial force,thus greatly reducing the bending moment, so it is easy to realize large span. At present,most of the researches on the failure mechanism and failure mode of arch under static load based on elastic-plastic ultimate strength failure analysis are based on experience instead of mechanism.Based on the result of solid web steel arch static ultimate bearing analysis and considering the nonlinear effects, this article explores the development law of the characteristic response such as energy and displacement of steel arch under the ultimate load. The rationality of using structure overall sum value of all square root of strain energy density(SQRTSENDSUM) to represent the structure tress state is verified. The failure criteria with mechanism and uniformity is established and the failure load and failure mode are predicted. The specific research content and results are as follows:1. Determination of stressing states characteristic parameter and limitation of steel arch strength failure form.Taking simple truss as an example, this article first shows the feasibility of using structure strain energy density sum value to represent the structure stressing states. Then the advantages of using square root of strain energy density sum value to represent structure stressing states is demonstrated. Next, the internal force distribution and difference of double-hinge arch and the simply supported beam with the same span are compared to illustrate the rationality of the arch structure stress. The influence of geometric nonlinearity on arch section axial force and bending moment is explored, and the conclusion is that the geometric nonlinearity has huge influence on the bending moment under all kinds of rise-span ratio. Finally, the law of ultimate strength destruction and in-plane elastic branch instability failure in the calculation example of this article are found out to ensure that the strength failure is prior to instability failure.2. The influence law of nonlinearity in energy analysis method.First, based on the different action principles of geometrical nonlinearity and material nonlinearity in the structure and the implementation methods of the two nonlinearities in the Ansys finite element program, four analysis algorithms are defined,and the APDL program code of the geometric nonlinear algorithm is compiled as a focus. Then, the geometric nonlinear algorithm, material nonlinear algorithm and double nonlinear algorithm are respectively used for calculation analysis of an arch structure. The change curve of energy and deformation with the increase of load is obtained and the action law of nonlinearity is analyzed by qualitative analysis. The influence of material nonlinearity is obvious in the plastic stage and the two nonlinearities couple to each other and aggravate each other. Finally, four parameters are defined which respectively represent the contribution rate of the two nonlinearitiesto energy and deformation. The parameters are used for quantitative analysis of the influence of nonlinearity in case of structure failure. The result is the same: the material nonlinearity is stronger than geometrical nonlinearity.3. Correspondence of structure stress pattern and energy growth index.Based on the finite element calculation data statistical analysis of solid web steel arch under different boundary constraints, rise span ratio, slenderness ratio and load conditions, the method to describe the structure stress pattern is found out, and the correspondence of stress pattern and characteristics inflection point on energy growth index curve is compared to provide calculation basis for presenting failure criterion and predicting failure mode. Finally, with the invariance of Lode parameter which reflects the local node stressing states and the high fitting of the two energies, the stability of the micro stressing states of arch structure in elastic stage and the nature of the integrated bearing structure are illustrated. The meaning of the concept of stressing states is deepened.