Ensuring the reliability of the results of computer modeling of the behavior of bridge structures

Abstract

It is noted that structural mechanics is developing in the direction of improving design schemes, allowing more correctly assess the stress-strain state of structures. One of the topical areas of improvement is the consideration of nonlinear behavior and spatial work of structures. Constructive and genetic nonlinearities are added to the geometric and physical. Attention is drawn to the problem of checking the correctness of design decisions, which are not always based on existing standards, but are justified by calculations of more correct, but also more complex calculation schemes, performed using powerful software systems. To solve this problem, the Glavgosexpertiza recommended making calculations for at least two certified, independently developed and tested in practice software systems, and conducting a comparative analysis of the results. The question that arose about which software systems to use, it is proposed to solve with the help of MIDAS/CIVIL (South Korea) and SOFISTIK (Germany) complexes that have proven themselves quite well in bridge organizations. The article provides a comparative analysis of the MIDAS/CIVIL and SOFISTIK software packages using the spatial calculation of a bridge structure as an example, and the results are also compared with the calculation using the standard methodology. For analysis, the span structure of the railway bridge was adopted, consisting of two main split trusses with a bottom ride, reinforced with longitudinal and transverse beams in the level of movement of the railway load, longitudinal and transverse ties combining the upper and lower truss belts. The main trusses of the diagonal system are reinforced with vertical struts and suspensions. In general, analysis of the calculation results shows that both software systems give fairly close values of the calculated values of forces and stresses, and the differences for individual elements do not exceed 13.90 %. The normative calculation method provides mainly overestimated in comparison with SOFISTIK PC results, and the excess can reach 53.73 % for longitudinal forces and 49.71 % for normal stresses. This difference is a consequence of the use of a flat design scheme in the regulatory methodology, which leads to an increase in the level of the acting longitudinal forces, transverse forces and bending moments. That is, the normative calculation for a number of elements of a bridge structure is, as it were, a margin of safety. In conclusion, the requirements are formulated for specialists involved in the calculation analysis and examination of project documentation.