This dissertation presents the analysis of the influence of creep strain on the critical speed and failure temperature of EN AW 6082 T6 aluminium columns exposed to transient heating. The model of transient heating represents an increase in temperature due to a constant load and thus simulates the real situation caused by fire. Current regulations for the design of aluminium structures exposed to fire do not include a detailed description of the development of creep strain and its influence on the reduction of load-bearing capacity and the rate of failure of the columns. Considering the significant increase in the use of aluminium and aluminium alloys in construction over the last fifty years, it is necessary to obtain a solid conclusion on the influence of creep on aluminium columns which stands for the most sensitive part of the structure. The biggest disadvantage of aluminium is its sensitivity to high temperatures since its material characteristics decrease already at temperatures above 100 °C, supporting the idea of this research. In the opening section of the research presented in this dissertation, the calibration of experimental results was carried out on test coupons of aluminium alloy EN AW 6082 T6 with the aim of obtaining parameters for the selected creep model. The calibrated creep model was applied to the experimental-numerical analysis of dominantly pressure-loaded aluminium columns exposed to transient heating. For transient tests, a low heating rate was applied because it simulates the existence of some form of fire protection that is obligatory in today's constructions due to strict regulations. The final part of the dissertation includes a parametric analysis of the influence of low heating rates (1 °C/min – 5 °C/min) of regular columns of simple aluminium construction and a comparison of the influence of creep strain on the failure time of the columns. The aforementioned parametric analysis was performed on the basis of the adopted creep model based on the results of the study carried out on aluminium test tubes and aluminium columns.

The paper presents the development of a creep model applicable for the analysis of aluminium members exposed to a constant temperature. The model is intended as a base for defining a creep model in a transient heating regime. The behaviour of aluminium members exposed to the transient heating regime is a relatively unexplored topic in the scientific community. There is a need for defining an advanced creep model for aluminium, which should cover any heating regime to model the influence of creep on members exposed to fire. A comparison of results between the existing experimental data and the built-in creep models from commercial software ANSYS 16.2 for specific temperature and stress levels is provided. The experimental data used was extracted from previous tests carried out on coupons of aluminium alloy EN 6082 AW T6 and fitted in the aforementioned ANSYS models which serve as a base for defining the representative advanced creep model.

The paper presents an experimental and numerical analysis of EN AW 6082 T6 aluminium alloy columns exposed to high-temperature creep in transient conditions. Transient tests with columns subjected to a constant heating rate for a persistent external load in the form of the horizontal and transversal forces were carried out. A total of ten columns were examined with varying ratios of horizontal and transversal loads. The test results were compared to numerical results obtained from ANSYS 16.2. The coefficients for an ANSYS built-in Modified Time Hardening creep model were calibrated from the previously conducted tests on coupons and used as a base for the numerical analysis of the column. The study results reveal that creep reduces column load-bearing capacity, starting at temperatures above 150 °C. Furthermore, the level of reduction in the aluminium column capacity, which manifests itself as a runaway failure of the column between the creep and creep-free model, deviates with a difference exceeding 160% in vertical displacement upon failure, while the creep model correlates very well with the results obtained from the tested specimens in terms of failure time and the displacement ratio.