Evaluating of a column-baseplate connection under temperature changes

Because of the high temperatures such as fire, the strength, and hardness of steel decreases, so it is necessary to know and study the behavior of steel structures at high temperatures, especially joints, as a place for distribution of force to other members. In this study, the connection behavior of the column to the baseplate in the fire was investigated using Abacus finite element software. Several different models were modeled by considering different variables such as applying different lateral loads to the column, changing the dimensions of the baseplate, and changing the bolt size in the software and were subjected to displacement-temperature coupling analysis in the software. Change of all mechanical properties of materials in heat increase was defined in accordance with EUROCODE۳ standard coefficients to the software. In this analysis, the models were first subjected to axial and lateral loads and the thermal regime was applied to the joint area in accordance with ISO۸۳۴ standard. Then, the behavior of the samples in heat increase was investigated and temperature-rotation diagrams were extracted for each of them. Analysis of models and results showed that increasing the lateral load applied to the samples (applied moment) reduces the connection capacity in temperature increase. Reducing the bolt diameter reduces the connection capacity in temperature increase and increasing the bolt diameter also increases the connection capacity in temperature increase. Reducing the thickness of the baseplate reduces the connection capacity in increasing temperature and vice versa. In connecting the column to the baseplate with increasing temperature due to the effect of various parameters, the probability of failure mode in the bolts is high.

Keywords:

Steel connections , Baseplate , Finite element method , Foundation