دانلود رایگان مقاله انگلیسی مقاومت فشاری محوری ستون های فولادی S460 جوشکاری شده در دمای بالا - الزویر 2018

ABSTRACT

This paper presents an investigation on the structural performance of welded S460 steel columns under axial compression at elevated temperatures using finite element analysis. Stub and long columns with box and Hsections were considered. A new stress-strain curve model for S460 steel at elevated temperatures was proposed and adopted to obtain the stress-strain curves for the finite element analysis. A finite element model was developed and verified against the available test data for welded S460 steel columns subject to axial compression at room and elevated temperatures. A parametric study was carried out to generate additional data of the axial compressive strength of box and H-section columns with various cross-section slenderness and column slenderness ratios at elevated temperatures. The obtained numerical results of the column strength were compared with the design predictions using the European and American specifications and the direct strength method by substituting the material properties at elevated temperatures. It was found that the provisions in European and American standards for elevated temperature conditions provide relatively conservative predictions. The direct strength method overestimates the strength of stub columns while accurately predicts the strength of long columns at elevated temperatures. Modifications are proposed for the European and American standards and direct strength method and these modified design rules are recommended to be used to more accurately estimate the design strength for welded S460 steel columns at elevated temperatures.

6. Conclusions

Axial compressive strength of welded S460 steel box and H-section columns at elevated temperatures was investigated using finite element analysis. A stress-strain curve model for S460 steel at various elevated temperatures was proposed to obtain accurate stress-strain relationship of S460 for structural design and analysis. A finite element model was developed with the incorporation of the stress-strain curves obtained based on the proposed model and validated using the experimental results of the ultimate compressive strength, load-deformation behaviour and failure modes of welded S460 steel columns with box and Hsections at room and elevated temperatures. A parametric study was carried out to determine the compressive strength of fixed-ended stub columns and pin-ended long columns with varying cross-sectional slenderness and column slenderness ratios at elevated temperatures.

The results of parametric study were compared with the design strength calculated according to the current European and AISC standards for structures subject to elevated temperatures as well as the original direct strength method, with the substitution of material properties at elevated temperatures. The European standard generally provides conservative predictions for the design strength of both stub and long columns with box and H-sections while the AISC standard significantly underestimates the strength of the columns. The original direct strength method overestimates the strength of stub columns at elevated temperatures while provides the most accurate predictions for long columns comparing with the predictions from both European and AISC standards. Modifications to the current design rules in European and AISC standards and original direct strength method have been proposed. The modified design rules are found to provide more accurate predictions for welded S460 steel box and H-section columns at elevated temperatures. Therefore, the modified design rules are recommended to be used for predicting the strength of welded S460 box and H-section columns at elevated temperatures for structural design.