Experimental and analytical investigation on fire resistance of circular tubed steel reinforced concrete medium-long columns

This paper presents experimental and numerical studies on the fire-resistance behavior of the circular tubed steel reinforced concrete (CTSRC) medium-long column. Parameters, including steel thickness, loading mode (axial or eccentric), and load ratio, were considered in the tests. Moreover, the furnace temperature, column temperature, axial displacement, lateral displacement, and applied load were recorded during the tests, and the failure pattern was obtained after the tests. The test results showed that when the load ratio increased from 0.4 to 0.6, it would lead to an approximately 37%-54% decrease in failure time. Moreover, when the specimen was loaded with an eccentricity ratio (e/D) of 12.5%, the failure time would be 17%-39% less than that of the axially loaded specimen. The finite element model (FEM) was developed by ABAQUS and validated against the test results. Furthermore, through parametric analyses, more parameters, such as cross-sectional diameter, material strength, and length to diameter ratio, were studied. It was found that the fire resistance increased with the cross-sectional diameter, concrete strength, yield strength of the H-steel, and the steel ratio of the H-steel, whereas it decreased with the eccentricity ratio, yield strength of steel tube, steel ratio of the steel tube, and load ratio. Based on the experimental and numerical results, a simplified design method for predicting the fire resistance of CTSRC columns under ISO-834 standard fire was proposed. The design method was proved to have a good agreement with numerical analyses and test results within a specific application range.

Automated summary

The fire-resistance behavior of CTSRC medium-long columns is influenced by various factors, such as load ratio and eccentric loading. A simplified design method was proposed for predicting fire resistance under ISO-834 standard fire, showing good agreement with numerical analyses and test results within a specific application range.