Fire performance of innovative slender concrete filled steel tubular columns

摘要

This paper investigates the experimental behaviour of innovative slender concrete filled steelrntubular (CFST) columns under standard fire test conditions.A total of 36 fire tests were carried out in the testingrnfacilities of AIDICO (Instituto Tecnológico de la Construcción) in Valencia, in the framework of the EuropeanrnProject FRISCC (Fire resistance of innovative and slender concrete filled tubular composite columns). The aimrnof this project was to provide a full range of experimental evidence on the fire behaviour of CFST columns ofrndifferent cross-section shape, a necessary basis for the development of numerical models and simplified designrnmethods. Four different section shapes were tested in this experimental program: circular (6 tests), square (6rntests), elliptical (12 tests) and rectangular (12 tests). Large eccentricities were used, in order to extend the currentrnexperimental database, with load eccentricity ratios up to 0.75. The study was focused on slender columns,rnall the specimens having a length of 3180mm and being in most cases hinged at both ends. The steel tubesrnhad a nominal yield strength of 355 MPa, while the concrete infill had a theoretical compressive strength ofrn30MPa. The load level applied to the columns was a 20% of their load bearing capacity at room temperature.rnThis experimental study allows understanding the influence of the cross-section shape on the fire performancernof CFST columns, as well as the effect of the load eccentricity and reinforcement ratio. The test results arerncompared and analysed in this paper, where the influence of the different parameters used in the experimentalrnprogram are studied, specially the effect of large eccentricities combined with high slenderness. Comparativerngraphs are given and conclusions are drawn on the basis of these results.