While the fire behaviour of concrete-filled steel tubular (CFST) columns with circular and square cross-section has been well established based on experimental programs and numerical investigations, the information about the fire behaviour of CFST columns with rectangular or elliptical cross-section is very scarce. Therefore, further research is needed in order to establish the structural behaviour of concrete-filled elliptical and rectangular hollow sections at elevated temperatures as a basis for the future development of new design guidance. In this paper, a series of slender CFST columns of rectangular and elliptical crosssection are tested at elevated temperatures under both concentric and eccentric loads, reaching large eccentricities. The effect of the load eccentricity and percentage of reinforcement is studied, considering both major and minor axis buckling. The influence of the cross-section shape, load eccentricity and percentage of reinforcement on the fire behaviour of these columns is investigated. The experimental results are subsequently used to assess the current design rules in Eurocode 4 Part 1.2 for these new section shapes. Relative slenderness at room temperature, for major axis buckling Espinos A, Romero ML, Serra E, Hospitaler A. Experimental investigation on the fire behaviour of rectangular and elliptical slender concrete-filled tubular columns. Thin-Walled Struct. 2015;93:137-48.

Slim-floor beams are a novel typology of steel beams where the steel profile is fully embedded within the concrete floor depth. While the use of this system is increasing fast in the construction practice, the available investigations on its fire performance are still scarce. This paper focuses on analysing the fire behaviour of slim-floor beams combined with hollow core slabs as flooring system. Two configurations are studied, namely Integrated Floor Beam (IFB) and Shallow Floor Beam (SFB). A finite element model is developed and validated by comparison with experimental results available in the literature as well as with thermal tests carried out by the authors. Subsequently, parametric studies are conducted with the aim of providing practical design recommendations. The influence of the composite beam configuration, concrete type, longitudinal reinforcement and steel plate thickness is studied.The conclusions drawn in this paper suggest that the SFB configuration may provide a significant enhancement in terms of fire resistance compared to IFB, provided that the appropriate combination of the parameters studied is used.

Previous investigations have revealed the unsafety of the current calculation methods in Eurocode 4 for evaluating the fire resistance of concrete-filled steel tubular (CFST) columns, which has given place to a movement in Europe for correcting the existing methods and developing new design rules. In order to support the development of new guidance, further experimental research is needed, especially concerning slender columns and large eccentricities. In this paper, the results of a series of fire tests on slender CFST columns of different section shape (circular and square) subjected to large eccentricities are presented. The influence of the cross-section shape, load eccentricity and percentage of reinforcement on the response of these columns at elevated temperatures is studied in this paper, focusing on the effect of large eccentricities combined with high slenderness. On the basis of the experimental results, the current design rules in Eurocode 4 are assessed, and a previous calculation method developed by the authors is also evaluated.

This paper describes 24 tests conducted on slender circular tubular columns filled with normal, high, and ultra-high strength concrete for plain, bar reinforced and steel fiber reinforced columns. These were reinforced and subjected to both concentric and eccentric axial load. It is a continuation of a previous research paper [1], which presented test results on eccentrically loaded plain concrete columns. The test parameters are nominal strength of concrete (30, 90 and 130 MPa), eccentricity e (0, 20 and 50 mm) and type of reinforcement. A comparison with the corresponding empty tubular columns is performed, as the aim of the paper is to analyze the influence of each type of infill and establish the best option for practical application. For the limited cases analyzed the results show that the addition of high or ultra-high strength infill is more useful for concentric loaded cases than for eccentric loaded ones, where it seems that the best design option is the utilization of bar reinforced concrete filling rather than steel fiber to reinforce CFST columns. The experimental ultimate load of each test was compared with the design loads from Eurocode 4, accurate for the eccentrically loaded tests.

Slim-floor beams have attracted the attention of designers in the last decades, owing to their ability for supporting intermediate loads without increasing the floor thickness. However, the behaviour of this type of beams at elevated temperatures has not been well understood yet. This paper presents the results of an experimental campaign carried out at the testing facilities of the Universitat Politècnica de València, Spain, where a series of slim-floor configurations were exposed to elevated temperatures into an electrical furnace. These tests had the novelty of considering different slim-floor beam typologies, as well as alternative ways for thermal protection, such as using intumescent coating, stainless steel or lightweight concrete into different cross-section parts. The test results were used to validate a finite element thermal model which allows for a detailed analysis of the cross-section thermal behaviour and the assessment of different ways to improve the slim-floor beam fire performance. The temperature results were subsequently imported into a computer code developed by the authors where a non-linear procedure was applied to obtain the plastic bending capacity of the cross-section at elevated temperatures. These final results reveal the different thermal performance of the Albero V, Serra E. Espinós A, Romero ML, Hospitaler A. Innovative solutions for enhancing the fire resistance of slimfloor beams: Thermal experiments.