Corrosion of carbon steel reinforcing bar can lead to deterioration of concrete structures, especially in regions where road salt is heavily used or in areas close to sea water. Although stainless steel reinforcing bar costs more than carbon steel, its selective use for high risk elements is cost-effective when the whole life costs of the structure are taken into account. Considerations for specifying stainless steel reinforcing bars and a review of applications are presented herein. Attention is then given to the elevated temperature properties of stainless steel reinforcing bars, which are needed for structural fire design, but have been unexplored to date. A programme of isothermal and anisothermal tensile tests on four types of stainless steel reinforcing bar is described: 1.4307 (304L), 1.4311 (304LN), 1.4162 (LDX 2101®) and 1.4362 (2304). Bars of diameter 12 mm and 16 mm were studied, plain round and ribbed. Reduction factors were calculated for the key strength, stiffness and ductility properties and compared to equivalent factors for stainless steel plate and strip, as well as those for carbon steel reinforcement. The test results demonstrate that the reduction factors for 0.2% proof strength, strength at 2% strain and ultimate strength derived for stainless steel plate and strip can also be applied to stainless steel reinforcing bar. Revised reduction factors for ultimate strain and fracture strain at elevated temperatures have been proposed. The ability of two-stage Ramberg-Osgood expressions to capture accurately the stress-strain response of stainless steel reinforcement at both room temperature and elevated temperatures is also demonstrated

Experiments on concrete-filled elliptical hollow section beam-columns have been conducted to examine their fundamental structural behaviour. A total of 27 specimens were tested — 3 stub columns and 24 longer members of varying slenderness. Seven of the tested specimens also contained steel reinforcement. The specimens were loaded in compression, either concentrically or with different major or minor axis eccentricities. Measurements of the applied load, the strains at mid-height, the axial displacement and the lateral deflection at mid-height were recorded. Plots of load against the lateral deflection at mid-height and load against axial displacement are presented for the specimens, along with values of strength index and ductility index. Comparisons have been made between the test results and the provisions of the European Standard EN 1994-1-1:2004 for determining the ultimate load of concrete-filled circular and rectangular hollow section columns. It was found that the predicted resistances are safe for use in the design of concrete-filled elliptical hollow section columns either with or without reinforcement, and loaded either concentrically or eccentrically

A numerical model simulating the behaviour of elliptical concrete-filled columns under either concentric or eccentric compressive load has been developed in ABAQUS. The numerical results have been compared against a range of experimental results for ultimate load, load–deflection behaviour and failure modes, with good agreement observed. An extensive parametric study has been undertaken whereby the slenderness, load eccentricity, cross-sectional geometry and reinforcement ratio of the concrete-filled columns were varied, creating a data set upon which to formulate design guidance since currently there are no specific provisions in the European Standard EN 1994-1-1 [1] for the design of concrete-filled steel elliptical section columns or beam-columns. It is shown that the current provisions of EN 1994-1-1 [1] for the design of concrete-filled steel columns of circular or rectangular cross-section are also appropriate for the design of members of elliptical cross-section, employing either buckling curve b or c, depending on the level of steel reinforcement. Finally, an assessment is made of the reliability of the design proposals for concrete-filled elliptical hollow section columns and beam-columns