Influence of steel reinforcements on the behavior of compressed high strength R.C. circular columns

In the present paper the focus is on the compressive response of short high strength reinforced concrete members having circular transverse cross-sections and reinforced with longitudinal steel bars and transverse spirals or hoops. An analytical model is proposed which allows one to estimate the confinement pressures exerted by transverse steel and by longitudinal bars during the loading process, taking into account the interaction of the hoops or spirals with the inner core both in the plane of the transverse steel and in the space between two successive hoops. Yielding of steel spirals or hoops and longitudinal bars including buckling phenomena and damage to the concrete core are also considered by means of variation in the elastic modulus and in the Poisson’s coefficient. The proposed mechanical model is able to reproduce the load-shortening curves of compressed members; it gives good agreement with several experimental data and with analytical results obtained by using other recent models available in the literature.