TIME-DEPENDENT ANALYSIS AND DESIGN OF COMPOSITE COLUMNS

The instantaneous and time-dependent behavior of composite steelconcrete columns subjected to eccentric axial load is examined analytically. The age-adjusted effective modulus method is used for the analysis of individual cross sections to include the time-dependent effects of creep and shrinkage in the concrete. Cracking of the concrete is also included. An iterative procedure is described to successively adjust the secondary moments as the geometry of the column changes with time. Agreement between analytical results and experimental measurements is shown to be good. Finally, a design-oriented procedure is proposed for estimating the maximum acceptable service load on a slender, eccentrically loaded composite column. This approach uses a factored strength prediction developed elsewhere that is described in the paper. The design-oriented procedure may be implemented readily on a hand calculator. © ASCE.