The constitutive parameters required for determining the axial shortening of tall concrete building columns exhibit natural variability which, in turn, results in uncertainty in their use in deterministic predictive methods of analysis. This paper describes a Monte Carlo method of incorporating probabilistic constitutive information into a rigorous analytical procedure for obtaining the time-dependent axial deformations of columns. This is based on the well known creep and shrinkage model of Trost and Bazant. Deterministic analyses have been investigated by the authors previously, where the absolute and differential shortening values were determined for a number of major buildings. These shortenings are influenced by, amongst other things, the complex load history of a building during its construction cycle and consequently, the critical concrete properties are investigated in this context. This is useful since the constructability of tall buildings depends on differential shortening in particular. To this end the authors have developed a computer program which merges the construction sequence of a building with the probabilistic time-dependent material properties of the columns. The constitutive concrete model employed is derived from the American Concrete Institute (ACI) recommendations for creep and shrinkage. The analytical model of reinforced concrete column behaviour is based on the Trost-Bazant Age-Adjusted Effective Modulus Method (TBEMM). To illustrate the results of this work, an example is considered.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £68 +P&P)