Long-term axial shortening of the vertical elements of tall buildings results in differential movements between these two elements and may lead to the additional moments of connection beam and slab elements, and other secondary effects, such as cracks of partitions or curtain walls.
Thus, accurate prediction of time-dependent column shortening is essential for tall buildings from both strength and serviceability aspects.
In this study, the uncertainty associated with assumed values for concrete properties such as strength, creep and shrinkage coefficients has been considered for the prediction of time-dependent column shortening of tall concrete buildings.
The column shortening analysis using Monte Carlo method is proposed and an example 70 story tall concrete building is used for illustration. The histograms of column shortening by probability analysis are investigated and the differential column shortening between exterior column and interior shear wall considering confidence interval is predicted. The differential column shortening subsequent to the installation of slabs is investigated and compared with the result of deterministic approach. The results in this research are as follows.
1. It has been proven that the same value in estimating the column shortening can be obtained through the Monte Carlo approach as can be through the deterministic approach. The variability of the column shortening can be predicted through the stochastic approach.
2. The results obtained by the stochastic approach are almost the same as those done by the deterministic approach as the frequency of the simulation increases. The Monte Carlo results become more convergent with increased simulations.
3. The predicted value of the column shortening by Monte Carlo approach is evaluated at each confidence interval. As the width of the confidence interval expands, the elastic, creep, and shrinkage shortening of the interior wall increases 1.6%, 11.8%, and 22.9% respectively. The variability of the inelastic shortening is more important than that of elastic shortening.
4. The differential shortening subsequent to the slab installation inducing the additional stress increases from 1.36 up to 1.72 times as the width of the confidence interval expands. Therefore, in the design of the structural member, the additional stress according to the maximal differential shortening should be considered.