Column shortening of concrete cores and composite columns in a tall building

The effect of column shortening is a major consideration in the design and construction of tall buildings, especially in concrete and composite structural systems. The method presented in the PCA report is the most widely used for the analysis of column shortening, but results can be very different depending on the time function of shrinkage suggested by ACI, CEB‐FIP and PCA. To determine which method is most appropriate, this paper presents predicted and measured shortenings of two reinforced concrete core walls and four steel‐embedded concrete columns in a 69‐storey building. The results show that the measured strains of both core walls and composite columns are more consistent with calculated strains using the shrinkage time functions of CEB‐FIP and PCA rather than of ACI. The results also indicate that further studies are needed on the effect of high steel ratio on the development of column shortening when composite columns of a building have much higher steel ratios than usual. Copyright © 2005 John Wiley & Sons, Ltd.