Title: Refining Differential Shortening Predictions In Tall Buildings For Improved Serviceability

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Publication: CIA

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Date: 2/13/2011

Abstract:
High strength concrete (HSC) or high performance concrete (HPC) is commonly used in vertical elements of tall buildings. Such material can provide reduced column cross-sectional areas and generally increase the functional efficiency of the structure. Vertical concrete elements axially shorten over time due to shrinkage effects, creep and elastic deformation. Models that are currently used to predict shortening generally use concrete strength (f’c) and derived values for concrete creep, elastic modulus and drying shrinkage. Much of the work in this area is theoretical. As materials used for concrete manufacture vary significantly across Australia, typical or generally derived values for various mechanical properties can be significantly different depending on where a building is to be constructed. For these reasons, estimations of shortening based solely on f’c and general values for concrete material properties may lead to inaccurate prediction and thereby potentially reduce serviceability. This paper presents a summary of research work currently under way on verifying model predictions of differential shortening in tall buildings.