Title: Estimation of Long Term Vertical Shortening of Tall Structures

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Publication: CIA

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Date: 2/14/2011

Abstract:
Design of high rise buildings challenges the engineer in terms of combining advanced methods of analysis and construction, the use of high performance materials and technologies to deliver an efficient and sustainable structure. Among these challenges is the estimation of the effect of elastic, creep and shrinkage shortening on vertical elements that are subjected to significant loads during construction and service stage. The magnitude of the vertical deformation and relative deformation of different vertical elements can negatively affect horizontal structural elements like beams, slabs and outrigger elements integrity of the services, façade, and, if not properly dealt with, induce extra unaccounted stresses into walls and foundations. One of the main difficulties for the designer is correlating the dynamic nature of the construction process with the accurate estimation over a significant time period of the elastic and long term axial deformation of vertical reinforced concrete elements, like columns and walls. The paper aimed to provide a design method for calculating the total and differential long term shortening between composite steel and high-strength concrete tower columns and reinforced high strength concrete core walls. A design case study on Dubai Tower Doha, a 438 m tall building currently under construction in Doha, Qatar, is presented.