Study of Creep, Shrinkage and Column Shortening on Behavior of High-Rise Buildings

Abstract

Axial shortening of columns affect the behavior of high-rise buildings. Differential axial shortening in the building structures causes axial force redistribution among columns and core walls and introduces additional forces in the horizontal members such as beams and slabs. Elastic as well as inelastic shortening of columns due to creep and shrinkage contributes a lot towards the axial shortening of columns and hence it need to be considered in the design and construction of medium to high- rise buildings. These effects increase with the height of the building and irregularity in vertical load paths resulting from geometric irregularity and complexity. General building codes do not give specific guidelines about consideration of differential col- umn shortening. Consequently, column shortening is usually left to the judgment of structural engineers. Analytical and experimental procedures available to quantify the magnitude of col- umn shortening effects are limited to a very few parameters and are not adequate to capture the complexity of nonlinear time dependent material response. A present study is carried out to develop the understandings of the column shortening behavior in reinforced concrete buildings. Parametric study is conducted to understand the in uence of controlling parameters such as material properties, structural element sizes, construction sequence and rate, environmental conditions and structural systems. For studying effect of axial shorten- ing, ETABS and MIDAS Gen software are used. Buildings with different structural systems like rigid frame structure and wall frame structure with different number of story are considered in the study. Generally, column shortening developed due to construction stages along with time dependent material properties and environmental conditions affect the design of beams and columns of mid height stories in high-rise buildings.