International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 06 | June 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 4884 COMPARATIVE STUDY ON DIFFERENTIAL AXIAL SHORTENING IN TALL STRUCTURES USING ACI CODE AND EUROCODE-2 Krish A. Mandavia 1 , Prof. Deepak R. Tarachandani 2 1 Post Graduate Student, Applied Mechanics Department, L.D. College of Engineering, Ahmedabad, Gujarat, India 2 Associate Professor, Applied Mechanics Department, L.D. College of Engineering, Ahmedabad, Gujarat, India ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - With increasing height of structures, the effect of column shortening, both elastic and non-elastic, take on added significance and need distinct consideration in design and construction. Axial shortening in tall buildings would be of little concern if all vertical elements shorten equally. However, vertical members such as walls and columns may shorten in different amounts due to different service axial stress. Axial shortening depends on number of parameters such as type of concrete, environmental conditions, and the rate and sequence of construction. Thus, it’s a difficult task to determine the exact value of axial shortening. This study is concerned with predicting of differential axial shortening by comparing two standards: ACI 209R-92 and Eurocode-2 (British Standards) for tall structures with different number of stories (40,60 and 80). Also, the effect of parameters such as construction sequence, rate of loading and type of concrete are considered. The analysis of the structures is carried using ETABS and results obtained from this study gives idea about different effects of changing parameters for different standards. Key Words: Differential Axial Shortening (DAS), Construction Sequence, Creep and Shrinkage of Concrete, ETABS 1. INTRODUCTION In tall buildings, columns carry massive loads which effectively compress the column along its axis. This can be commonly referred to as ‘axial shortening’. Differential axial shortening (DAS) for gravity load bearing components in tall buildings is a phenomenon which was first noticed in the 1960’s with the use of concrete in combination with reinforcing steel in tall buildings. As buildings increased by height, elastic shortening became apparent during construction, and methods for correcting of instantaneous shortening such as construction of each floor to a corrected level or datum, became more common practice. The components of column shortening are the elastic shortening and the inelastic shortening due to creep and shrinkage. Analysis of column shortening may be viewed as an application of long‐term analysis of concrete structures. The method of quantification of axial shortening of reinforced concrete columns was originally introduced by Fintel and Khan (1969) and this method was further refined by Ghosh (1996). A widely used method for predicting column shortening in a tall building is the method proposed by Fintel et al. (1987) and published by Portland Cement Association (PCA). Reliable shrinkage and creep material models for concrete has been an area of research interest for many years and there are several well-established empirical relationships between these long-term strains and the various properties of concrete. Among them are several popular models with an increasing number of factors to be considered such as the B3 (Bazant and Baweja 2000) model and simple but popular models like the ACI 209, EC2 (BSI 2004) and GL2000 (Gardner and Lockman 2001) method. The time dependent strain components of concrete considered in these material models are as given in Table 1. Table 1. Components for Different Models Features ACI 209R EC-2 Basic Creep   Drying Creep   Autogenous Shrinkage   Drying Shrinkage   The main objective of research are 1. To predict the effects of differential shortening in tall buildings and addressing them through design and construction. 2. To provide guidelines by comparing different standards available to calculate time dependent properties. 2. MODELING IN SOFTWARE The following was applied to reach the above objectives: 1. The present study was carried out for 40-story building with moment resisting frame + shear wall core, 60-story building with outrigger system and tube system, each and 80-story building with outrigger system and tube system, each. 2. These structural systems were analyzed using ETABS (v17) software. Both elastic and inelastic shortening were calculated using sequential analysis.