Investigating the Location of an Outrigger System to Reach the Highest Effectiveness in Reducing Uneven Shortening Deformation of Columns in High-rise Reinforced Concrete Buildings

Shortening reinforced concrete columns helps to considerably increase internal forces for girder structures in high-rise buildings. However, it is necessary to locate the outrigger system to reach the highest effectiveness in reducing the uneven shortening of columns, which is currently a matter of concern. This article examines the position to place the outrigger system in line with the height of a building in order to yield the highest effectiveness in reducing internal forces that may arise due to uneven deformation of columns and walls. The difference between columns and walls in shortening results from creep and elasticity in conformity with the regulations of the ACI 209R - 92 (1997) code. This process happens in the flow of time and consists of the construction stage and the operation stage. An example of a 30-storey building shows the effect of uneven shortening on the internal forces in girders, thereby proving that the position of the outrigger system exerts noticeable influence on the task of overcoming the above phenomenon