SHORTENING OF VERTICAL ELEMENTS IN

HIGH-RISE BUILDINGS

Vertical structural elements are commonly subjected to the time-dependent behavior effects caused by creep which causes shortening in these elements in the direction of the load being applied. Significant amount of creep takes place instantaneously with loading and carries on for the long-term dimensions. In high-rise buildings, the axial shortening in columns is inevitable, so it cannot be ignored. The shortening is differential between vertical structural members due to the difference in axial stiffness and load distribution areas on these elements. Conventional structural analysis assumes that all structural loads are instantaneously applied to the entire completed structure. The construction sequence and loading sequence may be different depending on the construction plan. Therefore, the actual structural behavior can be significantly different from the conventional analytical behavior based on the above assumption. The objective of this study is to highlight the effect of concrete creep behavior on the shortening of vertical elements specifically in high-rise buildings. In this study, we will be considering the ACI 209R-92 model. Based on experimental data, a procedure is developed to compute the elastic shortening due to creep. A 250 meters high-rise is studied taking into consideration the stress and modulus of elasticity depending its construction time and height.