Analysis of instability of tall buildings with prestressed and waffle slabs

The construction system of prestressed flat slabs has been gaining market in Brazil, since it eliminates the use of beams, allows you to perform structures under coluns by area and reduces the cycle of concrete slabs. Thus the analysis of global stability of buildings, takes into account the effects of 2nd order, and these additional effects to the structure obtained from the deformation thereof, calculated by the iterative method P-Delta. The Brazilian ABNT NBR 6118: 2014 [2] assesses the overall stability of reinforced concrete structures through practical parameters, which are the parameter a (Alpha) and gz (Gamma z) coefficient. In this research we seek to study the global stability of slender buildings consist of flat slabs, with slenderness (ratio of the smaller width with the height of the building) approximately one to six, from the modeling of a building with prestressed slabs nonadherent and waffle slabs. To model will use the commercial software CAD / TQS.