This paper discusses several possible ways to evaluate reinforced concrete frames designed for multiple floor buildings using flat slabs, from the standpoint of instability and second-order loads. Based on floor designs with simple flat slab frames and regular distribution of columns, models with different numbers of floors are considered. The models do not involve highly rigid elements such as staircases and elevator shafts. The modeling adopts simplified criteria to design vertical loads, forming frames with slab bands representing beams of little height. Based on the results, an analysis is made of the validity of the application of the criteria without considering the second-order loads presented in the NBR6118:2003 code. A comparison is also made of the results with and without the use of inverted edge beams.
instability; second-order loads; flat slabs