Eventos Anais de eventos
MecSol 2017
6th International Symposium on Solid Mechanics
INFLUENCE OF LIMIT STATES ON THE OPTIMIZATION OF REINFORCED CONCRETE BEAMS
Submission Author:
Marcela Alejandra Juliani , SC
Co-Authors:
Wellison Gomes
Presenter: Marcela Alejandra Juliani
doi://10.26678/ABCM.MecSol2017.MSL17-0018
Abstract
Most current structural design codes are based on the concept of limit states, that is, when a structural element fails to meet one of its purposes, it is said that it has reached its limit state. According to the Brazilian code ABNT NBR 6118:2014, in the design of reinforced concrete structures, the following limit states must be checked: A. Ultimate Limit State (ULS), related to collapse or any other way of structural ruin that results in the discontinuation of the structure use; B. Serviceability Limit State (SLS), related to the structures durability, appearance and performance and comfort of the user. However, there are not many studies in the literature that point out the influence of such limit states on the optimal design of a structural element. In view of this, this paper presents an optimization scheme for reinforced concrete structures, based on the lowest cost, considering two groups of constraints: the first is related to the ULS and the second to the SLS. The optimal characteristics of a structural element subject to each group of constraints, individually, as well as to both groups simultaneously, are discussed. The methodology is applied to simply supported beams using genetic algorithms to solve the optimization problem, since this problem involves several local minima. The objective function employed corresponds to the cost of the structural element, which includes the consumption of concrete, steel and formwork. The limit states are formulated according to the recommendations of the ABNT NBR 6118:2014. As a result, predominant characteristics were observed in the optimal sections, according to the limit states: for ULS, the sections presented more steel reinforcement; in the SLS predominance of concrete occurred; in ULS+SLS the optimal factors remained within the limit formed by ULS and SLS.
Keywords
Optimization, reinforced concrete, limit states, genetic algorithm
