Structural optimization and proposition of pre-sizing parameters for beams in reinforced concrete buildings

Medeiros, Guilherme Fleith de; Kripka, Moacir

doi:10.12989/cac.2013.11.3.253

Cited by 19 publications

(15 citation statements)

References 11 publications

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“…This work aims to minimize the cost of reinforced concrete building plane frames, taking into account the costs of steel, concrete and formworks. The developed formulation was adapted from previous studies regarding building grillage optimization [34] and columns optimization [35]. Preliminary results for plane frames without considering cardinality constraints were presented in [36].…”

Section: Formulation Of the Optimization Problemmentioning

confidence: 99%

“…Although beams reinforcement would be better represented as a discrete variable, as considered to columns, many research studies related to beams optimization assumed that treating the design variables as continuous leads to sufficiently accurate optimal results [37]. In addition, the compression reinforcement was not considered, based on former works of authors regarding grillage beams, which indicated that this consideration does not influence the optimum results [9,34].…”

Section: Design Variablesmentioning

confidence: 99%

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Optimization of reinforced concrete building frames with automated grouping of columns

Boscardin

Piqueras

Kripka

2019

Automation in Construction

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In structural design, it is common practice to adopt the same cross-section dimensions for a group of elements. This procedure is mainly for practical and aesthetic reasons, as well as to reduce labour costs, but it also has a positive effect of reducing the number of variables, which simplifies the usual trial and error design process. On the other hand, the total materials cost obtained is closely related to this grouping. Based on this, the present work aims to minimize the cost of reinforced concrete plane frames considering the automated grouping of columns. To achieve this objective, an optimization software was developed by the association of matrix structural analysis, dimensioning and optimization. The sections dimensions, the area of steel and the concrete strength of beams and columns were taken as design variables. For a given maximum number of groups, the optimum grouping and the corresponding values to design variables are obtained. The strategy proposed in this paper to obtain the grouping reduces significantly the number of infeasible candidate solutions during the search process and avoid the proposition of unrealistic designs. For the optimization, a variant of the Harmony Search method was adopted. Some structures were analyzed in order to validate the application of the proposed formulation, as well as to verify the influence of the grouping of elements on the final results. In these structures, it was possible to observe a significant additional reduction in the total cost when automated grouping is performed regarding a uniform grouping, even when a small number of groups is considered. For the 20floor building frame analyzed, the cost reduction from uniform to automated grouping varied from 5.53 to 7.35%. The influence of the concrete strength on optimal results was also investigated, indicating a cost reduction of 9.74% from best (40 MPa) to worst case (20 MPa). In general, it can be concluded that, when applied in conjunction with the usual design variables, the proposed procedure can enable a significant additional economy, without affecting the structural safety.

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Section: Formulation Of the Optimization Problemmentioning

confidence: 99%

Section: Design Variablesmentioning

confidence: 99%

Optimization of reinforced concrete building frames with automated grouping of columns

Boscardin

Piqueras

Kripka

2019

Automation in Construction

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“…In this way, the problem becomes less dependent on the initial solution (initial values assigned to the cross sections and nodal coordinates of the displaceable nodes). The same strategy was adopted successfully by the authors in previous works [7][8][9][10].…”

Section: Formulation Of the Optimization Problemmentioning

confidence: 98%

Geometric optimization of steel trusses with parallel chords

Kripka¹,

Drehmer²

2018

JCEMI

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The application of optimization to the solution of practical structural engineering problems has been very limited, despite the great development of the techniques. One of the main reasons for this is the complexity of the generated models, which employ nonlinear functions and generate a space of nonconvex solutions. In addition, most design variables, as in the case of steel profiles, can only assume discrete values. Traditional methods of mathematical programming are very limited in solving problems with these characteristics, opening space to the usage of heuristic methods and, more specifically, to metaheuristic methods. The main advantage of this class of methods is the fact that they only involve values of the functions in the optimization process, regardless of the existence of unimodality or even continuity in the derivatives of the functions involved. The present work presents the application of a heuristic method, the simulated annealing method, to the optimization of steel trusses with parallel chords, also called flat trusses. Initially, several usual configurations of trusses were analyzed, aiming to identify which led to the lowest cost. The top chord coordinates were also included as design variables, with the purpose of verifying the relations between span and height normally indicated in the literature as the most economical. Among the results, it was verified that the inclusion of the height of the truss among the design variables can lead to a significant additional cost savings.

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“…Optimization of reinforced concrete structures considering standard design constraints have been already studied in some papers from the literature [9], [13], [15], [19], [20]. In the context of the Brazilian design standard, some studies have also been developed, for example, Bordignon and Kripka [28], Medeiros and Kripka [29], [30], Kripka et al [31] and Correia et al [32]. However, there is a lack in studies that discuss the characteristics of the optimal structures found and their relationships with the design constraints.…”

Section: Introductionmentioning

confidence: 99%

Optimal configuration of RC frames considering ultimate and serviceability limit state constraints

Juliani

Gomes

2021

Rev. IBRACON Estrut. Mater.

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Most current structural design codes are based on the concept of limit states, that is, when a structure fails to meet one of its purposes, it is said that it has reached its limit state. In the design of reinforced concrete structures, the Ultimate Limit State (ULS) and the Serviceability Limit State (SLS) must be checked. Therefore, this paper presents an optimization scheme for reinforced concrete plane frames, in which the objective is to minimize the cost of structures for three cases of constraints: the first is related to ULS and SLS; the second refers only to the ULS; and the third is related only to the SLS. Computational routines for checking limit states of beams and columns are implemented in MATLAB, following the requirements of the Brazilian code. Structural analyses are performed by using the MASTAN2 software, taking into account geometric nonlinearities and a simplified physical nonlinearity method. The objective function considers the cost of concrete, reinforcement and formwork, and the optimization problems are solved by genetic algorithms. Two numerical examples of frames are presented. Regarding the optimal characteristics related to each type of limit state, it is noted that the beams and columns tend to have larger and more reinforced cross sections in the case of the ULS. Even so, optimal structures related to the ULS often do not satisfy SLS and vice versa, which indicates that the optimal characteristics related to each limit state may be different. In addition, it is observed that the SLS is less restrictive than ULS.

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Structural optimization and proposition of pre-sizing parameters for beams in reinforced concrete buildings

Cited by 19 publications

References 11 publications

Optimization of reinforced concrete building frames with automated grouping of columns

Optimization of reinforced concrete building frames with automated grouping of columns

Geometric optimization of steel trusses with parallel chords

Optimal configuration of RC frames considering ultimate and serviceability limit state constraints

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