Performance‐based optimum seismic design of reinforced concrete structures

Abstract

SUMMARYA fully automated design methodology based on nonlinear response history analysis is proposed for the optimum seismic design of reinforced concrete (RC) structures. The conventional trial-and-error process is replaced by a structural optimization algorithm that serves as a search engine capable of locating the most efficient design in terms of cost and performance. Two variations of the proposed design methodology are introduced. The first approach treats the optimum design problem in a deterministic manner, while in the second variation the optimum design is sought in the framework of a reliability-based optimization problem. The reliability-based approach seems to be a more rational procedure since more meaningful design criteria that correlate better with the performance-based design concept can be adopted. Thus, the practice of using the mean annual frequency of a limit-state being exceeded to assess the candidate designs is compared with the use of deterministic criteria. Both formulations take into consideration the structural response for a number of limit-states, from serviceability to collapse prevention. The proposed design procedure is specifically tailored to the design of RC structures, where a preliminary design step of generating tables of concrete sections is introduced. In order to handle the large size of the tables, the concept of multi-database cascade optimization is implemented. The final design has to comply with the provisions of European design codes. The proposed methodology allows for a significant reduction of the direct construction cost combined with improved control of the seismic performance under earthquake loading.

Contribution to sustainable seismic design of reinforced concrete members through embodied CO2 emissions optimization

“…Transverse reinforcement spacing sc and/or sb take values between 80mm and 300m with a step of 20mm. Longitudinal bar diameters dbc, dbb take values from (12,14,16,18,20,25)mm and transversal bar diameters dbwc, and dbwb from (8,10,12)mm discrete values sets.…”

“…Early efforts to optimise earthquake resistant structures were based on traditional seismic design approaches. More recent studies investigate optimum performance-based seismic design (PBSD) methodologies that provide better control of structural damage [11][12][13][14]. The author [15] developed optimum seismic designs of RC frames according to traditional [16] and PBSD methodologies [17].…”

Yield frequency spectra and seismic design of code‐compatible RC structures: an illustrative example

“…Still, such approaches lacked a rigorous probabilistic basis until the emergence of the Cornell-Krawinkler framework [5], adopted by the Pacific Earthquake Engineering Research (PEER) Center. The latter provided a fertile platform for assessing losses, casualties and downtime, which was gradually expanded to be used for design (rather than just for assessment purposes) of buildings and bridges (e.g., [6][7][8]). …”

“…Thus, iterations are necessary, severely increasing the computational burden as each cycle involves a sequence of re-design and re-analysis, where the latter is a performance-based assessment employing nonlinear static or dynamic analysis procedures. To mitigate the adverse effects of iterations, several researchers introduced numerical optimization techniques in order to hasten converge (e.g., [7][8][9][10]). The aforementioned methods offer considerable gains in efficiency, yet their implementation is beyond the means of most design offices.…”

Rational Seismic Retrofitting of Rc Structures Based on Genetic Algorithms

“…More specifically, the paper outlines a Genetic Algorithm (GAs) inspired to the well-known Darwin's "evolution of species" and the assumption of the "survival of the fittest" rule [17]. Although some pioneering applications of these techniques are already available in the field of structural engineering, they are mainly restricted to the design of new structures [18]- [21]]. The following sections summarize the main aspects of the proposed genetic algorithm and its application in the rational design of retrofitting interventions.…”