Evolutionary Aseismic Design and Retrofit of Buildings

Scientia Iranica, 2010

In this paper, the performance of semi-active viscous dampers in reducing the response of tall buildings to earthquake acceleration is optimized using genetic algorithms. Torsional e ects due to irregularities exist in the building and due to unsymmetrical placement of the dampers are taken into account through 3-D modeling of the building. For the numerical example, a twelve-story building is chosen. The building is modeled as a 3-D frame. The equations of motion of the building with semi-active viscous dampers, subjected to earthquake acceleration, is written, resolved in state space and the results are compared with those of the uncontrolled building. Moreover, in order to minimize building responses such as top story displacement and base shear, the required number and location of dampers are optimized using genetic algorithms.

2012

As more and more complex and sophisticated hardware and software tools are available, complex problems described by consistent mathematical models are successfully approached by numerical simulation: modelling and simulation are present at almost each level in education, research, and production. Numerical "experiments" have predictive value, and complement physical experiments. They are unique in providing valuable insights in Gedankenexperiment-class (thought experiment) investigations. This chapter presents numerical simulation results related to a structural optimization problem that arises in systems with gradients and fluxes. Although the discussion concerns the optimal electrical design of photovoltaic systems, it may be extended to a larger class of applications in electrical and mechanical engineering: diffusion and conduction problems. The first concern in simulation is the proper formulation of the physical model of the system under investigation that should lead to consistent mathematical models, or well-posed problems (in Hadamard sense) (Morega, 1998). When available, analytic solutions-even for simplified mathematical models-may outline useful insights into the physics of the processes, and may also help deciding the numerical approach to the solution to more realistic models for the systems under investigation. Homemade and third party simulation tools are equally useful as long as they are available and provide for accurate solutions. Recent technological progresses brought into attention the Spherical PhotoVoltaic Cells (SPVC), known for their capability of capturing light three-dimensionally not only from direct sunlight but also as diffuse light scattered by the clouds or reflected by the buildings. This chapter reports the structural optimization of several types of spherical photovoltaic cells (SPVC) by applying the constructal principle to the minimization of their electrical series resistance. A numerically assisted step-by-step construction of optimal, minimum series resistance SPVC ensembles, from the smallest cell (called elemental) to the largest assembly that relies on the minimization of the maximum voltage drop subject to volume (material) constraints is presented. In this completely deterministic approach the SPVC ensembles shapes and structures are the outcome of the optimization of a volume to point access problem imposed as a design request. Specific to the constructal theory, the optimal shape (geometry) and structure of both natural and engineered systems are morphed out of their functionality and resources, and of the constraints to which they are subject.

Scientia Iranica, 2013

Tuned Mass Dampers (TMDs) are a well-accepted control device widely used by the civil engineering community. The main purpose of this study is the robust multi-objective optimization design of this device using Genetic Algorithms (GAs) to control the structural vibrations against earthquakes. To enhance the performance of the TMD system, its parameters, including mass, stiffness, and damping ratio, have been optimally designed using multi-objective genetic algorithms. For doing this, three noncommensurable objective functions, namely: maximum displacement, maximum velocity, and maximum acceleration of each floor, are considered, which are to be minimized simultaneously. For this purpose, a fast and elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) approach is used to find a set of Paretooptimal solutions. Moreover, in order to take into account the uncertainties existing in the system, a robust design optimization procedure is performed using the Hammersley sequence sampling approach. In this study, the example building is modeled as a 3-D frame, and its responses are evaluated using coupled multi-mode analysis. From the numerical results of the study, it is found that the robust TMD system is capable of providing a reduction of about 28% on maximum displacement of the building.

Computational Optimization and Applications, 2023

An innovative strategy for an optimal design of planar frames able to resist seismic excitations is proposed. The optimal design is performed considering the cross sections of beams and columns as design variables. The procedure is based on genetic algorithms (GA) that are performed according to a nested structure suitable to be implemented in parallel on several computing devices. In particular, this bi-level optimization involves two nested genetic algorithms. The first external one seeks the size of the structural elements of the frame which corresponds to the most performing solution associated with the highest value of an appropriate fitness function. The latter function takes into account, among other considerations, the seismic safety factor and the failure mode that are calculated by means of the second internal algorithm. The proposed procedure aims at representing a prompt performancebased design procedure which observes earthquake engineering principles, that is displacement capacity and energy dissipation, although based on a limit analysis, thus avoiding the need of performing cumbersome nonlinear analyses. The details of the proposed procedure are provided and applications to the seismic design of two frames of different size are described.

Journal of Computing and Information Science in Engineering, 2001

This article presents an overview of the state-of-the art in modeling and simulation, and studies to which extent current simulation technologies can effectively support the design process. For simulation-based design, modeling languages and simulation environments must take into account the special characteristics of the design process. For instance, languages should allow models to be easily updated and extended to accommodate the various analyses performed throughout the design process. Furthermore, the simulation software should be well integrated with the design tools so that designers and analysts with expertise in different domains can effectively collaborate on the design of complex artifacts. This review focuses in particular on modeling for design of multi-disciplinary engineering systems that combine continuous time and discrete time phenomena.

Mathematics

The continuing achievements in Information Technology and Computer science in recent decades provide new tools for engineers in the design of devices and systems, with significant advances both in numerical and in analytical methods of analysis [...]

Proceedings of the 34th Annual Conference of the Association for Computer Aided Design in Architecture (ACADIA)

Vulnerability, Uncertainty, and Risk, 2014

An efficient robust design optimization (RBO) framework is developed for linear multi-degree-of-freedom (MDOF) structural systems subject to evolutionary stochastic earthquake excitations. A significant feature of the developed RBO framework relates to the consideration of both inter-storey drift and floor acceleration second order statistics as performance measures. Further, an efficient frequency domain approach is utilized for determining the system response Evolutionary Power Spectrum (EPS) matrix circumventing computationally intensive Monte Carlo simulations. Furthermore, the optimization problem is solved by employing a Genetic Algorithm based approach. An illustrative numerical example is included to demonstrate the efficiency and robustness of the proposed framework.

In this paper, the dynamic response of an isolated structure supported by lead rubber bearings is studied. The isolated building is modeled using finite element software. Each bearing is modeled using its yield force, elastic stiffness and plastic stiffness. The main objective of the paper is to find the optimal parameters of the base isolation system using genetic algorithms in order to minimize the displacement of the building. In order to minimize the objective function an elitist non-dominated sorting genetic algorithm is employed. The study focuses on a 10 story concrete structure rehabilitated according to new design prescriptions. The optimal distribution is determined using nonlinear time history analysis and three earthquakes pertinent to the Vrancea source.

Engineering Structures, 2019

This study aims to improve the computational efficiency and convergence rate of an already existing optimisation method for friction-based dampers based on the concept of Uniform Distribution of Deformation (UDD) and demonstrate the reliability of the results compared to Heuristic optimisation methods such as GA. In the proposed approach, the computational cost is considerably reduced by using a convergence factor that is modified in proportion to the level of performance violation. To investigate the efficiency of the proposed method, 3, 5 and 10-storey RC frames with friction dampers are optimised using adaptive UDD method, Genetic Algorithm (GA) and a coupled UDD-GA approach. The results indicate that the adaptive UDD method can lead to optimum design solutions with significantly lower computational costs (up to 300 times lower number of non-linear dynamic analyses) compared to both GA and coupled UDD-GA methods. It is shown that frames optimised under a under a single spectrum-compatible earthquake can efficiently satisfy the predefined performance targets under a set of synthetic earthquakes representing the design spectrum. Therefore, the proposed method should provide a reliable approach for more efficient design of friction-based dampers.