Harmony search based, improved Particle Swarm Optimizer for minimum cost design of semi-rigid steel frames

Hadidi, Ali,Rafiee, Amin Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.3

This paper proposes a Particle Swarm Optimization (PSO) algorithm, which is improved by making use of the Harmony Search (HS) approach and called HS-PSO algorithm. A computer code is developed for optimal sizing design of non-linear steel frames with various semi-rigid and rigid beam-to-column connections based on the HS-PSO algorithm. The developed code selects suitable sections for beams and columns, from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange W-shapes, such that the minimum total cost, which comprises total member plus connection costs, is obtained. Stress and displacement constraints of AISC-LRFD code together with the size constraints are imposed on the frame in the optimal design procedure. The nonlinear moment-rotation behavior of connections is modeled using the Frye-Morris polynomial model. Moreover, the P-${\Delta}$ effects of beam-column members are taken into account in the non-linear structural analysis. Three benchmark design examples with several types of connections are presented and the results are compared with those of standard PSO and of other researches as well. The comparison shows that the proposed HS-PSO algorithm performs better both than the PSO and the Big Bang-Big Crunch (BB-BC) methods.

On the progressive collapse resistant optimal seismic design of steel frames

Amin Rafiee,Ali Hadidi,Ramin Jasour 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.5

Design of safe structures with resistance to progressive collapse is of paramount importance in structural engineering. In this paper, an efficient optimization technique is used for optimal design of steel moment frames subjected to progressive collapse. Seismic design specifications of AISC-LRFD code together with progressive collapse provisions of UFC are considered as the optimization constraints. Linear static, nonlinear static and nonlinear dynamic analysis procedures of alternate path method of UFC are considered in design process. Three design examples are solved and the results are discussed. Results show that frames, which are designed solely considering the AISC-LRFD limitations, cannot resist progressive collapse, in terms of UFC requirements. Moreover, although the linear static analysis procedure needs the least computational cost with compared to the other two procedures, is the most conservative one and results in heaviest frame designs against progressive collapse. By comparing the results of this work with those reported in literature, it is also shown that the optimization technique used in this paper significantly reduces the required computational effort for design. In addition, the effect of the use of connections with high plastic rotational capacity is investigated, whose results show that lighter designs with resistance to progressive collapse can be obtained by using Side Plate connections in steel frames.

A new Hybrid Algorithm for Simultaneous Size and Semi-rigid Connection Type Optimization of Steel Frames

Ali Hadidi,Amin Rafiee 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.1

A hybrid algorithm based on Harmony Search (HS) and Big Bang-Big Crunch (BB-BC) optimization methods is proposedfor optimal design of semi-rigid steel frames. The algorithm selects suitable sections for beams and columns and assignssuitable semi-rigid connection types for beam-to-column connections, such that the total member plus connection cost of theframe, is minimized. Stress and displacement constraints of AISC-LRFD code together with the size constraints are imposedon the frame in the design procedure. The nonlinear moment-rotation behavior of connections and P-Δ effects of beam-columnmembers are taken into account in the non-linear structural analysis. Three benchmark steel frames are designed and the resultsare compared with those of standard BB-BC and of other studies. The comparisons demonstrate that proposed algorithmperforms better than standard BB-BC and HS methods in all examples and that the total cost of a frame can be reduced throughsuitable selection of its beam-to-column connection types.

Harmony search based, improved Particle Swarm Optimizer for minimum cost design of semi-rigid steel frames

Ali Hadidi,Amin Rafiee 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.3

This paper proposes a Particle Swarm Optimization (PSO) algorithm, which is improved by making use of the Harmony Search (HS) approach and called HS-PSO algorithm. A computer code is developed for optimal sizing design of non-linear steel frames with various semi-rigid and rigid beam-tocolumn connections based on the HS-PSO algorithm. The developed code selects suitable sections for beams and columns, from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange W-shapes, such that the minimum total cost, which comprises total member plus connection costs, is obtained. Stress and displacement constraints of AISC-LRFD code together with the size constraints are imposed on the frame in the optimal design procedure. The nonlinear moment-rotation behavior of connections is modeled using the Frye-Morris polynomial model. Moreover, the P-Δ effects of beam-column members are taken into account in the non-linear structural analysis. Three benchmark design examples with several types of connections are presented and the results are compared with those of standard PSO and of other researches as well. The comparison shows that the proposed HS-PSO algorithm performs better both than the PSO and the Big Bang-Big Crunch (BB-BC) methods.

Robust decentralized control of structures using the LMI H_∞controller with uncertainties

Raji, Roya,Hadidi, Ali,Ghaffarzadeh, Hosein,Safari, Amin Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.5

This paper investigates the operation of the $H_{\infty}$ static output-feedback controller to reduce dynamic responses under seismic excitation on the five-story and benchmark 20 story building with parametric uncertainties. Linear matrix inequality (LMI) control theory is applied in this system and then to achieve the desired LMI formulations, some transformations of the LMI variables is used. Conversely uncertainties due to material properties, environmental loads such as earthquake and wind hazards make the uncertain system. This problem and its effects are studied in this research. Also to decrease the transition of large amount of data between sensors and controller, avoiding the disruption of whole control system and economy problems, the operation of the decentralized controllers is investigated in this paper. For this purpose the comparison between the performance of the centralized, fully decentralized and partial decentralized controllers in uncoupled and coupled cases is performed. Also, the effect of the changing the number of stories in substructures is considered. Based on the numerical results, the used control algorithm is very robust against the parametric uncertainties and structural responses are decreased considerably in all the control cases but partial decentralized controller in coupled form gets the closest results to the centralized case. The results indicate the high applicability of the used control algorithm in the tall shear buildings to reduce the structural responses and its robustness against the uncertainties.

Robust decentralized control of structures using the LMI H_∞controller with uncertainties

Roya Raji,Ali Hadidi,Hosein Ghaffarzadeh,Amin Safari 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.5

This paper investigates the operation of the H_∞ static output-feedback controller to reduce dynamic responses under seismic excitation on the five-story and benchmark 20 story building with parametric uncertainties. Linear matrix inequality (LMI) control theory is applied in this system and then to achieve the desired LMI formulations, some transformations of the LMI variables is used. Conversely uncertainties due to material properties, environmental loads such as earthquake and wind hazards make the uncertain system. This problem and its effects are studied in this research. Also to decrease the transition of large amount of data between sensors and controller, avoiding the disruption of whole control system and economy problems, the operation of the decentralized controllers is investigated in this paper. For this purpose the comparison between the performance of the centralized, fully decentralized and partial decentralized controllers in uncoupled and coupled cases is performed. Also, the effect of the changing the number of stories in substructures is considered. Based on the numerical results, the used control algorithm is very robust against the parametric uncertainties and structural responses are decreased considerably in all the control cases but partial decentralized controller in coupled form gets the closest results to the centralized case. The results indicate the high applicability of the used control algorithm in the tall shear buildings to reduce the structural responses and its robustness against the uncertainties.

An efficient simulation method for reliability analysis of systems with expensive-to-evaluate performance functions

Bahman Farahmand Azar,Ali Hadidi,Amin Rafiee 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.5

This paper proposes a novel reliability analysis method which computes reliability index, most probable point and probability of failure of uncertain systems more efficiently and accurately with compared to Monte Carlo, first-order reliability and response surface methods. It consists of Initial and Simulation steps. In Initial step, a number of space-filling designs are selected throughout the variables space, and then in Simulation step, performances of most of samples are estimated via interpolation using the space-filling designs, and only for a small number of the samples actual performance function is used for evaluation. In better words, doing so, we use a simple interpolation function called “reduced” function instead of the actual expensive-to-evaluate performance function of the system to evaluate most of samples. By using such a reduced function, total number of evaluations of actual performance is significantly reduced; hence, the method can be called Reduced Function Evaluations method. Reliabilities of six examples including series and parallel systems with multiple failure modes with truncated and/or non-truncated random variables are analyzed to demonstrate efficiency, accuracy and robustness of proposed method. In addition, a reliabilitybased design optimization algorithm is proposed and an example is solved to show its good performance.

Heat transfer in a turbulent jet impinging on a moving plate considering high plate-to-jet velocity ratios

Mohammad Aghahani,Ghiyam Eslami,Amin Hadidi 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

In this paper, heat transfer characteristics of a turbulent slot jet impinging orthogonally on an isothermal moving hot plate is studiednumerically. The governing equations were discretized using the finite volume method and theu 2 - f turbulence model was employedfor turbulence modeling. The effect of the jet Reynolds number and the plate-to-jet velocity ratio (R) on the Nusselt were investigated. Despite of most previous studies, which have been restricted to R≤2, in the present research higher values of R, also were considered(0≤R≤6). Range of studied jet Reynolds number was between 3000 and 60000. The results indicate that at a fixed plate-to-jet velocityratio increment of the Reynolds number leads to the enhancement of the average Nusselt number. For each Reynolds number, the averageNusselt number reduces with increasing the plate-to-jet velocity ratio until it becomes minimum at R = 1.25. For R>1.25 trendchanges so that these parameters increase. In addition, it was found that only for R>2.5 the average Nusselt number is improved due tothe plate motion in comparison with the stationary jet. The results are validated against available experimental data, showing goodagreement.

Effects of uniform magnetic field on the interaction of side-by-side rising bubbles in a viscous liquid

Davood Jalali-Vahid,Amin Hadidi 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.3

Effects of uniform magnetic fields on the interaction and coalescence of side-by-side rising bubbles of dielectric fluids were not studied; so in the present research, effects of different strengths of uniform magnetic field on the interaction of two bubbles rising side by side in a viscous and initially stagnant liquid are studied, numerically. For numerical modeling of the problem, a full computer code was developed to solve the governing equations which are continuity, Navier-Stokes, magnetic field and interface capturing equations which are level set and re-initialization equations. The finite volume method is used for the discretization of the hydrodynamic equations where the finite difference method is used to discretization of the magnetic field equations. The results are compared with available numerical and experimental results which show a good agreement. It is found that the uniform magnetic field can be used for contactless control of side-by-side coalescence of bubbles.