An Inelastic Beam Element with Hysteretic Damping

In this work, an inelastic beam macro-element that incorporates hysteretic damping is presented. Based on classical theory of plasticity, a Bouc-Wen type model is utilized that simulates the hysteretic behavior of an inelastic spring element. Using this model, an inelastic nonlinear beam element is formulated based on the appropriate combination of two coupled nonlinear spring elements. The equations of motion are determined and are cast in a state-space form for the vector of the end displacements, velocities and hysteretic forces. The system is solved by employing a Runge-Kutta type of algorithm. The proposed inelastic beam model is then employed to simulate the experimental dynamic behavior of steel beams. The model parameters are estimated with the aid of a nonlinear system identification algorithm using existing experimental data. The proposed element approximates the inelastic behavior of steel beams adequately within plastic regions that do not undergo substantial stiffness degradation, or other relevant phenomena. Finally, the hysteretic damping features of the model are demonstrated

Self-adaptive randomized and rank-based differential evolution for multimodal problems

Differential evolution, Cauchy distribution, Ranking, Randomization, Optimization,

Multi-objective optimization design of bridge piers with hybrid heuristic algorithms

This paper describes one approach to the design of reinforced concrete (RC) bridge piers, using a three-hybrid multiobjective simulated annealing (SA) algorithm with a neighborhood move based on the mutation operator from the genetic algorithms (GAs), namely MOSAMO1, MOSAMO2 and MOSAMO3. The procedure is applied to three objective functions: the economic cost, the reinforcing steel congestion and the embedded CO2 emissions. Additional results for a random walk and a descent local search multi-objective algorithm are presented. The evaluation of solutions follows the Spanish Code for structural concrete. The methodology was applied to a typical bridge pier of 23.97 m in height. This example involved 110 design variables. Results indicate that algorithm MOSAMO2 outperforms other algorithms regarding the definition of Pareto fronts. Further, the proposed procedure will help structural engineers to enhance their bridge pier designs. © Zhejiang University and Springer-Verlag Berlin Heidelberg 2012.Project supported by the Spanish Ministry of Science and Innovation (No. BIA2011-23602), and the European Community with the European Regional Development Fund (FEDER), SpainMartínez Martín, FJ.; González Vidosa, F.; Hospitaler Pérez, A.; Yepes Piqueras, V. (2012). Multi-objective optimization design of bridge piers with hybrid heuristic algorithms. Journal of Zhejiang University Science A. 13(6):420-432. https://doi.org/10.1631/jzus.A1100304S42043213