A major difficulty in formulating a finite element for shear-deformable beams, plates, and shells is the shear locking phenomenon. A recently proposed general technique to overcome this difficulty is the discrete shear gap (DSG) technique. In this study, the DSG technique was applied to the linear, quadratic, and cubic Timoshenko beam elements. With this technique, the displacement-based shear strain field was replaced with a substitute shear strain field obtained from the derivative of the interpolated shear gap. A series of numerical tests were conducted to assess the elements performance. The results showed that the DSG technique works perfectly to eliminate the shear locking. The resulting deflection, rotation, bending moment, and shear force distributions were very accurate and converged optimally to the corresponding analytical solutions. Thus the beam elements with the DSG technique are better alternatives than those with the classical selective-reduced integration.
Symbiotic organisms search (SOS) is a simple yet effective metaheuristic algorithm to solve a wide variety of optimization problems. Many studies have been carried out to improve the performance of the SOS algorithm. This research proposes an improved version of the SOS algorithm called the "enhanced symbiotic organisms search" (ESOS) for global numerical optimization. The conventional SOS is modified by implementing a new searching formula into the parasitism phase to produce a better searching capability. The performance of the ESOS is verified using 26 benchmark functions and one structural engineering design problem. The results are then compared with existing metaheuristic optimization methods. The obtained results show that the ESOS gives a competitive and effective performance for global numerical optimization.
AbstrakPenelitian ini menyelidiki metode metaheuristik baru bernama symbiotic organisms search (SOS) dalam mengoptimasi ukuran penampang rangka batang baja. Syarat batasan desain diadopsi dari spesifikasi untuk bangunan gedung baja struktural, SNI 1729:2015, yaitu rasio gaya terhadap kapasitas dan rasio kelangsingan batang. Lima studi kasus optimasi struktur rangka batang digunakan untuk menguji performa dari SOS. Hasil simulasi dengan metode SOS ini kemudian akan dibandingkan terhadap tiga metode metaheuristik lainnya, yaitu particle swarm optimization, differential evolution, dan teaching-learning-based optimization. Hasil penelitian menunjukkan bahwa algoritma SOS lebih superior dan mempunyai kemampuan konvergensi yang lebih baik dibandingkan dengan metode metaheuristik lainnya dalam menyelesaikan problem optimasi struktur rangka batang.Kata-kata Kunci: Rangka batang, optimasi, metaheuristik, SNI 1729:2015, symbiotic organisms search.
AbstractThis study investigates a new metaheuristic method called symbiotic organisms search (SOS) for sizing optimization of steel truss structures. The design constraints are adopted from SNI 1729:2015 Indonesian code specification for structural steel buildings that includes the constraints on slenderness ratio and force capacity. Five practical case studies of truss design are employed to test the performance of the SOS algorithm. The simulation results of the SOS are compared to other metaheuristic methods, namely, the particle swarm optimization, differential evolution, and teaching-learning-based optimization, in terms of accuracy and consistency. The results show the superiority of the SOS as well as excellent convergence behavior over the other metaheuristic algorithms in solving the truss structure optimization problems.
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