Total potential energy optimization with metaheuristic methods (TPO/MA) adalah metode analisis struktur yang berdasarkan pada prinsip energi minimum. Metode ini dapat melakukan analisis non-linear pada berbagai struktur tanpa modifikasi yang signifikan dalam prosesnya. Salah satu struktur yang bersifat sangat non-linear adalah struktur tensegrity. TPO/MA dengan tiga algoritma metaheuristik yaitu teaching–learning-based optimization (TLBO), harmony search (HS), dan symbiotic organisms search (SOS) diaplikasikan dalam analisis non-linear geometri pada struktur tensegrity dua dan tiga dimensi. Analisis struktur dilakukan dengan pemberian beban bertahap (incremental) untuk menghasilkan grafik load-displacement yang menunjukkan perilaku non-linear struktur. Hasil penelitian menunjukkan TPO/MA dapat melakukan analisis non-linear pada struktur tensegrity dengan akurasi dan konsistensi yang tinggi. TLBO dan SOS memiliki performa yang lebih baik dibandingkan HS dalam menyelesaikan analisis non-linear pada struktur tensegrity menggunakan TPO/MA.

This study introduces an improved artificial intelligence (AI) approach called intelligence optimized support vector regression (IO-SVR) for estimating the compressive strength of high-performance concrete (HPC). The nonlinear functional mapping between the HPC materials and compressive strength is conducted using the AI approach. A dataset with 1,030 HPC experimental tests is used to train and validate the prediction model. Depending on the results of the experiments, the forecast outcomes of the IO-SVR model are of a much higher quality compared to the outcomes of other AI approaches. Additionally, because of the high-quality learning capabilities, the IO-SVR is highly recommended for calculating HPC strength.

Kriging-based finite element method (K-FEM) is an enhancement of the conventional finite element method using a Kriging interpolation as the trial solution in place of a polynomial function. In the application of the K-FEM to the Timoshenko beam model, the discrete shear gap (DSG) technique has been employed to overcome the shear locking difficulty. However, the applied DSG was only effective for the Kriging-based beam element with a cubic basis and three element-layer domain of influencing nodes. Therefore, this research examines a modified implementation of the DSG by changing the substitute DSG field from the Kriging-based interpolation to linear interpolation of the shear gaps at the element nodes. The results show that the improved elements of any polynomial degree are free from shear locking. Furthermore, the results of beam deflection, cross-section rotation, and bending moment are very accurate, while the shear force field is piecewise constant.

A development of Kriging-based finite elements method has been carried out by implementing the MITC3+ plate elements for modeling the plate structure. The MITC3+ element used is a development of the MITC3 element whose performance is considered quite good and can overcome problems that arise in the application of conventional Kriging-based finite elements, one of which is the shear-locking. The application of Kriging interpolation on MITC3+ elements is carried out with the Kriging shape function formulation in the formation of the bending stiffness matrix only. The elements are then tested with various benchmark problems such as Patch Test, hard clamped square plate, Rhombic Plate, and its ability to solve complex-shaped plates. The results showed that the MITC3+ was able to avoid the shear-locking mechanism and also produce an accurate solution. However, it appears there is an inconsistent convergence pattern on the Patch Test and Rhombic Plate.

Torsional problems commonly arise in frame structural members subjected to unsym­metrical loading. Saint-Venant proposed a semi inverse method to develop the exact theory of torsional bars of general cross sections. However, the solution to the problem using an analytical method for a complicated cross section is cumbersome. This paper presents the adoption of the Saint-Venant theory to develop a simple finite element program based on the displacement and stress function approaches using the standard linear and quadratic triangular elements. The displacement based approach is capable of evaluating torsional rigidity and shear stress distribution of homogeneous and nonhomogeneous; isotropic, orthotropic, and anisotropic materials; in singly and multiply-connected sections.  On the other hand, applications of the stress function approach are limited to the case of singly-connected isotropic sections only, due to the complexity on the boundary conditions. The results show that both approaches converge to exact solutions with high degree of accuracy.