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"This study explores the effect of increased concrete strength on the behavior of concrete failure. Experimental testing using a three-point bend (TPB) test proposed by RILEM was carried out to calculate the value of fracture energy (GF), stress intensity factor (KIC), and characteristic length (lch) of the concrete. The values of GF and lch, which are proportional to the fracture process zone based on the fictitious crack model, were employed to determine the effect of concrete strength on the concrete’s fracture characteristic. KIC was engaged to describe the initial crack in the concrete. Four different concrete strengths of 40, 47, 53, and 100 MPa—were manufactured to produce notched beam specimens with single-sized notches 25 mm deep. Results revealed that the values of GF and KIC increased in the stronger concretes. However, the value of lch decreased significantly as concrete strength increased."

"Penelitian pada tesis ini menyajikan perilaku konvergensi elemen Discrete Kirchhoff Mindlin Triangular (DKMT) terhadap analisis statik, getaran bebas, dan tekuk pada pelat Functionally Graded Material (FGM). Elemen DKMT memiliki tiga nodal dengan tiga derajat kebebasan (dof) di setiap nodalnya. Bukan hanya pada pelat tipis, elemen DKMT juga memberikan hasil yang baik pada pelat tebal. Elemen DKMT selanjutnya diformulasikan kembali untuk menganalisis studi kasus pelat FGM. FGM memiliki ketahanan terhadap suhu tinggi dan dapat mengurangi perbedaan tegangan antar material (delaminasi). Material yang digunakan dalam membentuk FGM pada penelitian ini adalah metal dan ceramic. Metal merupakan material yang tahan terhadap fleksibilitas struktur, sedangkan ceramic merupakan material yang tahan terhadap temperatur yang tinggi. Tujuan uji numerik pada pelat FGM ini adalah untuk menunjukkan perilaku konvergensi dari elemen DKMT dalam analisis statik, getaran bebas, dan tekuk. Non-dimensional perpindahan titik tengah pelat, frekuensi natural, beban tekuk kritis, dan suhu tekuk kritis selanjutnya dibandingkan dengan referensi dari literatur terkait. Perbedaan kondisi batas, tipe mesh, rasio L/h, dan indeks power-law dievaluasi. Elemen DKMT memberikan hasil yang baik dan konvergen dalam analisis statik, getaran bebas, dan tekuk pada pelat FGM.

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This research presents the convergence behavior of Discrete Kirchhoff Mindlin Triangular (DKMT) element in static, free vibration and buckling analyses. The DKMT element has three nodes with 3 degrees of freedom on each node. Not only for a thin plate, but the DKMT element is also valid to be used for thick plate. The DKMT element is further reformulated to analyze FGM plate problems. FGM has high-temperature resistance and eliminates stress differences between materials (delamination). The properties of FGM that used in this paper are metal and ceramic. Metal is a material that is resistant to structural flexibility, while ceramic is resistant to high temperatures. The aim of the numerical tests on the FGM plate problems is to show the convergence behavior of the DKMT element in static, free vibration and buckling analyses. Non-dimensional the central displacement, the natural frequency, the critical buckling load, and the critical buckling temperature of FGM plates are then compared to the reference solutions. Different boundary conditions, types of meshing, ratio L and power-law index are evaluated. The DKMT element gives good results in static, free vibration and buckling analyses of the FGM plates problems."