Analisa Kegagalan Crane Pedestal Akibat Beban Ledakan

Pada tugas akhir ini dianalisis kegagalan struktur crane pedestal yang terjadi akibat adanya beban ledakan. Struktur Crane pedestal yang dianalisis memiliki diameter 32 inch, tebal 0.598 inch dan berada pada jarak 1.775 m dari sumber ledakan. Analisa didasarkan akibat variasi beban ledakan yang terjadi dan beban kombinasi, yaitu ketika terkena ledakan sebesar 0.03 bar, 0.21 bar, 0.35 bar serta untuk kombinasi ditambahkan dengan beban statisnya dengan code yang digunakan adalah API RP 2A WSD 2000. Penelitian ini menyajikan metodologi berbasis time domain untuk menghitung kurva ledakan dan besarnya kurva tekanan ledakan serta respon dan nilai kegagalan yang terjadi. Dari perhitungan, didapatkan bahwa kurva tekanan dinamis ledakan yang mengenai struktur akan meningkat hingga 10 kali lipat dari kurva gelombang ledakan. hal ini dipengaruhi oleh kecepatan ledakan dan massa jenis ledakan. sedangkan dari analisa dengan bantuan software ANSYS 14.5, didapatkan bahwa tegangan secara berturut-turut yang terjadi pada struktur telah melebihi yield, yaitu : 348 MPa, 368 MPa dan 374 MPa, serta telah mengalami deformasi plastis, yaitu 18 mm, 34 mm dan 51 mm. Hal ini disebabkan karena peningkatan beban ledakan yang signifikan namun terjadi dalam waktu singkat. Nilai kerusakan struktur berdasarkan damage index modal adalah 10.68% (kategori ringan) sedangkan berdasarkan ductility limit, struktur mengalami kerusakan ringan (1.396) akibat kombinasi ledakan 0.03 bar, kerusakan sedang (3.53) akibat kombinasi ledakan 0.21 bar, dan kerusakan substansial (4.91) akibat kombinasi ledakan 0.35 bar. Sehingga dapat disimpulkan bahwa struktur mengalami kegagalan operasi. ================================================================================================================================= In this final project, focus on analyze failure of crane pedestal structure that occurs due to blast loads. Structure Crane pedestal analyszed has a 32 inch diameter, 0.598 inch thick and at a distance of 1,775 m from the source of the blast. The analyze is based due to a blast load variations and load combinations, which hit by a blast of 0.03 bar, 0,21 bar , and 0,35 bar, and added by the combination of the static loads with code used is API RP 2A WSD 2000. This study presents a methodology based on the time domain curve to calculate the magnitude of the blast and the blast pressure and then response curve with value of the failure. From the calculations, it was found that the explosion of dynamic pressure curve of the structure will increase up to 10 times from the blast wave curve. it is caused by the speed and density of the blast. while the analysis within help of ANSYS 14.5 software, it was found that stress occured to have exceeded the yield structure,i.e : 348 MPa, 368 MPa and 374 MPa, and has complitely plastic deformation, which is 18 mm, 34 mm and 51 mm . This is due to a significant increase in blast load occurs in a short time. Value of structural damage based on the damage index of modal is 10.68% (light category) while based ductility limit, the structure suffered minor damage (1.396) due to a combination of blast 0.03 bar, medium damages (3.53) due to a combination of blast 0.21 bar, and substantial damage (4.91) due to 0.35 bar of blast combination. It can be concluded that capability of the structure has failed

Tension Leg Rectangular Fish Cage Motion Analysis in Regular and Random Waves

This paper uses an analytical method to examine the motion of a Tension Leg Fish Cage (TLFC) in regular and random waves. TLFC is a conceptual design of a fish cage based on the Tension Leg Platform (TLP) working principle that is usually used in deep water offshore oil and gas exploration. The idea of providing a safe environment to combine ecotourism and fish farming in a single platform led us to perform an analytical calculation to assess the possibility of using the TLP concept in fish farming. A preliminary conceptual design of TLFC using an HDPE floater with steel cable tendon is presented. The analytical calculation of the response amplitude operator for surge and heave motion is presented using linear airy wave theory with head seas encountering angle. This paper also presents the calculation of TLFC surge and heave motion under random wave loads. The random wave spectra used in this paper are JONSWAP and ISSC spectra. The result shows that the surge and heave motion response of TLFC is relatively smalland, therefore, can be analyzed further with more detailed consideration. It is admitted that HDPE is a brittle material that cannot sustain any long period of constant tension. Hence the optimum tendon-floater connection for the structure is subject to further research