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Abstrak :
Penelitian ini bertujuan untuk mempelajari efektifitas sistem kabut air dalam memadamkan kebakaran terselubung shielded fire . Eksperimen dilakukan pada ruangan partisi dengan dimensi pxlxt 2x2x2.5. Digunakan lima buah nozzle kabut air yang terdiri dari dua tipe yaitu fogjet dan fine spray. Nozzle fogjet berjumlah satu buah yang dipasang pada bagian tengah atas ruangan dan nozzle fine spray berjumlah 4 dipasang pada setiap sisi ruangan pada ketinggian 1,5 m dari permukaan bawah. Tekanan sistem kabut air dipertahankan pada 20 bar yang akan mengalirkan air sebesar 2.6 lpm. Bahan bakar yang digunakan ialah susunan stik kayu dengan dimensi pxlxt 11,5 x 11,5 x 6 cm dan 6.5 x 6.5 x 6 cm. Selubung sebagai pelindung bahan bakar memiliki bentuk seperti meja yang terbuat dari lembaran dan batang besi dengan ketinggian selubung sebesar 0.5 m. Skenario penelian ini berdasarkan variasi ukuran bahan bakar dan lokasi dari bahan bakar dan selubung 1 selubung terletak di tengah ruangan dan bahan bakar di tengah selubung 2 selubung terletak di tengah ruangan dan bahan bakar di sisi selubung 3 selubung terletak di sudut ruangan dan bahan bakar di tengah selubung 4 selubung terletak di sudut ruangan dan bahan bakar di sisi selubung. Simulasi metode numerik menggunakan FDS juga dilakukan untuk mengetahui kemampuan FDS dalam mensimulasikan kebakaran seperti ini. Hasil eksperimen menunjukkan bahwa kabut air dapat memadamkan kebakaran dengan bahan bakar ukuran 6.5 x 6.5 x 6 cm pada skenario 1,2,3,dan 4 dalam waktu 20 s, 16 s, 30 s, dan 24 s. Namun tidak dapat memadamkan kebakaran yang menggunakan bahan bakar ukuran 11,5 x 11,5 x 6 cm. Selain itu juga teramati bahwa konsentrasi distribusi kabutair di sekitar selubung dan luas area perlindungan selubung berpengaruh terhadap kapasitas dan kecepatan sistem kabut air dalam memadamkan kebakaran terselubung. ......This study aims to investigate the effectiveness of water mist fire suppression system on suppressing shielded fire. Full scale experiments are carried out in a partition room of lxwxh 2x2x2.5 m size to study the performance of water mist suppression system against a shielded fire. Five water mist nozzle which consist of two type nozzle was used, high flow fogjet nozzle installed at top center of the room and fine spray nozzle installed at each side of room at high 1.5 m from ground. The pressure of water mist system was maintained at 20 bar which correspond to 2.6 lpm of water flow rate. Wood crib of 11,5 x 11,5 x 6 cm and 6.5 x 6.5 x 6 cm size was used as the fuel source. The obstruction used as a fuel shield has table like form and made from metal sheet with 4 mm thickness, 40 x 40 cm cover area and 0.5 m leg height. Skenario used was base on fuel size and location of fuel source and fuel shield was varied 1 fuel source and shield at centre of room, 2 fuel source at one side of shield and the shield at centre of room, 3 fuel source and shield at corner of room, and 4 fuel source at one side of shield and the shield at corner of room. Numerical simulation using FDS 6.5.3 was also performed to investigate the capacity of FDS. The results showed that water mist was able to extinguish the fire from fuel size 6.5 x 6.5 x 6 cm in around 20 s, 16 s, 30 s, and 24 s for scenario 1, 2, 3 and 4 respectively. However it fail to extinguish the fire from fuel size 11,5 x 11,5 x 6 cm. It is also observe that the mist distribution around the shield and cover area of the shield play a role on the capacity and time needed of water mist to extinguish the fire.

Abstrak :
ABSTRACT
Internal Erosion initiated by water movement along channels called tunnel erosion, often crack or defect the dam?s structure. It is one of the main causes of water structure?s (dams, dikes, etc.) collapse. This phenomenon can be divided into 3 phases, tunnelling, collapse, and the opening of the channel inside the dam [1]: - ?Tunnelling? transport large quantities of particles due to the hydraulic gradient. It?s happen fast in a preferential path especially in some point of dam structure?s weaknesses. - The gradual collapse of the roof of tunnel erosion allows the expansion of the channel. - The opening of the channel is started after the collapse of the channel by tunnel erosion. Research has been done to explain the phenomenon of collapse, but there are still questions, including the formulation, phase, and form of the rupture. Moreover, the equation used is not always adapted to the various cases of the soil. Research by Hunt and Hanson showed the different phases of a dam collapse with a rate of expansion of a hole driven only by the constraint of shearing. Through this numerical study, we find that their hypothesis is not correct, because there are other parameters that affect this phenomenon and also the effect of traction force. The study is simplified by modelling an earthen dam with a given cavity; where the undrained cohesion is controlled to see at which value of cohesion the fracture achieved. This simplification is the opposite in the real case, where the cohesion is fixed but the cavity expands. We find that the collapse of the earthen dam because of the tunnel erosion occurs in two stages: the arching effect in the channel across the dam that makes vertical sag then collapse, and the expansion of the channel which is inclined more like a slope. The high of the dam and the form of the ?tunnel? cavity also influenced the failure mode.

Abstrak :
Dalam struktur jembatan yang menggunakan sistem pracetak, sambungan merupakan titik terlemah dan menjadi suatu bagian yang krusial dalam sistem struktur jembatan. Sambungan memiliki fungsi untuk menyatukan antar segmen pracetak sehingga gaya geser dapat terdistribusi merata dari satu segmen ke segmen lainnya. Penelitian bertujuan untuk menganalisa perilaku kunci geser dengan material ferro casting ductile. Untuk mencapai tujuan tersebut, penelitian dilakukan secara numerik dengan mengacu pada hasil eksperimental penelitian kunci geser terdahulu dengan material ferro casting ductile. Studi numerik dilakukan dengan menggunakan pemodelan 2D dan 3D. Pemodelan 2D dengan SAP 2000 dan pemodelan 3D dengan Cast3M menggunakan model dengan skala 100% dengan kunci geser bertirus 2:1. Pemodelan 3D juga dilakukan dengan menggunakan program Midas FEA menggunakan model skala reduksi 50% dengan kunci geser tidak bertirus. Penelitian menggunakan male-female shear key ferro casting ductile dengan variasi kemiringan radial,variasi gaya pratekan dengan atau tanpa perekat pada sambungan. Dari hasil pemodelan 2D dengan SAP 2000 hasil pemodelan menunjukan hasil linear meskipun material non linear dan analisa non linear telah diterapkan. Untuk hasil pemodelan dengan Midas FEA, meskipun selisih perbedaan antara hasil eksperimen dan hasil numerik berada pada rentang 0-8% untuk beban maksimum tetapi perpindahan vertikal yang dihasilkan masih memiliki selisih mencapai lebih dari 30%. ......In structural bridge with precast segmental concrete. Joint between precast segmental is the weakest area of the structural system. Joint precast segmental is the most important part of the structural system with precast segmental due to its functionality. Joint of precast segmental has function to distribute shear stress among precast segmental parts. The objective of this paper is to study the mechanical behavior of FCD applied as shear key. Study analysis use numerical study and validate its results with reference experiment’s results from previous study experimental. Numerical study use model with basis 2D model and 3D model. 2D model use SAP 2000 and 3D model use Cast3M with model use scale 100% and radial shear keys with inclination scale 2:1. For Midas FEA use model reduction scale 50% and flat shear key. Numerical analysis use ferro casting ductile shear key with variation in inclination of radial shear key and horizontal force with or without epoxy. The results are 2D model with SAP 2000 resulting linear’s result despite non linear analysis has been implemented to the program and 3D model with Midas FEA has range margin error 0 – 8% for the maximum load occur on top of joint. Despite the maximum load’s error is quite small but the margin error for displacement reach more than 30%.

Abstrak :
The shear key is an important part of a precast segmental concrete bridge. Aside from its function of contributing to the distribution of shear force from one concrete segment to another, it helps to join precast concrete segments to become a complete bridge structure and provide continuity of movement for vehicles and pedestrian traffic. This numerical study discusses the behavior of a full-scale shear key connection without epoxy joining two concrete blocks representing segmental precast concrete at which two external forces load the blocks. Ferro Casting Ductile (FCD) is used as the metal shear key material where the shear key consists of two parts, a male and a female shear key. Numerical simulation is conducted using the ANSYS academic package, with nonlinear analysis implemented accordingly. The appropriate constitutive materials in relation to the numerical program, both for concrete and FCD, are taken from the appropriate literature. Two criteria are employed in the study; failure of the concrete block and yielding of the shear key that follows the von Mises criterion. Shear key connection system capacity is evaluated by applying different magnitudes of horizontal force. The validation of two numerical simulation studies is conducted by two experimental programs that cover laboratory experimentation of full-scale shear keys connecting two concrete blocks. The numerical and experimental results produce an almost similar relation of shear stress at the male shear key and vertical displacements of the upper block relative to the lower concrete block. Finally, a contour of shear key shear stress as a function of the different magnitudes of equivalent prestressing and different quality of concrete compressive strength is proposed.

Abstrak :
A single phase, incompressible turbulent flow through a 90º pipe bend with/without guide vane conditions has been studied here. The present work deals with the numerical simulation to investigate the change in flow separation and velocity distribution at the downstream section due to the effect of the guide vane. The k-? turbulence model has been adopted for simulation purposes to obtain the results. After the validation of existing experimental and numerical results, a detailed study has been performed for three different Reynolds number and four different positions of the guide vane. The value of the Curvature ratio (Rc/D) has been considered as one factor for the present study. The curvature ratio can be defined as the ratio between the bend curvature radius and hydraulic diameter of the pipe. The results obtained from the present study have been presented in graphical form. A flow separation region has been found at the bend outlet for flow through 90º pipe bend without the guide vane. This flow separation region was absent for the cases which dealt with the flow through 90º pipe bend with the guide vane. Velocity distribution at four different downstream positions for different cases and different Reynolds numbers have been compared and reported in the present study.