Pengaruh Strength Reduction Tanah Clay-Shale Akibat Pelaksanaan Pemboran Terhadap Nilai Daya Dukung Pondasi Tiang Di Jembatan Suramadu Berdasarkan Analisis Hasil Tes OC

. Suramadu Bridge, which will connect Surabaya and Madura, is designed to have 5,438 m total span. Considering bridge construction that is above sea and huge design load on its pile foundations, conventional static loading test can not be performed at the main bridge. Alternative pile load test that can be performed is OC Test, which followed Osterberg Cell Test procedure. Equipped with load cell, telltale, and strain gauge, this test can provide load-displacement curve of end bearing and skin friction at any depth. Soil investigation result shows existence of clay-shale layer, which contains montmorillonite, at bore pile's location. This soil is sensitive to lateral pressure reduction caused by boring and weathering process so that strength reduction can occur. Strength reduction of soil makes end bearing and skin friction difficult to be predicted. Strength reduction effect toward end bearing and skin friction are determined by means of comparing OC Test result to prediction result based on common empirical correlation. For end bearing, OC Test result shows value that close to prediction result's. Therefore, strength reduction of end bearing caused by boring is relative small. On the other hand, skin friction measurement result shows that its value is much smaller than prediction result's. For increasing bearing capacity, grouting through the pile base was conducted. Test result shows increasing of value either end bearing and skin friction after grouting through the pile base. Compared to end bearing's value, skin friction's value rise more and close to prediction value

Redesain Overhead Crane dengan Analisa Kegagalan di PLTU PAITON Berbasis Metode Elemen Hingga

Crane adalah alat bantu yang digunakan untuk mempermudah dalam memindahkan suatu obyek atau barang dengan ukuran yang relatif besar dan berat dari satu posisi ke posisi lainnya. Pada PLTU PAITON crane digunakan untuk proses maintenace mesin grinding mill. Hoist Grider Crane Mill terkendala ruang gerak yang terbatas. Terbatasnya ruang gerak menyebabkan tidak sejajarnya sumbu antara kawat penarik dengan sepesial tool yang menyebabkan beban pengangkatan menjadi 2x dari beban awal. Akibat tidak sejajarnya kawat overhead crane mengakibatkan terjadinya patahan pada housing motor crane yang bertugas untuk menggerakan grider kearah vertical. Oleh karena itu perlu adanya modifikasi overhead girder dengan menggunakan perangkat lunak SolidWorks. Tujuan dari penelitian ini adalah melakukan analisa pada girder origin dimana hasil dari sumulasi digunakan sebagai acuan pada modifikasi 1 dan 2. Hasil yang diperoleh dari penelitian ini yaitu berdasarkan hasil pengujian, tegangan (stress), displacement, dan angka keamanan. Modifikasi 1 memiliki hasil simulasi yang hampir sama dengan hasil dari simulasi awal dengan nilai stress sebesar 36,19 mpa, Displacement sebear 0,98 mm, dan angka keamanan sebesar 5,7. Pada modifikasi 2 perbedaan hasil simulasi yang paling besar terletak pada simulasi tegangan (stress) sebesar 158,3 mpa. sedangkan hasil simulasi defleksi dan angka keamanan tidak berbeda jauh dengan simulai awal dimana defleksi sebesar 0,93 dan angka keamanan sebesar 3,1

Tree-pulling experiment : an analysis into the mechanical stability of rain trees

Tree-pulling experiments were conducted in Singapore involving 20 rain trees (Samanea saman) growing in four different soil types (1) structural soil with 80% granite chips and 20% sandy loam soil, (2) structural soil with 50% granite chips and 50% sandy loam soil, (3) in situ soil and (4) top soil. The trees were pulled over with a winch attached to the stem at a standard height of 1.3 m and the force required to uproot or break the trees were recorded. The physical above and below ground characteristics of the trees were also measured. All 20 trees in this study failed via uprooting without any stem fracture. Analysis of the data showed that the maximum resistive bending moment (BMmax) was positively correlated with the overall size of the root plate, the size (diameter) of the individual roots and the extent of crown spread. The dry mass of crown was significantly greater in the 80:20 structural soil treatment while no significant difference was found between the other soil types. The trunk diameter was not significantly different between treatments. Significant differences were observed in the depth of root plates where those grown in top soil had significantly deeper root plates as opposed to the other treatments but though deeper, the vast majority of trees planted in top soil exhibited fibrous rather than structural roots. The cross-sectional area of roots which is indicative of the size of the individual roots showed a significantly greater value in the 80:20 structural treatment while the 50:50 structural and top soil treatments had the lowest values. Significant differences in BMmax were only observed in the in situ soil type while the rest of the planting substrates exhibited values that were comparable and not significantly different.Accepted versio