Perhitungan Pondasi Tiang Pancang

Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 243 Gambar 5. 91 Penulangan Badan Abutmen

F. Perhitungan Pondasi Tiang Pancang

Untuk mendapatkan kekuatan friksi yang maksimum dari tanah yang lunak, maka diperlukan tiang pancang berdiameter besar. Direncanakan tiang pancang pada jalan layang ini menggunakan jenis pancang bulat dengan diameter 30 cm. ƒ Luas tiang pancang A = 0,25. π. D 2 = 0,25 . 3,14 . 30 2 = 706,5 cm 2 ƒ Berat tiang pancang W pile = 0, 07065 .2,5 . 40 = 7,065 ton ƒ Keliling tiang pancang Θ = π . D = 3,14 . 30 = 94,2 cm ƒ Data tanah yang didapat dari hasil penyelidikan tanah pada kedalaman – 40 m : - Cone resistance q c = 50 kgcm 2 - Total friction TF = 787,5 kg cm 2 Formatted: I ndent: Left: 1.58 cm, Numbered + Level: 1 + Numbering Style: A, B, C, … + Start at: 1 + Alignment: Left + Aligned at: 1.69 cm + Tab after: 2.33 cm + I ndent at: Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, First line: 1.27 cm, Tab stops: Not at 2.22 cm Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Not Superscript Subscript Formatted: Font: I talic Formatted: I ndent: Left: 2.96 cm, Tab stops: 8.25 cm, Left + Not at 2.22 cm Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, Bulleted + Level: 3 + Aligned at: 6.14 cm + Tab after: 6.77 cm + I ndent at: 6.77 cm, Tab stops: 3.17 cm, Left + 8.25 cm, Left + Not at 2.22 cm + 6.77 cm Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: I ndent: Left: 2.96 cm, Tab stops: 8.25 cm, Left + Not at 2.22 cm Formatted: I ndent: Left: 2.54 cm, Bulleted + Level: 3 + Aligned at: 6.14 cm + Tab after: 6.77 cm + I ndent at: 6.77 cm, Tab stops: 3.17 cm, Left + Not at 2.22 cm + 6.77 cm Formatted: I ndent: Left: 3.6 cm, Tab stops: 8.25 cm, Left + Not at 2.22 cm Formatted: Font: I talic Formatted: Subscript Formatted: Font: I talic Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 244 ƒ Kekuatan tanah Bogeman P safe = 3 . c c A q + 5 . Θ TF = 3 5 , 706 . 50 + 5 2 , 94 . 5 , 787 = 26611,5 kg = 26,6115 ton P ult = P safe - W pile = 26,6115 – 7,065 = 19,5465 ton Meyerhoff P ult = 40 . Nb . Ab + 0,2 . N . As P ult = Daya dukung batas pondasi ton Nb = Nilai N-SPT pada elevasi dasar tiang Ab = Luas penampang dasar tiang m 2 N = Nilai N-SPT rata-rata As = Luas selimut tiang m 2 N = 2 2 1 N N + → N 2 N 2 = nilai rata-rata N,4D keatas dari ujung tiang = 41 + 37 + 37 + 37 4 = 38 N = 2 38 41 + = 39,5 P ult = 40 . 41 . 0, 07065 + 0,2 . 39,5. 37,68 = 413,538 ton P all = Fk Pult = 3 413,538 = 137,846 ton ƒ Jarak antar tiang pancang S Persyaratan jarak antar tiang ditentukan sebagai berikut : - perumusan dari Uniform Building Code- AASH T O syarat : s ≤ 2 . . . 57 , 1 − + n m n m D dimana : D = diameter tiang pancang m = jumlah baris Formatted: I ndent: Left: 2.54 cm, Bulleted + Level: 3 + Aligned at: 6.35 cm + Tab after: 6.98 cm + I ndent at: 6.98 cm, Tab stops: Not at 2.22 cm + 6.98 cm Formatted: I ndent: Left: 3.17 cm, Tab stops: Not at 2.22 cm Formatted: Underline Formatted: I ndent: Left: 3.17 cm, Tab stops: 4.44 cm, Left + 4.87 cm, Left + Not at 2.22 Formatted: Lowered by 12 pt Formatted: Lowered by 12 pt Formatted: Lowered by 3 pt Field Code Changed Formatted: Swedish Sweden Field Code Changed Formatted: Lowered by 12 pt Formatted: Swedish Sweden Field Code Changed Formatted: Swedish Sweden Field Code Changed Formatted: Swedish Sweden Formatted: Lowered by 12 pt Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, Bulleted + Level: 4 + Aligned at: 8.25 cm + Tab after: 8.89 cm + I ndent at: 8.89 cm, Tab stops: Not at 8.89 cm Formatted: Bullets and Numbering Formatted: Swedish Sweden Field Code Changed Formatted: Swedish Sweden Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 245 n = jumlah tiang dalam 1 baris s ≤ 2 4 8 4 . 8 . 50 . 57 , 1 − + s ≤ 251,2 cm - perumusan dari Dirjen Bina Marga Departemen Pekerjaan Umum s = 2,5 D ~ 3 D = 2,5. 30 ~ 3. 30 = 75 ~ 90 - perumusan mutlak dari Dirjen Bina Marga Departemen Pekerjaan Umum apabila diameter terlalu kecil atau terlalu besar s min = 60 cm s maks = 200 cm dalam perencanaan pondasi, diasumsikan bahwa pile cap dan poer merupakan satu kesatuan sehingga ukuran pile cap diusahakan sama atau lebih kecil daripada ukuran poer pada pilar, yaitu 4,00 x 14,5 m. sesuai dengan ukuran poer tersebut maka dapat ditentukan komposisi dari pile group sebagai berikut : → s = 1,5 m untuk arah x , dan s = 2,0 m untuk arah y → jumlah tiang pancang adalah 7 baris x 3 tiang = 21 tiang Formatted: Swedish Sweden Formatted: Bullets and Numbering Formatted: Swedish Sweden Formatted: Bullets and Numbering Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 246 Gambar 5. 92 Reaksi Tiang Pancang Abutmen Efisiensi kelompok tiang pancang Eff : Eff = 1 - 90 θ . ⎩ ⎨ ⎧ ⎭ ⎬ ⎫ − + − n m n m m n . 1 1 …..rumus Converse Labarre Ө = arc tan S D = arc tan 200 30 = 8,53 = 1 - 90 53 , 8 . ⎩ ⎨ ⎧ ⎭ ⎬ ⎫ − + − 3 . 7 3 1 7 7 1 3 = 0, 855 Daya dukung kelompok tiang : P ijin = P ult x efisiensi x jumlah tiang = 137,846 . 0, 855 . 21 = 2475,0249 ton Formatted: Swedish Sweden Formatted: Underline, Spanish I nternational Sort Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 247 Syarat P ijin P total Tabel 5. 56 Kombinasi Daya Dukung Kelompok Tiang kombinasi P ijin ton P total ton kestabilan I 2475,0249 1132,7112 aman II 3093,7811 933,3552 aman III 3465,0349 248,1476 aman IV 3712,5374 933,3552 aman VI 3712,5374 1132,7112 aman Daya dukung tiang pancang terhadap beban luar : Beban luar yang bekerja pada tiang pancang adalah gaya vertikal atau horisontal dan momen. Dalam konstruksi jalan layang ini momen yang ada hanya bekerja dalam satu arah saja. Karena hal tersebut maka tiang pancang memerlukan daya dukung untuk melawan. Contoh perhitungan kombinasi I : P = n V + ∑ 2 . . x ny x M Dimana : V = beban vertikal maksimum = 1132,7112 ton M = momen maksimum yang bekerja arah melintang = 394,2283 ton m x = lengan arah x maksimum = 1,5 m n = jumlah tiang pancang = 21 buah ny = jumlah tiang dalam 1 baris arah y = 7 buah Σ x 2 = 7 . 2 . 1,5 2 = 31,5 m 2 P = 21 1132,7112 + 5 , 31 . 7 5 , 1 . 394,2283 = 53,9386 + 2,6818 P maks = 56,6205 ton Pult=0, 855 . 137,846 = 117,8583 ton …aman P min = 51,2568 ton Pult=0, 855 . 137,846 = 117,8583 ton …aman Tabel 5. 57 Kombinasi Daya Dukung Tiang Pancang Terhadap Beban Luar komb V ton M tonm Pmaks ton P min ton P ult ton kestabilan Formatted: Tab stops: 3.92 cm, Left + 4.42 cm, Left + Not at 3.81 cm Formatted: Font: Default Arial, 9 pt Formatted: Underline Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, Tab stops: 3.17 cm, Left + 4.02 cm, Left + Not at 2.22 Field Code Changed Formatted: Lowered by 12 pt Formatted: Swedish Sweden Formatted: Underline, Swedish Sweden Formatted: No underline Formatted: Swedish Sweden Formatted: I ndent: Left: 3.17 cm, Tab stops: 3.17 cm, Left + 4.02 cm, Left + Not at 2.22 cm Formatted: I ndent: Left: 3.17 cm, Tab stops: 3.17 cm, Left + 4.02 cm, Left + 4.66 cm, Left + Not at 2.22 cm Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Underline Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: Swedish Sweden Formatted: I ndent: Left: 2.21 cm, Tab stops: 3.92 cm, Left + 4.42 cm, Left + Not at 3.17 cm + 4.02 cm Formatted: Font: Default Arial, 9 pt Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 248 I 1132,7112 394,2283 56,6205 51,2568 117,8583 aman II 933,3552 781,4388 49,7614 39,1296 147,3229 aman III 1132,7112 953,3868 60,4243 47,4530 165,0016 aman IV 933,3552 1308,9873 53,3502 35,5408 176,7875 aman VI 1132,7112 394,2283 56,6205 51,2568 176,7875 aman Gaya horisontal pada tiang pancang : Gambar 5. 93 Gaya Horisontal Tiang Pancang Abutmen Data pondasi tiang pancang : B = lebar poer yang menerima beban horisontal = 14,5 m La = Kedalaman poer = -1,0 m Lp = panjang tiang pancang yang masuk ke tanah = 40 m Panjang jepitan pada tiang pancang : Ld = 3 1 Lp = 3 1 . 40 = 13,333 m L H = La + Ld = 1,00 + 13,333 = 14,333 m L1 = 13,666 m L2 = 11,11 m L3 = 7,777 m Formatted: Underline, Swedish Sweden Formatted: Underline, Swedish Sweden Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, Tab stops: 3.17 cm, Left + 3.81 cm, Left + Not at 2.22 cm Formatted: Swedish Sweden Formatted: I ndent: Left: 2.54 cm, Tab stops: 3.17 cm, Left + 3.81 cm, Left + Not at 2.22 cm Formatted: Swedish Sweden Formatted: Spanish I nternational Sort Field Code Changed Formatted: Lowered by 12 pt Formatted: Spanish I nternational Sort Field Code Changed Formatted: Lowered by 12 pt Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort, Subscript Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 249 L4 = 5,555 m L5 = 2,222 m Pada kedalaman – 5,00 m : Ø 1 = 3 1 = 1,4720 grcm 3 Kp1 = tg 2 45 + 2 φ = tg 2 45 + 2 3 = 1,11 Pada kedalaman – 10,50 m : Ø 3 = 3 2 = 1,6199 grcm 3 Kp2 = tg 2 45 + 2 φ = tg 2 45 + 2 3 = 1,11 Perhitungan diagram tekanan tanah pasif : BC = Kp1. 1.1 . B = 1,11.1,4720.1 . 14,5 = 23,6918 ton m 2 DE = Kp1. 1.4,333. B = 1,11.1,4720.4,333. 14,5 = 102,6567 tonm 2 FG = Kp1. 1.7,666.B = 1,11.1,4720.7,666. 14,5 = 181,6216 tonm 2 HI = Kp2. 2.10,999.B = 1,11.1,6199.10,999. 14,5 = 286,7691 tonm 2 JK = Kp2. 2.14,333.B = 1,11.1,6199. 14,333. 14,5 = 373,6941 tonm 2 Tekanan tanah pasif efektif yang bekerja : Titik A = 0 ton m 2 BC = 23,6918 tonm 2 DE’ = ¾ . DE = ¾ . 102,6567 = 76,9925 tonm 2 FG’ = ½ . FG = ½ . 181,6216 = 90,8108 tonm 2 HI’ = ¼. HI = ¼. 286,7691 = 71,6923 tonm 2 Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: I ndent: Left: 2.54 cm, Tab stops: Not at 2.22 cm Formatted: Spanish I nternational Sort Field Code Changed Formatted: Swedish Sweden, Lowered by 12 pt Formatted: Spanish I nternational Sort Field Code Changed Formatted: Swedish Sweden, Lowered by 12 pt Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Spanish I nternational Sort Formatted: Swedish Sweden, Lowered by 12 pt Formatted: Tab stops: 3.39 cm, Left + 4.02 cm, Left + 7.2 cm, Left Formatted: Swedish Sweden Formatted: Tab stops: 4.23 cm, Left + 4.66 cm, Left Formatted: Tab stops: 4.23 cm, Left + 4.66 cm, Left + 6.14 cm, Left + 9.1 cm, Left Laporan Tugas Akhir Perencanaan Jalan Layang Pada Jalan Akses Bandara A.Yani Semarang 250 Titik J = 0 tonm 2 Resultan tekanan tanah pasif P1 = ½ . 1,0 . 23,6918 = 11,8459 ton P2 = ½ . 3,333 . 23,6918 + 76,9925 = 167,7904 ton P3 = ½ . 3,333 . 76,9925 + 90,8108 = 279,6442 ton P4 = ½ . 3,333. 90,8108 + 71,6923 = 270,8114 ton P5 = ½ . 3,333 . 71,6923 = 119,4752 ton + Σ P = 849,5671 ton Titik tangkap resultan tekanan tanah pasif : Σ P . Lz = P1.L1 + P2.L2 + P3.L3 + P4.L4 + P5.L5 = 11,8459 . 13,666+ 167,7904 . 11,11 + 279,6442 . 7,777 + 270,8114 . 5,555 + 119,4752 . 2,222 = 5970,6616 ton m Lz = 5970,6616 849,5671 = 7,0279 m Gaya horisontal maksimal yang dapat ditahan tekanan tanah pasif : Σ Ms = 0 H’. L H + Lz = Σ P . 2 Lz H’. 14,333 + 7,0279 = 849,5671 . 2. 7,0279 H’ = 21,3609 11941,3452 = 559,0282 ton H yang terjadi = 309,9327 ton Tiang pancang cukup aman menahan gaya horisontal yang terjadi.

G. Penulangan Kaki