Modifikasi Struktur Jembatan Bandar Ngalim Menggunakan Tipe Single-Span Diagonal Arch Bridge

Zakariyah, Athallah Rafi (2026) Modifikasi Struktur Jembatan Bandar Ngalim Menggunakan Tipe Single-Span Diagonal Arch Bridge. Other thesis, Sepuluh Nopember Institute of Technology.

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Abstract

Jembatan Bandar Ngalim di Kota Kediri merupakan infrastruktur penting yang menghubungkan dua kawasan strategis di atas Sungai Brantas. Struktur eksisting bertipe steel box girder tiga bentang (40 m + 70 m + 40 m) menimbulkan permasalahan teknis berupa gangguan aliran air, potensi scouring, serta menurunnya nilai estetika kawasan akibat adanya pilar di tengah sungai. Untuk mengatasi hal tersebut, dilakukan modifikasi menjadi Single-Span Diagonal Arch Bridge (DAB) dengan bentang tunggal 150 m dan lebar total 13 m (dua lajur kendaraan dengan lebar 5 m dan dua trotoar lebar 1,5 m), sehingga pilar tengah dapat dihilangkan. Busur utama dirancang menggunakan profil steel box berukuran 2000 × 3500 × 60 × 60 mm dari material ASTM A36 (Fy = 250 MPa) dengan tinggi efektif 50 m (≈ 0,345L) dan sudut kemiringan 19°. Gelagar utama berupa trapezoidal steel box girder setinggi 3 m dengan sistem lantai orthotropic deck yang menggunakan deckplate tebal 26 mm serta ribs tebal 10 mm. Sistem penggantung terdiri dari 28 kabel diagonal Macalloy M105 berdiameter 102 mm (kapasitas tarik 5.279 kN). Analisis struktur dilakukan menggunakan perangkat lunak Midas Civil berbasis metode elemen hingga (finite element method). Analisis dek dilakukan dengan pemodelan orthotropic shell element yang merepresentasikan deckplate, ribs, dan floorbeam. Hasil analisis menunjukkan lendutan maksimum dek akibat beban hidup sebesar 66 mm untuk beban terbagi rata dan 54 mm untuk beban satu truk yang keduanya jauh di bawah batas izin 150 mm. Tegangan maksimum pada elemen dek dan ribs juga berada dalam batas aman terhadap kapasitas leleh material baja. Evaluasi dinamis enghasilkan frekuensi alami lentur vertikal (fB) sebesar 0,984 Hz dan frekuensi torsi (fT) sebesar 2,702 Hz dengan rasio Mathivat 2,745 yang memenuhi kriteria stabilitas dinamis. Analisis aerodinamis menunjukkan kecepatan kritis teoritis 58,03 m/s, amplitudo osilasi vertikal 3,22 mm, dan percepatan osilasi 0,126 m/s² yang tergolong aman (Zone A – Acceptable). Selain struktur atas, direncanakan pula struktur bawah berupa pilar dan blok busur menggunakan beton bertulang dengan kuat tekan f’c 30 MPa. Fondasi yang digunakan adalah Bored pile berdiameter 1,0 m dengan kedalaman tanam 20 m untuk pilar dan 25 m untuk blok busur, yang mampu menahan beban aksial dan lateral hasil reaksi struktur atas. Analisis daya dukung, momen penahan guling, serta kontrol deformasi menunjukkan bahwa sistem fondasi memenuhi kriteria keamanan terhadap beban kombinasi maksimum. Dengan hasil analisis tersebut, modifikasi jembatan menjadi Single Span Diagonal Arch Bridge dinyatakan aman secara struktural, efisien secara konstruktif, stabil secara aerodinamis, serta mampu meningkatkan kualitas visual dan fungsi hidraulik Sungai Brantas dengan menghilangkan pilar tengah.
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The Bandar Ngalim Bridge in Kediri City is an important infrastructure connecting two strategic areas across the Brantas River. The existing structure, a three-span steel box girder bridge (40 m + 70 m + 40 m), presents several technical issues, including disruption of river flow, potential scouring, and reduced aesthetic value due to the presence of a central pier. To address these problems, the bridge was redesigned as a Single-Span Diagonal Arch Bridge (DAB) with a single span of 150 m and a total width of 13 m, consisting of two 5 m vehicle lanes and two 1.5 m sidewalks, thereby eliminating the central pier. The main arch is designed using a steel box section of 2000 × 3500 × 60 × 60 mm fabricated from ASTM A36 steel (Fy = 250 MPa), with an effective height of 50 m (≈ 0.345L) and an inclination angle of 19°. The main girder adopts a trapezoidal steel box girder with a depth of 3 m, combined with an orthotropic deck system comprising a 26 mm deckplate and 10 mm ribs. The suspension system consists of 28 diagonal Macalloy M105 cables with a diameter of 102 mm and a minimum breaking load of 5,279 kN. Structural analysis was performed using Midas Civil software based on the finite element method (FEM). The deck analysis employed orthotropic shell elements representing the deckplate, ribs, and floorbeams. The results show that the maximum deck deflection due to live load is 66 mm for distributed load and 54 mm for a single truck load both well below the allowable limit of 150 mm. The maximum stress on the deck and rib elements remains within the elastic range of the steel material. Dynamic evaluation yields a fundamental vertical bending frequency (fB) of 0.984 Hz and a torsional frequency (fT) of 2.702 Hz, with a Mathivat ratio of 2.745, satisfying the dynamic stability criteria. Aerodynamic analysis indicates a theoretical critical wind speed of 58.03 m/s, a vertical oscillation amplitude of 3.22 mm, and an oscillation acceleration of 0.126 m/s², classified as Zone A – Acceptable. For the substructure, reinforced concrete piers and arch blocks were designed with a compressive strength of f’c 30 MPa. The foundation system consists of Bored piles with a diameter of 1.0 m and an embedment depth of 20 m for pier and 25 m for arch block, capable of resisting axial and lateral loads from the superstructure. The bearing capacity, overturning stability, and deformation control analyses confirm that the foundation system meets the safety requirements under maximum load combinations. Based on these analyses, the modification of the Bandar Ngalim Bridge into a Single-Span Diagonal Arch Bridge is proven to be structurally safe, constructively efficient, aerodynamically stable, and capable of improving both the hydraulic performance of the Brantas River and the visual identity of Kediri City by removing the central pier.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Diagonal Arch Bridge, Finite Element Method, Orthotropic Deck, Hanger Cable, Bored Pile Foundation, Dynamic Stability.
Subjects:	T Technology > TG Bridge engineering T Technology > TG Bridge engineering > TG362 Box girder bridges--Design and construction.
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Civil Engineering > 22201-(S1) Undergraduate Thesis
Depositing User:	Athallah Rafi Zakariyah
Date Deposited:	21 Jan 2026 06:08
Last Modified:	21 Jan 2026 06:08
URI:	http://repository.its.ac.id/id/eprint/129956

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