Electronic Theses and Dissertation

Abstrak

Indonesia merupakan salah satu negara dengan tingkat risiko seismik tertinggi di dunia, sehingga perencanaan infrastruktur seperti jembatan perlu memperhitungkan pengaruh gempa secara cermat. Salah satu aspek penting yang masih sering diabaikan adalah interaksi tanah-struktur (Soil-Structure Interaction/SSI), padahal perilaku tanah yang berbeda dapat menghasilkan distribusi gaya dalam dan deformasi yang signifikan terhadap struktur. Penelitian ini bertujuan untuk menganalisis pengaruh variasi karakteristik tanah terhadap respons seismik jembatan rangka baja serta mengevaluasi perbedaan hasil antara pemodelan dengan dan tanpa mempertimbangkan SSI. Studi dilakukan pada Jembatan Lambeuso yang terletak di Kabupaten Aceh Jaya, dengan total bentang 100 meter. Pemodelan struktur jembatan sepenuhnya dilakukan pada software MIDAS Civil, termasuk input material, geometri, dan beban. Untuk analisis SSI, tanah dimodelkan di MIDAS GTS NX dan dikombinasikan dengan model struktur jembatan dari MIDAS Civil melalui metode langsung (direct method). Proses integrasi ini memungkinkan tanah dan struktur dianalisis secara simultan dalam satu sistem komputasi berbasis elemen hingga. Sementara itu, analisis non-SSI dilakukan secara terpisah di MIDAS Civil, dengan merepresentasikan tanah sebagai sistem pondasi kaku melalui perletakan jepit pada dasar struktur. Tiga jenis tanah direpresentasikan berdasarkan parameter dari literatur, yaitu tanah lunak, sedang, dan keras. Beban gempa dianalisis menggunakan metode respon spektrum zona seismik 3 berdasarkan data dari aplikasi LINI PUPR. Analisis mencakup tujuh parameter struktural, meliputi perpindahan vertikal, gaya aksial, gaya geser arah Y dan Z, momen lentur arah Y dan Z, serta torsi. Dari hasil analisis, diperoleh bahwa karakteristik tanah berperan penting dalam respons seismik struktur, dan bahwa penerapan model SSI dapat meningkatkan keakuratan analisis dan efektivitas desain jembatan pada kondisi geoteknik yang kompleks.

Kata Kunci: respons seismik, jembatan rangka baja, interaksi tanah-struktur, gempa.

Abstract Indonesia is one of the countries with the highest seismic risk in the world, making it essential to consider earthquake effects carefully in infrastructure design, particularly for bridges. One critical aspect that is often overlooked in such analyses is soil-structure interaction (SSI), despite the fact that varying soil behavior can significantly influence the distribution of internal forces and deformations within a structure. This study aims to analyze the influence of different soil characteristics on the seismic response of a steel truss bridge and to evaluate the differences between models with and without the consideration of SSI. The case study focuses on the Lambeuso Bridge located in Aceh Jaya Regency, with a total span of 100 meters. The bridge structure was fully modeled in MIDAS Civil, including geometry, material properties, and loading conditions. For SSI analysis, the soil domain was modeled in MIDAS GTS NX and integrated with the bridge model from MIDAS Civil using the direct method. This integration allows for the simultaneous analysis of the soil and structure within a unified finite element framework. In contrast, the non-SSI model was analyzed independently in MIDAS Civil, representing the soil as a rigid foundation by applying fixed supports at the base of the structure. Three types of soil—soft, medium, and stiff—were represented using parameters derived from literature. Seismic loads were applied using the response spectrum method for Seismic Zone 3, based on data obtained from the LINI PUPR application. The analysis considered seven structural parameters, including vertical displacement, axial force, shear forces in the Y and Z directions, bending moments about the Y and Z axes, and torsion. The results indicate that soil characteristics play a significant role in influencing the seismic behavior of the structure, and that the application of SSI modeling can enhance the accuracy of analysis and the effectiveness of bridge design under complex geotechnical conditions. Keywords: seismic response, steel truss bridge, soil-structure interaction, earthquake.