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"ABSTRAKKombinasi beban gravitasi dan gempa pada desain struktur penahan gempa memberikan desain girder dengan kebutuhan tulangan tumpuan yang banyak dan tulangan lapangan sebaliknya. Hal ini dapat menimbulkan permasalahan, diantaranya adalah kesulitan pelaksanaan akibat padatnya tulangan pada tumpuan girder dan keretakan pada lapangan girder akibat sedikitnya tulangan terpasang. Salah satu solusi yang ditawarkan adalah melakukan redistribusi momen. ACI318 mengijinkan penerapan redistribusi momen dengan mengurangi momen negatif maksimum dan mendistribusikannya ke daerah momen positif maksimum, dengan derajat redistribusi maksimum adalah 20%. Penelitian ini bertujuan untuk menganalisis efek penerapan redistribusi momen terhadap kinerja global dan lokal struktur. Pada penelitian ini empat struktur bangunan tahan gempa didesain sesuai ASCE 7-16, yaitu: (1) model M8, struktur gedung 8 lantai dengan denah lantai simetris, (2) M8A, struktur gedung 8 lantai dengan denah lantai asimetris, (3) M12, struktur gedung 12 lantai dengan denah lantai simetris, dan (4) M8L, model 8 lantai dengan geometri denah berbentuk L. Dari setiap model dikembangkan 4 model berbeda, dengan variasi tingkat redistribusi momen dan lokasi penerapannya. Analisis nonlinear riwayat waktu sesuai dengan ASCE 41-17 dilakukan terhadap hasil desain elastis. Hasil yang didapatkan adalah terjadi penurunan kekuatan, kekakuan, dan kinerja struktur secara global serta lokal komponen struktur, namun kinerja global dan kinerja lokal struktur masih berada pada tingkat kinerja desain awal.

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ABSTRACTCombination of gravity and seismic loads on a reinforced concrete seismic resisting structure leads to the needs of large number of rebar at the support and small number of rebar at mid-section of a girder. This leads to potential problems such as congestion at the support and cracking at girder's mid-section. ACI318 allows the application of moment redistribution by reducing the maximum negative moment and distribute it to maximum positive moment with maximum allowed redistribution is 20%. This study is done to investigate the effect of moment redistribution to global and local components' performance. Four models designed in accordance to ASCE 7-16 are developed, that is: (1) 8-story reinforced concrete (RC) building with symmetrical floor plan, (2) 8-story RC building with unsymmetrical floor plan, (3) 12-story RC building with symmetrical floor plan, and (4) 8-story RC building with L-shaped floor plan. From each models four variations will be developed based on moment redistribution degree and its location. Nonlinear time history analysis in accordance to ASCE 41-17 is done to all models. The result obtained from this study shows that there is reduction in the strength, stiffness, and peformance level of the global and local component performances, yet the global and local components' performance is still inside the range of acceptable response."

"Seismic waves used for exploration of geological structures are mostly generated from blast sources. A new blasting vibroseis apparatus, which utilizes the homogeneity, isotropy, and incompressibility of water to reduce damage to adjacent rock from blast waves, was developed. This method overcomes the low repeatability and low control issues of traditional blast methods (downhole charge) while maintaining the advantages of high explosive power, sharp pulse signal, and a wide range of frequency domains. Blasting vibroseis and traditional blasting tests were implemented in the Three Gorges Reservoir Region, China. The finite element method (FEM) method was used to numerically calculate blasting vibroseis-induced dynamic ground pressures. Through a series of comparison tests, the characteristics of the seismic waves generated by blasting vibroseis were summarized and the repeatability and controllability of the blasting vibroseis test was validated. The blasting vibroseis apparatus was then used to detect geological structures below the surface of the Maoping landslide, China, and the results were very consistent with previous drilling exploration (89%), which reflects the practical value of the new blasting vibroseis for the exploration of geological structures. Blasting vibroseis can be used as a practical and cost-effective method to detect geological structures."

"Penelitian ini membahas mengenai analisis perilaku dinamik struktur bangunan tahan gempa dengan perletakan terisolasi dengan cara membandingkannya dengan bangunan dengan perletakan tetap. Bangunan dengan perletakan terisolasi dimodelkan dengan menggunakan base isolation yang sesuai dengan yang digunakan oleh rumah sakit UI, sementara bangunan dengan perletakan tetap dimodelkan dengan menggunakan perletakan jepit. Beban gempa yang digunakan adalah beban gempa riwayat waktu northridge, kobe, dan el-centro yang telah diskalakan dengan respon spektrum Depok sesuai dengan SNI 1726:2012 Tata cara perencanaan ketahanan gempa untuk struktur gedung dan non gedung. Analisa yang digunakan yaitu nonlinear time history direct integration. Nonlinearitas dari bangunan didapatkan dari material dan geometri yang diwakilkan oleh sendi plastis pada bangunan dengan perletakan tetap dan base isolator yang telah berdeformasi melebihi batas lelehnya pada bangunan dengan perletakan terisolasi. Dari hasil penelitian menunjukkan penggunaan base isolator pada struktur bangunan tahan gempa meningkatkan peforma bangunan akibat beban gempa, serta memperkecil gaya dalam element-element struktur bangunan.

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This study discusses the comparison of the dynamic behaviour analysis of the isolated base seismic structure and fixed base structure. The isolator used in the mathematical model of the isolated base structure in this study is the same with the isolator that will be used in the real UI Hospital Building, while the fixed base structure modeled by rigid base. The seismic load used in this study are time history seismic load of Northridge, Kobe, and El Centro. The time history is scaled by the factor appropriate with SNI 1726:2012.

Nonlinear time history direct analysis method will be performed in this study. The nonlinearity of the structure consists of geometrical nonlinearity and material nonlinearity gained from the plastic hinge and the deformation of the isolator that exceed its yield deformation point. Result shows that isolated base structure has better performances than fixed base structure. It showed by the decreasing amount of the internal forces of each elements of the structure."

"Gempa merusak yang terjadi di Cianjur pada 21 November 2022 (Mw 5.6) disebabkan oleh sesar tersembunyi yang tidak teridentifikasi sebelumnya. Dalam praktik keinsinyuran ini, penulis bersama tim melakukan investigasi struktur penyebab rangkaian gempa tersebut dengan menganalisis pola distribusi gempa susulan. Data diperoleh melalui pemasangan 19 stasiun seismik temporer untuk merekam aktivitas seismik selama satu bulan. Analisis pola hiposenter dengan metode double-difference mengungkap adanya dua klaster seismik, yang mengindikasikan gempa ini dipicu oleh sepasang sesar conjugate (saling berpotongan) berorientasi NNW-SSE dan WSW-ENE. Praktik ini juga mencakup analisis aspek profesionalisme, kode etik, dan K3LL yang diterapkan dalam seluruh rangkaian kegiatan, mulai dari perencanaan, pelaksanaan, hingga diseminasi hasil. Profesionalisme dijunjung tinggi melalui penerapan teknologi dan rekayasa yang merupakan best practices di bidangnya, kolaborasi multidisiplin, dan dokumentasi yang transparan untuk memastikan hasil yang akurat dan dapat dipertanggungjawabkan. Penerapan kode etik terwujud dalam integritas dan akurasi ilmiah, serta tanggung jawab sosial dengan menyampaikan temuan secara objektif kepada masyarakat dan pemangku kebijakan. Aspek K3LL menjadi prioritas, dengan pelaksanaan survei yang mematuhi standar kesehatan dan keselamatan kerja, seperti penggunaan pakaian lapangan dan, penilaian risiko lapangan. Pendekatan yang terintegrasi dari analisis teknis, prinsip profesionalisme, penerapan kode etik, dan komitmen terhadap K3LL memberikan dasar yang kuat untuk memahami karakteristik gempa Cianjur dan menyusun rekomendasi mitigasi yang efektif serta berkelanjutan.

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The destructive earthquake that occurred in Cianjur on November 21, 2022 (Mw 5.6), was caused by a previously unidentified hidden fault. In this engineering practice, the author and the team investigated the structure responsible for the series of earthquakes by analyzing the distribution pattern of aftershocks. Data were collected through the installation of 19 temporary seismic stations to record seismic activity over one month. The analysis of hypocenter patterns using the double-difference method revealed two seismic clusters, indicating that the earthquake was triggered by a pair of conjugate faults (intersecting faults) oriented NNW-SSE and WSW-ENE. This practice also included an analysis of professionalism, ethics, and occupational health, safety, and environment (HSE) aspects applied throughout all stages of activities, from planning and implementation to dissemination of results. Professionalism was upheld by applying technology and engineering best practices, multidisciplinary collaboration, and transparent documentation to ensure accurate and accountable results. The implementation of ethics was reflected in the integrity and scientific accuracy, as well as social responsibility, by objectively sharing findings with the public and policymakers. HSE aspects were prioritized by conducting surveys in compliance with health and safety standards, such as wearing field gear and conducting risk assessments. This integrated approach of technical analysis, professionalism, ethical implementation, and commitment to HSE provides a strong foundation for understanding the characteristics of the Cianjur earthquake and formulating effective and sustainable mitigation recommendations. "