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An Overview of Soil Models for Earthquake Response Analysis Yunita, Halida; Hendriyawan, H.; Apriadi, Dedi
Journal of Engineering and Technological Sciences Vol 47, No 1 (2015)
Publisher : ITB Journal Publisher, LPPM ITB

Earthquakes can damage thousands of buildings and infrastructure as well as cause the loss of thousands of lives. During an earthquake, the damage to buildings is mostly caused by the effect of local soil conditions. Depending on the soil type, the earthquake waves propagating from the epicenter to the ground surface will result in various behaviors of the soil. Several studies have been conducted to accurately obtain the soil response during an earthquake. The soil model used must be able to characterize the stress-strain behavior of the soil during the earthquake. This paper compares equivalent linear and nonlinear soil model responses. Analysis was performed on two soil types, Site Class D and Site Class E. An equivalent linear soil model leads to a constant value of shear modulus, while in a nonlinear soil model, the shear modulus changes constantly,depending on the stress level, and shows inelastic behavior. The results from a comparison ofÂ both soilÂ modelsÂ areÂ displayed in the form of maximum acceleration profiles and stress-strain curves.

Development of Pre-consolidation Pressure Dependence of Mixed Hardening Multisurface Hyperplasticity Model for Better Prediction of Earthquakes Ground Response Analysis Apriadi, Dedi; Yunita, Halida; Likitlersuang, Suched; Pipatpongsa, Thirapong
Jurnal Teknik Sipil Vol 18, No 3 (2011)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (688.688 KB)

Abstract. It was known that soil behavior is dependent upon the history of loading and exhibits hardening behavior when deformed plastically. This paper presents a formulation of mixed hardening multisurface hyperplasticity model with stiffness factors of the kinematic hardening of the yield surfaces proportional to the pre-consolidation pressure to represent the history of loading. Formulation is emphasized for describing the cyclic loading behavior of clay soils. The advantages of this approach are that it can reproduce smooth transitions from elastic to plastic behavior and allows the stress-reversal history to be memorized by the internal variable function. The Modified Cam Clay yield function is selected as a key model to simulate the stress-strain response. The incremental stressâstrain response is calculated based on a rate-dependent formulation. Finally, this paper describes the importance of development of the formulated soil model to improve current constitutive models for evaluating the effects of local soil conditions on earthquake ground response analysis. Further results of numerical implementation and simulations and also model verification employing the proposed mathematical model formulation will be reported in a future publication. Abstract. Telah diketahui bahwa perilaku tanah akan tergantung dari sejarah pembebanannya dan juga memperlihatkan perilaku hardening apabila tanah mengalami deformasi secara plastik. Tulisan ini menyajikan sebuah formulasi model tanah mixed hardening multisurface hyperplasticity dengan faktor kekakuan kinematik hardening proporsional terhadap tekanan pra-konsolidasi guna merepresentasikan sejarah pembebanan yang terjadi pada tanah. Formulasi ditekankan untuk mendeskripsikan perilaku pembebanan siklik pada tanah lempung. Kelebihan dari pendekatan model hyperplasticity ini adalah dapat menghasilkan transisi dari perilaku elastik ke plastik secara smooth serta mampu âmengingatâ sejarah perubahan tegangan yang terjadi pada tanah dengan menggunakan fungsi variabel internal. Fungsi leleh Modified Cam Clay dipilih sebagai model utama untuk mensimulasikan respons tegangan-regangan. Selanjutnya, respons tegangan-regangan dihitung berdasarkan sebuah formulasi rate-dependent. Terakhir, tulisan ini mendeskripsikan pentingnya pengembangan model ini guna memperbaiki analisis respons tanah akibat gempa. Hasil-hasil lebih lanjut berupa implementasi dan simulasi numerik serta juga verifikasi model yang diusulkan akan disajikan dalam publikasi berikutnya.

Proposed New Strong Ground Motion Attenuation Relations for Subduction Zone Earthquakes Apriadi, Dedi
Jurnal Teknik Sipil Vol 11, No 4 (2004)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (169.348 KB)

Abstrak. Tulisan ini menyajikan usulan fungsi atenuasi terbaru untuk percepatan maksimum gempa di permukaan tanah tipe gempa subduksi interface dan intraslab pada moment magnitude lebih besar sama dengan 5 dan jarak 10 km sampai 500 km di batuan. Fungsi atenuasi telah dikembangkan dengan pendekatan Jaringan Syaraf Tiruan (JST) menggunakan algoritma propagasi balik. Studi memperlihatkan bahwa fungsi atenuasi berdasarkan JST akurat dan andal untuk memprediksi percepatan maksimum gempa. Studi parameter berbagai faktor input dari fungsi atenuasi juga telah dilakukan dan hasilnya akan disajikan di dalam tulisan ini.Abstract. This paper present proposed new attenuation relations at rock sites for peak ground acceleration for subduction zone interface and intraslab earthquakes of moment magnitude M 5 and greater and for distance of 10 to 500 km. The relations were developed by Artificial Neural Networks (ANN) approach using a back propagation algorithm. Studies show that the ANN-based attenuation relation is reliable and accurate to predict peak ground acceleration (PGA) due to earthquakes. Parameters studies of the various input factors of attenuation relations were also performed in this study and its results will be presented in this paper.

FINITE ELEMENT STUDY OF VACUUM PRELOADING AND PREFABRICATED VERTICAL DRAINS BEHAVIOR FOR SOFT SOIL IMPROVEMENT Apriadi, Dedi; Barnessa, Ressa Adrian; Marsa, Nisrina Aulia Is
Jurnal Teknik Sipil Vol 26, No 3 (2019)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2019.26.3.1

AbstractFinite element modeling of soft soil improvement with prefabricated vertical drains (PVD) and vacuum preloading behavior was carried out by considering smear effect and equivalent plane strain based on permeability conversion. Transfer of negative pore pressure due to vacuum preloading was modeled by using pore pressure boundary condition at soft soil layer and along the length of the PVD. The soft soil layer was modeled by using Modified Cam Clay constitutive model. Effect of constant and linearly decreasing vacuum pressure along the PVD length was investigated. Furthermore, prediction from this modeling such settlement was compared to Terzaghi 1-D consolidation. Degree of consolidation for radial only and combined vertical radial were predicted by using Barron?s and Carrillo?s formula, respectively. Numerical evaluation of vacuum preloading-induced lateral deformation compared to conventional preloading was also presented including its comparation with analytical method. Finally, several conclusions and recommendations related to modeling and behavior of combined PVD and vacuum preloading was given. AbstrakPemodelan elemen hingga perilaku perbaikan tanah lunak dengan vacuum preloading (pembebanan vakum) dan Prefabricated Vertical Drains (PVD) dilakukan dengan mempertimbangkan efek smear dan equivalent plane strain berdasarkan konversi permeabilitas. Transfer negative pore pressure akibat pembebanan vakum dimodelkan dengan menggunakan pore pressure boundary condition pada lapisan tanah lunak dan sepanjang PVD. Lapisan tanah lunak dimodelkan dengan menggunakan model konstitutif tanah Modified Cam Clay (MCC). Pengaruh distribusi tekanan vakum konstan dan bervariasi menurun secara linier di sepanjang PVD akan diteliti. Prediksi penurunan dari pemodelan elemen hingga selanjutnya dibandingkan dengan hasil perhitungan konsolidasi 1-D Terzaghi. Derajat konsolidasi dihitung menggunakan persamaan Barron untuk arah radial dan Carrillo untuk kombinasi arah vertikal dan radial. Evaluasi numerik perilaku deformasi lateral akibat penggunaan pembebanan vakum dibandingkan dengan preloading (timbunan) juga disajikan berikut perbandingannya terhadap metode analitis. Terakhir, beberapa kesimpulan dan rekomendasi terkait pemodelan dan perilaku kombinasi PVD dan pembebanan vakum diberikan.

An Overview of Soil Models for Earthquake Response Analysis Halida Yunita; H. Hendriyawan; Dedi Apriadi
Journal of Engineering and Technological Sciences Vol. 47 No. 1 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.1.5

Earthquakes can damage thousands of buildings and infrastructure as well as cause the loss of thousands of lives. During an earthquake, the damage to buildings is mostly caused by the effect of local soil conditions. Depending on the soil type, the earthquake waves propagating from the epicenter to the ground surface will result in various behaviors of the soil. Several studies have been conducted to accurately obtain the soil response during an earthquake. The soil model used must be able to characterize the stress-strain behavior of the soil during the earthquake. This paper compares equivalent linear and nonlinear soil model responses. Analysis was performed on two soil types, Site Class D and Site Class E. An equivalent linear soil model leads to a constant value of shear modulus, while in a nonlinear soil model, the shear modulus changes constantly,depending on the stress level, and shows inelastic behavior. The results from a comparison of both soil models are displayed in the form of maximum acceleration profiles and stress-strain curves.

Proposed New Strong Ground Motion Attenuation Relations for Subduction Zone Earthquakes Dedi Apriadi
Jurnal Teknik Sipil Vol 11 No 4 (2004)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2004.11.4.1

Abstrak. Tulisan ini menyajikan usulan fungsi atenuasi terbaru untuk percepatan maksimum gempa di permukaan tanah tipe gempa subduksi interface dan intraslab pada moment magnitude lebih besar sama dengan 5 dan jarak 10 km sampai 500 km di batuan. Fungsi atenuasi telah dikembangkan dengan pendekatan Jaringan Syaraf Tiruan (JST) menggunakan algoritma propagasi balik. Studi memperlihatkan bahwa fungsi atenuasi berdasarkan JST akurat dan andal untuk memprediksi percepatan maksimum gempa. Studi parameter berbagai faktor input dari fungsi atenuasi juga telah dilakukan dan hasilnya akan disajikan di dalam tulisan ini.Abstract. This paper present proposed new attenuation relations at rock sites for peak ground acceleration for subduction zone interface and intraslab earthquakes of moment magnitude M 5 and greater and for distance of 10 to 500 km. The relations were developed by Artificial Neural Networks (ANN) approach using a back propagation algorithm. Studies show that the ANN-based attenuation relation is reliable and accurate to predict peak ground acceleration (PGA) due to earthquakes. Parameters studies of the various input factors of attenuation relations were also performed in this study and its results will be presented in this paper.

Development of Pre-consolidation Pressure Dependence of Mixed Hardening Multisurface Hyperplasticity Model for Better Prediction of Earthquakes Ground Response Analysis Dedi Apriadi; Halida Yunita; Suched Likitlersuang; Thirapong Pipatpongsa
Jurnal Teknik Sipil Vol 18 No 3 (2011)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2011.18.3.4

Abstract. It was known that soil behavior is dependent upon the history of loading and exhibits hardening behavior when deformed plastically. This paper presents a formulation of mixed hardening multisurface hyperplasticity model with stiffness factors of the kinematic hardening of the yield surfaces proportional to the pre-consolidation pressure to represent the history of loading. Formulation is emphasized for describing the cyclic loading behavior of clay soils. The advantages of this approach are that it can reproduce smooth transitions from elastic to plastic behavior and allows the stress-reversal history to be memorized by the internal variable function. The Modified Cam Clay yield function is selected as a key model to simulate the stress-strain response. The incremental stress"“strain response is calculated based on a rate-dependent formulation. Finally, this paper describes the importance of development of the formulated soil model to improve current constitutive models for evaluating the effects of local soil conditions on earthquake ground response analysis. Further results of numerical implementation and simulations and also model verification employing the proposed mathematical model formulation will be reported in a future publication. Abstract. Telah diketahui bahwa perilaku tanah akan tergantung dari sejarah pembebanannya dan juga memperlihatkan perilaku hardening apabila tanah mengalami deformasi secara plastik. Tulisan ini menyajikan sebuah formulasi model tanah mixed hardening multisurface hyperplasticity dengan faktor kekakuan kinematik hardening proporsional terhadap tekanan pra-konsolidasi guna merepresentasikan sejarah pembebanan yang terjadi pada tanah. Formulasi ditekankan untuk mendeskripsikan perilaku pembebanan siklik pada tanah lempung. Kelebihan dari pendekatan model hyperplasticity ini adalah dapat menghasilkan transisi dari perilaku elastik ke plastik secara smooth serta mampu "mengingat" sejarah perubahan tegangan yang terjadi pada tanah dengan menggunakan fungsi variabel internal. Fungsi leleh Modified Cam Clay dipilih sebagai model utama untuk mensimulasikan respons tegangan-regangan. Selanjutnya, respons tegangan-regangan dihitung berdasarkan sebuah formulasi rate-dependent. Terakhir, tulisan ini mendeskripsikan pentingnya pengembangan model ini guna memperbaiki analisis respons tanah akibat gempa. Hasil-hasil lebih lanjut berupa implementasi dan simulasi numerik serta juga verifikasi model yang diusulkan akan disajikan dalam publikasi berikutnya.

Finite Element Study of Vacuum Preloading and Prefabricated Vertical Drains Behavior for Soft Soil Improvement Dedi Apriadi; Ressa Adrian Barnessa; Nisrina Aulia Is Marsa
Jurnal Teknik Sipil Vol 26 No 3 (2019)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2019.26.3.1

AbstractFinite element modeling of soft soil improvement with prefabricated vertical drains (PVD) and vacuum preloading behavior was carried out by considering smear effect and equivalent plane strain based on permeability conversion. Transfer of negative pore pressure due to vacuum preloading was modeled by using pore pressure boundary condition at soft soil layer and along the length of the PVD. The soft soil layer was modeled by using Modified Cam Clay constitutive model. Effect of constant and linearly decreasing vacuum pressure along the PVD length was investigated. Furthermore, prediction from this modeling such settlement was compared to Terzaghi 1-D consolidation. Degree of consolidation for radial only and combined vertical radial were predicted by using Barron's and Carrillo's formula, respectively. Numerical evaluation of vacuum preloading-induced lateral deformation compared to conventional preloading was also presented including its comparation with analytical method. Finally, several conclusions and recommendations related to modeling and behavior of combined PVD and vacuum preloading was given. AbstrakPemodelan elemen hingga perilaku perbaikan tanah lunak dengan vacuum preloading (pembebanan vakum) dan Prefabricated Vertical Drains (PVD) dilakukan dengan mempertimbangkan efek smear dan equivalent plane strain berdasarkan konversi permeabilitas. Transfer negative pore pressure akibat pembebanan vakum dimodelkan dengan menggunakan pore pressure boundary condition pada lapisan tanah lunak dan sepanjang PVD. Lapisan tanah lunak dimodelkan dengan menggunakan model konstitutif tanah Modified Cam Clay (MCC). Pengaruh distribusi tekanan vakum konstan dan bervariasi menurun secara linier di sepanjang PVD akan diteliti. Prediksi penurunan dari pemodelan elemen hingga selanjutnya dibandingkan dengan hasil perhitungan konsolidasi 1-D Terzaghi. Derajat konsolidasi dihitung menggunakan persamaan Barron untuk arah radial dan Carrillo untuk kombinasi arah vertikal dan radial. Evaluasi numerik perilaku deformasi lateral akibat penggunaan pembebanan vakum dibandingkan dengan preloading (timbunan) juga disajikan berikut perbandingannya terhadap metode analitis. Terakhir, beberapa kesimpulan dan rekomendasi terkait pemodelan dan perilaku kombinasi PVD dan pembebanan vakum diberikan.

PANDANGAN ALKITAB TERHADAP “FENOMENA HIPERREALITAS DI ERA REVOLUSI INDUSTRI 4.0” Apriadi, Dedi
GENEVA: JURNAL TEOLOGI DAN MISI Vol. 10 No. 2 (2020): Desember 2020
Publisher : Sekolah Tinggi Teologi Injili Abdi Allah

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.71361/gjtm.v10i2.36

Tujuan dari penulis ini adalah untuk melihat fenomena hiperrealitas di era revolusi industry 4.0.jika melihat media sosial faktanya fenomena ini menjangkit banyak orang baik dari kalangan bawah hingga atas. Dari yang terkenal sampai yang biasa biasa saja.Dari para masyarakat biasa sampai aparatur Negara.Dan tidak menutup kemungkinan adalah orang Kristen dan hamba Tuhan.Maka dari itu penulis ingin memaparkan mengenai konsep hiperrealitas. Karena tanpa disadari banyak orang ingin dan butuh pengakuan dari orang lain melalui media sosial. Bahkan tidak segan segan mengaburkan identitas diri, berbohong dan hanya sekedar pencitraan semata atas nama ketenaran dan ingin dikenal masyarakat. Hal ini penulis lihat sebagai fenomena yang berbahaya karena Alktab sendiri secara prinsip memberikan larangan untuk tidak pura pura dan mencari popularitas dalam Agama. Begitu juga kita sebagai orang awam juga jangan sampai terperdaya dengan segala hal yang ada dalam media sosial Karena kebenarannya belum tentu terbukti sama dengan kenyataan. Melalui media sosial tetaplah menjadi terang dan jujur dengan apa yang ada tanpa perlu mencari pengakuan dari oranglain.

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