Earthquake response analysis in the time domain for 2D soil-structure systems using analytical frequency-dependent infinite elements

2003 ◽  
Vol 58 (12) ◽  
pp. 1837-1855 ◽  
Author(s):  
Doo Kie Kim ◽  
Chung-Bang Yun
Keyword(s):  
Time Domain ◽  
Soil Structure ◽  
Earthquake Response ◽  
Response Analysis ◽  
Frequency Dependent ◽  
Infinite Elements ◽  
The Time Domain ◽  
Earthquake Response Analysis ◽  
Analytical Frequency

Time-Domain Nonlinear SSI Analysis of Foundation Sliding Using Frequency-Dependent Foundation Impedance Derived From SASSI

2008 ◽  
Author(s):  
Mansour Tabatabaie ◽  
Thomas Ballard
Keyword(s):  
Frequency Domain ◽  
Linear Systems ◽  
Time Domain ◽  
Soil Structure ◽  
Wave Radiation ◽  
Far Field ◽  
Frequency Dependent ◽  
Nonlinear Springs ◽  
Mat Foundation ◽  
The Time Domain

Dynamic soil-structure interaction (SSI) analysis of nuclear power plants is often performed in frequency domain using programs such as SASSI [1]. This enables the analyst to properly a) address the effects of wave radiation in an unbounded soil media, b) incorporate strain-compatible soil shear modulus and damping properties and c) specify input motion in the free field using the de-convolution method and/or spatially variable ground motions. For structures that exhibit nonlinearities such as potential base sliding and/or uplift, the frequency-domain procedure is not applicable as it is limited to linear systems. For such problems, it is necessary to solve the problem in the time domain using the direct integration method in programs such as ADINA [2]. The authors recently introduced a sub-structuring technique called distributed parameter foundation impedance (DPFI) model that allows the structure to be partitioned from the total SSI system and analyzed in the time domain while the foundation soil is modeled using the frequency-domain procedure [3]. This procedure has been validated for linear systems. In this paper we have expanded the DPFI model to incorporate nonlinearities at the soil/structure interface by introducing nonlinear shear and normal springs arranged in series between the DPFI and structure model. This combination of the linear far-field impedance (DPFI) plus nonlinear near-field soil springs allows the foundation sliding and/or uplift behavior be analyzed in time domain while maintaining the frequency-dependent stiffness and radiation damping nature of the far-field foundation impedance. To check the accuracy of this procedure, a typical NPP foundation mat supported at the surface of a layered soil system and subjected to harmonic forced vibration was first analyzed in the frequency domain using SASSI to calculate the target linear response and derive a linear, far-field DPFI model. The target linear solution was then used to validate two linear time-domain ADINA models: Model 1 consisting of the mat foundation+DPFI derived from the linear SASSI model and Model 2 consisting of the total SSI system (mat foundation plus a soil block). After linear alignment, the nonlinear springs were added to both ADINA models and re-analyzed in time domain. Model 2 provided the target nonlinear solution while Model 1 provided the results using the DPFI+nonlinear springs. By increasing the amplitude of the vibration load, different levels of foundation sliding were simulated. Good agreement between the results of two models in terms of the displacement response of the mat and cyclic force-displacement behavior of the springs validates the accuracy of the procedure presented herein.

scholarly journals Site Specific Response Analysis Kota Padang dari Input motion Conditional Mean Spectrum (CMS) Menggunakan Software NERA

2017 ◽  
Vol 14 (2) ◽  
pp. 28-38
Author(s):  
Merley Misriani
Keyword(s):  
Ground Motion ◽  
Time Domain ◽  
Earthquake Response ◽  
Response Analysis ◽  
Specific Response ◽  
Site Specific ◽  
Conditional Mean ◽  
Conditional Mean Spectrum ◽  
Input Motion ◽  
Earthquake Response Analysis

Dalam perencanaan struktur bangunan tahan gempa, tujuan umum dari analisa struktur dinamis adalah memprediksi respons dari struktur terhadap pengaruh ground motion yang memiliki Spectral Acceleration (Sa) pada periode tertentu berdasarkan tingkat kemungkinan terlampui (Probability of Excedence/PE) 10% atau 2% masa layan bangunan 50 tahun.  Prediksi respons struktur ditentukan dengan memilih ground motion yang cocok dengan beberapa target spektra dan nantinya ground motion tersebut digunakan sebagai input dalam analisis dinamis struktur. Pada paper ini menyajikan analisis perambatan gelombang gempa dari batuan dasar ke lapisan permukaan (Site Specific Response Analysis/ SSRA). Data-data yang diperlukan adalah data stratifikasi tanah dan parameter kecepatan gelombang geser yang didapatkan dari korelasi empiris terhadap data hasil pemboran dan uji N-SPT. Ground motion synthetic batuan dasar yang digunakan untuk perambatan gelombang gempa diperoleh dari hasil penelitian sebelumnya yang mengadopsi pendekatan statistik Conditional Mean Spectrum (CMS) agar ground motion  yang dihasilkan dipermukaan cocok dengan prediksi masalah respon struktur yang sebenarnya. SSRA dilakukan berdasarkan teori perambatan gelombang geser satu dimensi dalam time domain dengan menggunakan program Non-linear Earthquake Response Analysis (NERA). Hasilnya diperoleh percepatan maksimum gempa dipermukaan (peak surface acceleration/ PBA) berbeda-beda di kedua lokasi tergantung pada faktor amplifikasi, karakteristik dan jenis gempa yang terjadi. Direkomendasikan respons spectra desain untuk periode ulang 475 tahun dan 2475 tahun wilayah 4 kelas tanah sedang (SD) untuk kedua lokasi tersebut. Data-data tersebut digunakan sebagai input dalam penentuan beban gempa pada bangunan dalam analisis struktur dinamis.

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