Simplified seismic analysis of soil–well–pier system for bridges
TL;DR: In this article, the authors used three different approaches to evaluate their comparative performance and associated complexities: two-dimensional nonlinear (2D-NL), 2D-EqL, and one-dimensional spring-dashpot (1D).
About: This article is published in Soil Dynamics and Earthquake Engineering.The article was published on 2012-01-01. It has received 18 citations till now. The article focuses on the topics: Seismic analysis & Displacement (vector).
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TL;DR: In this article, the authors performed linear and equivalent linear site-response analyses at 100 Kiba-Kyoshin network (KiK-net) sites using 3,000 ground motions ranging in amplitude from weak to strong.
Abstract: Because of the limited number of strong‐motion records that have measured ground response at large strains, any statistical analyses of seismic site‐response models subject to strong ground motions are severely limited by a small number of observations. Recent earthquakes in Japan, including the M w 9.0 Tohoku earthquake of March 2011, have substantially increased the observations of strong‐motion records that can be used to compare alternative site‐response models at large strains and can subsequently provide insight into the accuracy and precision of site‐response models. Using the Kiban‐Kyoshin network (KiK‐net) downhole array data in Japan, we analyze the accuracy (bias) and variability (precision) resulting from common site‐response modeling assumptions, and we identify critical parameters that significantly contribute to the uncertainty in site‐response analyses. We perform linear and equivalent‐linear site‐response analyses at 100 KiK‐net sites using 3720 ground motions ranging in amplitude from weak to strong; 204 of these records have peak ground accelerations greater than ![Graphic][1] at the ground surface. We find that the maximum shear strain in the soil profile, the observed peak ground acceleration at the ground surface, and the predominant spectral period of the surface ground motion are the best predictors of where the evaluated models become inaccurate and/or imprecise. The peak shear strains beyond which linear analyses become inaccurate in predicting surface pseudospectral accelerations (PSA; presumably as a result of nonlinear soil behavior) are a function of vibration period and are between 0.01% and 0.1% for periods 0.5 s do not display noticeable effects of nonlinear soil behavior.
Online Material: Site‐specific information and model residuals at 100 KiK‐net stations.
[1]: /embed/inline-graphic-1.gif
153 citations
TL;DR: The Indian subcontinent has suffered some of the greatest earthquakes in the world as mentioned in this paper, and this earthquake was the first instance of an earthquake causing collapses of modern multi-storey buildings in India and triggered unprecedented awareness amongst professionals, academics and the general public.
Abstract: The Indian subcontinent has suffered some of the greatest earthquakes in the world. The earthquakes of the late nineteenth and early twentieth centuries triggered a number of early advances in science and engineering related to earthquakes that are discussed here. These include the development of early codes and earthquake-resistant housing after the 1935 Quetta earthquake in Baluchistan, and strengthening techniques implemented after the 1941 Andaman Islands earthquake, discovered by the author in remote islands of India. Activities in the late 1950s to institutionalize earthquake engineering in the country are also discussed. Despite these early developments towards seismic safety, moderate earthquakes in India continue to cause thousands of deaths, indicating the poor seismic resilience of the built environment. The Bhuj earthquake of 2001 highlighted a striking disregard for structural design principles and quality of construction. This earthquake was the first instance of an earthquake causing collapses of modern multi-storey buildings in India, and it triggered unprecedented awareness amongst professionals, academics and the general public. The earthquake led to the further development of the National Information Centre of Earthquake Engineering and the establishment of a comprehensive 4-year National Programme on Earthquake Engineering Education that was carried out by the seven Indian Institutes of Technology and the Indian Institute of Science. Earthquake engineering is a highly context-specific discipline and there are many engineering problems where appropriate solutions need to be found locally. Confined masonry construction is one such building typology that the author has been championing for the subcontinent. Development of the student hostels and staff and faculty housing on the new 400-acre campus of the Indian Institute of Technology Gandhinagar has provided an opportunity to adopt this construction typology on a large scale, and is addressed in the monograph. The vulnerability of the building stock in India is also evident from the occasional news reports of collapses of buildings under construction or during rains (without any earthquake shaking). Given India’s aspirations to be counted as one of the world’s prosperous countries, there is a great urgency to address the safety of our built environment. There is a need: to create a more professional environment for safe construction, including a system for code enforcement and building inspection; for competence-based licensing of civil and structural engineers; for training and education of all stakeholders in the construction chain; to build a research and development culture for seismic safety; to encourage champions of seismic safety; to effectively use windows of opportunity provided by damaging earthquakes; to focus on new construction as opposed to retrofitting existing buildings; and to frame the problem in the broader context of overall building safety rather than the specific context of earthquakes. Sustained long-term efforts are required to address this multi-faceted complex problem of great importance to the future development of India. While the context of this paper is India, many of the observations may be valid and useful for other earthquake-prone countries.
40 citations
TL;DR: In this paper, a new analytical model is proposed to predict seismic analysis of pile group supported bridges and a new approximate equation is proposed for calculating the natural frequency of these bridges based on the suggested analytical model.
Abstract: Because of the crucial role of free vibration frequency of a structure (e.g., a bridge) in design procedure, more realistic estimation of the frequency ends up in safer and more optimized design. As obtaining the free vibration frequencies of a bridge, considering soil-pile group-structure interaction, provide more realistic values, development of an analytical model to obtain such free vibration frequencies is studied in this research work. Most researchers have studied models with a single pile foundation. The purpose of this study is to assess soil-structure interaction (SSI) effects on dynamic performance of pile group supported bridges. A new analytical model is proposed to predict seismic analysis of these bridges. Applying the dynamic equations of motion for the system, SSI effects have been estimated. Based on the suggested analytical model, a new approximate equation is proposed for calculating natural frequency of pile group supported bridges. Equation accuracy has been investigated by comparing...
22 citations
14 Jan 2019
TL;DR: The exact solution of the passive resistance acting on a caisson foundation due to earthquake-induced loading is important for the seismic design of caissons as mentioned in this paper, and the three-dimensional s...
Abstract: The exact solution of the passive resistance acting on a caisson foundation due to earthquake-induced loading is important for the seismic design of caissons. In this study, the three-dimensional s...
11 citations
21 Feb 2020
9 citations
References
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TL;DR: In this paper, a numerical method for the dynamic analysis of infinite continuous systems is developed, applicable to systems for which all exciting forces and geometrical irregularities are confined to a limited region and is applicable to both transient and steady state problems.
Abstract: A numerical method for the dynamic analysis of infinite continuous systems is developed. The method is applicable to systems for which all exciting forces and geometrical irregularities are confined to a limited region and is applicable to both transient and steady state problems. The infinite system is replaced by a system consisting of a finite region subjected to a boundary condition which simulates an energy absorbing boundary. The resulting systems may be analyzed by the finite element method. Examples applying the method to foundation vibration problems are presented. Good agreement with existing solutions is found and new results for embedded footings are presented.
2,172 citations
"Simplified seismic analysis of soil..." refers methods in this paper
...Viscous boundary proposed by Lysmer and Kuhlemeyer [16] was used as radiation boundary at the two vertical boundaries and at the base of the FE model....
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01 Jan 1970
1,349 citations
"Simplified seismic analysis of soil..." refers background in this paper
...However, in absence of laboratory test, these can be estimated from empirical relationships available in the literature [23–26], or from the experimental results of a...
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01 Aug 2001
810 citations
"Simplified seismic analysis of soil..." refers background in this paper
...However, in absence of laboratory test, these can be estimated from empirical relationships available in the literature [23–26], or from the experimental results of a...
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TL;DR: In this article, the authors investigated the resistance of soil to harmonic motion of an infinitely long cylinder in terms of linear viscoelasticity and obtained a closed-form solution from which the complex stiffness can be evaluated.
Abstract: Resistance of soil to harmonic motion of an infinitely long cylinder is investigated theoretically in terms of linear viscoelasticity. Closed-form solution is obtained from which the complex stiffness can be evaluated. The numerical results agree with those obtained by means of the correspondence principle.
400 citations
"Simplified seismic analysis of soil..." refers background or methods in this paper
...[4] proposed the following dynamic impedances or complex stiffness of unit length of soil when an infinitely long rigid cylinder is embedded in homogeneous soil and subjected to translational and rotational modes of vibration independently assuming plane-strain condition along the length of the cylinder:...
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...Therefore, it can be concluded that the effects of simplification of Novak’s [4] spring and dashpot coefficients, and the base rotational spring on the maximum force and displacement responses of pier and well foundation are not significant....
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...In the 1D approach, various combinations of Novak’s [4]...
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