scholarly journals Numerical Study on Dynamic Response of Pile Group Foundation of Geotechnical Centrifuge

2015 ◽  
Vol 22 ◽  
pp. 04018
Author(s):  
Quansheng Mao ◽  
Tao Yue ◽  
Dianjun Zuo
Keyword(s):  
Dynamic Response ◽  
Numerical Study ◽  
Pile Group ◽  
Geotechnical Centrifuge

Online Dynamic Response Reconstruction in the Presence of Observation Outliers

2021 ◽  
Author(s):  
Chaodong Zhang ◽  
Jian’an Li ◽  
Youlin Xu
Keyword(s):  
Kalman Filter ◽  
Dynamic Response ◽  
Numerical Study ◽  
Frame Structure ◽  
System Model ◽  
Measurement Information ◽  
Model Errors ◽  
Process Noise ◽  
Robust Kalman Filter ◽  
Response Reconstruction

Previous studies show that Kalman filter (KF)-based dynamic response reconstruction of a structure has distinct advantages in the aspects of combining the system model with limited measurement information and dealing with system model errors and measurement Gaussian noises. However, because the recursive KF aims to achieve a least-squares estimate of state vector by minimizing a quadratic criterion, observation outliers could dramatically deteriorate the estimator’s performance and considerably reduce the response reconstruction accuracy. This study addresses the KF-based online response reconstruction of a structure in the presence of observation outliers. The outlier-robust Kalman filter (OKF), in which the outlier is discerned and reweighted iteratively to achieve the generalized maximum likelihood (ML) estimate, is used instead of KF for online dynamic response reconstruction. The influences of process noise and outlier duration to response reconstruction are investigated in the numerical study of a simple 5-story frame structure. The experimental work on a simply-supported overhanging steel beam is conducted to testify the effectiveness of the proposed method. The results demonstrate that compared with the KF-based response reconstruction, the proposed OKF-based method is capable of dealing with the observation outliers and producing more accurate response construction in presence of observation outliers.

scholarly journals Experimental and Numerical Study on Modal Dynamic Response of Water-Surrounded Slender Bridge Pier with Pile Foundation

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
Yulin Deng ◽  
Qingkang Guo ◽  
Lueqin Xu
Keyword(s):  
Dynamic Response ◽  
Water Level ◽  
Pile Foundation ◽  
Numerical Study ◽  
Fluid Structure Interaction ◽  
Bridge Pier ◽  
Experimental Program ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Tip Mass

This paper presents an experimental program performed to study the effect of fluid-structure interaction on the modal dynamic response of water-surrounded slender bridge pier with pile foundation. A reduced scale slender bridge pier specimen is built and tested through forced vibration method. The vibration periods of the first four lateral modes, including the first two modes along x-axis and the first two modes along y-axis, are measured based on the specimen submerged by 16 levels of water and designated with 4 levels of tip mass. Three-dimensional (3D) finite-element models are established for the tested water-pier system and analyzed under various combined cases of water level and tip mass. Percentage increases of vibration periods with respect to dry vibration periods (i.e., vibration periods of the specimen without water) are determined as a function of water level and tip mass to evaluate the effect of fluid-structure interaction. The numerical results are successfully validated against the recorded test data. Based on the validated models, the modal hydrodynamic pressures are calculated to characterize the 3D distribution of hydrodynamic loads on the pier systems. The research provides a better illumination into the effect of fluid-structure interaction on the modal dynamic response of deepwater bridges.

Design, Manufacturing and Testing of Small Shaking Table

2018 ◽  
Vol 7 (4.20) ◽  
pp. 426 ◽  
Author(s):  
Asad H. Humaish ◽  
Mohammed S. Shamkhi ◽  
Thualfiqar K. Al-Hachami
Keyword(s):  
Dynamic Response ◽  
Shaking Table ◽  
Single Frequency ◽  
Main Body ◽  
Maximum Displacement ◽  
Maximum Acceleration ◽  
Geotechnical Centrifuge ◽  
Concrete Gravity Dams ◽  
Sinusoidal Waveform ◽  
Model Weight

The seismic performance and the dynamic response of concrete gravity dams can be verified by several techniques. Both geotechnical centrifuge apparatus (under N-g values) and shaking table (under 1-g) are the commonly used techniques in the world. This paper deals with designing, manufacturing, and testing of small shaking table to investigate different geotechnical and engineering problems. The main body of the designed shaking table consists of steel frame (local iron) manufactured as a hollow box with steel plate, 6mm in thickness and one-direction movable platform (as a basket carrying the container of the model).  Inside this main box, all the mechanical parts that work as one system to generate the motion of the seismic wave with an acceleration that needed to the test.  The facilities of this shaking table, the movable base has a dimension of 0.8m x1.2m and the platform mass approximately 2 kN, the maximum allowable model weight of 10kN, the range of frequency from 0 to 20 Hz, the maximum acceleration amplitude of 1.2g and maximum displacement of 14mm. It can simulate only the single frequency motion (i.e. sinusoidal wave). The measured accelerations at different soil model level for the tested shaker under 0.6g sinusoidal waveform gave a reasonable prediction for the dynamic response and the amplification characteristics.  

Experimental and Numerical Study on Dynamic Response of FSRU-LNGC Side-by-Side Mooring System

2019 ◽  
Author(s):  
Jingxia Yue ◽  
Weili Kang ◽  
Wengang Mao ◽  
Pengfei Chen ◽  
Xi Wang
Keyword(s):  
Numerical Analysis ◽  
Dynamic Response ◽  
Numerical Study ◽  
Clean Energy ◽  
Coupled Analysis ◽  
Response Analysis ◽  
Mooring System ◽  
Test Results ◽  
Floating Bodies ◽  
Damping Parameter

Abstract Floating Storage and Regasification Unit (FSRU) becomes one of the most popular equipment in the industry for providing clean energy due to its technical, economic and environmental features. Under the combined loads from wind, wave and current, it is difficult for the prediction of the dynamic response for such FSRU-LNGC (Liquified Natural Gas Carrier) side-by-side mooring system, because of the complicated hydrodynamic interaction between the two floating bodies. In this paper, a non-dimensional damping parameter of the two floating bodies is obtained from a scaled model test. Then the numerical analysis is carried out based on the test results, and the damping lid method is applied to simulate the hydrodynamic interference between floating bodies. The dynamic response of the side-by-side mooring system including six degrees of freedom motion, cable tension and fender force are provided and analyzed. According to the comparisons between numerical results and the test results, it is shown that the proposed coupled analysis model is reliable, and the numerical analysis can properly describe the dynamic response of the multi-floating mooring system in the marine environment. Moreover, the non-dimensional damping parameter which is used in numerical analysis can act as a good reference to the dynamic response analysis of similar multi-floating mooring systems.

scholarly journals Flexible Pile Group Interaction Factors under Arbitrary Lateral Loading in Sand

2020 ◽  
Vol 8 (10) ◽  
pp. 800
Author(s):  
Miloš Marjanović ◽  
Mirjana Vukićević ◽  
Diethard König
Keyword(s):  
Numerical Study ◽  
Group Interaction ◽  
Pile Group ◽  
Lateral Loading ◽  
Soil Conditions ◽  
Offshore Platforms ◽  
Lateral Loads ◽  
Pile Groups ◽  
Main Hypothesis ◽  
Interaction Factors

Marine and harbor structures, wind turbines, bridges, offshore platforms, industrial chimneys, retaining structures etc. can be subjected to significant lateral loads from various sources. Appropriate assessment of the foundations capacity of these structures is thus necessary, especially when these structures are supported by pile groups. The pile group interaction effects under lateral loading have been investigated intensively in past decades, and the most of the conducted studies have considered lateral loading that acts along one of the two orthogonal directions, parallel to the edge of pile group. However, because of the stochastic nature of its source, the horizontal loading on the pile group may have arbitrary direction. The number of studies dealing with the pile groups under arbitrary loading is very limited. The aim of this paper is to investigate the influence of the arbitrary lateral loading on the pile group response, in order to improve (extend) the current design approach for laterally loaded pile groups. Free head, flexible bored piles in sand were analyzed through the extensive numerical study. The main hypothesis of the research is that some critical pile group configurations, loading directions, and soil conditions exist, which can lead to the unsafe structural design. Critical pile positions inside the commonly used pile group configurations are identified with respect to loading directions. The influence of different soil conditions was discussed.

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