Dynamics of structures

The dynamic behavior of rigid-block structures resting on a rigid foundation subjected to horizontal harmonic excitation is examined. For slender structures, the nonlinear equation of motion is approximated by a piecewise linear equation. Using this approximation for an initially quiescent structure, safe or no-toppling and unsafe regions are identified in an excitation amplitude versus excitation frequency plane. Furthermore, several possible modes of steady-state response are detected, and analytical procedures are developed for determining the amplitudes of the predominant modes and for performing stability analyses. It is shown that the produced stability diagrams can be beneficial to assessing the toppling potential of a rigid-block structure under a given amplitude-frequency combination of harmonic excitation; in this manner the integration of the equation of motion is circumvented.

Closure of "Rocking of Rigid Blocks Due to Harmonic Shaking"

SynOptics Communications Inc.

Written by a leader on the subject, Introduction to Geotechnical Engineering is first introductory geotechnical engineering textbook to cover both saturated and unsaturated soil mechanics. Destined to become the next leading text in the field, this book presents a new approach to teaching the subject, based on fundamentals of unsaturated soils, and extending the description of applications of soil mechanics to a wide variety of topics. This groundbreaking work features a number of topics typically left out of undergraduate geotechnical courses.

Geotechnical Engineering: Unsaturated and Saturated Soils

Automatic detection of atrial fibrillation using stationary wavelet transform and support vector machine

Comparison of rocking behavior between conventional and new-type of shallow foundations via centrifuge tests

Development of seismic CPT for shear wave velocity measurement in centrifuge models

To obtain a shear-wave velocity profile in geotechnical practice, various seismic investigation methods which have their own strength and weakness are being frequently used. In this study, harmonic wavelet analysis of wave (HWAW) method is applied to determination of Vs profile to overcome some of weaknesses in the existing surface wave methods. HWAW method which is based on timefrequency analysis using harmonic wavelet transform have been developed to determine phase and group velocities of waves. Field testing of this method is relatively simple and fast because one experimental setup which consists of one pair of receivers is needed to determine Vs profile of site. The proposed method uses the signal portion of the maximum local signal/noise ratio to evaluate the phase velocity to minimize the effects of noise, and uses single array inversion which considers receiver locations. In order to estimate the applicability of HWAW method, field tests were performed in 4 sites. 2 sites are for evaluating accuracy of test method and others are for estimating the applicability of 2-D imaging by HWAW method. Through field applications and comparison with other test results, the good accuracy and applicability of the proposed method were verified.

Seismic site characterization using hwaw(harmonic wavelet analysis of waves) method

Settlement prediction of large scale plate load test using shear wave velocity profile

The lateral deflection of a cylindrical diaphragm wall and the associated ground movement induced by deep excavation are analyzed by performing site instrumentations and numerical analyses in the coastal area of Korea. Wall lateral deflection, rebar stress, and pore water pressure were measured and analyzed in eight directions. Variations of soil properties with the decrease of confining pressure are compared by performing various in-situ tests before and after excavation. To calculate the wall lateral deflection accurately, the effects of small strain nonlinearity and confining pressure reduction developed during excavation are considered in the proposed numerical analysis. By comparing numerical results with measured ones, the importances of considering small strain nonlinearity and confining pressure reduction in the nonlinear FEM are emphasized. Also, parametric studies on the performance of cylindrical diaphragm walls are carried out for the future similar excavation in the coastal area.

Dong-Soo Kim

Papers

Comparison of rocking behavior between conventional and new-type of shallow foundations via centrifuge tests

Development of seismic CPT for shear wave velocity measurement in centrifuge models

Seismic site characterization using hwaw(harmonic wavelet analysis of waves) method

Settlement prediction of large scale plate load test using shear wave velocity profile

Deformation Analysis of Cylindrical Earth Retaining Structures during Excavation Considering Nonlinear Soil Behavior at Small Strain