Kohei Suzuki

Chaotic rocking behavior of freestanding objects with sliding motion

This paper examines the influence of effects of sliding on the non-linear rocking response behavior of freestanding rigid objects (blocks) subjected to harmonic horizontal and vertical excitations. It is well known that the rocking responses depend strongly on the impact effect between object and the base, which takes place with abrupt reduction in kinetic energy. In this study, it is shown that the rocking behavior is significantly affected by the presence of the sliding motion. A parametric response analysis is carried out over a range of excitation amplitudes and frequencies. Chaotic responses are observed over a wide response region, particularly for the case of large vertical amplitude excitation with significant sliding motions. The chaotic characteristics are demonstrated using time histories, Poincare sections, power spectral density and Lyapunov exponents of the rocking responses. The complex chaotic response behavior is illustrated by Poincare section in the phase space. The distribution of various types of rocking responses and the effects of sliding motion are examined via bifurcation diagrams and examples of typical rocking responses.

REPORT ON DAMAGE TO INDUSTRIAL FACILITIES IN THE 1999 KOCAELI EARTHQUAKE, TURKEY

The author got a chance to visit Turkey for investigating the damage of industrial facilities in the 1999 Kocaeli Earthquake which occurred on 17 August 1999 in the Kocaeli province of Turkey. This report provides a brief investigation obtained through the seismic damage survey, particularly, focused on the damages to industrial facilities. The epicentral area in the Kocaeli province is the most industrial region of Turkey. Severe excitation attacked this region and industrial plants and structures were more or less damaged. Since the author could only visit a few sites, the report mainly describes the damages of two plants; TÜPRAŞ oil refinery where big fire occurred and TOYOTA-SA car manufacturing factory where no significant damage appeared.

Study on the Frame Structure Modeling of the Beam Element Formulated by Absolute Nodal Coordinate Approach

Accurate seismic analyses of large deformable moving structures are still unsolved problems in the field of earthquake engineering In order to analyze these problems, the nonlinear finite element method formulated by the absolute nodal coordinate approach is noticed Because, this formulation has several advantages over the standard procedures on mass matrix, elastic forces and damping forces in the case of large displacement problems But, it has not been fully studied to build frame structure models by using beam elements in the absolute nodal coordinate formulation In this paper, we propose the connecting method of the beam elements formulated by the absolute nodal coordinate The coordinate transformation matrix of this element is introduced into the frame structure This beam element has the characteristic that the mass matrix and bending stiffiness matrix are constant even if in the case of large displacement problems, and this characteristic is being kept after the transformation In order to verify the proposed method, we show the numerical simulation results of frame structures for a vibration problem and a large displacement problem

Seismic Proving Test of Ultimate Piping Strength: Ultimate Strength Test

The proving test of a large-scale piping system with a piping bore of 200A (8B) and made from carbon steel material was conducted to assure the safety margin of the current and new design codes for piping. Two test models were used, one for the design method confirmation test and one for the ultimate strength test. The design method confirmation test model reflected the structural features and vibration characteristics of piping systems. For the ultimate strength test, the piping system was modified by adding one more mass and removing one horizontal support. The original seismic wave to the input seismic wave was selected to be the “S2 ” seismic wave for a PWR building. The time-pitch and the excitation level were then modified to meet the test conditions. For the ultimate strength test, a series of tests was initiated at a pseudo-elastic design stress level of about 9 times the current allowable primary stress limit (3Sm) for the “S2 ” seismic wave, and repeated until the occurrence of piping failure due to through-wall fatigue cracking was obtained during Run 5 of seismic shaking. Pre-test and post-test analyses were performed. The post-test analysis results, which assessed certain differences of actual input acceleration, damping ratio, mass distribution and fatigue damage, compare well with the ultimate strength test results of elasto-plastic global response, local strain and the number of runs to piping failure.Copyright

Seismic Proving Test of Ultimate Piping Strength: Simulation Analysis of Simplified Piping System Test

The six-year program for the Seismic Proving Test of Ultimate Piping Strength has been running since 1998 with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. To resolve outstanding technical issues before proceeding on to a seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. A simulation analysis related to the simplified piping system test is described with a focus on the methodology of the non-linear dynamic response analysis of the whole piping system and the strain behavior of the localized critical elements, such as elbows and nozzles.Copyright

Developments of Seismic Design Code for High Pressure Gas Facilities in Japan

The Seismic Design Code for High Pressure Gas Facilities was established in advance of other industrial fields in 1982. Only exception was that for nuclear power plants. In 1995, Hyogoken Nanbu earthquake brought approximately 6,000 deaths and more than 100,000 M

Seismic Proving Test of Ultimate Piping Strength: Test Results on Piping Component and Simplified Piping System

loss or property in Kobe area, Japan. This unexpected serious event enforced us that industrial facilities should pay to special considerations of their damages including ground failure due to the liquefaction. Their strong ground motions brought serious damages to urban structures in the area. Thus, the Seismic Design Code of the High Pressure Gas Facilities were improved to include 2 step design assessments, that is, Level 1 earthquake (operating basisearthquake, the probable strong earthquake in the service life of the facilities), and Level 2 earthquake (safety shutdownearthquake, the possible strongest earthquake with extremely low probability of occurrence). For Level 2 earthquake, the ground failure by possible liquefaction shall be taken into account. In regard to Level 1 earthquake, the system must be remained safety without critical damage after the earthquake, in addition to no leakage of “gas”. In regard to Level 2 earthquake, the required seismic performance is that peventing systems must be remained without gas leakage, and stable. It means a certain non-elastic deformation without gas leakage may be allowed. The High Pressure Gas Safety Institute of Japan has set up the Seismic Safety Promotion Committee to modify their code in advance of other industries, and continue to investigate more reasonable seismic design practice for more than 5 years. Andthe final version of the guideline has been established for the design practices both in Level 1 and Level 2 earthquakes. This paper explains the activities of the committee, their new design concepts and scope of applications.Copyright

Seismic Proving Test of Ultimate Piping Strength: Design Method Confirmation Test

In 1998FY, the 6 year program of piping tests was initiated with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. In order to resolve extensive technical issues before proceeding on to the seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. In this paper, the current status of the piping component tests and the simplified piping system tests is reported with focus on fatigue damage evaluation under large seismic loading.Copyright

Seismic Proving Test of Ultimate Piping Strength: Current Status of Preliminary Tests — II

The proving test of a large-scale piping system with a piping bore of 200A (8B) and made from carbon steel material was conducted to assure the safety margin of the current and new design codes for piping. Two test models were used, one for the design method confirmation test and one for the ultimate strength test. The design confirmation test model reflected the structural features and vibration characteristics of piping systems. For the ultimate strength test, the piping system was modified by adding one more mass and removing one horizontal support. The original seismic wave to the input seismic wave was selected to be the “S2 ” seismic wave for a PWR building. The time-pitch and the excitation level were then modified to meet the test conditions. For the design confirmation test, a series of tests was initiated at a level of the current allowable primary stress limit (3Sm) for the “S2 ” seismic wave (off-resonance), culminating in an elasto-plastic response test up to 4.5 times the allowable primary stress limit (on-resonance as an extreme case) with no evidence of piping failure. Pre-test and post-test analyses were performed. The post-test analysis results, which considered some differences of actual input acceleration and damping ratio, compare well with the design confirmation test results of elasto-plastic global response and local strain.Copyright

W-1-1-4 INTRODUCTION OF DAMPING MATRIX INTO ABSOLUTE NODAL COORDINATE FORMULATION

In 1998FY, the 6 year program of piping tests was initiated with the following objectives: i) to clarify the elasto-plastic response and ultimate strength of nuclear piping, ii) to ascertain the seismic safety margin of the current seismic design code for piping, and iii) to assess new allowable stress rules. In order to resolve extensive technical issues before proceeding on to the seismic proving test of a large-scale piping system, a series of preliminary tests of materials, piping components and simplified piping systems is intended. In this paper, the current status of the piping component tests and the simplified piping system tests is reported with focus on fatigue damage evaluation under large seismic loading.Copyright