Time filter

Source Type

Cox B.R.,University of Texas at Austin | Boulanger R.W.,University of California at Davis | Tokimatsu K.,Tokyo Institute of Technology | Wood C.M.,University of Texas at Austin | And 13 more authors.
Earthquake Spectra | Year: 2013

The 2011 MW = 9.0 Tohoku-oki earthquake generated a large number of unique soil liquefaction case histories, including cases with strong ground motion recordings on liquefiable or potentially liquefiable soils.Wehave compiled a list of 22 strong motion stations (SMS) where surface evidence of liquefaction was observed and 16 SMS underlain by geologically recent sediments or fills where surface evidence of liquefaction was not observed. Pre-earthquake standard penetration test data and borehole shear wave velocity (Vs) profiles are available for some stations, but critical information, such as grain size distribution and fines plasticity, are often lacking. In the heavily damaged city of Urayasu, we performed post-earthquake cone penetration testing at seven SMS and Vs profiles, using surface wave methods at 28 additional locations to supplement existing geotechnical data. We describe the liquefaction effects in Urayasu, the available site characterization data, and our initial data interpretations. © 2013, Earthquake Engineering Research Institute.

Watanabe T.,Kobori Research Complex Inc. | Kato K.,Kobori Research Complex Inc. | Fukumoto S.,Tokyo Soil Research Co. | Eto K.,Tokyo Soil Research Co.
Journal of Structural and Construction Engineering | Year: 2013

This paper describes vibration characteristics of Nikko-zan Rin-noji temple Hondo (main hall) for the 2011 off the Pacific coast of Tohoku Earthquake and its aftershocks. From rare records observed in the traditional wooden structure, the characteristics are identified by the forgetting factor recursive least squares method. In the first translational mode, the natural frequency decreases and the damping factor increases with increasing deformation. It is expected that the nonlinearity is recoverable, because the results of microtremor measurements almost never change before and after the mainshock. The vibration characteristics in torsional mode show independency on increasing deformation.

Yamanaka H.,Tokyo Institute of Technology | Chimoto K.,Tokyo Institute of Technology | Tsuno S.,Railway Technical Research Institute | Dhakal Y.P.,Tokyo Institute of Technology | And 4 more authors.
Journal of Disaster Research | Year: 2012

In this study we investigated site amplifications in shallow soil around Tsukidate station (MYG004) of K-NET in Miyagi prefecture with a seismic intensity of 7 during the 2011 off the Pacific Coast of Tohoku Earthquake from aftershock observation and microtremor explorations. We conducted aftershock observations by installing 8 temporary stations. We estimated site amplifications of S-wave from the observed data. We found that the predominant period of amplification at a site near MYG004 was 0.2 seconds. The amplification factor at a site on cut ground with a distance of 20 m from MYG004 was significantly different. Furthermore, the amplifications were also different with changing predominant periods from 0.1 to 0.5 seconds in an area of 1 km from MYG004. Shallow S-wave velocity profiles were deduced from microtremor array explorations at the stations. Results indicated that shallow low-velocity layers with a thickness of less than 30 meters are responsible for variation of the amplifications. Predominant periods in calculated 1D amplifications were similar to those observed in the aftershock observations. The observed amplification factor at the site near MYG004, however, was two times larger than the calculated one, suggesting the inappropriateness of the 1D assumption at the site possibly due to the effects of a cliff near MYG004. We also found from horizontal-vertical ratios of microtremors that the site effects on the cliff were also different at frequency higher than 10 Hz within 30 meters around MYG004. This also suggests lateral variation in the site effects at the high frequency near MYG004.

Kaneko O.,Toda Corporation | Nakai S.,Chiba University | Mukai T.,Japan Building Research Institute | Hirade T.,Japan Building Research Institute | And 2 more authors.
AIJ Journal of Technology and Design | Year: 2015

There were several cases reported the damage to precast concrete piles during the 2011 Great East Japan earthquake. To estimate the strength and deformation characteristics of precast concrete piles against big earthquakes, data of existing load tests were collected and analyzed. The characteristics obtained by calculation used cross-sectional correspond to the results of the load tests.

Rahimian M.,Kanagawa University | Ochiai T.,Kozo Keikaku Eng. Inc. | Ishii T.,Tokyo Soil Research Co. | Navarro M.,University of Almeria | And 2 more authors.
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium | Year: 2010

Japan has suffered greatly from natural destructive events such as 1923 Kanto earthquake. Numerous geological data have been collected from local governments and municipalities in Kanagawa prefecture, Japan in order to be applied on studies for the effect of surface geology on seismic motions as well as micro-zoning projects. Further more data from array measurements have been added to the database since the Vs data are not adequate in Sagami plain and in some locations of Yokohama city. Microtremors measurements were deployed at two major sedimentary basins; Ashigara and Sagami Plains and Yokohama city on a square mesh size 250m. The H/V Spectral ratio was used to obtain the predominant periods. All three kinds of data and the related analysis were stored on a geospatial database using a GIS platform. Distribution maps was provided for each characteristic parameter for example; predominant period, amplification factors, and so on. The database is being used for disaster management a pplications and studies.

Fukuyama H.,Japan Building Research Institute | Fujisawa M.,Tsukuba University of Technology | Abe A.,Tokyo Soil Research Co. | Kabeyasawa T.,Japan National Institute for Land and Infrastructure Management | And 2 more authors.
Journal of Disaster Research | Year: 2013

Unique foundations consisting of stones wrapped in vegetable fiber bags called shicra ("woven") have been found in many Pacific coast ruins constructed about 5,000 years ago as shrines in Peru. A shaking table test was conducted to investigate earthquake response properties of these shicra foundations. Results showed that in base isolation performance, shicra foundations "rolled" during earthquake vibration the same as in the case of roller base isolation systems.

Tokimatsu K.,Tokyo Institute of Technology | Tsuboi T.,Tokyo Institute of Technology | Suzuki H.,Tokyo Institute of Technology | Abe A.,Tokyo Soil Research Co.
Journal of Structural and Construction Engineering | Year: 2013

Performance of three pile foundations then under construction thus without superstructures during the 2011 Tohoku Pacific earthquake was examined on the basis of field investigation including inclinometer and camera survey as well as of numerical analysis. It is shown that: (1) a single and a 2×2 group pile foundations were vitally damaged at a depth of about 10 m, the bottom of the liquefied layer, and displaced horizontally by about 10∼60cm, whereas the other large group pile foundation did not suffer any damage; (2) the largest bending curvature in the two damaged pile foundations occurred at a depth of about 10 m, suggesting that the pile damage was probably caused by cyclic ground displacement of the liquefied sand; and (3) the difference in pile moment capacity as well as pile head connection might have differentiated the performance of the three pile foundations during the earthquake.

Kashima T.,Japan Building Research Institute | Koyama S.,Japan Building Research Institute | Iiba M.,Japan Building Research Institute | Okawa I.,Tokyo Soil Research Co.
NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering | Year: 2014

The Building Research Institute (BRI) of Japan is a national institute engaged in research and development in the fields of architecture, building engineering and urban planning. As one of its research activities, the BRI operates a strong motion network that covers buildings in major cities across Japan. On March 11, 2011, a massive earthquake occurred off the Pacific coast of northeastern Japan. Twenty-seven buildings of reinforced concrete (RC) or steel-framed reinforced concrete (SRC) structure in the high seismic intensity area were selected from the network in order to examine changes in dynamic characteristics during severe shaking. One building suffered destructive damage and several buildings suffered slight or light damage. The natural periods and the damping ratios of the initial, main and coda parts of strong motion data were identified for each building. On the damaged buildings, increases in the natural periods from the initial part to the coda part could be clearly recognized. On the buildings in the medium intensity area, the natural periods in the main part were slightly longer than in the initial part, but those in the coda part usually returned to the initial values. Ratios of the natural period of the coda part to the initial part became larger with the increase in seismic intensity. Buildings designed under the previous Japanese building code that suffered earthquake motions with peak acceleration exceeding 1.5 m/s2 showed obvious changes in natural periods. In the case of the buildings designed under the current building code, increases in the natural period ratios were unremarkable with the maximum building displacement angle of 1/300 radians.

Loading Tokyo Soil Research Co. collaborators
Loading Tokyo Soil Research Co. collaborators