Yoshitake I.,Yamaguchi University |
Uno T.,Eight Japan Engineering Consultants Inc. |
Scanlon A.,Pennsylvania State University |
Hamada S.,Yamaguchi University
Journal of Materials in Civil Engineering | Year: 2011
Most investigations dealing with research on shear focus on concrete members such as reinforced concrete (RC) and prestressed concrete (PC) beams, columns, and slabs. It is difficult for such investigations, which include effects of reinforcing materials and so on, to evaluate shear cracking load in detail. Cracking caused by shear, however, may be a significant consideration for durability evaluation of concrete structures. Pure shear strength is an important property for estimation of cracking because shear failure is caused by fracture of the element. A simple test setup that employs only a universal testing machine has been found to be suitable for obtaining the pure shear cracking strength of concrete without reinforcement. The purpose of the study is to reevaluate the pure shear cracking strength property of plain concrete elements through testing. Based on laboratory testing, it is reconfirmed that reinforcement has little influence on the pure shear cracking strength. However, the shear cracking strength is strongly related to tensile strength and Poisson's ratio. © 2011 American Society of Civil Engineers.
Kim C.W.,Kyoto University |
Kawatani M.,Kobe University |
Konaka S.,Toshiba Corporation |
Kitaura R.,Eight Japan Engineering Consultants Inc
Structure and Infrastructure Engineering | Year: 2011
This study is intended to investigate the seismic response of a highway viaduct under vehicle loadings during moderate earthquakes of high probability occurrence. The highway bridge design code of the Japan Road Association (JRA code) does not consider the live load in the seismic design of highway bridges because of the low possibility that both heavy traffic and an earthquake occur at the same time. However, frequent traffic jams in urban areas involve a high possibility of encountering an earthquake during a traffic jam. To clarify the effect of traffic to seismic responses of highway viaducts, heavy vehicles are considered as dynamic system in a three-dimensional dynamic response analysis. The design live load of the JRA code is assumed to be a critical traffic condition for the highway bridges, even during earthquakes. Observations through numerical analyses demonstrate that considering heavy vehicles as a dynamic system reduces seismic responses of the highway viaduct compared with those responses disregarding vehicular loadings and considering vehicles as additional mass. © 2011 Taylor & Francis.
Kandemir E.C.,Kumamoto University |
Mazda T.,Kumamoto University |
Nurui H.,Kumamoto Prefecture |
Miyamoto H.,Eight Japan Engineering Consultants Inc.
Procedia Engineering | Year: 2011
In Japan, the seismic behavior of the bridge structures is a much under-researched area of the civil engineering field since bridges have enormous importance and number for providing connection between the scattered islands. In this sense seismic design and analysis methods are paid much attention to get optimum behavior under severe earthquakes during bridge service life. In this paper, the retrofitting process of an existed upper-deck type steel arch bridge located in the Ground Type I which include good diluvial ground and rock is investigated. Since the bridge has been designed by the old code of 1980, it is in need of retrofitting. As a first step of dynamic response analysis, the dynamic characteristics along both longitudinal and transverse directions are analyzed by eigenvalue analysis to figure out the natural behavior under the dead load. The nonlinear dynamic response analysis is conducted under Hyogoken Nanbu earthquake occurred in 1995. After detecting the critical sections as abutments the viscous dampers are installed to increase the seismic performance of the bridge under severe earthquakes. The comparative results between undamped and damped structures are presented in terms of acceleration and displacement values at the critical points to evaluate the advantages of dampers. By this research, an application of seismic retrofitting and isolation methods are presented. Selection.
Yoo J.-Y.,Eight Japan Engineering Consultants Inc. |
Kawahara Y.,Eight Japan Engineering Consultants Inc. |
Enokida A.,Eight Japan Engineering Consultants Inc. |
Washio S.,Eight Japan Engineering Consultants Inc. |
And 2 more authors.
Geotechnical Aspects of Underground Construction in Soft Ground - Proceedings of the 8th Int. Symposium on Geotechnical Aspects of Underground Construction in Soft Ground, TC204 ISSMGE - IS-SEOUL 2014 | Year: 2014
A tunnel is closed space, and it is necessary to ensure proper sight distance of the tunnel on all tunnel design. Moreover, if the field of view is hindered, the light-dark adaptation will significantly affect driving safety in clear weather in the entrance of tunnel. Thus, the tunnel design that incorporates driving safety will be required in every cases of the location if the distance of both tunnels is short. The significance of light fluctuation in relationship for driving safety at the entrance of the tunnel of driving safety in a continuous tunnel is expressed by using the computer aided driving simulator. © 2014 Korean Geotechnical Society.
Yoshitake I.,Yamaguchi University |
Yasumura N.,Yamaguchi Prefecture |
Syobuzako M.,Eight Japan Engineering Consultants Inc. |
Scanlon A.,Pennsylvania State University
Journal of Cold Regions Engineering | Year: 2011
In order to prevent traffic accidents on snow-covered bridge decks, the writers developed a new pipe heating system that uses only groundwater stored in a large underground tank. The underground tank provides geothermal energy, i.e., groundwater of constant temperature, through heating pipes embedded in concrete pavements with no electric heater or fuel boiler. The pipe heating system was constructed at approximately 50% of the cost of comparable systems. In addition, there is a reduction of 10% in operating costs compared with the previous system. The present paper outlines its design and construction and provides fundamental data for the developed system. The piped heating system has kept the road conditions safe during the winter season by always removing the snow and ice from the heated road and bridge sections earlier than the surrounding roads. According to long-term temperature measurements, this system has prevented the road temperature from decreasing below 0°C, even through nighttime and morning periods. This report presents the system as an economical and effective solution for snow thawing and ice prevention. © 2011 American Society of Civil Engineers.
Hata Y.,Osaka University |
Yoshida T.,Osaka University |
Tokida K.,Osaka University |
Fukushima Y.,Eight Japan Engineering Consultants Inc. |
Ikeda T.,Tobishima Research Institute of Technology
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
In this report, ground shaking characteristics in residential land in Kanagawa Ward, Yokohama City, Japan are evaluated based on temporary earthquake observation records. In particular, first, 33 seismographs installed with very high density at not only cutting sites but also banking sites in the residential land of interest. Seismic waveform records are then observed at the created 33 sites during some moderate earthquakes. Based on the analysis consequence of the observed seismic waveforms, finally, site amplification factors and site phase effects focused on Tokyo Bay Area were evaluated. The obtained findings will be useful in future study of strong motion prediction in the residential land of interest. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Isohata H.,Nihon University |
Kurebayashi A.,Tokyo Metropolitan Government |
Mori A.,Eight Japan Engineering Consultants Inc.
Proceedings of the ICE - Engineering History and Heritage | Year: 2016
Both the Kiyosu and Eitai Bridges, registered as important cultural properties in 2007, are located in the lower reaches of the Sumida River in Tokyo. They were rebuilt in the latter half of the 1920s after the great Kanto earthquake of 1923 in the Japanese capital. By examining their anti-earthquake performance under the revised new standards based on the information obtained from the magnitude M7.3 great Hanshin Awaji earthquake of 1995, it was discovered that strengthening was required for both bridges. Strengthening design was considered and discussed from 2012 to 2014. It was concluded that with respect to the Kiyosu Bridge, the installation of dampers on both girder ends was required. With respect to the Eitai Bridge, the bearings on both piers were immobilised by placing additional horizontal bearings. Also, the addition of stiffeners to the arch ribs was deemed necessary to increase rigidity. The strengthening work was carried out from 2014 to 2015. This experience is expected to supply useful information for strengthening and repair/design work of historical bridges. © ICE Publishing: All rights reserved.
Watanabe K.,Ehime University |
Watanabe K.,Eight Japan Engineering Consultants Inc. |
Koji S.,Kanazawa University |
Hidaka K.,Ehime University |
Nakamura K.,Kanazawa University
Environmental Entomology | Year: 2013
Recent introduction of modern drainage systems has produced intensely dry conditions in rice farmlands and has degraded habitats for aquatic animals. In this study, we compared water beetle (Coleoptera) and water bug (Heteroptera) communities within rice fields cultivated under different management regimes: V-furrow no-till direct-seeding (DS) and conventional regimes. In DS fields, rice is sown in well-drained fields, and flooding is performed a month later than in conventional rice fields. DS fields are then continuously flooded until harvesting; unlike in conventional fields, where midseason drainage is performed in summer. We observed that DS fields supported higher densities of water beetles and water bugs than conventional fields, probably because of the high compatibility between the flooding period and the reproductive season of the insects. The species richness of water beetles was higher in DS fields than in conventional fields. Overall, DS fields showed higher water beetle and water bug abundance, but the effect was variable for individual species: seven species were more abundant in DS than in conventional fields, whereas two species showed opposite tendencies. Considering the differential responses among species to the management regimes, a mosaic of DS and conventional fields is preferable to either field alone for the conservation of aquatic insects in rice agroecosystems. © 2013 Entomological Society of America.
Ichimura T.,University of Tokyo |
Fujita K.,RIKEN |
Errol Quinay P.,Niigata University |
Hori M.,University of Tokyo |
And 4 more authors.
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2016
We demonstrate a comprehensive earthquake response analysis method for improving the seismic input force estimation of buried pipelines by combining ground motion and soil amplification analyses. Using this method, the seismic input force of an actual pipeline was estimated and its seismic performance was checked for a largest assumed seismic fault scenario. Three-dimensional inhomogeneity of ground and surface topography is known to greatly affect the results of ground motion and soil amplification analyses. To consider these effects, a linear wave propagation analysis using a 10 × 109 degree-of-freedom three-dimensional finite element model was conducted for the ground motion analysis, and a nonlinear wave propagation analysis using an 80 × 106 degree-of-freedom three-dimensional finite element model was conducted for the soil amplification analysis. The application example showed that three-dimensional inhomogeneity of ground and surface topology caused complex seismic input forces to buried pipelines, and demonstrated the effectiveness of the comprehensive seismic analysis method proposed in this study. © 2016 by ASME.
Suzuki M.,Yamaguchi University |
Fujimoto T.,Eight Japan Engineering Consultants Inc. |
Taguchi T.,Yamaguchi University
Soils and Foundations | Year: 2014
The shear strength of cement-treated soil can be changed by both cementation and consolidation during the early stages of hardening because of cement hydration. Based on the results of triaxial and unconfined compression tests, this paper describes the effects of isotropic and one-dimensional consolidation stress, applied during the curing period, on the undrained peak and residual shear strengths of cement-treated soil. The sample used was a mixture of fine-grained sand and ordinary Portland cement. A consolidated undrained triaxial compression test (ICU) was conducted on the specimens immediately after the cement treatment. Each test was conducted under different consolidation pressures, curing times and delayed loading times. The following conclusions were developed from the results and discussions: (1) the undrained peak shear strength of cement-treated soil, cured under different consolidation conditions, increases with an increase in either the consolidation pressure or the curing time, whereas it gradually decreases with an increase in the delayed loading time. (2) The rate of undrained strength increase resulting from consolidation differs significantly between isotropic and one-dimensional consolidations. (3) For a curing time of between one and seven days, the rate of strength increase by isotropic consolidation exceeds that by one-dimensional consolidation. The simultaneous volumetric change of cement-treated soil during consolidation depends on the stress conditions of the specimen, that is, the difference between isotropic and one-dimensional consolidations. (4) When the test is not conducted under nearly in-situ conditions, the undrained shear strength may be underestimated, depending on the time interval between the cement treatment and the start of consolidation. (5) The shear strength in the residual state is influenced by the consolidation pressure during curing. (6) As the consolidation pressure during curing increases, the specimens exhibit a higher residual strength. © 2014 Japanese Geotechnical Society.