Time filter

Source Type

Kim C.W.,Kyoto University | Kawatani M.,Kobe University | Konaka S.,Toshiba Nuclear Energy Systems and Services Division | 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. Source

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. Source

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. Source

Numada M.,University of Tokyo | Kondo S.,University of Tokyo | Inoue M.,Eight Japan Engineering Consultants Inc. | Meguro K.,University of Tokyo
Journal of Disaster Research | Year: 2012

This paper gives attention to the phase of safety of work in wide-area support and considers differences in description in local disaster management plans drafted by supporting local governments and supported ones, assuming that standardization of such descriptions could bring more smooth and effective implementation of plans. This paper targets desirable directions toward arrangement for a highly effective wide-area cooperation system. A framework is introduced in examining on what wide-area support should be like, referring to previous studies on actual situation of the support at the time of the 1995 Southern Hyogo Prefecture Earthquake and of the 2004Mid Niigata Prefecture Earthquake. Then the disaster response activities in wide-area support are examines and local disaster management plans among different local governments are compared and differences in descriptions in plans. Necessary information for supporting sides and introduces the exchange of opinions with Kawasaki City that stood on the supporting side after the 2011 Great East Japan Earthquake is discussed. To make cooperation among the Japanese Government, prefectures, and municipalities more effective, the description of local disaster management plans should be standardized to some degree. Source

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. Source

Discover hidden collaborations