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Kim C.W.,Kyoto University | Kawatani M.,Kobe University | Ozaki R.,Kobe University | Makihata N.,JIP Techno Science Corporation
Structural Engineering and Mechanics | Year: 2011

This paper presents recovering of missing vibration data of a bridge transmitted from wireless sensors. Kalman filter algorithm is adopted to reconstruct the missing data analytically. Validity of the analytical approach is examined through a field experiment of a bridge. Observations demonstrate that, even a part of recovered acceleration responses is underestimated in comparison with those responses taken from cabled sensors, dominant frequencies taken from the reconstructed data are comparable with those from cabled sensors. Source

Taniguchi T.,Tottori University | Nakashima T.,JIP Techno Science Corporation | Okui D.,Kawasaki Heavy Industries
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

For the unanchored flat-bottom cylindrical tanks located in the seismic prone area, uplift of the tank bottom plate is inevitable. Besides the work of Nakashima, effects of out-of-plane deformation of the cylindrical shell on uplift of the tank bottom plate have been paid little attention. In analyzing uplift of the tank bottom plate, for design purpose in particular, its effects should be included. First, employing a cylindrical shell tanks with multistage rigid or elastic stiffeners, their uplift responses to the horizontal sinusoidal base acceleration are compared to highlight effects of out-of-plane deformation on uplift of the tank bottom plate. Next, employing the numerical results of the cylindrical shell tank with multistage rigid stiffeners, analytical accuracy of the simplified calculation for evaluating the angular acceleration accompanying the tank rock motion is examined. Copyright © 2015 by ASME. Source

Noguchi H.,Chiba University | Kashiwasaki T.,Chiba University | Hong J.,JIP Techno Science Corporation
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium | Year: 2010

Three-dimensional FEM analysis was conducted on joint shear failure type plane RC beam-column joints, using the amount of lateral reinforcement and bond characteristics of beam reinforcement in the joint section, in addition to beamcolumn joint eccentricity, as parameters. The stress component in the strut direction was analyzed quantitatively. The investigation revealed that, within a joint at ultimate strength, there exists a region in which the amount of compressive force transmitted is almost consistent irrespective of parameters; and that bond characteristics mainly have an effect on stress distribution in the strutdepth direction, while the amount of lateral reinforcement and joint eccentricity mainly have an effect on stress distribution in the strut-width direction. Based on these results, an estimation equation for shear strength of beam-column joints, including those with joint eccentricity, was proposed. Source

Chai J.-C.,Saga University | Shrestha S.,Saga University | Hino T.,Saga University | Ding W.-Q.,Tongji University | And 2 more authors.
Computers and Geotechnics | Year: 2015

The behaviour of a test embankment constructed on a soft clayey deposit in Saga, Japan, was simulated by both three-dimensional (3D) and two-dimensional (2D) finite element analyses (FEA). Floating soil-cement columns had been installed in the clay prior to construction of the embankment. Comparing the results of 3D and 2D FEA indicates that 2D analysis predicts incorrect results in terms of the lateral displacement and bending moment in the columns under the toe of the embankment. In the 2D analysis, the rows of columns were modelled by continuous walls, which partially block the interaction between the soil layers and the columns and influence the simulated lateral displacement and bending moment in the column. It has been postulated that compaction of fill material during the construction process has a significant influence on both the magnitude and pattern of the lateral displacement of the column under the toe of the embankment. Pragmatically, this influence can be indirectly simulated by reducing the stiffness and increasing Poisson's ratio of the embankment fill material. Finally, both the measured and FEA results indicate that the columns not only reduced the total settlement but also accelerated the settlement rate of the deposit under the embankment loading, due to the much higher stiffness of the column material. © 2015 Elsevier Ltd. Source

Nagayama T.,University of Tokyo | Moinzadeh P.,University of Illinois at Urbana - Champaign | Mechitov K.,University of Illinois at Urbana - Champaign | Ushita M.,University of Tokyo | And 6 more authors.
Smart Structures and Systems | Year: 2010

Wireless smart sensor networks (WSSNs) have been proposed by a number of researchers to evaluate the current condition of civil infrastructure, offering improved understanding of dynamic response through dense instrumentation. As focus moves from laboratory testing to full-scale implementation, the need for multi-hop communication to address issues associated with the large size of civil infrastructure and their limited radio power has become apparent. Multi-hop communication protocols allow sensors to cooperate to reliably deliver data between nodes outside of direct communication range. However, application specific requirements, such as high sampling rates, vast amounts of data to be collected, precise internodal synchronization, and reliable communication, are quite challenging to achieve with generic multi-hop communication protocols. This paper proposes two complementary reliable multi-hop communication solutions for monitoring of civil infrastructure. In the first approach, termed herein General Purpose Multi-hop (GPMH), the wide variety of communication patterns involved in structural health monitoring, particularly in decentralized implementations, are acknowledged to develop a flexible and adaptable any-to-any communication protocol. In the second approach, termed herein Single-Sink Multi-hop (SSMH), an efficient many-to-one protocol utilizing all available RF channels is designed to minimize the time required to collect the large amounts of data generated by dense arrays of sensor nodes. Both protocols adopt the Ad-hoc On-demand Distance Vector (AODV) routing protocol, which provides any-to-any routing and multi-cast capability, and supports a broad range of communication patterns. The proposed implementations refine the routing metric by considering the stability of links, exclude functionality unnecessary in mostly-static WSSNs, and integrate a reliable communication layer with the AODV protocol. These customizations have resulted in robust realizations of multi-hop reliable communication that meet the demands of structural health monitoring. Source

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