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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.

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.

Nagayama T.,University of Tokyo | Urushima A.,Taisei Corporation | Fujinoa Y.,University of Tokyo | Miyashita T.,Nagaoka University of Technology | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Fundamental functionalities of wireless smart sensors to measure full-scale bridge vibration, such as time synchronization, loss-less multihop communication, and capability to capture small ambient vibrations, are maturing; dense vibration measurement of large structures using wireless smart sensors is expected to reveal the detailed condition of existing structures. An arch bridge is chosen as a target bridge and densely instrumented by 48 wireless smart sensors. Traffic induced vibration of the bridge has been measured before and after its seismic retrofit. The differences between the measured dynamic characteristics are considered to represent the effects of seismic retrofit. The dense measurement allows comparison of spatial characteristics such as detailed mode shapes, in addition to comparison of natural frequencies. Comparison of densely measured mode shapes reveals their changes, which are then used to update the finite element model of the bridge. The measurement, data analysis, and model updating indicate a potential use of dense instrumentation of wireless smart sensor network for structural condition assessment. © 2012 SPIE.

Watanabe E.,Kyoto University | Watanabe E.,Regional Planning Institute in Osaka | Furuta H.,Kansai University | Yamaguchi T.,Osaka City University | Kano M.,JIP Techno Science Co.
Structure and Infrastructure Engineering | Year: 2014

The Japanese Society of Steel Construction (JSSC) had organised a special task committee and conducted a study on the recent development of maintenance, renewal and retrofitting for buildings and bridges of Japan. This paper describes the outline of the study by the working group of bridges and consists of two parts. The first part is concerned with the survey on the recent developments of technologies for the longevity of bridges, whereas the second part is specifically concerned with the structural health monitoring technologies. In view of the fact that important terminologies such as lifetime and service life differ considerably throughout the world, some fundamental terminologies are reviewed, discussed and redefined in this paper on a unified viewpoint. Furthermore, recent developments on the structural health monitoring technology are also reviewed and the results are summarised in a matrix form. © 2013 Taylor & Francis.

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.

Nakashima T.,JIP Techno Science Co. | Taniguchi T.,Tottori University
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2013

The rocking motion of tanks due to earthquakes causes the large uplift deformation of the tank bottom plate that has been considered to contribute to the various damages of the tanks. For analyzing the uplift displacement of the tank bottom plate statically and precisely, this paper develops a shell element, ring element and spring element partially attached to the ring element. These elements are defined as a semi-analytical finite element. Fourier series give its circumferential displacement function, while the polynomial gives its radial displacement function. In addition, the ring element can deal with effects of the large deformation, while the spring element enables to express the partial contact between the tank bottom plate and foundation. On the other hand, the loads considered are dead load, hydro-pressure and inertia force due to earthquakes acceleration as well as dynamic pressure of fluid induced by bulging and rocking motion of the tank. The numerical analyses model of the LNG Storage Tank was created using the semi-analytical finite elements shown here, and the uplift displacement of the tank bottom plate accompanying the tank rocking motion was calculated with the static analyses. For evaluating analytical accuracy of the proposed method, numerical results of the proposed method are compared with that of the explicit FE Analysis. Copyright © 2013 by ASME.

Makihata N.,JIP Techno Science Corporation | Zhao B.,University of Tokyo | Toyoda M.,University of Tokyo | Takahashi M.,JIP Techno Science Corporation | And 2 more authors.
Transforming the Future of Infrastructure through Smarter Information - Proceedings of the International Conference on Smart Infrastructure and Construction, ICSIC 2016 | Year: 2016

Response-based road condition evaluation is expected to provide road surface conditions effectively and efficiently. A large scale road surface condition evaluation using a large number of commercial vehicles is conducted based on Dynamic Response Intelligent Monitoring System (DRIMS); DRIMS estimate the International Roughness Index (IRI) using vehicle responses. A mobile device version of DRIMS, iDRIMS, is employed. The data is first analyzed to construct a Half-Car (HC) model of measurement vehicles. The parameters of the Half-Car (HC) model is identified through Unscented Kalman Filter(UKF) and Genetic Algorithm(GA). Then, IRI is estimated by analyzing vertical acceleration responses using the HC model. To verify the effectiveness of this method, the estimated IRI is compared with the reference IRI obtained by a road profiler. The comparison shows good agreement between iDRIMS and the reference and indicates the validity of large-scale road surface evaluation using general commercial vehicles. Finally, the data collection and analysis platform is built which succesfully collected and analyzed 6 months data from about 50 commercial vehicles. © The authors and ICE Publishing: All rights reserved, 2016.

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.

Nagayama T.,University of Tokyo | Ushita M.,University of Tokyo | Fujino Y.,University of Tokyo | Ieiri M.,JIP Techno Science Corporation | Makihata N.,JIP Techno Science Corporation
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Wireless smart sensors equipped with computational and wireless communication capabilities are expected to provide rich information for structural health monitoring (SHM); inexpensive nature of sensors nodes and wireless communication allow dense sensor instrumentation over structures. While dense measurement is advantageous with regard to spatially characterizing structural dynamic behaviors, limited sensing accuracy of inexpensive wireless sensor nodes possibly bounds applications. For example, small ambient vibration may not be captured by smart sensor nodes. This paper proposes a combined use of low-cost smart sensors and high accuracy sensors for dynamic measurement of bridges to alleviate the influence of this limitation. © 2010 Copyright SPIE - The International Society for Optical Engineering.

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.

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