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DOI： 10.1080/15732479.2024.2413637

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/15732479.2023.2218351

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study attempts to construct a traffic environment sensing system using a bridge vibration response and proposes a method for detecting traffic using time-domain feature extraction and a neural network. Analysis was performed by examining the feature values of bridge acceleration, the wave group period, and the delay of the waveforms that focus on the mode shape. After evaluating the features, a neural network was constructed to identify the traffic environment around the bridge. According to the verification, the matching rate reached 90 % if there was no congestion, demonstrating the possibility of meeting the accuracy requirement of the mechanical traffic census.

DOI： 10.11532/jsceiii.4.3_715

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>High-strength bolted joints are widely used in steel bridges. However, bolt axial force may decrease during the service life of a bridge for many reasons including relaxation, traffic load, and earthquake. Consequently, the remaining bolt axial force is considered a factor with uncertainty that is important to evaluate. In a previous study, the authors proposed an axial force evaluation method using eddy current. In this study, to apply the proposed axial force evaluation method to the actual measurements, new evaluation indices with the possibility of reducing measurement errors and simplifying measurement have been considered. The applicability of the improved method for high- strength bolts using weathering steel has also been examined. An experiment using both high- strength bolts and weathering steel high-strength bolts was conducted to investigate the possibility of evaluating the stress change due to the axial force with the new indices.

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DOI： 10.2749/prague.2022.1148

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>In this study, an influence line of the girder displacement of the bridge was estimated by Bridge- Weigh-In-Motion using an accelerometer. Displacement was calculated by two times of integration of the measured acceleration. The data has the problem of low sensitivity due to a single sensor, and it contains measurement noise. To compensate for these problems, two correction methods were applied to the integration result. They were the baseline correction method and the drift correction method using boundary conditions of traffic-induced vibrations. It was shown that the result of integration was improved by using these methods. A calibration process to estimate the influence line of the bridge was proposed using iterative calculation method to optimize the result using local buses. It was shown that by using this method, vehicle detection and weight estimation can be performed with high accuracy, especially for large vehicles.

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DOI： 10.2749/prague.2022.0407

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>Thermoelectric energy harvesting was studied using the temperature difference in concrete bridges. A design of the heat sink unit of thermoelectric energy harvesters was parametrically analyzed using FE models. Prototype thermoelectric energy harvesters were fabricated and tested in a simple wind tunnel. The experiment was carried out on a concrete bridge. The concrete bridge accumulated thermal energy from sunlight, and the temperature difference with the air occurred. The thermal energy was harvested especially in daytimes. On the other hand, electric power was less generated at night-times than expected. The harvesting energy would be significantly improved if the problem is solved.

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DOI： 10.2749/prague.2022.0458

DOI： 10.2208/jscejj.23-00293_references_DOI_I5lS5w3xYp0194AZeqPaxUao9Lk

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Publisher：Elsevier BV  

Abstract This paper presents a verification of tensile strength and failure mechanism of internal diaphragms in wide flange (WF) beam-to-box column connections with and without concrete filling. The flexural load transfer mechanism from the beam flange to column was locally evaluated based on a plate-to-box column connection with an internal diaphragm. The objective of this study is to establish an efficient design method for the internal diaphragms in WF-beam-to-box column connections. First, theoretical and experimental approaches were used to evaluate a strength equation considering the effects of the plate-to-column width and column width-to-thickness ratios and concrete filling. Finally, the cyclic performance of the WF-beam-to-box column connections was numerically assessed to validate the design and response of the internal diaphragms. The results showed that concrete filling was able to improve the connection strength by approximately 30% compared to that without concrete filling. It was also confirmed that the plate-to-column width and column width-to-thickness ratios did affect the tensile strength of the connection and must be considered in the strength equation. More importantly, the response of an internal diaphragm designed using the proposed equation in this study was validated and confirmed by both the experiment and the numerical evaluation.

DOI： 10.1016/j.jobe.2020.102037

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>The hammer test is generally used as one of the non-destructive methods for detecting defects such as voids and delamination in concrete structures like tunnels and bridges. It is necessary to eliminate human mistakes and improve quantitative analysis so that Impact Acoustics Method (IAM) was proposed and studied. IAM helps human decision of the defective concrete parts through comparing waveform and frequency distribution between healthy and defective parts which are taken from sensor or microphone. Hence, artificial intelligence (AI) is expected to replace or assist the human labor inspection by quantifying the defects. This research aims to inspect defects quickly and efficiently the only microphone through promoting a machine learning AI analysis system flow which mainly includes neural networks. Two experiments were held to achieve the purpose.

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DOI： 10.2749/ghent.2021.0955

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>Many bridges have been in service for over 40 years and face to the repapering or reinforcing period due to deterioration. Particularly, in a high-strength bolts used for joints may be loosened due to co-rotation, corrosion, or vibration caused by the vehicles. Thus, it is important to evaluate an axial force of the high-strength bolts. In this research, an axial force evaluation of high-strength bolt using eddy current that does not require measurement preparation has been investigated. The eddy current method is capable of capturing the change in permeability of steel members due to the stress change. Further, the stress distribution of the bolt head is assumed uniform without directionality. Therefore, a numerical simulation and an experiment that measures the output signal of the eddy current probe while introducing axial force to the high-strength bolt has conducted.

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DOI： 10.2749/christchurch.2021.0045

DOI： 10.2208/jscejseee.78.1_108_references_DOI_KdqNvwTxWX9VgSfhIHPHYlZz5ts

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Publisher：Informa UK Limited  

In this paper, a method called “least-work solution” was empirically simplified to evaluate shear lag stress in the steel box moment connections with internal diaphragms in order to serve for the p...

DOI： 10.1080/15376494.2019.1710004

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This paper presents determination of the stress state of steel bridges, due to stress redistribution because of corrosion or cracking, as a new important parameter in structural health monitoring f...

DOI： 10.1080/15732479.2019.1703759

DOI： 10.2208/jscejseee.78.2_231_references_DOI_3m8qk9s5M8LP3Tq2hUjkfrEkXIT

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Publisher：Elsevier BV  

Abstract This paper presents numerical and theoretical studies on the performance of internal diaphragm connections to box columns. The study aims to investigate the static and cyclic performances of the connections including the behavior of diaphragms. This paper contains an assessment of the numerically and theoretically parametric studies on plate-to-box column connections considering several influence parameters, such as diaphragm, plate width, and column thickness. Subsequent sections discuss the prediction and validation of strength of the connections, followed by the performance of wide flange (WF) beam-to-box column connections. The results are presented and discussed as finding that diaphragms were the key elements to enhance the performance of the connections.

DOI： 10.1016/j.tws.2019.106221

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Publisher：Informa UK Limited  

This article presents corrosion profile estimation as a method to determine the extent of corrosion in steel members having corroded exterior, with or without protective cover, when the only side a...

DOI： 10.1080/15732479.2019.1615961

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Publisher：American Society of Civil Engineers (ASCE)  

DOI： 10.1061/(asce)be.1943-5592.0001356

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Publisher：Springer Science and Business Media LLC  

This study aims to investigate the effects of strain rate on the low-cycle fatigue strength of steel welded joints. Load-carrying cruciform joints with different material mismatch ratios were fabricated in order to observe the effects of material mismatching. A series of displacements that generate low-cycle fatigue damage were applied to the specimens. The experiment was conducted by fast cyclic loading and displacement control, using feedback from a displacement transducer. The feedback control algorithm was found to be critical. Thus, a non-linear feedback control algorithm, i.e., PID control, was implemented in the testing machine. An experimental setup capable of fast cyclic loading was developed. Fatigue life based on the load drop curve indicated that higher strain rates caused lower fatigue life. Failure behavior regarding the strain rate effects of steel welded joints was observed.

DOI： 10.1007/s13296-018-0026-x

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;The authors have proposed a corrosion damage evaluation method for corroded steel members to estimate rust layer and residual thickness. In this method, detected voltage signal obtained by a low frequency eddy current of 500 Hz or less was used as an index. In this research, in order to further advance the method and to simplify the measurement system, a more sophisticated method utilizing a phase characteristic which is considered to be able to simultaneously estimation of thickness information together with the detected voltage has been investigated. Firstly, to clarify the low frequency eddy current characteristics assuming the difference in damaged condition by numerical simulation was performed. Then evaluation method focusing on the phase between the detected voltage and the input current and the detected voltage as an index to capture the differences has investigated. Based on results of all process, a corrosion damage evaluation method focused on phase characteristics which can obtain information of rust layer and residual thickness simultaneously was proposed. Finally, the applicability of proposed method was clarified by experiment.

DOI： 10.2208/jscejseee.74.145

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In this research, a method which is able to analyze corrosion damage condition such as local thickness reduction or formation of rust layer of steel members of steel members at same time has been investigated. Considering eddy current testing which uses especially low frequency eddy current such as 1~1000Hz, corrosion damage condition analysis method which performs inspection from only one side of steel members has investigated to become easy non-destructive testing method. Firstly, differences of dynamic magnetic field characteristics due to damage form was clarified using numerical simulation, and further data analyzing method to obtain the differences was investigated. Then sweep wave and frequency step wave were designed as induced wave and analysis using both detected voltage and wavelet coefficient was performed. Based on results of all process, a corrosion damage condition analysis method was proposed. Finally, in the applicability of proposed method was clarified by experiment.

DOI： 10.2208/jscejseee.73.387

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Publisher：Informa UK Limited  

AbstractApplication of maintenance to ensure the safety, extend the service life and reduce the life-cycle cost of civil structures is important. In this paper, a new inspection method is proposed using a robot which can effectively approach target sections of structures, such as areas that are either too narrow or too dangerous to approach and perform both visual and detailed inspection with various devices. The small-sized self-propelled robot was initially developed. The test model can freely move on the surfaces of various types of structures. Next, the function to detect the deterioration of concrete or steel surfaces by attached cameras to the robot was examined. Moreover, a function was installed to identify the location of the robot automatically using a phase-only correlation method and to determine structural behaviours using an accelerometer. Finally, the applicability of robotic movement and all installed functions was tested on an existing bridge.

DOI： 10.1080/15732479.2016.1236132

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Abstract A bridge vibration energy harvester has been proposed in this paper using a tuned dual-mass damper system, named hereafter Tuned Mass Generator (TMG). A linear electromagnetic transducer has been applied to harvest and make use of the unused reserve of energy the aforementioned damper system absorbs. The benefits of using dual-mass systems over single-mass systems for power generation have been clarified according to the theory of vibrations. TMG parameters have been determined considering multi-domain parameters, and TMG has been tuned using a newly proposed parameter design method. Theoretical analysis results have shown that for effective energy harvesting, it is essential that TMG has robustness against uncertainties in bridge vibrations and tuning errors, and the proposed parameter design method for TMG has demonstrated this feature.

DOI： 10.1016/j.jsv.2015.10.002

DOI： 10.2183/pjab.94.008_references_DOI_LJcTqyrbMlyQPgZ5QbXlkpdxLLC

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DOI： 10.3390/s16050601

PubMed

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Other Link： https://dblp.uni-trier.de/db/journals/sensors/sensors16.html#DungS16

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Language：English   Publisher：Japan Society of Civil Engineers  

This study aims to investigate the effects of very high strain rate on low-cycle fatigue behavior of structural steel under large plastic strain with strain rate order of 1.0 s^-1 as expected during earthquakes. Low-cycle fatigue tests were conducted using compact-tension specimens at various strain rate levels. Fatigue life based on crack size indicated that the higher strain rate caused lower fatigue life in large plastic strain region. The energy approach was employed to clarify the low-cycle fatigue mechanism in this region. Finally, a prediction method for fatigue life regarding high strain rate effect in large plastic strain region is proposed in this study.

DOI： 10.2208/journalofjsce.4.1_118

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Publisher：Springer Science and Business Media LLC  

There are a number of existing steel railway bridges which has problems regarding structure-borne noise under train passage. Authors have proposed a performance improvement method of existing steel railway bridges by installing concrete deck. By this method, the vibration of the girder and the structure-borne noise are expected to be reduced. Generally, it is known that concrete deck can reduce the vibration and the noise. However, the noise reduction effect has not been clarified. In this study, impact hammer tests were carried out to figure out the reduction effect of the concrete deck on the vibration and the noise. Through the test, it was found that the response acceleration of the steel girder web was reduced by installing the concrete deck, as a result of reducing the propagation of on-girder vibration into the steel girder.

DOI： 10.1007/s13296-015-3015-3

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Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s13296-015-3018-0

DOI： 10.2208/jscejseee.74.145_references_DOI_BAvI0SXsXcvCUE81eK6IP2TKKcZ

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Other Link： http://link.springer.com/article/10.1007/s13296-015-3018-0/fulltext.html

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Brittle fractures could occur from shallow surface cracks on welded parts of steel structures during earthquakes. Since the occurrence of that fracture is significantly influenced by the shape of the welded parts, the existing methods cannot predict the fractures. This study focused on a modified Weibull stress which considers the processes of nucleation and propagation of microcracks, and affirmed the applicability to evaluation of the brittle fracture initiation during earthquakes. Additionally, the relationship between critical deformation of a steel bridge bent corner to the fracture from a shallow crack and its weld toe radius was quantitatively evaluated as an example of actual use of the modified Weibull stress based evaluation.

DOI： 10.2208/jscejseee.71.173

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

DOI： 10.2749/222137815815622915

DOI： 10.3151/coj.60.1_134_references_DOI_XoQjS65rkgXGSqoMdCfUUSxRtPx

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Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>Bridge Structural Health Monitoring (SHM) system could provide the assessment of the bridge structure condition immediately after the occurrence of a major seismic event, potentially enhancing safety and reducing the time needed for evaluating the bridge state before bridge is being returned to service.

The bridge wireless SHM sensor node operates on batteries and records data intermittently, when triggered. The sensors located on the bridge records both seismic events and various traffic induced vibrations. An independent triggering algorithm of each sensor node using the acceleration data recorded on the bridge has been adopted. Several trigger algorithms are being compared for enhancing detection of seismic events in the presence of the traffic and wind induced vibration. The preliminary analysis of the data at the bridge sensor setup location is being used for the validation of the proposed triggering algorithm. An in-memory event classification algorithm is being used to determine seismic events triggers and traffic induced triggers. Trigger detection with simulated earthquake records data was conducted to evaluate the effectiveness of trigger detection algorithm.

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DOI： 10.2749/222137815815775781

DOI： 10.2183/pjab.94.008_references_DOI_XQBFsIK9ig7QePwE16iwfnTG2KA

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Publisher：Springer Science and Business Media LLC  

A common practice for the manufacture of orthotropic steel decks in Japan is to use 75% partial joint penetration welds between closed ribs and deck plates. To evaluate the effectiveness of the proposed 100% penetration on improving the fatigue strength of rib-to-deck welded joints in orthotropic steel bridge decks, four full-scale orthotropic deck specimens were subjected to laboratory testing. Specimens, consisting of a 12-mm-thick deck plate and 6-mm-thick rib, with one closed rib, were fabricated with 75% and 100% penetration. Fatigue test results showed that fatigue cracks initiated from the weld toe inside the rib in the 100% penetration specimens, but from weld root inside the rib in the 75% penetration specimens. To investigate this fatigue behavior, strain measurements were taken at 5 mm from the rib-to-deck weld line. Results of finite element analysis using the effective notch stress method indicate that a deeper partial penetration results in a slightly higher effective notch stress at the weld root of the partial penetration weld. The effective notch stress at the crack initiation location with 100% penetration is lower than that obtained with partial penetration. The open angle appears to have a significant effect on the effective notch stress at the upper weld toe when using 100% penetration. Therefore, the proposed 100% penetration appeared to have a positive effect on enhancing the fatigue resistance of rib-to-deck welded joints.

DOI： 10.1007/s13296-014-1103-4

DOI： 10.2208/jscejseee.72.393_references_DOI_N2NdX9JxKW5ORFyf8E1zKGAClNU

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Other Link： http://link.springer.com/article/10.1007/s13296-014-1103-4/fulltext.html

Publisher：Springer Science and Business Media LLC  

The present study deals with the effect of uniform and non-uniform local corrosion damages at the bearing stiffener and nearby web on the bearing capacity of plate girder. Five plate girder ends simulated with different uniform and non-uniform types of corrosion damage, at the base of the bearing stiffener are used in the experimental program. The experimental results are modeled and verified on a Finite Element (FE) software ABAQUS, considering shell-solid coupling elements formulation. The study is further extended to various damage cases i.e., stiffener damage, stiffer plus web damages etc. considering different damage heights and residual thicknesses. The study concludes that minimum thickness within any damage height may be used to simulate the corrosion damage in a FE analysis. At the end, some empirical relationships are also proposed to estimate the bearing strength of the plate girder affected by the local corrosion damage at plate girder end.

DOI： 10.1007/s13296-014-3023-8

DOI： 10.2208/jscejseee.73.443_references_DOI_KSXODRsniO93rkCtNU8SuHjQjFV

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Other Link： http://link.springer.com/article/10.1007/s13296-014-3023-8/fulltext.html

Publisher：Elsevier BV  

Abstract Load carrying cruciform joints with incomplete penetration generally have two fatigue cracking points which are the weld root and toe. The crack initiation point in high cycle fatigue region depends mainly on weld leg size and incomplete penetration ratio, while the material mismatching between the base and weld metal becomes significant in the low cycle fatigue region. Elasto-plastic analysis was performed on load carrying cruciform joints with difference in size of weld leg, incomplete penetration and material mismatching. The effective notch was assigned at the weld root and toe, and the strains around both notches were compared. It was demonstrated that the cracking points estimated from the analysis agreed with the experimental results.

DOI： 10.1016/j.ijfatigue.2013.09.002

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This study discusses the effect of local corrosion damages nearby the bearing region including the bearing stiffener and adjacent web damage on the ultimate shear and post-buckling strength of steel plate girder bridges. A computer package ABAQUS is utilized for the verification and extension of the numerical study. Various corrosion damage cases, specifically the bearing stiffener are studied considering different damage thickness and damage heights. The study concludes that local damage on bearing stiffener damage is more fatal than the local web damage for the shear resistance of the plate girder. Further, some empirical relationships are also derived to assess the residual shear capacity of the locally corroded plate girder at the bearing region.

DOI： 10.1007/s13296-013-4004-z

DOI： 10.2208/jscejseee.74.145_references_DOI_vjWEkYs4FAh8wxzRtx1UmvV3La

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Other Link： http://link.springer.com/article/10.1007/s13296-013-4004-z/fulltext.html

Publisher：Springer Science and Business Media LLC  

Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of them have problems such as corrosion and fatigue. In this study, we proposed a method to improve the performance, such as the load-carrying capacity, of the existing steel railway bridges by installation of concrete decks. To figure out the applicability of the proposed method, we discussed the applicable range of span and the effect of stress reduction. Considering application into actual bridges, we proposed an installation method using pre-cast concrete decks and girder-deck connection with filler mortar and steel fasteners. Finally, we carried out loading tests of the connection with fasteners and bending tests of the applied girders. As a result, we found that the girder-deck connections have enough static capacity for lateral force and train loads, under the condition that the studs are installed and the gaps between the pre-cast decks are filled with mortar.

DOI： 10.1007/s13296-013-3007-0

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The thickness reduction due corrosion of weathering steels can be estimated by using alloy index V and local corrosive environment index Z. However, it is required to calculate Z that costly measurement of air borne salt, sulfur oxides and so on. Thus, atmospheric corrosion monitor sensor (ACM sensor) was examined as an alternative way of environmental corrosivity measurement. At first, characteristics of ACM sensor output were checked by laboratory test. Then, the measurements of environmental corrosivity with ACM sensor were conducted at exposure test sites under un-sheltered condition. ACM sensor output and corrosion behavior of weathering steels were compared to identify adequate index of ACM sensor output. As a result, followings were obtained: (1) ACM sensor's output current was not affected by temperature. Thus, temperature must be considered as an additional factor. (2) Annual electric charge Q_ACM was suited as an index of ACM sensor output because log (Q_ACM) was proportional to corrosion rate parameter B_s of Y = A_sX^B_s . (3) The estimation equation of thickness reduction due corrosion was statistically obtained as Y = (166 + 8.71/V - 0.276Q_ACM - 0.480T) X^{(0.326/V + 0.0918 log(Q_ACM - 0.0165T) - 0.154[Cr])} , where Y is thickness reduction due corrosion [μm], X is exposed period [year], T is annual averaged temperature [K] and [Cr] is mass percent of chromium in the steel. It might be said from the findings in this study that thickness reduction due corrosion of new weathering steels can be estimated more accurately by combination of one year exposure test of small samples for A_s and ACM sensor measurement for B_s.

DOI： 10.2208/jscejseee.69.275

DOI： 10.2208/jscejam.72.i_731_references_DOI_7tUr5tztd0nDczgls2ZZdjl83Rv

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This study examined the effects of inherent defects due to plate assembling and material mismatched condition between base and weld metal on the fatigue strength of beam-to-column connections. Low cycle fatigue tests were carried out on specimens with different plate assembling systems and material mismatched conditions. The test results revealed that the global load-displacement relationships from specimens with different plate assembling systems and material mismatched conditions are similar, meaning these effects involve only local behavior of specimens. However, the fatigue strength of the specimens strongly depends on the location of defects resulting from plate assembling and mismatched conditions. The specimen with the undermatched conditions and the existing defect located closer to the corner of beam-to-column connection tends to have lower fatigue strength. The fracture surfaces indicated that failure patterns of specimen are different regarding mismatched conditions. While the crack propagated through the weld metal for the undermatched condition, it propagated towards the boundary between base and weld metal for overmatched condition. Elasto-plastic shell analysis was performed under the same condition as the experiments. And it is found that when evaluating fatigue strength of beam-to-column connections, the effects of plate assembling system and material mismatched condition should be considered.

DOI： 10.1007/s13296-012-3005-7

DOI： 10.2208/journalofjsce.4.1_118_references_DOI_7ilEraUsa3IyqyiFtReqlOlNPFK

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Other Link： http://link.springer.com/article/10.1007/s13296-012-3005-7/fulltext.html

Publisher：Informa UK Limited  

Many field surveys depict that steel plate girder ends tend to corrode due to the leakage of water from construction joints and/or detention of rain water near bearing regions. In many cases, buckling failures of plate girders were observed due to the excessive loss of material at the bottom portion of bearing stiffeners. In this study, the effect on the buckling strength of steel plate girder due to the corrosion damage at bearing stiffeners was investigated. Full-scale experimental tests were performed on two plate girder ends to determine the bearing capacity. Bearing capacity and failure modes were also verified by numerical analyses. Initial imperfections and welding residual stresses were also taken into account in analytical models. The simulation of the model was extended to the various corrosion damages, considering different damaged heights and thicknesses of the bearing stiffener near weld seam. All results were plotted in terms of remaining bearing capacity versus damage thickness ratio keeping the damage height of the stiffener constant. In this study, a damage parameter Reduced Thickness Ratio was used to assess the ultimate capacity and buckling of steel plate girder end with various corrosion levels.

DOI： 10.1080/15732479.2012.697904

DOI： 10.2208/jscejseee.74.145_references_DOI_MRV4eNpvtiWaLfyYg0H9AUuDoSD

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Publisher：SAGE Publications  

<jats:p> This article proposes the degree of nonlinearity as a feature for damage detection on large civil structures due to earthquakes. The degree of nonlinearity, which is a numerical value, represents how nonlinear structures behave during earthquakes. The degree of nonlinearity is computed directly from the data of the ground motion and vibration of the structure. The computation of the degree of nonlinearity uses a Hilbert transform and does not require any other nonlinear structural or mathematical models. Therefore, the damage detection process is very fast. Thus, an immediate decision about the condition of structures after strong earthquakes is possible. This article shows theoretically that a plot between the degree of nonlinearity against the magnitude of the ground motion represents the behavior of a structure. This plot is considered the signature of that structure. A structure that is healthy will have its specific healthy signature. If a new earthquake strikes and the new degree of nonlinearity deviates from its healthy signature, the structure may be damaged by that earthquake. To verify the validity of the degree of nonlinearity, numerical studies of nonlinear systems are presented. Although the application of degree of nonlinearity on a real civil structure is still not totally conclusive due to the limitation of data, the results from currently available data are encouraging. With more investigation, the degree of nonlinearity could be an additional or alternative feature for vibration-based structural health monitoring. </jats:p>

DOI： 10.1177/1475921712437182

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

During the Kobe earthquake, unexpected brittle fracture was occurred in a corner of steel bridge bent. In this study, based on the temperature rise which was obtained from elastic-plastic FEM considering heat transfer and the transition temperature shift of critical CTOD curve due to the strain rate, dynamic loading effect on the fracture origin during the earthquake was estimated. As a result, it was shown that, the effect of dynamic loading acted to inhibit the brittle fracture because amount of rise in temperature exceeded that of transition temperature shift due to the strain rate. Besides, it was confirmed that, even if it was affected by the effect of dynamic loading, brittle fracture could be occurred by the effect of strain history.

DOI： 10.2208/jscejseee.68.226

DOI： 10.2208/journalofjsce.4.1_118_references_DOI_2J7k2iUt1AwQpo1cFIyuU9YeV4f

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22760340/

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Weathering steel were steel with high atmospheric corrosion resistance by alloying Cu, Ni, etc. Use of weathering steels was limited by environmental conditions especially for airborne salts. Thus, new weathering steels with higher corrosion resistance in more salty condition were developed by adjusting composed elements. However, increasing alloying element will increase its cost. Thus, selecting weathering steels fit for construction sites is important. This study is aiming to understanding relationships among corrosive resistance, composite effects of weathering steels and local environments in order to select the best weathering steel. For this purpose, exposure tests of several weathering steels were conducted under various environmental conditions. Following findings were obtained: (1) The corrosion rate parameter A_s could be proportional to the weathering alloy index V and the regional corrosivity index Z. (2) Another corrosion rate parameter B_s could be proportional to log(Z), had almost no relation with V. (3) Specimens with a butt weld joint do not have any significant deterioration but, the existence of weldment increased A_s about 20%. And, (4) Rainfall effects could be explained as modification factor for A_s and the factor related with index Z. Based on these facts, the index V can be used to select adequate weathering steel if design period, allowable thickness reduction and index Z were given.

DOI： 10.2208/jscejseee.68.610

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Publisher：Japan Society of Civil Engineers  

Flow patterns around a bluff body are governed by small-scale turbulence and simulation of large-scale turbulence in a wind tunnel is often difficult. A turbulence partial simulation technique that simulates the normalized PSD in a high-frequency sub-inertia range was introduced. In this study, the technique was experimentally investigated using “reduced turbulence intensity”. Base pressure of rectangular cylinders with various slenderness ratios and surface pressures of hexagonal bridge deck models were compared for pairs of turbulences partially simulated. The result showed that the reduced turbulence intensity can be an index of turbulence partial simulation. In addition, the technique can be applied to a hexagonal bridge deck cross section.

DOI： 10.11532/structcivil.57a.629

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study investigated on the cause of brittle fracture during earthquakes from the viewpoint of structural peculiarities focusing on the stress triaxiality. The target structure is the actually fractured steel rigid bent of a highway bridge. From the investigations using nonlinear finite element analysis, it was confirmed that high stress triaxiality was generated at a point supposed as fracture origin depending on the geometry of weld bead, in which the level of stress triaxiality at the point increases in the case of bead toe radius is small or two bead leg lengths are unequal.

DOI： 10.2208/jsceja.66.420

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Language：Japanese   Publisher：Japan Wind Energy Association  

DOI： 10.11333/jweasympo.32.0_199

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Language：English   Publisher：Japan Society of Civil Engineers  

This paper proposes a practical method for input-output vibration-based health monitoring. The method using degree of nonlinearity (DON), which overcomes the limitation of linear models, is proposed. Derived from the Hilbert transform of the frequency response function, the DON can measure how much the nonlinearity is present in the vibration response. The results in this paper show that the DON of a structure has a specific relationship with the magnitude of the excitation. When computed from the structure that is still healthy, this relationship can be used as a baseline for the health monitoring. If the structure is not healthy, the new computed DON will deviate from this baseline.

DOI： 10.11532/structcivil.55A.809

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Language：Japanese  

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Language：English   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publisher：東京 : 日本建設機械施工協会  

資料形態 : テキストデータ プレーンテキスト
コレクション : 国立国会図書館デジタルコレクション > デジタル化資料 > 雑誌

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I026618037

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

A bridge vibration energy harvester has been proposed in this paper using a Tuned Mass Damper (TMD) system, named hereafter tuned mass energy harvester. To harvest and make use of the unused reserve of energy the aforementioned damper system absorbs, an electromagnetic transducer has been applied. To investigate the configuration of the tuned mass energy harvester considering performances of bridge vibration control and energy harvesting, single-mass and dual-mass systems where one or two masses are connected in series with the electromagnetic transducer and spring are proposed. According to the theory of vibrations and electric circuits, it has been clarified that dual-mass systems have several advantages over single-mass systems for power generation and vibration control. It has also been clarified that for effective energy harvesting or vibration control, it is essential to consider the power factor of electromagnetic transducer and electric circuit.

DOI： 10.2208/jscejseee.71.267

DOI： 10.2208/journalofjsce.8.1_103_references_DOI_U4sPfqJId0hvhlnrEnbtDxY8Q3e

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15J06103/

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Language：Japanese   Publisher：東京 : 土木技術社  

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I024065145

Language：Japanese   Publisher：東京 : 日本計算数理工学会  

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I024216997

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Language：Japanese   Publisher：東京 : 建設図書  

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I9639553

DOI： 10.11532/structcivil.54A.582

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Language：English   Publisher：Japan Society of Civil Engineers  

In this paper, time-domain modeling of bridge deck flutter is first developed. The frequency dependent self-excited forces acting on a bridge deck are approximated in the Laplace transform domain by rational functions. The least-square matrix formulation of the rational function approximation is applied to flutter derivatives of the Akashi Kaikyo Bridge and airfoil. Besides, numerical analyses of the wind-induced response of the Akashi Kaikyo Bridge were conducted to facilitate the discussion. After that, the vertical deflection and torsion at the span center of the Akashi Kaikyo Bridge caused by buffeting and self-excited forces using the results of approximated flutter derivatives are examined to investigate the sensitivity of the approximation to the wind-induced response.

DOI： 10.11532/structcivil.54a.420

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DOI： 10.2208/journalam.11.997

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Language：English   Publisher：The University of Tokyo  

A real-time bridge remote monitoring system for a quick detection of the damage caused by earthquakes and for a reliable measurement of the damage caused by its aging was developed. The system is consisted of various sensors, high-speed data transmission networks, and an information center that produces high-level information associated with the bridges-health. A demonstration system was developed on a Metropolitan expressway in Tokyo, Japan, where many heavy vehicles over regulation weight passes on. By this system, the reliability and the durability of our system was confirmed. [This abstract is not included in the PDF]

DOI： 10.11188/seisankenkyu.60.230

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Other Link： https://jlc.jst.go.jp/DN/JALC/00314451321?from=CiNii

Language：English   Publisher：Japan Society of Civil Engineers  

The static and dynamic wind-induced instability analyses of super long-span cable-stayed bridges with main span length of 1200～1800m are presented in this paper. Firstly, the static aeroelastic behaviors of bridges against displacement-dependent wind load are investigated by three-dimension geometrical nonlinear analysis. Secondly, the free vibration and flutter analyses are carried out. The comparisons of structural dynamic properties between cable-stayed and suspension bridges are discussed and the impact of the cable vibration effect on the dynamic characteristics and the flutter behavior is studied. The analytical results show that static instability controls the dimension of the girder and the safety against both static and dynamic instabilities can be ensured even with main span length of 1800m.

DOI： 10.11532/structcivil.53A.650

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Language：Japanese  

DOI： 10.2208/jsceja.62.950

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Language：Japanese   Publisher：建設図書  

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DOI： 10.2208/jscej.2005.801_97

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Recently, many fatigue cracks were found in the beam-to-column connections of steel bridge frame piers in metropolitan expressway bridges. It was pointed that high stress concentrations occurred at the corner of beam-to-column connections, and caused fatigue cracks. In order to improve the fatigue performance of the beam-to-column connections, we proposed rib-installation. Effects of rib-installation were evaluated by the Finite Element Analyses and fatigue tests. As a results, it was found that the rib-installation was effective to reduce stress concentration at the corner of the beam-to-column connection, and rib-installation could improve fatigue performance of beam-to-column connections.

DOI： 10.2208/jscej.2004.773_137

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Language：Japanese  

DOI： 10.2208/jscej.2004.766_233

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Language：Japanese   Publisher：Japan Welding Society  

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DOI： 10.1002/stab.200301150

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Language：Japanese   Publisher：土木学会  

DOI： 10.2208/journalam.6.1009

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, the investigations were conducted on the required fracture toughness of steels to prevent brittle fracture during earthquakes in steel bridge piers. By considering the scenarios of the occurrence of brittle fracture, the patterns of prestrain that should be considered were shown, and then the effects of various patterns of prestrain on fracture toughness of steels made to be clear by the development of the method to introduce prestrain into specimens. Finally, by arranging all the results of this study and our previous study on the effects of plastic prestrain, the level of the required fracture toughness was suggested. To prevent brittle fracture during earthquakes, the temperature shift of 50 degrees of Celsius of the critical CTOD curves by plastic prestrain should be considered.

DOI： 10.2208/jscej.2003.731_93

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I6395840

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DOI： 10.2208/jscej.2002.710_141

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DOI： 10.2208/jscej.2001.689_201

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, the deterioration of fracture toughness by effect of prestrain of 6 types of steel was investigated by CTOD tests. As a result, it came to be clear that before strain aging effect appears, the fracture toughness of most types of steels can be deteriorated by prestrain itself and that how much fracture toughness is deteriorated is differs from steel to steel. Furthermore, the influence of the direction of prestrain was found on all the types of steel but one, and so the causes of the difference between tensile prestrain and compressive prestrain were also discussed.

DOI： 10.2208/jscej.2000.640_165

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Applicant：国立大学法人東京工業大学

Application no：特願2015-024381  Date applied：2015.2

Announcement no：特開2016-148549  Date announced：2016.8

Patent/Registration no：特許第6473008号  Date registered：2019.2 

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Applicant：国立大学法人東京工業大学

Application no：特願2015-024381  Date applied：2015.2

Announcement no：特開2016-148549  Date announced：2016.8

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Applicant：オムロン株式会社, 国立大学法人東京工業大学

Application no：特願2012-123487  Date applied：2012.5

Announcement no：特開2013-250088  Date announced：2013.12

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Applicant：国立大学法人横浜国立大学

Application no：特願2009-177238  Date applied：2009.7

Announcement no：特開2011-032651  Date announced：2011.2

Patent/Registration no：特許第5388318号  Date registered：2013.10 

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Applicant：国立大学法人東京工業大学, 国立大学法人横浜国立大学, 首都高速道路株式会社, 株式会社エヌ・ティ・ティ・データ

Application no：特願2009-043124  Date applied：2009.2

Announcement no：特開2010-197249  Date announced：2010.9

Patent/Registration no：特許第5327796号  Date registered：2013.8 

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Applicant：株式会社エヌ・ティ・ティ・データ, 国立大学法人横浜国立大学

Application no：特願2008-081687  Date applied：2008.3

Announcement no：特開2009-237805  Date announced：2009.10

Patent/Registration no：特許第5164100号  Date registered：2012.12 

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