| 1. |
Mujtaba Amin, Yukihide Kajita, SHAKE TABLE EXPERIMENT ONF GIRDER-ABUTMENT POUNDING EFFECT AND ITS NUMERICAL SIMULATION, Proceedings of 26th Australasian Conference on Mechanics of Structures and Materials, SS1-MA1-27, 2023.12, Bridge damage due to poundings has been observed in many major earthquakes. It is essential to predict estimate the pounding damage and to propose develop a numerical model that can reproduce accurately simulate the effect of poundings between a girder and an abutment. First, a 1/20 scale model of the steel pier-RC girder-RC abutment system was constructed and shake table experiments were conducted under different harmonic periodical excitations. The dynamic behavior of the girder and the abutment with poundings were analyzed by comparing the obtained results with those without considering girder-abutment poundings. Second, numerical simulations were developed using a 3-D finite element model with the contact model. The mesh sensitives sensitivity and contact types were considered. The experimental results show that considering the pounding effect can reduce the strain energy in the steel pier while also there is less strain energy stored in theand abutment. In addition, damage to the abutment and back wall is not severe even if the frequency of the harmonic shake table movement coincided coincides with the natural frequency of the girder-abutmentpier system . The numerical simulations show that the pounding behavior can be well described with the Mortar contact algorithm. The displacements and accelerations of the bridge deck and the strain at the pier agreed well with those from the shake table experiments.. |
| 2. |
Mujtaba Amin, Yukihide Kajita, NUMERICAL SIMULATION OF IMPACT EFFECT FOR DAMAGE ASSESSMENT OF HIGHWAY BRIDGE ABUTMENTS, Proceedings of 26th Australasian Conference on Mechanics of Structures and Materials, SS1-MA1-26, 2023.12, Damage to bridge abutments due to girder impact has been confirmed observed in many major earthquakes. Very limited studies are beinghave been conducted. None of the past studies has incorporated the abutment damage as an integrated system, i.e., the interaction between the deck and the back wall as well as between abutment and backfill. First, the reliability of the numerical model for damage assessment is validated with the result of the shaking table test. Second, numerical simulations of the impact effect were carried out on four types of actual abutments with different wing wall shapes and dimensions. The developed innovative numerical models can simulate the nonlinear backfill soil, the interface between the backfill and the back walls, damage to the concrete, and the yielding of the reinforcement steel with the strain rate effect of the concrete and steel reinforcement. Parametric studies were conducted to investigate the influence of the nonlinearity of the backfill soil nonlinearity, back wall-to-backfill friction, constitutive law of concrete, hourglass ratio, and impact energy. The results show that the displacement and the impact force on the back wall are affected by the nonlinear variations behavior of the backfill soil and wing wall. Since poundings can be repetitive, this study confirms that the velocity of the initial impact of a bridge deck can precisely predict the severe damage to bridge abutments.. |
| 3. |
Kyeong-Hoon Park, Taiji Mazda, Yukihide Kajita, Dynamic loading tests and analytical modeling for high-damping rubber bearings, Earthquakes and Structures, https://doi.org/10.12989/eas.2023.25.3.161, 25, 3, 161-175, 2023.09, High-damping rubber bearings (HDRB) are commonly used as seismic isolation devices to protect civil engineering structures from earthquakes. However, the nonlinear hysteresis characteristics of the HDRB, such as their dependence on material properties and hardening phenomena, make predicting their behavior during earthquakes difficult. This study proposes a hysteretic model that can accurately predicts the behavior of shear deformation considering the nonlinearity when designing the seismic isolation structures using HDR bearings. To model the hysteretic characteristics of the HDR, dynamic loading tests were performed by applying sinusoidal and random waves on scaled-down specimens. The test results show that the nonlinear characteristics of the HDR strongly correlate with the shear strain experienced in the past. Furthermore, when shear deformation occurred above a certain level, the hardening phenomenon, wherein the stiffness increased rapidly, was confirmed. Based on the experimental results, the dynamic characteristics of the HDR, equivalent stiffness, equivalent damping ratio, and strain energy were quantitatively evaluated and analyzed. In this study, an improved bilinear HDR model that can reproduce the dependence on shear deformation and hardening phenomena was developed. Additionally, by proposing an objective parameter-setting procedure based on the experimental results, the model was devised such that similar parameters could be set by anyone. Further, an actual dynamic analysis could be performed by modeling with minimal parameters. The proposed model corresponded with the experimental results and successfully reproduced the mechanical characteristics evaluated from experimental results within an error margin of 10%.. |
| 4. |
Kyeong-Hoon Park, Yuki Fujiwara, Taiji Mazda, Yukihide Kajita, Research on Hysteresis Model of High Damping Rubber Bearing with Neural Networks, Conference Paper on Experimental Vibration Analysis for Civil Engineering Structures(EVACES 2023), https://doi.org/10.1007/978-3-031-39117-0_45, 2023.08, Home Experimental Vibration Analysis for Civil Engineering Structures Conference paper
Research on Hysteresis Model of High Damping Rubber Bearing with Neural Networks
Kyeonghoon Park, Yuki Fujiwara, Taiji Mazda & Yukihide Kajita
Conference paper
First Online: 29 August 2023
256 Accesses
Part of the Lecture Notes in Civil Engineering book series (LNCE,volume 433)
Abstract
High Damping Rubber bearing (HDR) is a seismic isolator widely applied to infrastructures such as road bridges and hospital facilities to improve seismic performance. However, since it is difficult to predict the actual behavior of HDR due to various dependencies and nonlinearity to shear deformation, the hysteresis model considering the hysteresis characteristics of HDR is required. The purpose of this research is to propose a methodology for modeling the nonlinear history of HDR by utilizing the functional approximation ability of neural networks. Specifically, based on the results of the dynamic loading test with HDR specimens, the feasibility of the proposed neural networks and applicability as a numerical computation subroutine for dynamic analysis is investigated. To achieve the research purpose, three phases are performed. Initially, the stress-strain relationship of HDR is measured to obtain training data of the neural networks by conducting the dynamic loading test. Subsequently, the structure of the neural networks is designed to recognize the mechanical properties and nonlinearity of HDR. In this research, input factors and output factors of neural networks are suggested from the results of the dynamic loading test. Finally, the validity of the trained neural networks as a subroutine of dynamic analysis is evaluated by reproducing the dynamic loading test, and the mechanical properties are compared with the test results. As a result, the proposed neural networks are applicable to dynamic analysis as a subroutine of the hysteresis model that can recognize the hysteresis characteristics and nonlinearity of HDR.. |
| 5. |
Kunyang Wang, Yukihide Kajita and Yaoxin Yang, Bayesian RC-Frame Finite Element Model Updating and Damage Estimation Using Nested Sampling with Nonlinear Time History, Buildings, https://doi.org/10.3390/buildings13051281, 13, 5, 1281, 2023.05, This paper proposes a Bayesian RC-frame finite element model updating (FEMU) and damage state estimation approach using the nonlinear acceleration time history based on nested sampling. Numerical RC-frame finite element model (FEM) parameters are selected through nested sampling, and their probability density is estimated using nonlinear time history. In the first step, we estimate the error standard deviation and select the FEM parameters that are required to be updated by FEMU. In the second step, we estimate the probability density of the selected parameters and realize the FEMU through the resampling method and kernel density estimation (KDE). Additionally, we propose a damage state estimate approach, which is a derivative method of the FEMU sample. The numerical results demonstrate that the proposed approach is reliable for the Bayesian FEMU and damage state estimation using nonlinear time history..  |
| 6. |
Kyeong-Hoon Park, Yuki Fujiwara, Taiji Mazda, Yukihide Kajita, Research on Hysteresis Model of High Damping Rubber Bearings Considering Mechanical Properties Based on Dynamic Loading Test, Proceedings of 2022 5th International Conference on Civil Engineering and Architecture, 2022.12, The aim of this research is to develop an advanced hysteresis model of High Damping Rubber (HDR) bearing. Based on the experimental research so far, various dependences and nonlinearities can be confirmed in the experimental hysteresis curves of HDR. In particular, the gap in the stiffness between the first cycle and the cycle after the second of the hysteresis curve is confirmed due to the dependence of the maximum shear strain. The advanced hysteresis model of HDR, tentatively named the bilinear Double Target model, was proposed by conducting the dynamic loading test in this research. To assess the technical feasibility of this hysteresis model, three phases were performed in this research. The preliminary proportion was carried out to confirm the mechanical behaviors of HDR by performing a dynamic loading test. Subsequently, based on the experimental results, a modeling procedure of the bilinear Double Target model was proposed and the hysteresis curve of HDR was modeled. Finally, dynamic analyses by design seismic motion are performed on the structural model of the actual bridge pier. The validity of the proposed model was confirmed by investigating the behavior of the bearing part and the lower part of the pier. As a result, it was possible to propose a hysteresis model considering the dependence of HDR and to conduct seismic response analysis.. |
| 7. |
Kyeong-Hoon Park, Yuki Fujiwara, Taiji Mazda, Yukihide Kajita, Dynamic analysis of bridge pier considering hysteresis characteristics of High Damping Rubber bearings, Proceedings of 2021 4th International Conference on Civil Engineering and Architecture, https://doi.org/10.1007/978-981-16-6932-3_25, 2022.01, The aim of this research is to develop an advanced hysteresis model of High Damping Rubber (HDR) bearing. Based on the experimental research so far, various dependences and nonlinearities can be confirmed in the experimental hysteresis curves of HDR. In particular, the gap in the stiffness between the first cycle and the cycle after the second of the hysteresis curve is confirmed due to the dependence of the maximum shear strain. The advanced hysteresis model of HDR, tentatively named the bilinear Double Target model, was proposed by conducting the dynamic loading test in this research. To assess the technical feasibility of this hysteresis model, three phases were performed in this research. The preliminary proportion was carried out to confirm the mechanical behaviors of HDR by performing a dynamic loading test. Subsequently, based on the experimental results, a modeling procedure of the bilinear Double Target model was proposed and the hysteresis curve of HDR was modeled. Finally, dynamic analyses by design seismic motion are performed on the structural model of the actual bridge pier. The validity of the proposed model was confirmed by investigating the behavior of the bearing part and the lower part of the pier. As a result, it was possible to propose a hysteresis model considering the dependence of HDR and to conduct seismic response analysis.. |
| 8. |
Taiji Mazda, Yukihide Kajita, Shunya Miyatake, A study on assessing the damage of a bearing with multilayer neural network using the acceleration response of a bridge, Proceedings of 10th International Conference on Structural Health Monitoring of Intelligent Infrastructure, 2021.06. |
| 9. |
Yukihide Kajita, Taiji Mazda, Kunihiko Uno and Takeshi Kitahara, 2-dimensional effective stress analysis for a damaged bridge located in the caldera of Mt. Aso in 2016 Kumamoto Earthquake, Resilient technologies for sustainable infrastructure, 1142-1149, 2021.02, In this paper, we conducted a two-dimensional effective stress analysis in consideration of the interaction between the ground and the structure for the Kurumakaeri Bridge which is located in the caldera of Mt. Aso. From the results of the analyses, it is confirmed that the ground around the abutment subsided by about 26cm due to the deformation of the soft volcanic ash soil. Furthermore, it is confirmed that the collision between the superstructure and the abutment happened because the abutment moved to the front side. Due to this movement, the deformation of about 34cm occurred at the rubber bearing after the earthquake ended.. |
| 10. |
Yukihide Kajita, Seiji Fukui, Takeshi Kitahara, Kunihiko Uno and Taiji Mazda, INVESTIGATION FOR SUBSIDENCE AT THE APPROACHING AREAS OF ABUTMENTS INDUCED BY SEQUENCED GROUND MOTIONS, Proceedings of the 17th World Conference on Earthquake Engineering, Paper No. 2d-0072, 2020.09. |
| 11. |
Kaname Iwatsubo, Yukihide Kajita, Akira Kasai, Horizontal biaxial direction vibration experiment to investigate horizontal response of bridge during earthquake, Proceedings of the 17th World Conference on Earthquake Engineering, Paper No. 2i-0225, 2020.09. |
| 12. |
Kyeong-Hoon Park, Yuki Fujiwara, Taiji Mazda, Yukihide Kajita, Evaluation of mechanical properties considering hysteresis characteristic of high damping rubber bearing, Journal of Physics: Conference Series (International Conference on Engineering Systems 2020), 10.1088/1742-6596/1687/1/012019, 2020.06, Recently, laminated rubber bearings are widely used as seismic isolators for road bridges. Although many studies have been conducted on the dynamic model of High Damping Rubber (HDR) bearings, few models can reflect phenomena such as the dependency of experienced shear strain on initial history. To develop a model that can represent the dependency of the experienced shear strain of HDR and a dynamic loading test was conducted using HDR specimens. The hysteresis characteristics of HDR was measured by applying a horizontal vibration using a hybrid actuator under a constant vertical load. Based on the cyclic shear test, the mechanical properties of HDR were calculated such as absorbed energy, hysteresis loop area, equivalent stiffness, equivalent damping ratio. Dynamic analysis was also performed from the experimental results. The dynamic model applied in program analysis is a bilinear type doubletarget model. This model can express the nonlinear characteristics related to the initial history of HDR bearings. The parameters required for dynamic analysis were determined from the experimental results. Through this dynamic analysis, the effectiveness of the bilinear type double target model was verified. In this research, a high damping rubber specimen was used.. |
| 13. |
Mujtaba Amin, Pennung Warnitchai, Yukihide Kajita, Seismic performance of highway bridges considering sacrificial abutment: a case study in Afghanistan, Innovative Infrastructure solutions, https://doi.org/10.1007/s41062-020-0276-2, 5, 1, 2020.02, The effect of skewness on the sacrificial seat-type abutment and abutment interaction with the skew deck is quite well known. Unlike the simplified approach, this study focuses on the effect of skewness on the seating width of seat-type abutment by providing a rigorous deck model in the analysis while the sacrificial seat-type abutment interacts with the straight deck. This effect is investigated by comparing the seismic performance of two case study bridges, the bridge with elastomeric bearing pad as a bearing mechanism, namely the conventional bridge and the bridge with lead rubber bearing, as an isolated bridge. Realistic seismic response behaviors of these bridges were simulated by nonlinear 3D models. The models are capable of simulating the flexural yielding of piers, the bilinear behavior of isolation bearings, the elastic perfect plastic behavior of elastomeric bearings of the conventional bridge and the other important nonlinear behaviors of these structures. The results highlight the effectiveness of isolation bearing on seismic performance of the isolated bridge, and it was revealed that in the early pounding frequencies, passive forces on the sacrificial backwall springs are uniformly distributed. Whereas for the last pounding frequencies, the passive forces on the backwall are not uniform anymore, this implies that the increase in the pounding frequency leads to an increase in the possibility of deck rotation in the straight deck. Moreover, the result confirms that the earthquake energy absorbed by the fusing backwall could significantly lead to a reduction in dissipation energy by the pier. These results suggest recommendations to improve the seismic performance of the conventional bridge system in the country.. |
| 14. |
Taiji Mazda, Yukihide Kajita, Takashi Akedo and Tsubasa Hazama, Recognition of nonlinear hysteric behavior by neural network using deep learning, Proceedings of the 5th international conference on Architecture, Materials and Construction, https://doi.org/10.1088/1757-899x/809/1/012010, Paper No. B19-2021, 2019.12. |
| 15. |
Yukihide Kajita, Gankhuu Khurelbaatar, Kenya Yabe, Taiji Matsuda, Finite element analysis on damage of lateral displacement confining structure and abutment due to collision with superstructure, Modern Developments in Performance of Structures Under Extreme Loading, Paper No.71, 2019.09, The lateral displacement confining structure (LDCS) is installed to prevent the superstructure from being unseated. In this study, we mainly focused on the damage form of the LDCS and the abutment due to collision with superstructure during a severe ground excitation such as 2016 Kumamoto Earthquake in Japan. Our target bridge is the Oginosaka bridge which is one of the damaged bridges in 2016 Kumamoto Earthquake. In order to examine how large impact force is applied to the LDCS of Oginosaka bridge and in order to analyze an optimal location and geometrical properties of the LDCS, three numerical models are prepared. From the results of the static loading analyses, firstly, it is found that the applied force of the LDCS of the Oginosaka bridge would be a little larger than the seismic design load. Secondly it is found that not only the LDCS but also the abutment damages severely when the LDCS is installed at the edge of the abutment. . |
| 16. |
Yukihide Kajita, Kazuki Onoda, Taiji Matsuda, Kunihiko Uno, Takeshi Kitahara, Investigation on the effect of countermeasures for subsidence at the approaching areas of abutments, 10th International Structural Engineering and Construction Conference, ISEC 2019
ISEC 2019 - 10th International Structural Engineering and Construction Conference, 2019.01, The purpose of this study is to confirm the effect of soil improvement methods on preventing ground subsidence at the back of abutments. Earthquake seismic analysis is performed for three models. One is a model with no ground improvement. Next is a model with deep mixing method. The third is the model with lightweight banking method. As a result, from the perspective of the passage possibility of the emergency vehicles, both the deep mixing method and lightweight banking method are effective in preventing ground subsidence at the approaching area of abutments. However, in the case of the deep mixing method, it is found that the maximum bending moment of the pile under the liquefaction layer increases because a lump of improved rigid soil that falls down toward the piles.. |
| 17. |
Mujtaba Amin, Yukihide Kajita, Taiji Mazda, Numerical Simulation of Pounding Effect on Damage Assessment of an Abutment for Highway Bridge, Proceedings of the 7th Asia Conference on Earthquake Engineering, Paper ID 0009, 2018.11, The current study mainly focuses on the impact damage assessment of the abutments considering the non-linearity of backfill soil which has not ever quantitatively estimated. The numerical simulation of pounding effect on four types of the abutments with wing wall variation in shapes and dimensions were carried out using the explicit FE code LS-DYNA. The pounding scenario was simulated by the initial impact velocity on the entire nodes of the superstructure. The numerical models are capable of simulating the nonlinearly of backfill soil, damage of concrete and yielding of reinforcement steel with strain rate effect behavior of concrete and steel reinforcement. The study indicates that the response displacement and the impact force on the back wall are affected by the non-linear backfill soil and wing wall variations. At the initial instant of impact, there is No significant effect on the impact forces whereas, for the rest of the time, the impact force on the back wall slightly decreased and the abutment displacement at the crown of back wall increased due to soil non-linearity. In the case of low impact velocity, damage only occurs at the base of the back wall whereas, in the case of maximum velocity impact, the damage spread over the entire Back wall and damage to the entire abutment was confirmed. In the design, only one impact is considered. However, in a real situation, a few or several impacts would occur during an earthquake. So, if the damage to abutment is predicted precisely, the non-linear property of backfill soil should be considered.. |
| 18. |
Mujtaba Amin, Pennung Warnitchai, Yukihide Kajita, A comparison of seismic performance of an isolated highway bridge and a conventional bridge system in Afghanistan, Proceedings of the 13th annual meeting of Japan association for earthquake engineering, CD-ROM(Paper No. P4-37), 2017.11. |
| 19. |
JOONHO CHOI, Toshiyuki Nagahara, Yukihide Kajita, Analytical study on the collision load distribution between a large vessel and a cable stayed bridge tower due to Tsunami, Proc. of the 16th World Conference on Earthquake Engineering, Paper No.1250, 2017.01, By the tsunami on 11 March 2011, many vessels drifted and they caused not a few damages on bridge structures such as the collision between a vessel and a pier or a superstructure. In order to design tsunami resisting structures, it is required to clarify the influence of the collision force on the bridge structure. In this study, in order to clarify the collision load distribution when a large vessel drifted by tsunami collides with bridge structures, collision analyses using FEM were conducted. Here in, it was presupposed that the drifted large vessel would collide with a tower of a long span cable stayed bridge with 1000 m length. Taking account of various collision conditions, the parametric analyses which were varied with collision positions and collision directions carried out. It was found that the collision load when the vessel collided with the
lower part of the tower was larger than it when the vessel collided with upper part of the tower. And the collision load when the vessel collided in a vertical direction was smaller than it when the vessel collided in horizontal direction. Additionally, we compared the value of a collision load formula based on a log normal distribution and it calculated from the FE analytical result. From the result, the maximum collision load of FE result was a little larger than it of the formula due to the difference in the vessel behavior evaluation after the collision. . |
| 20. |
H. Hazarika, N. P. Bhandary, Y. Kajita, K. Kasama, K. Tsukahara, R. K. Pokharel, The 2015 Nepal Gorkha Earthquake
An overview of the damage, lessons learned and challenges, lowland technology international, 18, 2, 105-118, 2016.09, This paper describes the damage brought by the 2015 Nepal earthquake to urban infrastructures, modern and traditional buildings as well as some word heritage sites in and around Kathmandu city. The paper also focuses on a disaster brought to a hydropower plant by the compound action of a previous landslide and this time earthquake. Some of the possible reasons for such damage were brought to light, and challenges of the geotechnical community towards the retrofitting and recovery of the devastated structures were discussed.. |
| 21. |
Yukihide Kajita, Damage report on 2016 Kumamoto Earthquake, Proc. of the 9th Taiwan-Japan Workshop on Structural and Bridge Engineering, 2016.05. |
| 22. |
Yukihide Kajita, Investigation of ground subsidence level of the backfill soil of the abutment on the soft ground due to severe earthquakes, Proc. of the 2016 2nd Workshop with NCREE and Kyushu University, 2016.04. |
| 23. |
Yukihide Kajita, Kyosuke Kakinaga, Kunihiko Uno, Takeshi Kitahara, Seismic response analyses of the pile foundation of the abutment on the soft soil layer, Proc. of the Tenth Pacific Conference on Earthquake Engineering, Paper No.38, 2015.11, The purpose of this study is to obtain the seismic response of the abutment on the liquefaction ground. Especially, the bending moment of the piles and the horizontal displacement of the abutment are focused on.. |
| 24. |
Y. Kajita, T. Kitahara, Loading capacity on steel piers corroded at the contact area between steel column and concrete footing, 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014
Life-Cycle of Structural Systems
Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014, 255-259, 2015.01, The purpose of this paper is to grasp the loading capacity of the corroded steel piers. Firstly, we investigate the steel piers which are corroded at the contact area between the steel column pier and the concrete footing. The corroded area and the depth of the corrosion are measured. Secondly, the static analysis is carried out to check the redundancy of a corroded steel pier by increasing the horizontal load gradually. From the results of the static analysis, even though the corroded area is spread on the basement of the steel pier, the initial stiffness and the yield load are not hardly changed. But the displacement after the yielding is increasing with the increasing corrosion depth. Therefore, it must be cautious if large seismic inertia force is applied to the corroded steel pier.. |
| 25. |
Wenjun Gao, Hisanori Otsuka, Yukihide Kajita, Effect of the loading condition on the restoring force characteristics of the rigid frame RC pier with the shear wall
, Proc. of the first international conference on construction materials and structures, pp.989-997, 2014.11, 2014.11. |
| 26. |
Yukihide Kajita, A Horizontal Loading Test and Its Simulation Analysis of the Abutment Model with Backfill Soil
, Proc. of the 2014 Taiwan-Japan Workshop on Structural and Bridge Engineering, 2014.05. |
| 27. |
T. Kitahara, Y. Kajita, Y. Kishi, Effect of return period and its variation of input ground motion on partial safety factors, 11th International Conference on Structural Safety and Reliability, ICOSSAR 2013
Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures - Proceedings of the 11th International Conference on Structural Safety and Reliability, ICOSSAR 2013, 4477-4481, 2013.12, Application of performance-based design, which is promoted as an international trend that is representative of ISO2394, emphasizes the importance of evaluating structural safety based on the reliability design method. This paper describes an effect of return period and its variation of input ground motions on partial safety factors for use of the reliability design method for steel rigid-frame piers. For this study, seismic hazard assessment was evaluated from the probabilistic seismic hazard data. Then, partial safety factors are calculated using AFOSM. The results show that the consideration of the variation of the seismic load in each site is necessary to evaluate the optimum partial safety factors against the objective reliability index. Therefore, the effect of the return period and its variation of input ground acceleration is confirmed by the trail design of a steel rigid frame pier to withstand the local buckling against ground excitation.. |
| 28. |
Yukihide Kajita, T. Kobayashi, H. Otsuka, Investigation on the risk of traffic passage by the damage of girder and abutment due to severe earthquakes, 11th International Conference on Structural Safety and Reliability, ICOSSAR 2013
Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures - Proceedings of the 11th International Conference on Structural Safety and Reliability, ICOSSAR 2013, 4185-4188, 2013.12, In this study, we extracted all seismic ground motions of the maximum in ground level acceleration 300 (cm/s2) and more from 1996 to 2011 by using the K-NET. From the ground level acceleration data, we formulated the relationship between the peak response velocity and the peak velocity of the ground excitation. Then, we obtained the relationship between the collision velocity and the height of the vertical gap between adjacent girders. By using two obtained relationships, we did the risk evaluation for the car trafficability by the damage of the girder ends due to severe earthquakes. As a result of the risk evaluation, it is understood that the return period that we can't drive a car at the speed of 80 km per hour and more about 5% in the next 30 years due to a severe earthquake in Shizuoka City.. |
| 29. |
Yukihide Kajita, Takeshi Kitahara, Damage estimation of expansion joint by collision between girders
, Proc. of the 2013 World Congress on Advanced in Structural Engineering and Mechanics, Paper No. MS509_267(CD-ROM), 2013.09. |
| 30. |
Takeshi Kitahara, Yukihide Kajita, Yasuo Kitane, Investigation on the Damage Cause of the Bridge Rubber Bearings in the 2011 Off the Pacific Coast of Tohoku Earthquake
, Proc. of the 15th World Conference on Earthquake Engineering, Paper No.2815(CD-ROM), 2012.09. |
| 31. |
Yukihide Kajita, Hisanori OTSUKA, Yuki Fujiyoshi, A Horizontal Test and Its Simulation Analysis of the Abutment Model with Backfill Soil
, Proc. of the 15th World Conference on Earthquake Engineering, Paper No.0339(CD-ROM), 2012.09. |
| 32. |
Takeshi Kitahara, Yukihide Kajita, Yusuke Kishi, Correlation Between Partial Safety Factor and Return Period of Input Motions for Seismic Reliability Design Method of Steel Rigid Frame Piers, Proc. of the 5th Asian-Pacific Symposium on Structural Reliability and its Applications, Paper No.234(CD-ROM), https://doi.org/10.3850/978-981-07-2219-7_p234, 2012.05. |
| 33. |
Ryoji Miyasada, Yukihide Kajita, Hisanori Otsuka, Takeshi Kitahara, Damage estimation of girder end for pounding of girders and investigation of serviceability for the emergency car, Doboku Gakkai Ronbunshuu A, 10.2208/jsceja.65.1027, 65, 4, 1027-1036, 2009.12, In this paper, we carried out numerical analyses on pounding superstructures, which consist of expansion joint, concrete floor slab and steel girder, by using the 3-dimensional finite element method. To be more precise, the damage level of the expansion joint and concrete slab is simulated. From the numerical analyses, the finger part of the expansion joints is lifted up from about 20mm to 200mm. The serviceability for the emergency car is also investigated by using the vertical gap between the expansion joints. From the result, it is found that the emergency cars are necessary to traverse in low speed when the impact velocity is larger than 2.0m/sec.. |
| 34. |
Y. Kajita, K. Yoshida and H. Otsuka, The effect pf pounding model between girder and abutment on seismic response of bridge, Proc. of the 5th International Conference on Computational Design in Engineering, Paper No.P-12(CD-ROM), , 2009.11. |
| 35. |
Yukihide Kajita, Hisanori Otsuka, A proposal on the determination of partial safety factors for steel piers using seismic hazard maps, Safety, Reliability and Risk of Structures, Infrastructures and Engineering Systems, Taylor & Francis Group, London, 2009.09. |
| 36. |
Y. Kajita, K. Sakaguchi and H. Otsuka, Investigation on the Seismic Redundancy of a Damaged Steel Truss Bridge , Proc. of the 5th International Symposium on Steel Structures, 2009.03. |
| 37. |
Y. Kajita, R. Miyasada and H. Otsuka, Numerical Analysis on Pounding Superstructures with Shock Absorber, Proc. of the 14th World Conference on Earthquake Engineering, 2008.10. |
| 38. |
Y. Kajita，T. Takahashi, Y. Sonoda and S. Katsuki, A Proposal on the Determination of Partial Safety Factors for Steel Piers under Severe Ground Motions, First International Confrence on Modern Design, Construction and Maintenance of Structures, Vol.2, pp.261-266, 2007.12. |
| 39. |
Y. Kajita, R. Miyasada and H. Otsuka, Numerical Analysis on Pounding Steel Girders with Shock Absorber, Vietnam-Japan Seminar/Workshop on Earthquake Engineering, CD-ROM, 2007.12. |
| 40. |
H. Tamai, Y. Sonoda, K. Gotou and Y. Kajita, A Numerical Study on Impact Damage Assessment of PC Box Girder Bridge by Pounding Effect, First International Workshop on Performance, Protection, and Strengthening of Structures under Extreme Loading, CD-ROM, 2007.08. |
| 41. |
A proposal on the determination of partial safety factors for steel piers under severe ground motions. |
| 42. |
Y. Kajita, T. Kitahara, Y. Nishimoto and H. Otsuka, Simulation analysis on collision test between two steel bars, 4th International Conference on Urban Earthquake Engineering, pp.245-252, 2007.03. |
| 43. |
A fundamental study on the damage evaluation of bridge abutment and the characteristics of impact spring element by pounding effect. |
| 44. |
A suggestion on the determination of partial safety factors for buckling design of steel piers. |
| 45. |
Relative Velocity during Pounding between Girders Considering Elasto-plastic Response. |
| 46. |
Simulation Analysis on Collision Test between Two Steel Bars. |
| 47. |
Yukihide Kajita, Takeshi Kitahara, Yasushi Nishimoto and HisanoriOtsuka, Estimation of Maximum Impact Force on Natural Rubber during Collision of Two Steel Bars, First European Conference on Earthquake Engineering and Seismology, Paper No.488, 2006.09. |
| 48. |
Estimated formula of maximum impact force on natural rubber during collision between two steel bars. |
| 49. |
Study on Interactive Optimal Design of Steel Dam Supported by GA. |
| 50. |
Daisuke Haraki, Satoshi Katsuki and Yukihide Kajita, Fracture Analysis of Concrete Column under High Speed Load by 3-D Distinct Element Method, 5th International Conference on Micromechanics of Granular Media, pp.1457-1461, 2005.07. |
| 51. |
Takeshi Sakuda, Naoki Bouhara, Satoshi Katsuki, Yukihide Kajita and Yoshimi Sonoda, Application of Multi-Pattern Differentiation Neural Network System for Monitoring of Fatigue Damage of Concrete Material, 3rd International Conference on Structural Stability and Dynamics, 2005.06. |
| 52. |
An application of multi-pattern differentiation neural network system for monitoring of fatigue damage. |
| 53. |
Experimental study on the resistance characteristics of filled concrete in CFT using an air floating collision test device. |
| 54. |
Takeshi Kitahara, Yukihide Kajita, Yasushi Nishimoto, Satoshi Katsuki, Collision test between steel bars with shock absorbing rubber for bridge restrainer system using fricitonless impact testing apparatus, 1st International Conference on Advances in Experimental Stuctural Engineering, AESE 2005
AESE 2005 - Proceedings of the 1st International Conference on Advances in Experimental Stuctural Engineering, 901-907, 2005.01, In the Japanese Specifications for Highway Bridges, shock absorbing rubbers should be required to reduce the impact load with the collision between a superstructure and a device which prevents a superstructure from falling off, or between two superstructures. However, the specification has no detail prescript regarding the thickness of shock absorbing rubbers. Therefore, it is very important to investigate the effect of the thickness of shock absorbing rubbers on the reduction of impact load. In this study, the collision test between two steel solid bars using a new experimental apparatus is carried out in order to assess the above effect. This new apparatus can levitate a steel bar by using compressed air so that there is little friction between a steel bar and a guide rail against the horizontal movement. We name this apparatus as “frictionless impact testing apparatus”. The steel bar has 1000mm long, 200mm wide, 200mm high and about 3.0kN weight and the thickness of shock absorbing rubbers ranges from 2mm to 40mm and the collision velocity ranges from 0.2m/sec to 1.0m/sec on 7 stages. From the test results, it is confirmed that the sliding friction force is very small. In addition, the qualitative influence of the rubber thickness and collision velocity on the reduction of the maximum impact load is clarified in collision between two steel bars with shock absorbing rubber for bridge restrainer system.. |
| 55. |
D. Haraki, S. Katsuki, Yukihide Kajita, Fracture analysis of concrete column under high speed load by the 3-D distinct element method, 5th International Conference on the Micromechanics of Granular Media: Powders and Grains 2005
Powders Grains - Proc. Int. Conf. Micromechanics Granular Media, 2, 1457-1461, 2005, Over the past few years, several studies have been made on fracture analysis of concrete structures by the distinct element method. But little attention has been given to the analysis of concrete structures subjected to high speed load. It has been reported by several experimental researches that the maximum strength and the stiffness of concrete material becomes larger as the speed of the applied load becomes faster. Therefore, the objective of this study is to simulate the fracture behavior of concrete column under high speed load by 3-D distinct element method. In this analysis, bi-linear elastic plastic theory in compressive, tension-softening model in tension and Mohr-Coulomb yield criterion are employed to represent properties of concrete. Referring to the results of high speed loading test and considering the increase of the yield stress, the analytical result of the load-deformation relationship is in good agreement with the test result. And this numerical simulation can mostly express the fracture behavior of concrete column, which is, scattering of fragments of broken concrete.. |
| 56. |
Collision between girders on shock absorbing rubber using air floating equipment. |
| 57. |
Experimental study on the residual strength of concrete filled tube damaged by rock collision. |
