||Hiroki Tamai, Chi Lu, Yoshimi Sonoda, An Experimental Study on the Impact Resistance of RC Members with Reinforcement Corrosion, Proceedings of 6th Annual International Conference on Architecture and Civil Engineering, 10.5176/2301-394X_ACE18.128, 336-340, 2018.05.
||Yoshimi Sonoda, Mari Okamura, Hiroki Tamai, A Fundamental Study on Hammering Sound Test of Deteriorated Concrete Structures, Proceedings of 6th Annual International Conference on Architecture and Civil Engineering, 10.5176/2301-394X_ACE18.118, 89-94, 2018.05.
||Chi Lu, Hiroki Tamai, Yoshimi Sonoda, A Numerical Study on the Impact Resistant Capacity of RC Beams with Corroded Reinforcement, Procedia Engineering, https://doi.org/10.1016/j.proeng.2017.11.086, 341-348, Volume 210, 2017, Pages 341-348, 2017.12, To evaluate the remaining service life and determine the appropriate timing and method for repair and reinforcement for the reinforced concrete (RC) structures, it is important to quantitatively evaluate the residual load capacity of RC structures deteriorated by rebar corrosion due to chloride attack or neutralization. There have been many studies on the load capacity during static loadings. However, for disaster-prone areas, the evaluation of the residual load should be conducted also against the dynamic and impact loads. In this study, to clarify the impact resistance of the RC beam members with rebar corrosion, a falling weight impact experiment is conducted on the RC beam specimen with accelerated deterioration. Based on the experimental results, the relationship between the degree of deterioration and impact resistance is clarified. To numerically simulate the rebar corrosion by FEM, FE modelling of RC beam with corroded rebar is proposed focusing on the following 3 factors related to the mass loss ratio of the rebar: the reduction of the cross-sectional area of the reinforcement is reproduced by adjusting the parameters of the rebar material; an interface element is defined to describe the reduction of the bond strength; the cracks are generated by subjecting expansion pressure to the concrete. Uneven corrosion model is introduced to simulate the actual corrosion result. By comparing the analytical result with the experimental result, it can be found that the experimental result is accurately reproduced..
||Hiroki Tamai, Yoshimi Sonoda, A Study on Impact Resistant Capacity of RC Slab with Corroded Reinforcement and its retrofitting method, Proceedings of 6th International Conference on Design and Analysis of Protective Structures, 559-564, 2017.11, The reinforcement corrosion of RC structures due to chloride attack or neutralization is a serious problem to shorten the service life of them. In order to properly maintain and manage the RC structure with corroded reinforcement, it is necessary to clarify the relationship between the degree of deterioration and the remaining loading capacity. However the existing studies mainly focused on the evaluation of the load bearing capacity of RC beams subjected to static load, and there are few studies on the impact loads involved in natural disasters. Considering the fact that the large-scale natural disasters happened more frequently in recent years, it is important to quantitatively evaluate the impact behavior and resistance of the RC structures with corroded reinforcement for disaster-prone countries like Japan. In this study, to clarify the impact resistance of the RC slabs with corroded reinforcement under medium velocity impact by a rigid projectile, a horizontal impact test was conducted on the RC slab specimen with corroded reinforcement made by electrolytic corrosion method. In a series of impact tests, an air-acceleration type horizontal impact test machine like a launcher was used, and a flat nose projectile of a mass of 3kg and a RC slab with 600 mm x 600 mm in length and width, 80 mm in depth were used. Impact velocity was set to 15m/s. Through the impact tests, the difference of impact response and fracture pattern between the RC slabs without and with corroded reinforcement was clarified as a fundamental information. The relationship between the degree of corrosion and impact resistance of the slabs was also clarified. In addition, we tried to clarify the impact resistance improvement effect of RC slab retrofitted by continuous fiber composite panel (CFC panel) which has already been applied to repair and reinforcement such as renewal of tunnel lining and seismic reinforcement of pillar parts..
||Yang Sun, Hiroki Tamai, Yoshimi Sonoda and Hirotoshi Obi, Experimental study on impact resistance of corroded rc beams reinforced by CFC plate, Proceedings of the 12th International Conference on Shock & Impact Loads on Structures, 978-981-11-2850-9, 409-418, 2017.06, In recent years, as the aging of existing reinforced concrete (RC) structures is progressing, research on reinforcement and repair methods has become a concern. However, most of these researches mainly focus on the study of static behaviour for RC structures. Therefore, it is necessary to clarify the decrement of the impact resistance of the protective structure that is expected to be subjected to impact loads due to deterioration damage. It is important to provide an appropriate repairing and reinforcing method. From these backgrounds, in this research, we first attempted to corrode the rebar by electrolytic corrosion and to do the drop weight impact test to clarify the decrement of the impact resistance of the RC beam due to deterioration. Furthermore, by doing the same test, we tried to clarify the impact improvement effect of RC beam reinforced by continuous fiber composite panel (CFC panel) which has already been applied to repair and reinforcement such as renewal of tunnel lining and seismic reinforcement of pillar parts. As a result, we could get some findings. Firstly, reinforcement with CFC panel can greatly improve the
impact resistance of the RC beam by reinforcing the bottom surface or three surfaces of the RC beam, and it was confirmed that this tendency does not depend on the deterioration degree before reinforcement. Second, although the upper surface reinforcement does not exert much effects on the deformation of the RC beam, it was found that it is effective for preventing the compressive failure of the collision surface..
||Chi Lu, HIROKI TAMAI, YOSHIMI SONODA, A STUDY ON IMPACT COMPRESSIVE PROPERTIES OF CUSHION RUBBER FOR CABLE BRIDGE RESTRAINERS, 4th International Conference on Protective Structures, 476-485, 2016.10.
||Yoichi Yuki, HIROKI TAMAI, Hironori Ishii, YOSHIMI SONODA, Toshihiro Kasugai, Weight-drop tests of bridge restrainers under large weights, 11th German Japanese Bridge Symposium, 2016.08.
||HIROKI TAMAI, ISAO KUWAHARA, YOSHIMI SONODA, A STUDY ON THE EFFECT OF CORROSION RATE OF REINFORCING STEEL ON ITS EXPANSION PRESSURE AND LOAD BEARING CAPACITY OF RC BEAM, 41st Conference on OUR WORLD IN CONCRETE & STRUCTURES, 275-284, 2016.08.
||ISAO KUWAHARA, HIROKI TAMAI, YOSHIMI SONODA, Experimental Study on Impact Load Resistance of RC Beam with Corroded Reinforcement, MATEC Web of Conferences, 47, 02004-p1-02004-p7, 2016.04.
||Hariyadi, HIROKI TAMAI, Enhancing the performance of porous concrete by utilizing the pumice aggregate, Elsevier: Procedia Engineering, 125, 732-738, 2015.11.
||HIROKI TAMAI, ISAO KUWAHARA, YOSHIMI SONODA, An experimental study on static and impact load resistance of RC beam with corroded reinforcement, Proceedings of 40th Conference on OUR WORLD IN CONCRETE & STRUCTURES, 467-474, 2015.08.
||HIROKI TAMAI, YOSHIMI SONODA, Evaluation of cumulative damage of RC members under repeated impact loading, Applied Mechanics and Materials, 784, 500-507, 2015.07.
||HIROKI TAMAI, YOICHI YUKI, YOSHIMI SONODA, TOSHIHIRO KASUGAI, A study on shock absorbing properties of rubber pieces for bridge seismic restrainers, Proceedings of the Fifth International Workshop on Performance, Protection & Strengthening of Structures Under Extreme Loading (PROTECT 2015), 27-35, 2015.06.
||Kozo Onoue, HIROKI TAMAI, Hendro Suseno, Shock-absorbing capability of lightweight concrete utilizing volcanic pumice aggregate, Elsevier: Construction and Building Materials, 83, 261-274, 2015.05.
||HIROKI TAMAI, LU CHI, YOSHIMI SONODA, FUNDAMENTAL STUDY ON EVALUATION OF IMPACT LOAD OF COLLAPSED SOIL BY EXTENDED DISTINCT ELEMENT METHOD, Proceedings of 11th International Conference on Shock & Impact Loads on Structures, 27-35, 2015.05.
||YOSHIMI SONODA, HIROKI TAMAI, Damage evaluation of the existing PC bridge by vehicle collision using numerical analysis, Proceedings of the 3rd International Conference on Protective Structures ICPS3, 550-560, 2015.02.
||Shinobu Sano, HIROKI TAMAI, Yoshihiko Murata, YOSHIMI SONODA, Numerical study on a thermal crack control effect of concrete structures using delayed-setting mortar, Proceedings of 39th conference on Our World in Concrete & Structures, XXXⅢ, 425-434, 2014.08.
||HIROKI TAMAI, Mariko Uno, Yoichi Yuki, YOSHIMI SONODA, Toshihiro Kasugai, A Study on the Effectiveness of Energy Absorbing Rubber in Pin-Fixed Cable Restrainer of a Bridge, International Journal of Protective Structures, 5, 2, 219-237, 2014.06, The Japanese specifications for highway bridges require unseating
prevention devices to be installed on bridges as necessary. Recently, a
new type of cable restrainer was developed where the assembly allows
the cable to rotate without restriction on the brackets’ mounting angle.
Cylindrical rubber pieces are inserted around pins to absorb impact
forces. However, no standard design method has been established for
the shock absorbers so far. This paper presents the impact-resisting
characteristics of a pin-fixed cable device; design indications for shock
absorbers were acquired based on the results of impact tests on bracket
models of actual restrainers. The results showed that the pin-fixed
restrainers had sufficient impact resistance for all tested sizes and that
the maximum impact load showed consistent trends. Finite element
analysis was also performed on the device assuming hyper-elastic
bodies for rubber pieces. The numerical results sufficiently represented
the impact response trend obtained from the experimental results..
||Yoichi Yuki, HIROKI TAMAI, Naoki Wada, YOSHIMI SONODA, Toshihiro Kasugai, A Fundamental Study on the Shock Cushioning Characteristics of a Novel pin-Fixed Aseismatic Connector for Bridges, Applied Mechanics and Materials, 566, 637-642, 2014.06, This paper presents a novel pin-fixed aseismatic connector for bridges. A feature of this device is that the anchorage areas of both ends are connected with hinges; thus, there are no restrictions with respect to their mounting angles. Additionally, the PC cable of this device is given an appropriate amount of sag; thus, within the range of the sag the structure is capable of absorbing the amount of displacement because of temperature changes and live loads. In addition, this device has a certain shock-cushioning effect because of the rubber material surrounding the hinge pins. However, there is no quantitative evaluation method on the shock-cushioning effect of this device. Therefore, in this study, the shock-cushioning effect of the novel pin-fixed aseismatic connector for bridges is investigated using impact load tests and numerical analysis. It is found that the shock-cushioning effect of this device is almost equal to similar aseismatic connectors. Furthermore, it is also confirmed that their effects can be quantitatively evaluated using impact response analysis..
||Mariko Uno, HIROKI TAMAI, Yoichi Yuki, YOSHIMI SONODA, Toshihiro Kasugai, A study on the impact resistance of pin fixed cable restrainers for bridges, Proceedings of 10th International conference on Shock and Impact Loads on Structures, 471-480, 2013.11, The Japanese Specification for Highway Bridges requires the installation of unseating prevention device on bridges identified as necessary. Recently, a new type of cable restrainer was developed, whose assembly allows the cable to rotate and creates no restriction to their brackets’ mounting angle. Cylindrical rubbers are inserted around pins to absorb impact forces. However, no standard design method of the shock absorber has been established yet. This paper presents the study of the impact resisting characteristics of the pin-fixed cable device with a goal of developing the appropriate design method of the shock absorbing rubbers by conducting impact load tests on bracket models of the actual restrainers. As a result, it was observed that pin fixed restrainer has sufficient impact resistance and that there are some trends with maximum impact load. We have also conducted FE analyses on the device assuming the hyper-elastic behaviour of three-parameter Mooney-Rivlin model. The analyses could nearly demonstrate the impact response trend obtained from the conducted experiments..
||HIROKI TAMAI, Seongbong Cheon, Satoshi Goya, YOSHIMI SONODA, Case study of damage of PC bridge by vehicle collision and its numerical analysis, Proceedings of 10th International conference on Shock and Impact Loads on Structures, 451-460, 2013.11, Accidental collisions occur frequently between bridge superstructures and over-height vehicles passing under the bridges. In order to keep the damaged bridge in a serviceable state, it is important to conduct quantitative evaluation of its damage level and residual performance. In this study, we performed FE simulation of an actual collision accident between PC girder and container truck, and confirmed that the simulation reproduced the condition of damage from the actual incident such as cracks and deformation. In addition, we conducted the collision analyses assuming various collision cases and also static vertical loading analyses of PC girder received collision. The analyses elucidate the effect of collision speed, collision angle, gross vehicle weight on the damage of PC girder. Based on results of each analysis, the correlation of damage and residual performance is assessed..
||YOICHI YUKI, HIROKI TAMAI, NAOKI WADA, YOSHIMI SONODA, TOSHIHIRO KASUGAI, A fundamental study on the shock cushioning characteristic of a new pin fixed aseismatic connector for bridges, Proceedings of the 8th International Symposium on Impact Engineering, 2013.08.
||HIROKI TAMAI, YOSHIMI SONODA, A fundamental study on the impact resistance of damaged RC slab under single and repeated low-velocity impact, Proceedings of 4th International Workshop on Performance, Protection, and Strengthening of Structures under Extreme Loading-PROTECT2013, 2013.08.