The Experts below are selected from a list of 87162 Experts worldwide ranked by ideXlab platform
Yuichi Sato - One of the best experts on this subject based on the ideXlab platform.
-
development of a simplified bond stress Slip Model for bonded frp concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
-
Development of a simplified bond stress–Slip Model for bonded FRP–concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
Stijn Matthys - One of the best experts on this subject based on the ideXlab platform.
-
development of a simplified bond stress Slip Model for bonded frp concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
-
Development of a simplified bond stress–Slip Model for bonded FRP–concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
Aniello Palmieri - One of the best experts on this subject based on the ideXlab platform.
-
development of a simplified bond stress Slip Model for bonded frp concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
-
Development of a simplified bond stress–Slip Model for bonded FRP–concrete interfaces
Construction and Building Materials, 2014Co-Authors: Stijn Matthys, Aniello Palmieri, Yuichi SatoAbstract:Abstract An important need in assessing the performance of externally bonded fiber reinforced polymer reinforcement (FRP EBR) for RC structures is to have a constitutive Model for the bond stress–Slip behavior. Various bond stress–Slip Models have been proposed and their effectiveness has been verified based on experimental and analytical data. Nevertheless, the Models show significant variations and degrees of complexity. In this paper, bond interface Modelling of EBR is explored and experimentally supported by double bond testing on 18 test specimens as part of an international Round Robin Testing (iRRT), to investigate the bond mechanisms between FRP reinforcement and concrete. Investigation of the database of Models proposed by researchers in literature, shows that often reference is made to the so-called bilinear bond stress–Slip Model for externally bonded reinforcement. This Model is based on three parameters: maximum bond stress, Slip at maximum bond stress, and maximum Slip. Applicable to this bilinear bond stress–Slip Model, simplified engineering equations are proposed to define the bond behavior, considering the effect of concrete strength and FRP stiffness on the three parameters identified. The simplified Model has been verified against a database of experimental results, showing good correlation (with a coefficient of determination of more than 0.9). It is expected that the Model will provide engineers with a basic design guideline to design safe EBR systems, and be a simple Model for designing FRP strengthening applications.
David E. Orin - One of the best experts on this subject based on the ideXlab platform.
-
terrain blind humanoid walking based on a 3 d actuated dual Slip Model
International Conference on Robotics and Automation, 2016Co-Authors: Yiping Liu, Patrick M. Wensing, James P. Schmiedeler, David E. OrinAbstract:While a number of controllers exist for dynamic humanoid walking over known uneven terrain, the ability to negotiate moderate changes in ground height without environment perception is still lacking. Such capability would mitigate problems caused by inaccurate sensing and reduce online terrain-dependent computational requirements. This letter proposes a 1-step terrain adaptation strategy for humanoid walking based on the 3-D actuated Dual-Slip Model. A flexible gait to negotiate unknown terrain is synthesized from a series of consistent gait adaptations acquired from off -line optimization with this simple Model. Being open-loop prior to touchdown, the strategy requires no perception of the terrain. Also, the resultant terrain-robust swing foot trajectory exhibits human-like characteristics such as leg retraction and extension near the end of the swing phase. Through a task-space control framework, the Model-derived gait is embedded into the high-DoF ATLAS humanoid Model. In the final result, a “blindfolded” ATLAS Model reliably walks over randomly generated uneven terrain (with per-step height changes of up to 5% of the leg length) at a constant midstance speed.
-
trajectory generation for dynamic walking in a humanoid over uneven terrain using a 3d actuated dual Slip Model
Intelligent Robots and Systems, 2015Co-Authors: Yiping Liu, Patrick M. Wensing, David E. Orin, Yuan F. ZhengAbstract:The Dual-Slip Model has been proposed as a walking template that inherently encodes a rich set of human-like features. Previous work has used the 3D Dual-Slip with bio-inspired leg actuation to generate a human-like dynamic walking gait over a wide range of speeds. The work presented in this paper extends the 3D Dual-Slip walking strategy to uneven terrain. With nonlinear optimization based on a multiple-shooting formulation, actuated Dual-Slip walking gaits over uneven terrain are identified that handle 1-step elevation changes up to ±10 cm. Moreover, this Dual-Slip actuation strategy enables a constant center of mass (CoM) forward speed at leg midstance to be maintained. The resultant gaits have revealed a leg lengthening/shortening strategy that is similar to that adopted by a human when walking over prepared, uneven terrain. Results demonstrate that the CoM trajectories and ground reaction force patterns found with the approach are comparable to the human data found in the biomechanics literature. The trajectories generated by the Dual-Slip Model are also demonstrated to orchestrate a dynamic walking motion with an anthropomorphic humanoid Model in simulation over uneven terrain.
-
Dynamic walking in a humanoid robot based on a 3D Actuated Dual-Slip Model
2015 IEEE International Conference on Robotics and Automation (ICRA), 2015Co-Authors: Patrick M. Wensing, David E. Orin, Yuan F. ZhengAbstract:This paper presents a method for the generation of dynamic walking gaits with a 3D Dual-Slip Model and its application to a simulated Hubo+ based humanoid. Previous approaches with the Dual-Slip Model have only focused on the planar case, wherein self-stable gaits can be found. When extended to 3D here, this Model has not been found to exhibit self-stable gaits, requiring new methods for gait optimization and control. By taking advantage of a newly discovered symmetry condition for the Dual-Slip Model, this work proposes a quarter period (half step) optimization process to find periodic walking gaits in 3D. An LQR controller is developed to regulate the state of the Model at leg midstance (MS) based on its return map dynamics. The Dual-Slip Model is extended by introducing a bio-inspired leg length actuation scheme in order to describe high-speed walking gaits (up to 2 m/s for human-compatible parameters). Finally, the CoM trajectory and footstep positions from the 3D Dual-Slip are used as a reference in a task-space controller with a Hubo+ based humanoid Model. By tracking these references, the methods successfully produce human-like dynamic walking gaits in simulation which are robust to disturbances. The whole-body control system for walking can handle uneven terrain with variation up to 10% of its leg length. This represents the first humanoid dynamic walking approach based on a 3D Dual-Slip Model.
-
ICRA - Dynamic walking in a humanoid robot based on a 3D Actuated Dual-Slip Model
2015 IEEE International Conference on Robotics and Automation (ICRA), 2015Co-Authors: Yiping Liu, Patrick M. Wensing, David E. Orin, Yuan F. ZhengAbstract:This paper presents a method for the generation of dynamic walking gaits with a 3D Dual-Slip Model and its application to a simulated Hubo+ based humanoid. Previous approaches with the Dual-Slip Model have only focused on the planar case, wherein self-stable gaits can be found. When extended to 3D here, this Model has not been found to exhibit self-stable gaits, requiring new methods for gait optimization and control. By taking advantage of a newly discovered symmetry condition for the Dual-Slip Model, this work proposes a quarter period (half step) optimization process to find periodic walking gaits in 3D. An LQR controller is developed to regulate the state of the Model at leg midstance (MS) based on its return map dynamics. The Dual-Slip Model is extended by introducing a bio-inspired leg length actuation scheme in order to describe high-speed walking gaits (up to 2 m/s for human-compatible parameters). Finally, the CoM trajectory and footstep positions from the 3D Dual-Slip are used as a reference in a task-space controller with a Hubo+ based humanoid Model. By tracking these references, the methods successfully produce human-like dynamic walking gaits in simulation which are robust to disturbances. The whole-body control system for walking can handle uneven terrain with variation up to 10% of its leg length. This represents the first humanoid dynamic walking approach based on a 3D Dual-Slip Model.
-
high speed humanoid running through control with a 3d Slip Model
Intelligent Robots and Systems, 2013Co-Authors: Patrick M. Wensing, David E. OrinAbstract:This paper presents new methods to control highspeed running in a simulated humanoid robot at speeds of up to 6.5 m/s. We present methods to generate compliant target CoM dynamics through the use of a 3D spring-loaded inverted pendulum (Slip) template Model. A nonlinear least-squares optimizer is used to find periodic trajectories of the 3D-Slip offline, while a local deadbeat Slip controller provides reference CoM dynamics online at real-time rates to correct for tracking errors and disturbances. The local deadbeat controller employs common foot placement strategies that are automatically generated by a local analysis of the 3D-Slip apex return map. A task-space controller is then applied online to select whole-body joint torques which embed these target dynamics into the humanoid. Despite the body of work on the 2D and 3D-Slip Models, to the best of the authors' knowledge, this is the first time that a Slip Model has been embedded into a whole-body humanoid Model. When running at 3.5 m/s, the controller is shown to reject lateral disturbances of 40 N·s applied at the waist. A final demonstration shows the capability of the controller to stabilize running at 6.5 m/s, which is comparable with the speed of an Olympian in the 5000 meter run.
Jinguang Teng - One of the best experts on this subject based on the ideXlab platform.
-
bond Slip Model for cfrp strips near surface mounted to concrete
Engineering Structures, 2013Co-Authors: Shi Shun Zhang, Jinguang TengAbstract:Abstract A relatively recent method for the strengthening of concrete structures involves the embedding of fiber reinforced polymer (FRP) bars/strips into pre-cut, adhesive-filled grooves in the cover concrete. This paper presents a finite element (FE) study into the bond behavior of NSM CFRP strip-to-concrete bonded joints using a three-dimensional (3-D) meso-scale FE Model developed by the authors. The effects of various parameters on the bond behavior of NSM CFRP strips are first clarified with the assistance of FE results, leading to the identification of the groove height-to-width ratio and the concrete strength as the two important parameters for the bond behavior. Based on the results of a FE parametric study on the effects of these two parameters, an analytical bond–Slip Model is proposed.
-
Bond-Slip Model for FRP Laminates Externally Bonded to Concrete at Elevated Temperature
Journal of Composites for Construction, 2013Co-Authors: Jian-guo Dai, Wan-yang Gao, Jinguang TengAbstract:AbstractThis paper presents a nonlinear local bond-Slip Model for fiber reinforced polymer (FRP) laminates externally bonded to concrete at elevated temperature for future use in the theoretical Modeling of fire resistance of FRP-strengthened concrete structures. The Model is an extension of an existing two-parameter bond-Slip Model for FRP-to-concrete interfaces at ambient temperature. The two key parameters employed in the proposed bond-Slip Model, the interfacial fracture energy, Gf, and the interfacial brittleness index, B, were determined using existing shear test data of FRP-to-concrete bonded joints at elevated temperature. In the interpretation of test data, the influences of temperature-induced thermal stress and temperature-induced bond degradation are properly accounted for. As may be expected, the interfacial fracture energy, Gf, is found to be almost constant initially and then starts to decrease when the temperature approaches the glass transition temperature of the bonding adhesive; the int...
-
Bond-Slip Model for FRP-to-concrete interface
Journal of Building Structures, 2005Co-Authors: Jinguang Teng, Jiangbo ZhuangAbstract:The local fiber reinforced polymer (FRP)-to-concrete bond-Slip Model is the fundamental relationship to analyse the behavior of FRP-strengthened RC structures. Due to the peculiarity of the load-bearing mechanism of FRP-to-concrete interface, it is hard to acquire their bond-Slip relationship directly from test, so the existing bond-Slip constitutive Models have more or less unsolved problems. In this paper, a group of new Models and the formulas for calculating the debonding strength of interface are presented based on the predictions of a meso-scale finite element Model. These Models are named as Precise Model, Simplified Model and Bilinear Model respectively according to different levels of sophistication. Among them, the Precise Model can consider different stiffnesses of adhesive layer, while Simplified Model and Bilinear Model are suitable for normal adhesive layer. Through comparisons with the large test database, the suggested bond-Slip Models are shown to provide more accurate predictions of both the debonding strength and the strain distribution in the FRP sheet than the existing Models.
