The adequacy of using Fiber Reinforced Polymer (FRP) retrofit technique to restore the flexure-compression behavior of deteriorated bridge timber piles is examined experimentally in this paper. Sixteen specimens are t...The adequacy of using Fiber Reinforced Polymer (FRP) retrofit technique to restore the flexure-compression behavior of deteriorated bridge timber piles is examined experimentally in this paper. Sixteen specimens are tested monotonically under eccentric compressive loading. The specimens are first tested in their unretrofitted condition to determine their elastic properties. Each specimen is then cut and connected (posted) using the proposed FRP retrofit technique, and retested. The results show that the retrofitted specimens are capable of reaching same or higher strengths than that of the unretrofitted specimens with minimal reduction in their stiffness. Based on the experimental results, a design equation is presented to compute the volumetric ratio of FRP needed for retrofitting bridge timber piles under eccentric load.展开更多
In order to investigate the effect of piles on tooth restoration and their service life, micro-computed tomography （CT） was used to scan the first maxillary canines by establishing a three-dimensional finite element...In order to investigate the effect of piles on tooth restoration and their service life, micro-computed tomography （CT） was used to scan the first maxillary canines by establishing a three-dimensional finite element model for pile restoration. The stress distributions after tooth restoration with different pile materials were analyzed using a 100 N bite force. Then, the S-N fatigue characteristic curve of zirconia material was obtained using experimental data. The fe-safe fatigue analysis software was used to study the service life of zirconia piles in teeth. The static analysis results demonstrate that when fiber piles are used to repair, the stress from the dentin neck is larger than that by zirconia piles, but the stress from the apical of the dentin is smaller than that by zirconia piles. Besides, the stress exerted by fiber piles is lower than that by zirconia piles. Furthermore, the fatigue analysis results indicate that under normal conditions, zirconia piles can be used in teeth for over 20 years. Compared with fiber piles, zirconia piles have a better effect on the repair of tooth defects.展开更多
To explore the seismic performance of a high-rise pile cap foundation with riverbed scour, a finite element model for foundations is introduced in the OpenSees finite element framework. In the model, a fiber element i...To explore the seismic performance of a high-rise pile cap foundation with riverbed scour, a finite element model for foundations is introduced in the OpenSees finite element framework. In the model, a fiber element is used to simulate the pile shaft, a nonlinear p-y element is used to simulate the soil-pile interaction, and the p-factor method is used to reflect the group effects. A global and local scour model is proposed, in which two parameters, the scour depth of the same row of piles and the difference in the scour depth of the upstream pile and the downstream pile, are included to study the influence of scour on the foundation. Several elasto-plastic static pushover analyses are performed on this finite element model. The analysis results indicate that the seismic capacity （or supply） of the foundation is in the worst condition when the predicted deepest global scout depth is reached, and the capacity becomes larger when the local scour depth is below the predicted deepest global scout depth. Therefore, to evaluate the seismic capacity of a foundation, only the predicted deepest global scout depth should be considered. The method used in this paper can be also applied to foundations with other soil types.展开更多
文摘The adequacy of using Fiber Reinforced Polymer (FRP) retrofit technique to restore the flexure-compression behavior of deteriorated bridge timber piles is examined experimentally in this paper. Sixteen specimens are tested monotonically under eccentric compressive loading. The specimens are first tested in their unretrofitted condition to determine their elastic properties. Each specimen is then cut and connected (posted) using the proposed FRP retrofit technique, and retested. The results show that the retrofitted specimens are capable of reaching same or higher strengths than that of the unretrofitted specimens with minimal reduction in their stiffness. Based on the experimental results, a design equation is presented to compute the volumetric ratio of FRP needed for retrofitting bridge timber piles under eccentric load.
基金The National Numerical Control Equipment Major Projects(No.2013ZX09008011)
文摘In order to investigate the effect of piles on tooth restoration and their service life, micro-computed tomography （CT） was used to scan the first maxillary canines by establishing a three-dimensional finite element model for pile restoration. The stress distributions after tooth restoration with different pile materials were analyzed using a 100 N bite force. Then, the S-N fatigue characteristic curve of zirconia material was obtained using experimental data. The fe-safe fatigue analysis software was used to study the service life of zirconia piles in teeth. The static analysis results demonstrate that when fiber piles are used to repair, the stress from the dentin neck is larger than that by zirconia piles, but the stress from the apical of the dentin is smaller than that by zirconia piles. Besides, the stress exerted by fiber piles is lower than that by zirconia piles. Furthermore, the fatigue analysis results indicate that under normal conditions, zirconia piles can be used in teeth for over 20 years. Compared with fiber piles, zirconia piles have a better effect on the repair of tooth defects.
基金National Natural Science Foundation of China Under Grant No.50878147
文摘To explore the seismic performance of a high-rise pile cap foundation with riverbed scour, a finite element model for foundations is introduced in the OpenSees finite element framework. In the model, a fiber element is used to simulate the pile shaft, a nonlinear p-y element is used to simulate the soil-pile interaction, and the p-factor method is used to reflect the group effects. A global and local scour model is proposed, in which two parameters, the scour depth of the same row of piles and the difference in the scour depth of the upstream pile and the downstream pile, are included to study the influence of scour on the foundation. Several elasto-plastic static pushover analyses are performed on this finite element model. The analysis results indicate that the seismic capacity （or supply） of the foundation is in the worst condition when the predicted deepest global scout depth is reached, and the capacity becomes larger when the local scour depth is below the predicted deepest global scout depth. Therefore, to evaluate the seismic capacity of a foundation, only the predicted deepest global scout depth should be considered. The method used in this paper can be also applied to foundations with other soil types.
