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Wang C.,Dalian Maritime University | Wang C.,Key Laboratory of Highway Engineering of Liaoning Province | Guo N.-S.,Dalian Maritime University | Guo N.-S.,Key Laboratory of Highway Engineering of Liaoning Province | And 3 more authors.
Dalian Haishi Daxue Xuebao/Journal of Dalian Maritime University | Year: 2014

To analyze the effect of homogeneous model and heterogeneous model on the results of numerical simulation and the choice of optimum test section in creep test under two-dimension numerical condition, X-ray computed technique and digital image processing technique were performed and the Burgers model was adopted to characterize the viscoelasticity of asphalt mortar and asphalt mixtures, and furthermore numerical model was established based on finite element method to study creep behaviors for homogeneous model and heterogeneous model and analyze the location of the optimum test section through choosing three sections along the height direction of the specimen. Results show that creep deformation curves of numerical test of heterogeneous model was close to laboratory test, and the variety of creep deformation curves of numerical experiment for different sections along the height direction of the specimen is almost consistent. Moreover, heterogeneous model displays the distribution of complicated stress of every component in the specimen. Therefore, heterogeneous model can simulate the laboratory creep test more accurately, and every test section of it can be chosen arbitrarily to be the optimum test section.


Shi Y.,Dalian Maritime University | Shi Y.,Key Laboratory of Highway Engineering of Liaoning Province | Wang D.-S.,Dalian Maritime University | Wang D.-S.,Key Laboratory of Highway Engineering of Liaoning Province | And 3 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2014

According to the damage characteristics of skew bridges during earthquakes and the stiffness and strength of rubber bearings changing with low temperature environment, the seismic behavior of a skew bridge isolated with lead rubber bearings (LRBs) was studied. 3-D nonlinear dynamic models of the bridge with various skew angles, considering the pounding between girder and abutment with the Hertz-damp impact model, were developed using the computational platform OpenSees. The distribution of pounding force on abutments with various skew angles was discussed. The seismic responses of two isolated bridges with bearing of different mechanical properties were compared with each other. By investigating the relationships between seismic responses of piers, skew angles, and various ambient temperatures, it is shown that the seismic pounding happens firstly at the obtuse corners of bridge deck due to the coupling of bidirectional translation and in-plane torsion motion of superstructure; and the in-plane rotation of skewed bridge deck is further increased by pounding response. The seismic response of isolated skew bridge is increased due to the change of mechanical properties of the LRBs by low temperature. If the effect of low temperatures is not considered, the shear and bending moment on piers will be underestimated by about 10%, 20% and 40% than in the case at nomal temperature while the isolated bridge stays at low temperatures of 0°C, -10°C and -30°C.


Shi Y.,Dalian Maritime University | Shi Y.,Key Laboratory of Highway Engineering of Liaoning Province | Wang J.,Communications Planning and Design Institute of Yunnan Province | Wang D.,Dalian Maritime University | And 4 more authors.
Journal of Earthquake Engineering and Engineering Vibration | Year: 2014

Based on the layout features of bridges in mountainous areas, 7 sets of continuous bridges were constructed, which were taken as examples. Fiber element models for bridges were built. Seismic damage to isolated bridges with rubber bearings(RBs) and with lead rubber bearings(LRBs) was evaluated by time history response analysis. Results show that the seismic damage to bridges with LRBs compared with RBs has a slight increase, such as drift ratio of piers, curvature ductility coefficient, maximum compressive strain of confined concrete, and the maximum tensile strain of reinforced steel bars; but bridges with LRBs can effectively control the relatively residual displacement between pier and beam, which is favorable to the repair and recovery of emergency traffic function after earthquakes.


Shi Y.,Dalian Maritime University | Shi Y.,Key Laboratory of Highway Engineering of Liaoning Province | Wang J.,Planning and Design Institute of Yunnan Province | Shen Y.,Planning and Design Institute of Yunnan Province | And 2 more authors.
World Information on Earthquake Engineering | Year: 2014

The mechanical properties of isolated bearing are continuously changed with the environmental and aging conditions. So the property modification factors, accounting for the effects of the temperature, aging, velocity, cumulative movement or travel, contamination and scragging, are proposed by some foreign scholars. According to the Guide Specification for Seismic Isolation Design compiled by AASHTO of USA and the latest research abroad, the concept, choice of value, and the background of theory and experiment of the property modification factors were introduced, for the purpose of providing references to Chinese bridge engineers and to the revision of chinese design code for seismic isolation.


Shi Y.,Dalian Maritime University | Shi Y.,Key Laboratory of Highway Engineering of Liaoning Province | Wang D.-S.,Dalian Maritime University | Wang D.-S.,Key Laboratory of Highway Engineering of Liaoning Province | And 2 more authors.
Bridge Construction | Year: 2014

To have an understanding of the seismic mitigation effect of the continuous girder bridge used with the combined seismic mitigation system of shock absorbers and cable restrainers subjected to the near-fault ground motion, a high-speed railway prestressed concrete continuous girder bridge with span arrangement (40+64+40) m was taken as an example, the structural analysis software SAP2000 was used to set up the dynamic elastic-plastic calculation model considering the pounding effect of the adjacent girders and the nonlinear time-history response analysis of the model was carried out by inputting the near-fault ground motion with velocity pulse characteristic and the ground motion without the characteristic. The results of the analysis demonstrate that under the near-fault ground motion with the velocity pulse effect, the utilization of the combined seismic mitigation system of the shock absorbers and cable restrainers can achieve good effect of the seismic mitigation and the seismic mitigation ratio can exceed 60%. The near-fault ground motion with the velocity pulse effect may cause the seismically mitigated and isolated bridge to have stronger seismic response and also may easily cause the adjacent girders to pound. The ignoring of the pounding effect will result in overestimation of the seismic mitigation effect.


Shi Y.,Dalian Maritime University | Shi Y.,Key Laboratory of Highway Engineering of Liaoning Province | Wang D.,Dalian Maritime University | Wang D.,Key Laboratory of Highway Engineering of Liaoning Province | And 2 more authors.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2014

Based on the design idea of "functional separation", a new seismic isolation system including steel energy absorbers and cable restrainers was proposed for high speed railway bridges. The steel energy absorbers reduced the seismic response of bridge through yield energy dissipation. The cable restrainers were effective in controlling the excessive deformation of steel energy absorbers and falling-off prevention. The design criteria and methods for steel energy absorbers and cable restrainers under frequent earthquake, design earthquake and rare earthquake were given respectively. Taking a continuous beam bridge for high speed railway as an example, three groups of ground motions with distinct characteristics such as forward rupture directivity, fling-step effect and without velocity pulse were selected as seismic excitation. The seismic performance of bridge with new seismic isolation system was investigated. Results indicate that the bridge isolated with steel energy absorbers alone is not safe due to the excessive deformation of steel energy absorbers under near-fault ground motions with velocity pulse. Cable restrainers can effectively control the deformation of steel energy absorbers and the relative displacement of piers and beams. The seismic performance of the bridge of the new isolation system with steel energy absorbers and cable restrainers is effectively improved, and the decreasing ratio of seismic response can exceed 60%.


Li X.-L.,Dalian Maritime University | Li X.-L.,Key Laboratory of Highway Engineering of Liaoning Province | Sun Z.-G.,Dalian Maritime University | Sun Z.-G.,Key Laboratory of Highway Engineering of Liaoning Province | And 4 more authors.
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2015

Taking the severely damaged Gaoyuan bridge in Wenchuan earthquake as background, the seismic longitudinal pounding effect among girder, abutment and backfilling, and the influence of pounding on the seismic behavior of the bridge were analyzed by using multi model-multi platform analysis method. Firstly, the nonlinear 3D finite element model for the abutment and backfilling in Gaoyuan bridge was developed by ANSYS software, and the lateral force-displacement relationship of the abutment under girder pounding was obtained by static pushover analysis. The force-displacement relationship of the abutment was introduced into MIDAS software to simulate pounding effect on the bridge based on gap element. Also, the seismic analysis model of Gaoyuan bridge was established. Longitudinal pounding effect between girder and abutment was studied by nonlinear time-history analysis considering the damages to abutment and backfilling, and installation of pounding bumper device at expansion joint. Also, the analysis results were compared with those of damage investigation during Wenchuan earthquake. The results show that the pounding damage to abutment and backfilling would increase the gap between girder and abutment, and bridge superstructure may be unseated. Also, the influence of bumper device on pounding force between girder and abutment is random as a result of different earthquake excitations and abutment locations. It is finally suggested that the stiffness of pounding bumper device should be taken as 1%~5% of the abutment and backfilling stiffness, and energy dissipation device would be preferentially selected in order to decrease pounding effect between girder and abutment. ©, 2015, Editorial Department of Journal of Chang'an University (Natural Science Edition). All right reserved.


Guo N.-S.,Dalian Maritime University | Guo N.-S.,Key Laboratory of Highway Engineering of Liaoning Province | Wang C.,Dalian Maritime University | Zhao Y.-H.,Dalian Maritime University
Dalian Haishi Daxue Xuebao/Journal of Dalian Maritime University | Year: 2013

To analyze dynamic behaviors of graded iron tailing, two gradations (continuity tightness and framework tightness) are chosen for gradation composition design based on the recommended range of graded gravel in China, and furthermore triaxial test is performed to obtain dynamic modulus of graded iron tailing. Results show that graded iron tailing represent nonlinear relationship between dynamic modulus and stress state, which has better consistency with graded gravel, and model can be used to express the relationship. Framework tightness is superior to continuity tightness according to stress characteristics of structure layer and dynamic modulus derived from the model, whereas dynamic modulus of two gradations of iron tailing can satisfy the design requirement.


Sun Z.,Dalian Maritime University | Sun Z.,Key Laboratory of Highway Engineering of Liaoning Province | Wang D.,Dalian Maritime University | Wang D.,Key Laboratory of Highway Engineering of Liaoning Province | And 3 more authors.
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2014

The objective of this research is to evaluate the effectiveness of the proposed technique to reduce the seismic damages to Reinforced Concrete (RC) bridge piers by using prestressing tendons. Six RC bridge piers with vertical unbonded prestressing tendons and one without tendon were designed and tested under constant axial load and reversed cyclic lateral loads. The seismic behavior of the piers were presented and compared with each other, with special attention to the seismic damages to the piers including concrete crack width and residual displacement. It is found that employing prestressing tendons in the bridge piers could result in obvious reductions of concrete crack width and residual displacement, and enhanced strength and lateral stiffness of the piers, but the energy dissipation capacity of the piers would be decreased. Avoiding tendon rupture or relaxation are the key measures for the seismic damage control design of the piers. Increasing the initial stress of the tendons would result in reduction of the concrete crack width, ductility and energy dissipation capacity of the piers, but has little influence on the residual displacement and stiffness degradation of the piers. And the seismic behavior of the piers, including the concrete crack width, residual displacement, ductility and energy dissipation capacity and stiffness degradation, would not be affected by the location of the prestressing tendons.


Wang D.,Dalian Maritime University | Wang D.,Key Laboratory of Highway Engineering of Liaoning Province | Li X.,Dalian Maritime University | Li X.,Key Laboratory of Highway Engineering of Liaoning Province | And 6 more authors.
Journal of Earthquake Engineering and Engineering Vibration | Year: 2013

The elastic and the elastoplastic response spectra of the near field records without pulse-like wave, near-field records with pulse-like wave and far field records with basin effects were studied by statistic analysis method u-sing digital ground motion records in Wenchuan earthquake. The strength reduction factor spectra with constant ductility(Ru), the displacement ratio spectra with constant ductility (Cu), and the displacement ratio spectra with constant strength reduction factor(C R) were included in the inelastic spectra of the Wenchuan earthquake records. By comparing with the response spectra of the PEER near field ground motions without pulse-like wave and the Chi-Chi ground motions with pulse-like wave on the same site, it can be drawn that the elastic response spectra of the Wenchuan near-field ground motions with pulse-like wave are obviously small in periods between 0.2 s and 0.8 s, and its elastoplastic spectra are almost the same with that of the Wenchuan near-field ground motions without pulselike wave in periods between 0.1s and 0.4 s, but the Rμ spectrum is bigger and the displacement ratio Cu and CR spectrum are smaller than that of the Chi-Chi ground motions. When the period is longer than 0. 6 ∼ 1. 0 s, all the inelastic spectra of the Wenchuan pulse-like wave ground motions are beginning to be equal to that of the Chi-Chi ground motions. The platform of the elastic response spectra of the Wenchuan far field ground motions with basin effects is wide and the values are increasing with the periods gently, and the characteristic period of the spectra can reach to exceed 1. 7s. The concept of elastic displacement response ratio spectra and elastoplastic displacement rati-o spectra between far-field ground motions with basin effects and near-field ground motions are proposed.

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