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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. Source


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. Source


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. Source


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. Source


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. Source

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