Beijing Collaborative Innovation Center for Metropolitan Transportation

Beijing, China

Beijing Collaborative Innovation Center for Metropolitan Transportation

Beijing, China
SEARCH FILTERS
Time filter
Source Type

He H.,Beijing University of Technology | He H.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Wang W.,Beijing University of Technology | Xu H.,Beijing University of Technology
Shock and Vibration | Year: 2017

Due to the eccentric characteristics and the torsional excitation of multidimensional earthquakes, the dynamic response of asymmetry structure involves the translation-torsion coupling vibration and it is adverse to structural performance. Although the traditional tuned mass damper (TMD) is effective for decreasing the translational vibration when the structure is subjected to earthquake, its translation-torsion coupled damping capacity is still deficient. In order to simultaneously control the translational responses and the torsional angle of asymmetry structures, a new type of tuned mass damper with tuned mass blocks, orthogonal poles, and torsional pendulums (TMDPP) is proposed. The translation-torsion coupled vibration is tuned by the movement of the mass blocks and the torsional pendulums. According to the composition and the motion mechanism of the TMDPP, the dynamic equation for the total system considering eccentric torsion effect is established. The damping capacity of the TMDPP is verified by the time history analysis of an eccentric structure, and multidimensional earthquake excitations are considered. The damping effect of the traditional TMD and the TMDPP is compared, and the results show that the performance of TMDPP is superior to the traditional TMD. Moreover, the occasional amplitude amplification in TMD control does not appear in the TMDPP control. The main design parameters which affect the damping performance of TMDPP are analyzed. © 2017 Haoxiang He et al.


He H.,Beijing University of Technology | He H.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Xie X.,Beijing University of Technology | Wang W.,Beijing University of Technology
Shock and Vibration | Year: 2017

Tower structure is sensitive to hurricane and earthquake, and it is easy to generate large deflection and dynamic response. The multiple cardan gyroscope has two rotational degrees of freedom, which can generate strong moments to constrain the two horizontal orthogonal deflections if the rotor operates in high speeds, so the structural dynamic responses can be decreased. Hence, the method of dynamic control of the tower structure under wind load and earthquake action is proposed by using the multiple cardan gyroscopes as the dampers. The dynamic mechanism and the fixed axis principle of the multiple cardan gyroscope are introduced, and the dynamic equation of the gyroscope is established. The damping mechanism of the gyroscope is also described. For the tower structure equipped with the multiple cardan gyroscope dampers, the multidimensional control equation considering torsion effect is established, and the equivalent state space equation is presented. Taking a TV Tower with a number of gyroscope dampers as an analysis example, the structural dynamic responses and damping performance under fluctuating wind loads and earthquake action is studied. The results show that the multiple cardan gyroscope dampers with suitable parameters can effectively decrease the structural vibration in horizontal directions and torsional direction. © 2017 Haoxiang He et al.


Yang H.,Beijing University of Technology | Yan W.-M.,Beijing University of Technology | Yan W.-M.,Beijing Collaborative Innovation Center for Metropolitan Transportation | He H.-X.,Beijing University of Technology | He H.-X.,Beijing Collaborative Innovation Center for Metropolitan Transportation
Zhendong Gongcheng Xuebao/Journal of Vibration Engineering | Year: 2017

The traditional damping models generally include such models as the viscous damping, the coulomb damping, the complex damping and the stress damping. These models cannot sufficiently reveal the rule and phenomenon how the damp varies with the damage evolution. It is assumed that the damping energy dissipation of the reinforced concrete structures mainly consists of the viscous damping and the residual stress damping, and the residual stress damping includes the bond stress between the reinforcement and the concrete and the friction stress of the concrete cracks. On the basis of this assumption, a combined damping model based on the residual stress is proposed. The dynamic equation of the structure containing viscous and coulomb damping is established, and the formula of the damping ratio with the development of damage is derived. The damping change regulation of the reinforced concrete structures under different damage states is analyzed. It is found that the damping ratio of different damage degree is remarkably affected by the ratio of the residual stress and the stiffness, and diverseparameters of the combined damping model are available and has better adaptability. Finally, the change of damping with the damage of reinforced concrete simply-supported beam is tested by the static damage experiment, and the mechanism of the change of the damping ratio with different damage is analyzed combined with numerical simulation. The results show that the combined damping model has a definite mechanical mechanism, and the phenomenon that the damping ratio of the reinforced concrete beam originally increases and subsequently decreases with the damage degree is accurately revealed. © 2017, Nanjing Univ. of Aeronautics an Astronautics. All right reserved.


He H.,Beijing University of Technology | He H.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Chen K.,Beijing University of Technology | Wang X.,Beijing University of Technology | Wang X.,Beijing Collaborative Innovation Center for Metropolitan Transportation
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2017

The design for traditional steel rigid connection cannot fulfill the desired seismic requirements. Though beam-column connections with reduced beam end section can approximately realize the concept about 'strong column-weak beam', the local buckling in the weakened zone may be occur in strong earthquake and the capacity is not enough. The filled connection with low yield point steel is proposed base on the concept of earthquake resilient structure. In this connection, the weakened parts in the flange and web plate are filled with low yield point steel, and the low yield point steel firstly yields and dissipates energy sufficiently in earthquake. Hence, the damage of the main parts in the connection is minor and the low yield point steel can be replaced after the earthquake. According to the insufficiency of the existing seismic damage models, the damage model based on differential ratio of elasto-plastic dissipated energy is proposed. Low cycle loading experimental research was carried out on three types of connections which included traditional connection, beam end weakened connection and filled connection. Comprehensive assessments of damping performance are proposed through a variety of performance evaluation parameters. It is proved that the filled connection has excellent bearing capacity, ductility and energy dissipation capacity. In addition, the proposed energy damage index can represent damage evolution process and damage law. © 2017, Editorial Office of Journal of Building Structures. All right reserved.


Li Y.,Beijing University of Technology | Li Y.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Lin H.,Beijing University of Technology | Lin H.,Beijing Collaborative Innovation Center for Metropolitan Transportation | And 2 more authors.
Construction and Building Materials | Year: 2017

Fly ash (FA) is one of the common supplementary cementitious materials used in cement and concrete. Because of the complexity of morphology, component, hydration and other factors of FA, it is very difficult to measure the content of FA in hardened concrete. According to the characteristic of the unburned carbon in FA neither dissolving in concrete nor participating in the chemical reaction, three different kinds of FA were used to prepare FA-cement pastes with different volumes. Then selective dissolution method and thermal analysis were used to quantitatively analyze the content of FA in hardened paste. The results indicated that the differences of testing data were less than 1.5%, compared with the theoretical values by the method of selective dissolution combined with thermal analysis. Therefore, it is concluded that the method of selective dissolution combined with the thermal analysis can measure the content of FA in hardened FA-cement system more accurately. © 2017 Elsevier Ltd


Li P.,Beijing University of Technology | Li P.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Wang F.,Beijing University of Technology | Wang F.,Beijing Collaborative Innovation Center for Metropolitan Transportation
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2017

Based on the Pu's sliding failure model of rock mass around a deep single tunnel, an analytical model of rock pressure for deep-buried and non-symmetry closely-spaced tunnels was proposed by considering asymmetrical structure and the construction processes. Meanwhile, based on the deduced formula, the causes that affect the rock pressure such as buried depth, rock pillars thickness, excavation span and excavation height were discussed. Finally, the comparison analysis was made between monitoring data from practical tunnel engineering and theoretical values from the model. The results show that the calculated model and the theoretical method proposed are rational and practicable. The experience and conclusions can be referred to the analysis of the design of supporting structure and reasonable construction scheme of deep-buried and non-symmetry closely-spaced tunnel. © 2017, Editorial Department of Journal of Beijing University of Technology. All right reserved.


Zhou H.,Beijing University of Technology | Zhou H.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Wang Y.,Tsinghua University | Yang L.,Beijing University of Technology | Shi Y.,Tsinghua University
International Journal of Fatigue | Year: 2014

Abstract A general methodology for seismic low-cycle fatigue assessment of welded beam-to-column connection in steel moment resisting frames (SMRFs) is presented. Fatigue deformability curves of seven connection categories are elaborated using the available cyclic tests. Inter-storey drift history imposed on each connection of SMRF is generated by seismic dynamic analysis and adopted in fatigue damage calculation based on Palmgren-Miner's rule and the experimentally determined fatigue curve. The most critical connection identified by preliminary fatigue evaluation is refined with solid finite elements in global-local model where the cyclic void growth model is integrated to give a more accurate fatigue prediction including load sequence effects. The proposed approach is applicable to fatigue evaluation of welded connections in SMRFs under earthquakes.© 2014 Elsevier Ltd. All rights reserved.


He H.,Beijing University of Technology | Chen K.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Li R.,Beijing University of Technology
Advances in Materials Science and Engineering | Year: 2015

Compared with the traditional steel rigid connection, the beam-column connections with weakened beam end have better ductility, but the local buckling in the weakened zone and the overall lateral deformation may occur in strong earthquake. The replaceable steel connection with low yield point metal is proposed based on the concept of earthquake resilient structure. In this connection, the weakened parts in the flange slab and web plate are filled with low yield point metal, and the metal firstly yields and dissipates energy sufficiently in earthquake; hence, the main parts are intact and the yield point metal can be replaced. The seismic performances of the three types of connections which include traditional connection, beam end weakened connection, and replaceable connection with low yield point steel under low cycle reciprocating load are studied. In addition, the energy dissipation capacity and damage characteristics of different connections are compared. The multiscale finite element models for the steel frames with different connections are analyzed by time-history method; both the computational efficiency and the accuracy are assured. The analysis results approve that the replaceable connection can confine the major damage in the replacement material and have better energy dissipation ability, safety reserves, and resilient ability. © 2015 Haoxiang He et al.


Du X.,Beijing University of Technology | Du X.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Ma C.,Beijing University of Technology | Ma C.,Beijing Collaborative Innovation Center for Metropolitan Transportation | And 2 more authors.
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | Year: 2014

The failure of material can be concluded to the shear fracture and each material has a specific shear sliding surface. The shear strength is the function of normal stress on sliding surface. A series of shear sliding surface is unified and nonlinear unified strength model of geo-materials is proposed. Sliding surface of nonlinear unified strength model is isoclinic surface in β stress space. The Strength surface of nonlinear unified strength model is circular conical surface in the β stress space and a series of conical surfaces are continuous smooth and convex in principal stress space. The nonlinear unified strength model can be illustrated as a curve between the Drucker-Prager and SMP in deviatoric plane, and as a straight line in meridian plane. There are only three mechanical parameters in the model which have definite physical meanings. Compared with large numbers of data under true triaxial tests, the applicability of nonlinear unified strength model is verified to different materials. And the proposed model can describe the nonlinear strength property of various materials reasonably.


Xu C.-S.,Beijing University of Technology | Xu C.-S.,Beijing Collaborative Innovation Center for Metropolitan Transportation | Liu H.-Q.,Beijing University of Technology | Du X.-L.,Beijing University of Technology | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

A test method is developed to simulate the deformation and strength characteristics of soils in real sites. This test method reveals the mechanism of seismic liquefaction of saturated sand under confined condition. A dynamic true triaxial test system is applied. This device provides mixed boundary conditions for samples and installation of advanced CATS test control system. The test results show that use of the dynamic true triaxial apparatus for sand liquefaction test research is feasible. Moreover, the mechanism of soil liquefaction under confined condition is investigated. Namely, the liquefaction will be generated when the axial and lateral pressures as well as the pore water pressure are equal to each other. It indicates that in the process of vibration load, the stress redistribution has a significant influence on the strength of sand liquefaction and the development mode of pore water pressure.

Loading Beijing Collaborative Innovation Center for Metropolitan Transportation collaborators
Loading Beijing Collaborative Innovation Center for Metropolitan Transportation collaborators