Advanced Materials Research Vols. 255-260

Abstract: Subways have found wide application in many countries relying on their unique advantages. Urban subway stations usually have a dense crowd and a closed environment; therefore, once the terrorist blast attack occurs, people’s life and property security is seriously threatened. For the purpose of avoiding heavy damage (especially continuous collapse) of subway stations suffering from terrorist blast attack, numerical model of a subway station was established with the software LS-DYNA3D, and the internal explosion was analyzed and studied; subsequently, influential effect of blast shock wave on the subway station was obtained. The research results can provide basis for emergency countermeasures establishment of the subway structure coping with terrorist blast attack.

Abstract: Vibration sources, which caused the vibration of a shear-wall residential building, are inversed in this paper. In light of the test data, frequency-domain analysis is presented, and a finite element model is established. Furthermore, the time-domain acceleration responses of the structure are obtained. In compare with the British standard Vibration Dose Value (VDV) method, an Annoyance-Based Checking Procedure (ABCP) is proposed to evaluate the vibration of the building. The analysis indicates that both results agree reasonably well. A suggestion for structure engineers is proposed to consider the effect of environment vibration in the vicinity of the building.

Abstract: Firstly, synchronous field measurements were carried out for the road roughness of the left and right wheels to obtain the roughness profile using a high speed laser roadway testing vehicle. Secondly, programming idea of multi-girder vehicle-bridge coupled vibration analysis module was presented briefly. Finally, a three-axle heavy truck crossing a rigid-frame arch bridge was taken as an example, detailed comparing and analyzing was carried out for the influence on the dynamic responses and spectrum characteristics of the vehicle-bridge system from three excitation cases which include using measured road roughness corresponding respectively to left and right wheels, using measured road roughness of left wheels and right wheels simultaneously. The analysis shows that when the differences in road roughness between left and right wheels are significant, the responses computed with inconsistent excitation is smaller than that with both of the latter two excitation cases, and there are some differences between the vertical contact forces of wheels and the spectrum characteristics of the vehicle-bridge system.

Abstract: An arch-truss roof structure with circular steel tube is applied to a gymnasium, which is supported by two three-dimensional trusses with square steel tubular, and the connections between arch-truss and spatial truss are set to hinged supports. Natural frequency and modes of this overall roof structure are analyzed, and time-procedure analysis is acted by applying ANSYS software. The analysis results demonstrate that this roof structure has larger stiffness, and its maximum node displacement under earthquake can meet the requirements.

Abstract: In this paper, the finite element program LS-DYNA was used to simulate the dynamic response of RC column with different constraints subjected to blast pressure. Through analyzing the five group columns with fixed end as well as one end fixed and one end simply supported, the maximum middle displacement and its relation with T/Tω were obtained. Thereby the dynamic factor of the column under blast pressure was acquired. Consequently the displacement response spectrum curve of the column was drawn. The results provide reference value to the design and protection of the RC column.

Abstract: Taking Yujiang River Bridge on Nanning-Guangzhou railway line as study background, the refined numerical simulation model of whole vehicle and whole bridge system for coupled vibration analysis is set up. The dynamic analysis model of the cable-stayed bridge is established by finite element method, and the natural vibration properties of the bridge are analyzed. The German ICE Electric Multiple Unit (EMU) train refined three-dimensional space vehicle model is set up by multi-system dynamics software SIMPACK, and the multiple non-linear properties are considered. The space vibration responses are calculated by co-simulation based on multi-body system dynamics and finite element method when the ICE EMU train passes the long span cable-stayed bridge at different speeds. In order to test if the bridge has the sufficient lateral or vertical rigidity and the operation stability is fine. The calculation results show: The operation safety can be guaranteed, and comfort index is “excellent”. The bridge has sufficient rigidity, and vibration is in good condition.

Abstract: As the floating type cable-stayed bridge has no longitudinal constraint between the main girder and the pylon, it may cause the main girder a large longitudinal displacement and the root of tower a large longitudinal bending moment, and affect the normal use and safety of the bridge under the earthquake or the train braking. It is an important part of the design to select an appropriate vibration control scheme. Taking a long-span railway bridge for example, this paper build the finite element model and analyses the damping effect in the view of train braking, moreover, the present study also examines the dynamic behavior with focus on two parameters of damping coefficient C and damping exponent αof the viscous dampers through dynamic time-history analysis. The results show that setting viscous dampers with the reasonable parameters can reduce the vibration and the response of the bridge by train braking and have a good energy dissipation effect.

Abstract: Based on the small deflection theory of elastic thin plate and the equivalence principle of deflection and stress, the concentrated vehicle load which acts on the CRCP is translated into the equivalent half-wave sine load by Fourier transform. On the basis of this transform, the deflection and stress formulas are put forward when CRCP is subjected to a concentrated vehicle load with hollow foundation. The following results are obtained from the analysis. The maximal deflection is proportional to the concentrated vehicle load and slab width, and inversely proportional to the lateral bending stiffness and slab thickness. The slab width and thickness have a significant influence on the maximal deflection. The maximal stress is proportional to the concentrated vehicle load and slab width as well as inversely proportional to the slab thickness. The influence of slab thickness is significant to the maximal stress. In conclusion, increasing the slab thickness is the preferential choice to reduce the maximal deflection and stress.

Abstract: Vehicle-track-bridge dynamic interaction analysis is applied to compute local dynamic responses of a trough beam under urban rail transit train by mode superposition method. The modal acoustic transfer vectors (MATVs) are obtained by boundary element method. The bridge-borne noise at different field points is then computed based on the MATVs and Fourier spectra of the mode coordinate responses of the bridge. The numerical results show that the noise level is significantly affected by the train speed but hardly influenced by the fastening stiffness. The residents in the high-rise buildings near the bridge may be much affected by the bridge-borne noise.

Abstract: In order to observe the three-phase boundary (TPB) variation of the porous gas electrode, a new laying style of the porous gas electrode was proposed. Two electrodes with different ingredient were taken in the experiment under the same condition to testify that there are three distinct stages of the TPB dynamic variation.Each stage has its own apparent phenomenon and the variation time of each stage is different for each electrode. The relationship between the electric conductance and the TPB variation of the electrode were also analyzed by the theoretical calculating formula. The result showed that the internal resistance increases as the decrease of the electric conductance created by the TPB variation. The research above illustrated this laying style of the porous gas electrode can be effectively used to observe the TPB dynamic variation.