Applied Mechanics and Materials Vols. 501-504

Abstract: In order to solve the problem of the linear measurement of arch ring for the detection of bridge,a new method is presented that measures the arch ring using a reflectorless total station on the side of the arch bridge and the detail operations are given. Taking account of weakness of edge suveying using a reflectorless total station,some formulas on the 3d coordinates calculation of the above and down edge of the arch ring based on the arch ring points are deduced.According to the law of error propagation, the accuracy of the X and Z axial coordinates are analysed.It is helpful for calculating lateral and vertical deformation and biridges elevation map that the transformation from free-station coordianates to the birdge axis coordinate by programming using EXCEL software is achieved.The method is used for bridges arch ring axial measurement in Qingcheng town,Yuzhong county,Gansu province,and its deformation is consistent with the measured results of the dial indicator,which satisfies the requirement of bridge detecton accuracy.So it is showed that the method is a good way of linear measuring of bridges arch ring.

Abstract: Seismic response of the Shidian basin to moderate scenario earthquake is investigated considering 3D basin model incorporated with real topography by using the spectral-element method and parallel computing technique. The wave propagation process, the generation of surface wave, and the impact of soil deposits velocity to the basin-induced surface wave are studied in this paper. The results show that the amplification behavior of the basin is the interactions of basin geometry and low velocity soil deposits. First, locally small hollows in the basin are apt to trap seismic waves and produce much stronger ground motion, basin edge and areas with deep sediments are also characterized with large amplification. Then, basin with softer soil deposits produces stronger surface waves with lower propagation velocity and higher mode.

Abstract: Reinforced concrete rib arch bridge is widely used in southwest of china, therefore, it is practically significant to assess the seismic performance of this kind of bridge. In this paper, a deck-type double ribs arch bridge which has eleven large continuous spans is taken for instance. The finite element calculation models for the bridge are established considering arch effect. The M-method principle is used to simulate the pile-soil-structure interaction (PSSI), and multiple Ritz vector method is introduced to analyze the dynamic characteristics. Moreover, the seismic response of arch bridge is analyzed by the response spectrum method. Numeral results show that, the dominant vibration mode of the Multi-span continuous deck-type reinforced concrete rib arch bridge is out-of-plane mode, owing to the weak lateral stiffness. The arch effect can reinforce the longitudinal stiffness of bridge, but weaken the lateral stiffness. Combined with horizontal direction orthogonal seismic action, arch effect can significantly reduce the axial force of rib, while increase the moment and shear of the arch foot and the displacement of the arch. The rib arch, the 1/4 points and the junctions of ribs and beams are the seismic control points. PSSI is the key factor of bridge seismic.

Abstract: Seismic response of the Weihe basin generated by 5.12 Wenchuan earthquake is simulated by using the spectral-element method and parallel computing technique, considering 3D basin model incorporated with real topography. The wave propagation and the comparison of the synthetic and observed records are studied in detail in this paper. The result shows that appropriate source and detailed basin model and accurate numerical technique can simulate the wavefield and large basin ground motion well.

Abstract: The maximum intensity of Lushan earthquake in Sichuan Province is IX degree and the area of influence regions above VI degree is 18,682 square kilometers, which resulting in a large number of buildings destructed. Based on seismic field data collected from works of damage investigation, loss assessment and intensity survey in the first time, seismic damage phenomena and characteristics as well as damage photographs for different structural types of buildings are summarized and analyzed, and some suggestions are put forward to structure anti-seismic designs.

Abstract: Corrugated steel web continuous rigid frame bridge is a new form of bridge. Using the finite element analysis software Midas Civil to analyze dynamic characteristics of the corrugated steel web continuous rigid frame bridge in a method of subspace iron and the nonlinear dynamic time history analysis method is used to analyze the seismic performance of the bridge, then compared with the ordinary concrete web continuous rigid frame bridge. The results show that the natural frequency of the corrugated steel web continuous rigid frame bridge is smaller than that of the concrete web continuous rigid frame bridge, and the seismic performance of the corrugated steel web continuous rigid frame bridge is superior to that of concrete web continuous rigid frame bridge, the improvement of the seismic performance of piers is most significant.

Abstract: As a region with little or very low level background seismicity, the impoundment of the Three Gorges Reservoir in June 2003 was related to increasing reservoir-induced seismicity. Analysis of the spatial pattern of seismicity showed that a majority of the seismicity was associated with the heavily fractured, deep crustal Jiuwanxi Fault, especially in regions of permeable Carbonate rocks formations. Analysis of the temporal pattern of the seismicity and a comparison with the filling history of the reservoir showed that the frequency and intensity of induced seismicity started at low level accompanying the impoundment of the Three Gorges Reservoir, and then increased with the increasing of water level and decreased thereafter. The amplitude of fluctuation of water level was found to be related to the frequency and intensity of induced seismicity. The pore pressure diffusion plays an important role in reservoir induced seismicity.

Abstract: During the seismic damage investigation of Wenchuan earthquake, it is found that some of the entrance lining structures, such as that of the Longxi Tunnel, suffered significant pavement blowup, which can be attributed to the effect of Rayleigh wave. Unlike the conventional analysis under shear wave propagating upwards, numerical dynamic analysis under the effect of Rayleigh wave in time domain is much more complicated in practice. In this paper, a practical wave motion input method for three-dimensional Rayleigh wave propagation problems in time domain is proposed and consequently applied in a numerical model to analysis the dynamic response characteristics of tunnel entrance. Desirable simulation result and sufficient accuracy is accomplished with the proposed approach. The particular seismic damage of tunnel entrance that was observed in Longxi tunnel is reproduced successfully in the simulation.

Abstract: According to No.3 dam section of Dahuaqiao gravity dam, a three-dimensional finite element model is built by finite element software ANSYS. Mechanics of materials method, response spectrum method and time history analysis method are employed to analyze the strength of the dam section. Results show that the stress of dam toe, dam heel and downstream fold slope are relatively high and stress concentration emerges in those positions. The phenomenon indicates that these areas are vulnerable under the earthquake and precautions must be taken. But under the designed earthquake, the maximum stress of the dam section is below the allowable stress, representing the dam is in a safe state and the strength requirement is satisfied.

Abstract: With a 10 layer of concrete filled square steel tubular column beam frame structure as the object of study ,discrete structure into multiparticle system and establish a dynamic differential equation,solve this dynamic equation by Newmark -β method .Establish thefinite element model of the structure is based on Sap2000 ,then dynamic elastic-plastic time history analysis are carried out, the research results show that the dynamic characteristics of structure,s story drifts,story shear and acceleration with energy dissipating devices are smaller than the model without energy dissipating devices under different earthquake intensities. the damped effect is considered obvious.