Applied Mechanics and Materials Vols. 405-408

Abstract: This paper reports several issues on structural dynamics of aqueduct bridges. These issues include the modeling of sloshing water, dynamic characteristics of aqueduct bridges with fluid-structure interaction, seismic responses of aqueduct bridges, wind-induced buffeting responses of aqueduct bridges, equivalent wind load on aqueduct bridges. The results mentioned in this paper can be referred for the investigation and design of the wind and seismic resistance of the aqueduct bridges.

Abstract: The Eigen mode reduction method and active control and passive base isolation strategies are exerted on one continuous isolated prestressed concrete bridge. The goal of this study is to check the applicability of the eigen mode reduction method and LQR control law on the isolated continuous or rigid-connection type bridge, to find a more effective control strategy when nonlinearity is introduced. A spaced frame finite-element model is developed by a MATLAB program coded by the author, its validity is checked through comparisons with a sap2000 model. In this program, the nonlinearities of 3 different columns and 5 isolators are considered with their bilinear force-deformation relationship. the factors such as the control devices, sensors, and the corresponding noises and time delay are all considered in the model. Eigen mode reduction method was applied to set up the controllers. The seismic response measurements and regulated outputs are adjusted to optimize control effects.

Abstract: Through analysis and comparison of some nonlinear seismic response analysis models for structures of bridges with pile foundation, considering the effect of deformation performance of pile foundation whose nonlinear properties of foundation and the component are taken into account, this paper presents an improved model relatively. In order to verify the rationality of the improved model proposed in this paper, the calculation and analyses of the test model of a single pier with pile foundation through pushover are done, and the results are compared with the experiment results.The pile foundation does not damaged under seismic load; The improved model can reflect material nonlinearity of the actual soil contact between soil and pile, and the dispersed spring model can be better to simulate the postural nonlinear of pile-soil contact and separation; at the same time, we need to consider vertical friction spring in the pile side.

Abstract: China is a seismic country, which not only has its own features of high intensity and frequency but also has a wide range of distribution .The bridge, as the transportation hub engineering of lifeline,will endanger people's safety of life and cause huge economic losses ,and meanwhile hinder the relief and reconstruction in disaster area once damaged in the earthquake. Based on the documents of bridge seismic reinforcement methods from home and abroad, a preliminary research and analysis are conducted and the basic structure of the form and corresponding seismic reinforcement methods of the current city bridge are summarized, moreover, the preliminary induction and analysis are also carried on.The study will have important significance to existing bridge seismic reinforcement methods , as well to the reasonable seismic design and seismic construction measures of the newly built bridge.

Abstract: In order to simplify the analysis and calculation of multi-span simply supported girder bridge, the seismic frequency response function equation of longitudinal vibration for single-span simply supported girder bridge is established, based on the Fourier transform of the motion equations of multi-degree-of-freedom system. The calculation method of the seismic frequency response for the vertical moment and displacement of multi-span simply supported beam bridge is proposed according to the transfer matrix principle. Taking a bridge of Qinghai-Tibet Railway as an example, the maximum displacement and moment are solved. The result shows that: the displacement of the control section of the side spans is smaller than that of the middle of the bridge, while the moment is opposite. The corresponding Fourier amplitude spectrums under the pulse loads are given finally.

Abstract: LRB energy dissipation wall is a type of energy dissipation device for building structures. According to the results of an quasi-static test, structure with LRB energy dissipation wall shows a stronger energy dissipation capacity and a better seismic performance than the normal frame-shear wall structure. This paper also introduces the applications technology of LRB energy dissipation wall in High-level framework structure. According to the dynamic property analysis of a three-dimensional finite element model which was built by the finite element analysis software ETABS, LRB energy dissipation wall can effectively prolong the natural vibration period of high-rise frame structure and significantly reduce the maximum acceleration, shearing force and horizontal displacement in different floors to make the variation more smooth which is important the to the energy dissipation and earthquake mitigation.

Abstract: The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.

Abstract: Taking the typical reinforced concrete stiffening truss suspension bridge as example, finite element analysis model under seismic action is established. Dynamic response analysis is done on this suspension bridge using finite element software ANSYS and contrast is done between this analysis result and structural response under gravity load effect. Contrast result shows that structural response under seismic action is obviously higher than that under gravity load effect in which internal force response is greater than displacement. The function of dynamic load should be taken into account in the design of bridge structure in order to provide reference for the structural design of long-span flexible bridge.

Abstract: Aiming at the uncertainty of design spectrum raised by the construction methods, a comparative study is conducted in which different methodologies performed calculations of seismic response spectra using the same set of ground motion data from recent large earthquakes. The results of the research allowed some estimates to be made of the scaling method and model uncertainty involved in these calculations. These results were compared with the uncertainty derived from the proposed spectrum of a double-parameter-based bi-normalized response spectrum (DPBNS) approach. It is concluded that the sources of uncertainty that the results reflected are mainly impacted by the spectral type, scaling parameters, as well as imposed fixed conditions adopted in the calculations, for the scaling of the design spectra. Then, a discussion is provided on the limitations of these predications, in particular, of the approaches adopted in the construction of seismic spectra.

Abstract: It is very important to develop reinforced block masonry structure system with a good anti-seismic performance and convenient construction. This paper mainly researched the displacement response of the reinforced masonry structure under earthquake. The maximum storey drift and displacement of the structure are calculated in Y direction by numerical analysis method.