Advanced Materials Research Vols. 163-167

Abstract: The nonlinear dynamic response analysis of substation with structure-equipments interaction is studied in this paper. The results comparing with that of no interaction are shown that it’s necessary to considering structure-equipments interaction in substations. In frequent earthquakes, the structure-equipments interaction in substation is inconspicuous and the traditional equivalent load method is feasible. However, in strong earthquakes, the electric equipments really participate in the dynamic response and operate the reaction on main structure and the action goes against the main structure seismic design and couldn’t be ignored. In this condition, the traditional equivalent load method will be insecure any more. Because of the visible torsional response effect, the seismic ability of the corner columns in structure should be increased. The research results can be referenced by similar lifeline system.

Abstract: Based on isolation theory, time-history analysis on isolation system with limiting displacement protective devices was studied by Fortran program. Isolation effect of non-isolated structure, isolated structure and limit isolated structure were analyzed. Adhesion phenomenon of algorithm is solved by subdividing time steps during program analysis. And it gets good effect. According to comparing with isolation effect of different isolated structure, the result that isolation effect of isolated structure and limit isolated structure is obvious is reward; and limit isolated structure can isolation and prevent large displacement of isolation layers to avoid structure failure under rare earthquake condition. So limit isolated structure plays a double protection for structure.

Abstract: In this paper, first order reliability method (FORM) is generalized to the seismic reliability analysis of long-span bridges and the first excursion probability of a single tower cable-stayed bridge is studied. The seismic motivation is firstly dispersed as a series of random variables. Then the cross velocities on the dispersed time points can be obtained by solving the motivation of the design checking points with FORM. The upper bound of first excursion probability is also obtained by integrating the cross velocities at different time. The results show that the seismic reliability analysis method based on the FORM is feasible and effective to solve the first excursion probability problem. The single tower cable-stayed bridge studied in this paper has a higher reliability under strong seismic.

Abstract: The wave function expansion method is used to analyze the interaction process of the blasting seismic wave and the adjacent circular tunnel with steel lining, the stress expression, displacement expression and vibration velocity expression of circular tunnel under the action of blasting vibration are deduced, the stress, displacement and vibration velocity distribution of surrounding rock mass and steel lining are presented under the definite condition. In terms of the stress and vibration velocity distribution and the tensile strength of the rock mass, the critical failure vibration velocity of surrounding rock mass is obtained.

Abstract: Dynamic characteristics and seismic response for unequal height double-tower structure models were analyzed by finite element software. The effort of the connecting beam location changes to the structural vibration period, the maximum displacement on top and the maximum shear force at bottom were analyzed and compared. The results indicate that horizontal displacement under the seismic waves in x direction is larger than the displacement under seismic waves in y direction. When the locations of the connecting body vary, the influence to structural vibration period is different as vibration modes change. The effort to the maximum shear force of the structure at bottom under the seismic waves in x direction is larger than the displacement in y direction. The above results provide references for design and further studying.

Abstract: Using the parameter identification method of analysis on the test records of soil acceleration and pore water pressure from the shaking table tests for dynamic liquefiable soil-pile-structure interaction system, the dynamic properties of soil are obtained. Based on the recognized soil parameters, numerical simulation of liquefiable soil-pile-structure interaction test has been carried out. The results of the comparision of acceleration response and pore water pressure obtained from numerical simulation and tests show that the rule drawn from the numerical simulation is agreed well with those from the tests, though there are some disparities in quantity. So the reliability of parameter identification and numerical simulation technology in shaking table tests is validated. The result in this dissertation can be referred for future similar research.

Abstract: In order to forecast the vibration affecting the nearby buildings, the analysis methods that the adjacent buildings are influenced due to the construction vibration are researched in the paper. The highway vibration affecting the near chimney is taken as an example. The curve of characteristics seismic coefficient is used as response spectrum. The max values of ground velocity and acceleration come from the vibration roller parameters. The effect range of vibratory roller and the distance of the chimney to the highway are used to analyze the vibration effect and control countermeasures by geotechnical engineering software. Results show that the vibration main effect is foundation soil not the chimney, and we can take reducing construction vibration, establishing isolation measures or strengthening building to ensure safety of the buildings.

Abstract: Rain-wind induced vibration (RWIV) is a violent oscillation that appears on cable stayed bridge under rainy weather. Many researchers agree that the rivulets (specially the upper one) play an important role during the vibration. In present work, the upper rivulet’s effect is focused. A circular cylinder with an arches attachment on its surface is modeled to take the place of cable- rivulets system section in RWIV. Using finite volume method (FVM), 3D Flow past the cylinder-arch model is simulated for subcritical Reynolds Number (Re, ≈6.8×10⁴). Large Eddy Simulation (LES) method is drawn in as a closure of turbulence model. The attachment locating at different positions are calculated. The results show many differences between cylinder-arch model and bare circular cylinder, including force coefficients change dramatically and velocity distributions in wake zone vary remarkably. Responses of cylinder-arch system driven by aerodynamic forces are also studied. Fourth order Runge-Kutta Method is introduced to solve second order ODEs that describe the vibration of cylinder model. The first four modal response are calculated and then added to analyze cable oscillating properties.

Abstract: In order to study the dynamic of the pier under seismic and wave action , based on fluid mechanics principle , A FEM model and dynamic equation was established by nonlinear Morison equation. Considering both the effect of added mass of water and the coupling effect of fluid and structure, the Newmark-β method is applied to solve the coupling equation. The results are compared with the simplified linear algorithm. By the numeric analysis, the pier response is studied and analysed deeply under earthquake and wave force effect.

Abstract: Because the traditional pushover analysis can not take the contributions of higher modes into account, To overcome this limitation, a modal pushover analysis procedure (MPA) is proposed by some researchers, which can involve the combination of multi-mode contributions to response. In this paper, much improvement on MPA procedure is made with consideration of the changes of seismic response after structural yielding and anew distribution of inertia forces. The method is verified by one example of bridge structure. It is concluded that the improvement part-sectionalized MPA presented in this paper has high accuracy.