Applied Mechanics and Materials Vols. 166-169

Abstract: Based on the requirement of earthquake resistance and disaster prevention in city’s master planning, taking the city's urban disaster prevention function and safety of residents in the great earthquake, large earthquake, middle seism into account, an idea for planning the layout of seismic disaster-prevention space treating city as an object was brought forward in this thesis. Especially, we mainly studied the restrictive conditions of the urban planning and construction from urban disaster prevention and reasonably planned urban disaster prevention security space structure and layout. Then it would certainly gain the spatial pattern of disaster-prevention and obtain the right resources of earthquake emergency relief, and ensure the safety of cities against earthquake disaster.

Abstract: With the rapid development and extensive application of SRC (steel reinforced concrete) frame structures, the study on seismic fragility of SRC structure under earthquakes seems rather important. The seismic fragility of the SRC frame structures is studied by the method of Incremental Dynamic Analysis (IDA) in this paper. IDA method is conducted on 9 storey SRC frame structure to obtain the IDA curves of this model. Meanwhile, the seismic fragility of the model is analyzed to get the fragility curve. The result shows that IDA can describe the quantitative relationship between the exceeding probability of different states and damage degree of the target.

Abstract: Based on the experiments of a reinforced concrete frame column, 5 new members with different volumetric percentage of stirrups which are applied with constant axial load and horizontal low-frequency cyclic load are analyzed with ABAQUS. This paper aims to study the relationship between volume-stirrup ratio and seismic behavior of reinforced concrete column. By analyzing skeleton curve and hysteretic curve of members, the results show that, if stirrups are reasonably arranged and the volume-stirrup ratio is larger enough, the good ductility, carrying capacity, energy dissipation capacity, and seismic behavior still be obtained with high axial compression ratio.

Abstract: For large-scale water-conveying tunnel, the spatial variation characteristics of earthquake excitation, namely, multi-point input has great effects on seismic response of the water-conveying tunnel. Aim at this problem, the paper considers interaction of surrounding rock-tunnel lining-water system and considers traveling wave effect. The result indicates: compare with the coincident earthquake excitation, traveling wave effect brings disadvantageous influence on seismic response of the water-conveying tunnel.

Abstract: In order to estimate the urban economic losses after earthquakes, builds the prediction model based on grey relation and genetic neural network. According to the grey correlation analysis, screens out the major factor effecting the earthquake losses as input vectors of neural network first, adopts genetic algorithm to optimize the initial weights and bias of BP network and then, solves the problem that the traditional neural network has slow convergence velocity and can not easy to get the global optimum. According to the example, we can get the model that has good forecast accuracy and convergence rate and checks the rationality and effectiveness at last.

Abstract: The current equivalent linearization method for evaluation of seismic response of soil layers has been widely used by engineers, but it obviously has limits while considering severe earthquake action and dealing with extremely soft soil layers. Developing a direct time-domain integral method is essential. In this paper, a direct-domain integral method is proposed. In the method, the dynamic skeleton curve constitutive model is introduced and it can fit test results of dynamic shear modules ration curve and damping ratio curve simultaneously, central difference integration method is used to solve the dynamic equation, multi-transmitting artificial boundary condition has been conducted to consider the effect of energy transmission through bedrock boundary. In order to implement this method, a program called Dymatlab has been compiled, strong motion records got from the NGA data base for site effects on strong ground motion have been used to analysis the offshore engineering site with thick soft soil layers. The results show that this program can be applied as a reasonable and feasible method for nonlinear seismic response of soil layers.

Abstract: Optimization design is the significant development in the structure design which could adopt the better from several plans in the same task. This paper build the finite element model of sixteen-floors shear wall structures, which control the deformation as the restraint condition, to make the thickness of shear wall as the design variable and to take the light structure as the objective function in order to execute the optimization. After the optimization, the bottom and internal stress become higher, whereas the centralized stress will occur in the corner and the middle of the rooftop and the opening of the shear wall. The horizontal earthquake of the various floors presents the curve like S with the increasing of the floors. And the floor which occur earthquake effect and the biggest displacement angle is in the middle of the structure and the whip tip effect will emerge in the top of the structure.

Abstract: In order to enhance the accuracy of regional disaster-carrying capability assessment, the dissipative structure of the regional urban earthquake relative disaster-carrying system is highly complicated and nonlinear. Moreover, the problem is multi-attribute, multi-index and multilevel. Based on the evaluation index system of regional relative disaster-carrying capability, This paper used the entropy weight assignment method to work out each index’s objective weight, quantitatively researched the 29 cities’ earthquake relative disaster-carrying capability, worked out every city’s relative disaster-carrying capability and divided its grades using the mean deviation method. The research results showed that the earthquake relative disaster-carrying capability of our country was much unbalanced. It was positively correlation with the economic performance, the eastern, central and western cities’ earthquake relative disaster-carrying capabilities were mainly distributed in the shape of the ladder. The eastern cities’ capabilities were much higher than the western cities’. So, we suggested that the eastern cities should further improve its earthquake disaster-carrying capability and the central and western cities should spend more efforts to develop its earthquake disaster-carrying capability. Only in this way, our country’s urban earthquake disaster reduction can develop evenly.

Abstract: A probability model based on urban land types and probability reliability was put forward to predict seismic casualties. The casualty probabilities of different urban land types were got by classifying the urban land types, combining with the historical earthquake casualty statistics and statistic residence status in the architecture of different urban land types, and then the upper value of earthquake casualties in certain probability might be estimated. Meanwhile, an example was analyzed with the proposed method. Results show the feasibility of the proposed method.

Abstract: Accelerograms recorded by accelerographs are of fundamental importance in seismic engineering, forming the basis of ground shaking employed for anti-seismic design. By analysis on the general solution of wave equation, this article demonstrated that the ground tilting is related with the ground velocity and displacement histories. For accelerograms with co-seismic permanent displacement, this ground tilting would be presented continuously with a tiny constant value after severe shock terminated. The co-seismic permanent displacement might be the reason of baseline drift, which caused that the real velocity and displacement histories could not be achieved by the direct integration of accelerograms. A baseline correction method was also proposed based on this finding, with which the ground velocity and displacement histories of several near-fault stations were given. But this proposed method still needed improvement because of the divergence in its iterative process.