Applied Mechanics and Materials Vols. 90-93

Abstract: With the development of modern constructional technique, more attention on the size effect is paid by academics and engineers. Shear failure mechanism of reinforced concrete column is analyzed firstly, and then the advances on the size effect of reinforced concrete column is introduced. the effects of sectional size on the shear behaviors of reinforced concrete column is studied by theoretical analysis and experimental summary, and the formula of the size effect of shear resistance of reinforced concrete column is proposed.

Abstract: Abstract: It is analyzed and obtained the result that the debris flow is currently in mature stage with medium risk and high occurrence through the gray correlation method of fractal research and effect measure of debris flow gully. Therefore, it is necessary to take corresponding governance measures. In this article, check dam is used as main preventive engineering measures to set up two check dams in the passing area of debris flow, with total capacity about 2800m3 and design reservoir capacity of flood once per 50 years. Construction of the check dam will effectively reduce risk of debris flow.

Abstract: In order to correctly evaluate urban comprehensive disaster-carrying capability and then to establish scientific basis for disaster prevention and reduction, a fractal method for urban comprehensive disaster-carrying capability is proposed on the basis of system principle which is that structure determines function. The fractal dimensions of 29 cities are calculated and analyzed. The results show that relative stronger, middling and weaker are respectively 13.79%, 65.52% and 20.69%, which are completely consistent with the actual situation. So the method can construct a characteristic index, and the main impact effects can be analyzed according to the result. Tested by examples together with the other two methods, i.e. the fuzzy assessment method and exponent method, the results verify effectively that this method is useful and feasible.

Abstract: The characteristic of soil is one of the main factors that influence the modal parameters of retaining wall. This paper analyzes the influence to modal parameters of retaining wall by the elastic modulus of soil. Due to the complexity of the interaction of soil and retaining wall and based on the three-dimensional numerical test, dynamic response signals of retaining wall are obtained, processing of which and identification of modal parameters lead to the modal parameters of retaining wall. Lastly, vibration characteristic, frequency characteristic and the relationship of frequency and elastic modulus are also obtained.Therefore, the real elastic modulus of soil is gained by response signals in practical projects, and the degree of soil compaction can be pre-judged.

Abstract: In long-term operation process, highway subgrade is subjected to strength decrease easily，and the water environment around often causes the side slope side-slipping. In allusion to the common clay, massive indoor triaxial tests have been carried on, the relationship between the shear strength index and the water content, compactness of the compaction clay has been determined. Based on the above research, slope stability analysis software GEO-SLOPE is used, to analyze common earth fill subgrade, soft soil ground, mountainous area subgrade and earthquake area subgrade separately. The impact of subgrade strength decrease on the slope stability has been studied considering different subgrade filling height. The results indicate that no matter what kind of subgrade form, strength decrease of the subgrade causes highway slope safety coefficient to reduce, this especially obvious in the high subgrade condition. Partial jitter possibly happens when strength decrease of the subgrade achieves to above 80% of the common earth fill subgrade. The subgrade side-slipping possibly happens when strength decrease of the subgrade achieves to 50% of the soft soil subgrade. The subgrade safety coefficient decreases the most when the main performance is side-slipping jitter of the intersection between fills and digs of the mountainous area part-cut and part-fill subgrade. The subgrade jitter happens when the shear strength index decreases to 50% under the combination of strength decrease and seismic force of the earthquake area subgrade. The high subgrade and the maintenance management of the special road section should be strengthened to avoid the project disaster.

Abstract: For the displacement-constraint device with hysteric-friction isolation system, the judgment condition of soft-collision between the isolation layer and displacement-constraint device is put forward, the motion equation of the isolation system in consideration of friction and soft-collision is established, the nonlinear analysis program is worked out, and several kinds of inflection points in the program are given and the corresponding processing method of the inflection points is introduced. The nonlinear response analysis of the isolation system results indicate the displacement-restraint device can ensure the upper structure safety; also can decrease the displacement of the isolated layer.

Abstract: The keyword LOAD_BLAST in LS-DYNA has been established to simulate the response of the structure under blast loading since V960. The ConWep algorithm in it is described in this paper. As the load and impulse computed by keyword LOAD_BLAST are smaller than those they should be, the accuracy and reliability of parameters in keyword LOAD_BLAST should be verified and adjusted according to the experiment results of the blast loading on blast door. The results show that the load and impulse computed by ConWep module in LS-DYNA will be close to the experimental results when the TNT equivalent in keyword LOAD_BLAST is multiplied by a factor of 1.35.

Abstract: Taken examples of recent major disasters，the deficiencies of shelter and evacuation system in planning，construction, etc.. and the inadaptability of protecting security needs of the city under extreme disasters is analyzed. Given this, on the basis of the analysis of the connotation of catastrophic environment and adaptation and the relationship between them, the concept of adaptive planning of urban shelter and evacuation system under the disastrous environment is proposed. Based on dynamic planning idea, the adaptive planning is preliminarily discussed in the three perspectives of disaster prevention functions, fortification level, hierarchical structures and spatial characteristics and some planning strategies and measures coping with catastrophes are given.

Abstract: Data and parameters of the proposals being selected may be not assured. This uncertainty of data and parameters can be expressed as random variables. The paper is about how to use random decision criteria to select independent proposals where investment capitals available are limited and cash flows or parameters are random variables. The paper first simply introduces the decision criteria on random condition, and gives the common methods to get these values of decision criteria. Then the general model of independent proposals decision with limited capital under random condition, and the solutions of proposals selection are put forward. In the last section a numeric example is given to show how to use software to select independent proposals with random cash flows and limited total investment capital.

Abstract: The means of inflicting hot or cold interfere at the key place of typhoon was put forward to alter the locomotive route of the typhoon to avoid the important engineering and important region, or to weaken the intensity of the typhoon and to prevent the occurring of the typhoon at source. The basic principle and the academic foundation of the controlling of the typhoon were studied, and the model of typhoon configuration and the inherent relation between the parameters such as wind speed, wind pressure, temperature and etc were brought forward. The research trend of the typhoon controlling was introduced and the existing problems and the prospects were discussed.