Applied Mechanics and Materials Vols. 438-439

Abstract: This paper presents nonlinear amplification of seismic ground motion by twin cavities in layered sites. The equivalent linear method is used in the dynamic analysis and Lysmer-Kuhlemeyer transmitting boundary is used at the left and right boundaries of the computation region. It is shown that, cavities have significant effect on seismic ground motion, and soil nonlinearity has significant effect on seismic ground motion around cavities. The PGAs in linear and nonlinear analysis may be increased by 24.4% and 19.2%, compared with those in the free-field response. The PGA in nonlinear analysis may be decreased by 44.6%, compared with that in the linear analysis.

Abstract: This paper studies nonlinear amplification of seismic ground motion by alluvial valley in layered sites. The equivalent linear method is used in dynamic analysis and transmitting boundaries are added at boundaries of the computation region. It is shown that, soil nonlinearity has significant effect on seismic ground motion around alluvial valley. The amplitudes in the case of linear alluvium and soil layers are the largest, those in the case of nonlinear alluvium and soil layers are the smallest, and those in the case of nonlinear alluvium and linear soil layers fall in between. The periods in the case of nonlinear alluvium and soil layers are the longest, those in the case of nonlinear alluvium and soil layers and those in the case of linear alluvium and linear soil layers are almost the same.

Abstract: Due to the uncertainties and randomness of earthquake loads, it is more logical that reliability method should be employed in dynamic geotechnical engineering analysis. A methodology of 2-D effective stress FEM analysis based on dynamic reliability of seismic response of soft ground including silt is proposed in this paper, Duncan-Chang and Hardin-Drnevich hyperbolic models are used for static and dynamic constitutive relations of soils, respectively. Furthermore, three stochastic dynamic reliability analysis approaches based on the cumulative damage, cyclic shear stress and pore water pressure ratio are respectively suggested. The proposed methodology was applied to the stochastic dynamic reliability analysis of ground seismic response of two typical soft soil profiles in Shanghai in terms of seismic wave input depths of 50m and 280m. Basically consistent conclusions can be drawn in the three aforementioned perspectives. In addition, the filtering effect of frequency components by deeper soil layers plays perhaps an important role in dynamic reliability analysis in view of the fact that remarkable differences of dynamic reliability analysis results exist between 50m and 280m seismic wave input depths.

Abstract: In order to study the seismic response of slope under the effect of seismic load, a numerical model was established by ANSYS program. It was mainly analyzed the dynamic responses of slope under the effect of both general earthquake and rare one. The results indicate that under general earthquake, slope deforms a little, there is small stress within slope, and small tensile stress on the top of slope; under rare earthquake, slope deforms greatly, slope surface has large displacement, and there is larger tensile strain on the slope top. At the same time, stress concentration effects expand further within slope and slope toe. Consequently, with regard to slopes in higher fortification intensity area, some steps should be taken to strengthen slope in order to improve slope seismic stability.

Abstract: In order to confirm the calculation model of multi-ribbed slab structure and transmission of earthquake action, this paper improved existing multi-ribbed slab structure. The calculation model of improved multi-ribbed slab structure confirmed the stress relationship among three seismic fortification lines, and the transmission of earthquake action became clear, the same calculation model could be applied in structural analysis. For studying the features of characteristic parameters of restoring force changing in the first seismic fortification line, blocks, and correcting the parameters, the experimental study was carried out. The experiment shows that when a unidirectional horizontal load was applied, that blocks in grid frame could be regarded as a slanted strut that with specific section and elasticity, the ideal slanted struts nominal elastic modulus is roughly in 20~60 N/mm2.

Abstract: Landslides constitute a major geologic hazard because they are widespread and commonly occur in connection with other major natural disasters such as earthquakes, rainstorms, wildfires and floods. Nonlinear dynamical system (NDS) techniques have been developed to analyze chaotic time series data. According to NDS theory, the correlation dimension and predictable time scale are evaluated from a single observed time series. The Xintan landslide case study is presented to demonstrate that chaos exists in the evolution of a landslide and the predictable time scale must be considered. The possibility for long-term, medium-term and short-term prediction of landslide is discussed.

Abstract: In order to overcome some deficiency of design, American earthquake engineering and structural engineering experts have profound conclusion after the previous earthquakes, improved bearing capacity design method, put forward the theory of performance-based design. Methods of performance-based design mainly include displacement coefficient method; direct displacement based design method, capacity spectrum method and improved capacity spectrum method. Through the understanding of the main methods, enable us to better understand performance-based design, so as to improve the design of civil engineering.

Abstract: Constructional engineering was always faced with the threaten of earthquake and the problem of large energy consumption. As a new type of green building material, straw concrete has better ductility than normal concrete. In the straw concrete multi-ribbed slab structure, as the filling material of wall board, straw concrete improved the energy dissipation and deformability of wall board. When the load was applied, the filling blocks, grid frame and outer frame in straw concrete wall board work cooperatively, have good mechanical properties. The straw concrete wall board has advantages that light, high strength, energy conservation and seismic resistance. Considering the effect of different components in straw concrete wall board, this paper proposes the formula of vertical bearing capacity of straw concrete wall board to provide the basis for engineering application. The construction of straw concrete multi-ribbed slab structure include three processes that steel bar bind, blocks prefabrication and integral pouring, which fits for field fabrication in the building construction site.

Abstract: This paper proposes a new risk assessment model on account of the fuzziness and uncertainty of risk factors in the reservoir after earthquake. The paper adopts methods of information entropy and fuzzy mathematics to assess risk level of the model. After analyzing the statistical data of earthquake-damaged reservoirs, we present comprehensive weight composed of importance and improved entropy weight. Base on comprehensive weight, we can adopt membership function to establish single factor evaluation of the model. Moreover, we combine fuzzy weighting method to assess risk level of a reservoir after earthquake. The result shows that risk level of the reservoir is high-risk. The case study verifies the practicability and rationality of the risk assessment method. Therefore, the method could be applied in the emergency rescue and reinforcement for reservoir after earthquake.

Abstract: The overall adoption of Building Information Modeling (BIM) has increased considerably in recent years; however, utilization of BIMs post-construction is still seldom explored or documented. Much of this may be due to the fact that there still remains great inconsistency between stakeholders levels of BIM proficiency. In order to achieve a life-cycle use of BIMs, it is critical that the Architecture, Engineering, Construction, and Operations (AECO) industry determine if it is moving closer to achieving a mature BIM standard or if organizationally it is still just grazing the surface of what BIM can do. Based on a survey of a diverse sample of the construction industry, this study evaluates the quality and maturity of BIM implementation across various organizations as well as the quality of BIM execution on current construction projects.