Advanced Materials Research Vols. 250-253

Abstract: This paper presents a simple Self-resetting sliding isolation system, which is composed of graphite sliding device and simple rubber bearing. Theoretical analysis is carried out. Shaking table test for a typical brick masonry structure in village of China is performed on a 1:4 scale. Results show that the proposed new isolation system can achieve a favorable level of performance.

Abstract: In order to understand the anchorage mechanisms the fracture behavior of jointed rock masses reinforced with rockbolts was compared with those of the jointed rock masses without rockbolts. Firstly the unaixal tensile tests were conducted on the specimens with inclined surface cracks, horizontal through cracks and horizontal a quarter through cracks to investigate the crack growth of the jointed rock masses without rockbolts. The experimental results show the fracture of the specimens without rockbolts belonged to tensile fracture in the catastrophic way under uniaxial tensile conditions. However the experimental results of the specimens reinforced with rockbolts show that rockolts can change the initiation of the pre-existing cracks, incur the secondary cracks and there existed stable crack propagation.

Abstract: The seismic behavior of a single-story ten-bay confined masonry structure was investigated using substructure pseudo-dynamic tests. Only one bay of the prototype was regarded as the test model and the remainder was regarded as numerical model. The test results show that the test model withstood, with slight damage, strong earthquakes with peak ground acceleration of 1600 gal. It is found that prototypes of the tested type exhibited satisfactory seismic performance. Hence, the confinement can be reduced if the budget of the building is limited.

Abstract: It is a complicated process to adjust the tensile forces of cables to their target forces in the practical tensioning construction of prestressed space reticulated structure. In this paper a calculation method for whole-process analysis of the multi-stage and multi-batch tensioning construction is presented to improve the tensioning efficiency. By diminishing the difference between the actual tensile forces of the cables and their target values gradually, the initial strains of the cables for tensioning in construction can be obtained. All the cables can reach to their target values one time if they are stretched to the calculated initial strains in accordance with the predetermined tensioning sequence. The analysis on a prestressed spherical reticulated mega-structure with span of 150m is carried out; the results indicate that this method is feasible in practice.

Abstract: The technology of the composite ground under a flexible foundation have been widely used in transportation, water conservancy and other departments, yet its theory of characterizing the behavior of the composite ground needs to be further researched. A simplified analytical model is presented, considering the above four parts which includes the flexible foundation, the cushion, the composite ground, and the underlying soils as an interactive system, allowing for the relative movement between piles and soils, and assuming different settlement of foundation soil at the same elevation. The force equilibriums of a typical element are established. And then, according to the compatibility of stress and deformation on the interfaces between these four components, the formulas on settlement and stress ratio of pile-soil, which is used to characterize the behavior of the composite ground, are derived.

Abstract: Logistic model is modified through introducing the pseudo construction settlement. Based on the observed settlement data of foundation in Yangshan deepwater port project, Logistic growth model and modified Logistic growth model are used for nonlinear regression analysis of foundation settlement respectively. It is indicated that the fitting curves by using modified Logistic growth model agree better with the observed settlement values than those by using Logistic growth model and that the correlation coefficients by using modified Logistic growth model are also bigger. Model parameters of different geological conditions obtained by nonlinear regression analysis can be used for significant reference to foundation settlement prediction of similar geological condition in other deepwater port.

Abstract: As a rule,the natural slope is not homogeneous,and its sliding surface is arbitrary. However,the common slope stability analysis methods used to assume shape of sliding surface and slope homogeneity,and the calculation process is so complex that accuracy of results is decreasing.In this study,the potential energy function of sliding body is established for slope with arbitrary sliding surface on multi strata.Using minimum potential energy principle, the displacement of sliding body can be got. Then based on Moore - Coulomb criterion and condition of force equilibrium in the sliding direction, the safety factor can be got directly. Case studies show: ①This slope stability analysis methods is valid.② Different definition of safety factor leads to different analysis result.

Abstract: Deformation behavior of endangered earthen heritage slope makes sense to scientific conservation of earthen architecture. It realizes qualitative and quantitative description of diseases. Based on random process and description theory, deformation behavior of endangered earthen heritage slope (Jiaohe Ruins) is studied using high-accuracy, real-time, dynamic information obtained by deformation monitoring appliance. Research result indicates that mathematic model can be established by use of modern mathematic method. The mathematic model of Jiaohe slope proves that short-term deformation behavior owns periodicity (36h) and occasional mutation. Simultaneously, tendency deformation performs weakly. The conclusion lays foundation for the research on quantitative deformation behavior and the following forecasting of similar earthen heritage slope damages.

Abstract: The objective of the paper is to present a method for structural damage presence detection from the time-varying modal parameters identified from the seismic response records in great earthquake. The time-domain system identification method RARX (Recursive Auto-Regression with exogenous variables) model is adopted to identify the time-varying parameters including modal frequencies and damping ratios from the seismic response data. Then the damage presence is detected from the change of parameters during earthquake. A 7-story reinforced concrete building, which had suffered moderate damage and recorded seismic response in Chi-Chi Earthquake, is used for the analysis. It is found that the damage presence can be determined from the decrease of the modal frequencies or the increase of damping ratios, and the time at which the building is damaged can also be detected from the time-varying modal frequencies. The results can be considered as the supplement materials for structural safety evaluation, structural damage investigation and related works.

Abstract: Considering the features of underwater shield tunnel with large cross-section, a prototype test of segmental lining structure for Nanjing Changjiang Tunnel (Φ14.5m) is carried out by using a new loading test method. And with “Multi-function Shield Tunnel Structure Test System” developed according to this test method, the effect of high hydraulic pressure can be equivalently imposed upon the structure by hoop, and then the earth pressure can be equivalently applied to the structure by radial concentrated force. The structures were loaded by the device according to a certain hydraulic and earth pressure. Meanwhile, the mechanical characteristics can be further studied. In a word, it can provide reliable test means for research, design and construction of underwater shield tunnel project.