Advanced Materials Research Vol. 859

Abstract: The finite element analysis model was built as the real scale for mortar arch framework slope protection, and the displacement and strain at different points were collected by vertical loading pressure. So the mechanical mechanism can be studied, and the analysis was done between calculation results and testing results of solid miniature model. The studying results show that the point on the arch foot is the worst stress place for each arch, and the total displacement increase nonlinear as the distance from the slope top increases, and the bump phenomenon exists in the bottom of slope, the points are likely to be broken.

Abstract: Combined with practical experience in engineering, this paper analyzed the necessity of the bridges for detection with the use of on-site static load test. Also, it introduced the content and methods of the trial, as well as the studied domestic and international inspection techniques, thus discovering the engineering mechanical performance for bridges.

Abstract: Based on a certain loess tunnel in Kelan-Linxian Expressway in Shanxi province, the influence to primary support forces by different stress release is analyzed by the Ansys FE software in the step method excavation. The analysis results can reasonably reflect the actual case of primary support forces, and can offer related reference to the selection of reasonable design parameters for primary support.

Abstract: Six pieces of building models were designed for studying the multilayer buckling restrained braced steel frame in this paper. The main parameter in the study included the frame strength and the level Participation ratio β. Second-order nonlinear time history analyses for models are conducted based on plastic hinge theory. The parametric analysis was performed on story displacement and shear. The results revealed that story bending deformation become more remarkable when the frame strength is increasing from 0.3 to 0.5 or the level Participation ratio β from 30% to 90%, and this situation is more obvious on the upper layer. The share of shear by the buckling restrained brace and the largest story shear ratio get larger in these models as the frame strength and the level Participation ratio β increasing.

Abstract: Modal parameter identification of civil engineering structures under seismic excitations has important implications for health diagnosis, plastic analysis and optimization design of structure. A numerical simulation model of frame construction was carried out. Apply two types of seismic waves on the structure. The seismic excitations are Kobe wave and Shanghai wave which are both generated by actual earthquake records. According to the acceleration response of the layers, the first three order modal parameters can be identified by using complex exponential method. Compared the results with theoretical values, and analyzed the accuracy, the method was considered to have an effective application.

Abstract: Natural excitation technique has found an increasingly wide utilization in civil engineering field. Modal parameter identification in time domain method can identify the structural parameters in the use of impulse response data as input data. The theory of NExT method is presented. By constructing a numerical simulation example under white-noise excitation, and calculating the data by NExT method, the modal parameters can be identified according to complex exponential method and time series-method in time domain. The results and analysis indicate the validity of the method and provide a reference for engineering practice.

Abstract: Cement-based grouting material is used for the grouting of gravel soil, and do compressive strength tests for the grouting concretion stones. Use the method of support vector machines for regression (SVR) to deal with the test data and predict the grouting concretion stones strength. Specific methods are as follows: randomly select 20 groups of the specimens for training, the remaining specimens for predicting, and then establish the relationship between the performance of soil body medium, grouting materials, grouting pressure and strength of concretion stones strength. The research results show that the support vector machines method can judge the sensitivity to impact indicators of grouting stones strength, and predict and analysis the grouting stones strength under multiple factors.

Abstract: Concrete structure in reality mostly in complicated stress state, dynamic characteristics and static characteristics under earthquakes and other dynamic loads are very different. For a further understanding of the dynamic characteristics of the concrete, true triaxial testing machine system was used to the C30 concrete at different strain rates and different side of the cube concrete specimens stress biaxial dynamic compression tests. Biaxial stress state concrete elasticity modulus, peak stress, peak strain, was obtained by the experimental study, and carries on the comparative analysis. Results show that: the dynamic characteristics of concrete under biaxial compression state of concrete and uniaxial condition are very different.

Abstract: In order to analysis the internal relation between the matric suction change and the tunnel disease, the paper combines the Dayoushan tunnel as an engineering example, uses the mathematical, field monitoring and model shear test and to analysis the the change rule of the martic suction and the influence of martic suction on the tunnle supporting force and plastic zone. The results show that when the water content is increasing, the unsaturated loess matric suction is reduction, the force of tunnel support is increasing and the radius of plastic zone is increasing. Due to the influence of surface water infiltration, the matric suction of the around soil in Dayoushan tunnel is reduction and cause the crown settlement, landslides and lining cracks. The disease treatment mainly lies in keeping the drainage system is smooth and secure for waterproof. For the similar unsaturated loess tunnel, the research results have reference significance.

Abstract: In numerical simulations of reinforced concrete (RC) columns with ADINA, when the REBAR element model is applied to simulate the reinforcement, the load-displacement curve of RC is similar to that of concrete, without reflecting the contribution of reinforcement. Therefore, employing another element model-BEAM element model for reinforcement, nonlinear analyses of RC columns are carried out and compared against the REBAR element model. The nonlinear analysis of reinforced concrete filled steel tubular (RCFT) columns, then, is performed with the BEAM element model. Meanwhile, the axial compression tests of concrete, RC and RCFT columns are also conducted to validate the nonlinear analysis. Comparing the results of nonlinear analysis against the results of experiment, it is concluded that the BEAM element model can simulate the reinforcement more reasonably than REBAR element model and can be applied to the nonlinear analysis of RCFT columns.