Advanced Materials Research Vols. 639-640

Abstract: Differential ground settlement is a key parameter to be monitored in engineering practices. The common instruments and techniques available for surface and subsurface settlement measuring, such as surface surveying, settlement platforms, extensometer, inclinometers, and so on, provide point-specific measurements. The number of data points obtained by these methods is pre-determined by the number of the measuring points, and hence the spatial resolution of the measuring system is limited. This paper presents the development of a tension-sensitive time domain reflectometry (TDR) sensor and the experimental program to evaluate its performance for monitoring soil settlement. Testing results show that the looped TDR cable is highly sensitive to tension and effective in detecting subsidence zone in sand.

Abstract: Physical soil models are often used to study slope failure in centrifuge and/or shaking table tests. An important part of such physical modeling is to monitor the subsurface deformation patterns of failing slopes. As an emerging technology to monitor internal deformation of geo-materials, time domain reflectometry (TDR) has been successfully applied in field monitoring of unstable slopes. This paper presents the development of a custom-made TDR sensor and its application in a 1-g slope failure model test. The test results show that the TDR system is capable of capturing localized shear deformation in small soil models. Trial studies of using the TDR system in centrifuge and shaking table experiments demonstrate that the system has the potential of being successfully applied in centrifuge and shaking table testing.

Abstract: Fully Polarimetric Synthetic Aperture Radar (PolSAR) image classification, with the complexity for its data’s scattering mechanism and statistical property, has expected to be performed by an automatic categorization. This paper presents a supervised method called Fuzzy support vector machine (FSVM), which is a variant of the SVM algorithm to classify the PolSAR image data. In order to take advantages of PolSAR data, five scattering features (entropy, total power, three Eigenvalues of Coherent Matrix: λ1,λ2,λ3) are input as original data space of the FSVM algorithm. The feasibility of this approach is examined by the JPL/AIRSAR PolSAR data. The classification results show that the proposed FSVM method has out-performed the SVM method.

Abstract: Based on the pseudo-dynamic testing method and substructure technique, a remote hybrid dynamic testing method for asymmetric-plan buildings considering torsional effects is described. Besides, this paper presents the method and control principle for testing substructures in a single-story frame system under loading due to eccentric lateral responses of superstructure to earthquake motion. Several validated simulation tests of an asymmetric bridge system have been conducted successfully based on the remote testing platform NetSLab and the crossed-response of torsional and translational vibration of bridge structures under three representative ground motions was studied.

Abstract: A networked structural laboratories system for evaluating the seismic performance of large-scale structure systems by seamlessly integrating geographically distributed experimental and computational substructures into a single test is described in this paper. It consists of an independent network based communication platform and various applications. The effectiveness of the proposed system is demonstrated by remote hybrid tests of a six-span bridge system at the Hunan University, Harbin Institute of Technology, Tsinghua University, China and the University of Southern California, USA. Successful application shows the system enables the shared use of testing resources by integrating single structural laboratories into a powerful and networked laboratory with advanced capability.

Abstract: This paper presents a new method to study the impact factor of an old bridge strengthened with high strength materials based on the model updating technique. Using the genetic algorithm (GA) by minimizing an objective function of the residuals between the measured and predicted responses, the bridge and vehicle coupled vibration models were updated. Based on the displacement relationship and the interaction force relationship at the contact patches, the vehicle-bridge coupled system can be established by combining the equations of motion of both the bridge and vehicles. The simulated results show that the present method can simulate precisely the response of the tested bridge.

Abstract: The fire has brought great harm to human, so it is of vital significance to establish a scientific method of structural fire resistance design to avoid personnel casualties and economic loss in the destroy or collapse of the structure in fire. The mechanical properties of materials deteriorate at the high temperature of the fire, and the structure can be damaged easily, so the damage cumulative impact must be considered in the structural resistance capability to fire. Damage mechanics is a powerful tool in the study of structural damage and destroy. In the paper, the damage mechanics is introduced into the calculation of resistance capability to fire of concrete structure, and the thermal-damage analysis of concrete member is achieved through the second development on ANSYS platform by using the residual strength thermal-damage model at high temperature.

Abstract: Damage mechanics is introduced into the fire response calculation of the concrete structure. The damage mechanics equations for fire response calculation are established. They are the damage evolution equation based on “residual strength” theory, heat conduction equations, and elastic mechanical equations. The fire response calculation of a concrete slab under external load and fire is shown. ANSYS is selected for calculating. The temperature field and stress field are obtained, the damage and failure process are described using the technique of killing or activating elements in ANSYS, and the fire resistance of the slab is obtained.

Abstract: The temperature stress calculation of multi-storey structure is very complicated. Many researches have been taken for the frame structures with rectangular plane, but very few references about annular plane. Based on the ANSYS program, the structure temperature effect of a multi-storey reinforced concrete frame which plane shaped like the elliptic is analyzed in this paper. The overall temperature load and concrete shrinkage equivalent temperature are considered in the analysis. The results reflect that curvature has an apparent influence on the temperature stress of annular super-long structure. Besides, the structure temperature effects are studied on both cases of the structure with expansion joint and without it, which shows that reasonable installation of expansion joint can decrease the temperature stress of annular structure. The influence of structure member rigidity on temperature effect is also discussed by changing the size of the section; all of these could offer reference for engineering design.

Abstract: In the present study, an experimental setup was made to measure the aerodynamic characteristics of vehicles on the bridge for different cases in a wind tunnel considering the aerodynamic interference. The influence of the wind turbulence, the vehicle interference, and the distance of vehicle from the windward edge of the deck on the aerodynamic coefficients of vehicles were investigated based on the experimental results. The measured results showed that the wind turbulence, the vehicle interference, and the vehicle distance from the windward edge significantly affected the aerodynamic coefficients of vehicles.