Applied Mechanics and Materials Vols. 351-352

Abstract: According to characteristics of frequency-intensive on spatial truss structures, maximum isolation each modal is a good solution to this question. Considering this idea, calculating modal weighting coefficients of spatial truss structures through dynamic response expression, mode vector and objection vector can be obtained. An objection function was established based on euclidean distance. When the euclidean distance between mode vector and objection vector minimize, the optimal excitation position can be also received.

Abstract: Large-span V structure tied arch bridge structure system is complex. In order to make the actual state of the bridge into the ideal state of maximum close to the design, we must make real-time monitoring in the key parts of the structure, and adjust to the design of the data by analysis calculated, to ensure the safety and reliability of arch bridge in the course of construction and into stress after the completed bridge. Combined with the construction monitoring of the main Xinglong Bridge on Si River, this paper introduces the main bridge construction process measurement a preliminary study on the large span V configuration basket tied arch bridge construction monitoring technology. Based on the construction monitoring of Xinglong Bridge on Si River, this paper introduces the main contents and methods of monitoring point location, monitoring control of construction process, and discussed the construction monitoring technology of long-span X-style tied arch bridge V structure.

Abstract: Space frame structure of no damage and injury finite element models were established with ANSYS, and analyze 3D curvature mode as well three-dimensional vibration mode variety rate of the space rigid frame based on modal analysis. Curvature mode and three-dimensional vibration mode variety rate as the labeled amount was selected and applied to structural damage. The calculated results showed that the first-order curvature mode not only identify against single or multiple damage location, but also determine the initial degree of injury, and the axial curvature mode is better than the horizontal curvature mode for damage identification; The calculated results also showed that the variety rate of the first-order vibration mode can identify against damage location. Methods were provided by identifying the space frame structural damage of the curvature mode or three-dimensional vibration mode variety rate.

Abstract: The embedded temperature and acoustic emission sensors were used for monitoring thermal gradient and crack development of the concrete in a large foundation. The results show that the vertical thermal gradient is obvious, while the transverse is relatively stable during 3 and 8 days, and when the peak temperature is reached at the third day after the concrete was cast, the crack development is most intense. Therefore, measures should be mainly taken to care the concrete, especially at the peak temperature.

Abstract: Research on the problem to process the stability of bedded rock slope of monitoring, deformation monitoring were carried out difficulty .This paper carrying out the stress monitoring method to evaluate it. Use the strength reduction FEM to reach the slope failure location with different structure planes distance, and use the theory and project test of blot stress monitoring to verify. The result of the project test shows that the slope stress were tend to stability about 60 days after cut,the bolt maximum force value were 57.6 MPa,meet the requirement of reinforced design tensile strength,the test result shows that this slope tend to stability.

Abstract: Based on the building application, the Pall frictional damper is innovated. The relevant mechanical model is shown in this paper. According to this model the scientist and his colleague obtained theoretical hysteresis curve by Dichotomy Method and compared it with results that is from the semi-real-scale test. In the end of paper the authors give some example for the GLQW-1 frictional dampers.

Abstract: A monitoring method based on impedance method was researched for bolt looseness of steel structure. First, the basic principle of impedance method and its characters were introduced. Then, the root mean square of admittance (reciprocal of impedance) real part was used as the index to identify the damage degree. At last, a numerical simulation research on the monitoring of bolt loosen based on impedance method was hold by finite element analysis software. In research, a model of bolted connection joint of steel structure was built according to subsistent test by finite element method (FEM) software, and different levels of bolt loosen were simulated. The researched results had shown that the impedance method is efficient for the monitoring of bolt loosen. And the damage index could reflect damage tendency well. The simulation results are good agreement with test.

Abstract: Based on the statistics probability of certain order frequenciy deviates from its normal range, this paper puts forward a new damage alarm index and corresponding damage alarming method for structural health monitoring. Demonstrating the feasibility of this method, this article introduces the damage alarming method to analize the benchmark steel frame in frequency domain. The results show the abnormal index and its corresponding alarming method defined in sense of statistics indicates the abnormity of corresponding test cases clearly.

Abstract: In order to increase the sensitivity, frequency bandwidth and longitudinal resolution of the 1-3 cement-based piezoelectric ultrasonic sensor, different metal powder/epoxy resin composite materials were used to make backing layer, and the performances of sensors were evaluated and compared. The results indicated that the increase of the sensitivity and the frequency bandwidth, as well as a decrease of the pulse wave number can be observed when the backing materials of metal powder/epoxy resin composite materials were added to the sensor. A 42%-increase of the maximum peak-to-peak value of the echo pulse response, a 52%-reduction of the ring down time and a 200%-increase of the bandwidth can be achieved by using the backing material.

Abstract: The environmental factors have complex effects on the bearing properties of group pile foundation. Based on the "growth" process of the Sutong Bridge and the combination characteristics of environment factors, the relationships between the measured values of the group pile foundation and environmental factors were established. Then, the correlation decision determinations between the measured values and environmental factors were obtained by using the Bayes estimation fusion algorithm. Finally, the impacts of different environment factors on the bearing properties of group pile foundation had been got. The results showed that the impact of seasonal temperatures on the mechanical performances of the group pile foundation is very large.