Advanced Materials Research Vols. 919-921

Abstract: According to energy principle, the influence line equation for displacement at any point of simply supported beam with local damage was derived. Based on the load symmetry positions’ difference of influence line for displacement at midspan point, a index that detects the local damage of simply supported beam without initial data was proposed. The influence line characteristics of simply supported beam with local damage were theoretically analysed. Through further numerical experiments, the sensibility of the influence line for displacement at midspan point was analysed when a local damage is in different location of the beam respectively. The equations and numerical experiments show that the index peak appears in the damaged area and the additivity of multi-damage index is proved. Using the facile and accurate displacement information in engineering, this algorithm provides some reasonable suggestions for the damage detection and analysis of this kind of structure.

Abstract: Investigation is carried out aiming at analysis of bridge cable detection and monitoring. Detection and monitoring technology characteristics are summarized, while technology advantages and disadvantages analyzed. Dynamic detection technology of cable force is used most often. Effects of various factors of this technology are analyzed. Cable structure internal and external injury detection technologies are analyzed. Nondestructive testing technology specific comparison is carried out, the advantages and disadvantages of each technology and application. Nondestructive damage detection technique prospect is presented.

Abstract: At present, point sensors are mainly used in the measurement of the vehicle and bridge coupled vibration system. And only limited points of the system are measured. Test results can not be compared with calculated and analyzed results in the full field of the system. In the model test of the vehicle bridge vibration, test video is captured with a camera, each frame of the video is processed by the sub-pixel edge detection techniques to identify the deformation of the beam at each time, and the time history of the vibration response at each point of the beam. The model test results are compared with the calculated results of the vehicle bridge coupled vibration system. It is shown in the comparison that the beam deformation curves of both the test and analysis at each time are agreed quite good, and the time history responses of each point of the beam are also in good agreement. It means that the application of the video detection techniques in the vehicle and bridge coupled vibration model test is successful. Taking into account the advantages of the full field high density measurement and the synchronized measurement of the moving vehicle and bridge, further research and extension on the video detection technology are necessary.

Abstract: PIV is a velocity-measuring technology commonly applied for the measurement of deformation and displacement in the field of experimental fluid mechanics, but no previous report is found for the application of this technology in dynamic centrifugal tests. As soil is a type of complicated materials with mechanical properties closely tying with the stress condition it suffered, centrifugal shaker shows great superiority to the research of soil dynamics and geotechnical earthquake engineering. PIV capable of measuring deformation and displacement of any point at any time supplies overall visible information for full understanding of failure mechanism. For only the deformation of selected points captured by transducers in current instrumentation, the application of PIV in dynamic centrifugal tests is advantageous to understand the complex behavior of soil under earthquake and high-stress loading. This paper analyses the critical technology of PIV application in dynamic centrifugal tests and proposes the requirements of image acquisition system design as well as a method, which provide some guidance and reference for construction of centrifugal shaker.

Abstract: The karst cavities can cause great harm to the construction or running of expressway. During the construction of expressway, the detection of these unfavorable geological objects is usually by use of high density resistivity method, and the physical background of the method is the combination of high resistivity of bedrock and low resistivity of karst cavities. In the study area, the Kaihua segment of Hangzhou-Xinanjiang-Jingdezhen Expressway, the widely distributed rich carbonaceous bedrock shows low resistivity, and the conventional interpretation idea of high density resistivity method is not applicable. The research results of this paper suggest that the U shape of relative high resistivity can be an indicative for detection of unfavorable geological objects such as karst cavities. 6 out of 11 boreholes drilled for purpose of calibration revealed karst cavities, and the karst ratio is from 1.2% to 10.3%, indicating the new interpretation method is feasible and reliable.

Abstract: The importance of construction monitoring trend is required rational method to take health and safety and effective maintenance control from uncertainity and associated risks. Thus, timely field monitoring can overcome the gap between the prediction and real situation through the analyzing validity for the construction. This study suggests automated monitoring system with three kinds of communication methods to achieve effective operation of the system. The example of case study helps to easily understand for practical application with use of the mobile phones.

Abstract: The all-weather, non-contact and high-accuracy deformation monitoring can be realized by using the GB-SAR system, which includes three key technologies such as Stepped Frequency Continuous Wave (SF-CW), synthetic aperture radar (SAR) and interferometry. In this paper, a deformation monitoring experiment made at Geheyan Dam is described. The effects on the monitoring data caused by atmospheric changes are analyzed, and the monitoring results are statistically analyzed. The results show that the deformation information of the entire dam surface can be reflected accurately with the monitoring data corrected by the environmental correction methods, and these corrected data can be used for analyzing the stability of the dam.

Abstract: A new reinforcement measure with no-fire operation is presented, which is very suitable for space trusses which are located in gas stations. A finite element model (FEM) is presented with shell elements and multipoint constraint elements. With this FEM, nonlinear analyses are carried out. Analytical results show that integral failure of reinforced pipe is caused by yielding of original pipe inside. So it is not necessary to reinforce original pipe using steel pipe bonded outside with high yield strength. With the increase of length of bonded pipe outside, loading according to elastic stage and ultimate bearing loading increase, it is clear that the length of bonded pipe outside is an important factor which influences the bearing capacity.

Abstract: 3 masonry columns were strengthened by Sprayed Glass Fiber Reinforced Polymer (SGFRP), and a research of the seismic behavior of them tested by axial loading experiment was presented. The failure modes of the specimens were described, and the data about the load capacity and deformations of masonry columns strengthened by SGFRP were gathered during the experiment. The results showed that the ultimate loads of the reinforced columns increased greatly, and the deformation capacity and the ductility of the columns improved significantly too. Comparing the strengthening effects of the columns when the thickness of strengthen layer and the length of the glass fiber are different, the most effective and reasonable reinforce suggestions are proposed.

Abstract: The paper presents some considerations on the experimental tests already carried out on a kind of shear reinforcement of masonry not yet still employed. Indeed that is the use of FRP (fibre reinforced polymer) mesh rebar externally connected to the masonry samples through steel joints to improve their shear performances. The study try to learn final information about the design with this kind of shear reinforcement optimizing the very large experimental investigation on masonry sample subjected to shear diagonal test