Applied Mechanics and Materials Vols. 71-78

Abstract: Although modern bridge are carefully designed and well constructed, damage may occur in them due to unexpected causes. Currently, many different techniques have been proposed and investigated in bridge condition assessment. However, evaluation efficiency of condition assessment has not been paid much attention by the researchers. A fast evaluation of the urban railway bridge condition based on the cloud computing is presented. In this paper dynamic FE model and Artificial neural networks technique is applied to model updating. The cloud computing model provides the basis for fast analyses. It was found that when applied to the actually railway bridges, the proposed method provided results similar to those obtained by experts, but can improve efficiency of bridge

Abstract: In order to convenient application in optimum design of large and complex structures, theoretical formula of nominal tensile stress of concrete is deduced relating to the maximum crack width of RC beam in serviceability. By further statistical analysis of test data in certain reliability, simplified and practical formulas are proposed for calculating the nominal tensile stress of concrete. Therefore, the control of maximum crack width is replaced by control of nominal tensile stress of concrete, which shall be easier to realize in optimum design of concrete structures.

Abstract: This paper presents an inclinometer-based deflection curve reproduction system which can reconstruct the deflected shapes of bridges directly. Because the conventional deflection-measuring methods are performed by collecting the deflection data at just a few discrete points along the bridges, the bridges’ deflected curves are not smooth enough. The operation of the proposed system is performed by utilizing the displacement transducer to determine the measuring intervals, using inclinometer to collect the angles of the measured points, calculating the deflection values, further applying Gradient Mean Prediction Filtering (GMPF) algorithm to filter the deflection data, and finally reproducing the deflection curves of bridges. The precision, feasibility, reliability, and effectiveness are verified by laboratory tests and field applications.

Abstract: As we all know, buildings always have a certain post–settlement after using many years. Differential settlement often led to the building collapse, cracking. It even affects the using seriously. Therefore, in order to reduce the differential settlement of buildings, it should research preventive measure based on settlement causes. According to this, the purpose of this activity is that it can achieve effective prevention, control uneven settlement production. Finally, these measures can eliminate the root of the accident.

Abstract: This paper analyzes the mechanism of earth-rock dam Seepage, discusses the Strengthening technology, and it proposes several proposals on Strengthening technology.

Abstract: Pall-typed dampers(PFD) have good energy dissipation, and shape memory alloy(SMA) brace has good super-elastic performance, so the PFD-SMA support system is put forward. Through the test study of PFD-SMA support system, analyze the influence to its hysteretic characteristic by preload force of Pall-typed frictional damper, the stiffness and length parameters of shape memory alloy support. The test results show that PFD-SMA support system s have good energy dissipation and good reposition due to its super-elastic performance, with pre-load force increase, its super-elastic performance acts better, its hysteretic curve show super-elastic performance too, and it verifies the correctness of the finite element analysis.

Abstract: There are mainly three phenomena, i.e. cracks, infiltration and denuding for judging the aging and defects from hydraulic concrete constructions. The inland waterlocks’ concrete ageing with salt free contamination are found basically the concrete denuding, rebar erosive expansion cracks and concrete surface gravel exposure and freeze thawing peeling-off as well occasionally. The severe aging phenomena always occur in some small structures in work bridges, sub work bridges, railway bridges and concrete waterlocks etc, especially in boundary beams or flange plates of the said beams. The result manifests that the test result is completely in conformity with the actual situation in the test of internal concrete steel bar erosion by means of Eigenvalue K method and half-cell potential method. In order to prevent steel bars in the concrete from eroding and guarantee the durability of waterlocks, currently the treating method used most frequently is the waterlock concrete surface carbonization resistance treatment

Abstract: The cause detection and analysis have been made over the surface cracks of external thermal insulating rendering systems made of mortar with bonding powder and using expanded polystyrene granule as aggregate (ETIRS) by means of integrating the basic concept of the cracks and actual project practices, on the basis of structure design, materials performances and construction. The result shows that the major causes for surface cracks, the hazardous ones are caused by poor construction quality. In order to guarantee the quality of external thermal insulation wall, the structure design of the said thermal insulation system shall be underlined and building quality on the key parts, stressed.

Abstract: It is well known that Somali pirates frequently hijack ships, which has great negative impact on the global shipping industry. To crack down on the pirates’ abominable crime is a common challenge that all shipping practitioner face. The international community has paid close attention to the issue of piracy. In view of the present situation, the author gives a summarization of piracy attacks in recent years in this paper, further to analyze in detail the background and characteristics of frequent piracy attacks and provide some suggestions on the specific preventive measures to deal with the problem.

Abstract: The bridge health monitoring system can collect large amounts of data, but it lacks the trend analysis of monitoring data. This article introduced the method of Time series analysis into the analysis of bridge monitoring data, and adopted ARIMA model in time series analysis of monitoring data, used the least square method for parameter estimation, established the prediction model for bridge deflection, and conducted the goodness of fit test. Take the actual bridge monitoring data as an example, it was demonstrated that the method is feasible in the prediction of bridge condition trend.