Advanced Materials Research Vols. 368-373

Abstract: The basic modeling principal and method of grey mathematics model is introduced , taking the case of JiangYa RCC gravity dam, on the basis of the interior of dam concrete temperature monitoring data , According to Multi-Variables grey principal, model is founded , change character of concrete temperature is analyzed, and the development tendency of interior concrete temperature is predicted on the basis of the influencing factor-water temperature, air temperature and rock temperature by Multi-Variables grey principal. It is proved that the model founds successfully and it’s goodness-of-fit is very well. calculation base for the temperature stress of dam concrete is provided by founding ,scientific evidence is offered to prevent the temperature crack and ensure the dam safe operation ,the model has some engineering valuable significance.

Abstract: Temporary or permanent supports are necessary in underground construction for maintaining the stability and limiting the damage of surrounding rock. Due to the uncertainty of geological structure, the specificity of the underground environment as well as other factors, the quality and performance of supporting structure are often difficult to satisfy the design requirements, which not only seriously affects the normal construction and operation of mines but also has the potential threat to the safety of underground production. In order to investigate the influence of the unfavorable geologic environment on supporting concrete and evaluate the real performance of roadway supports of a mine, 17 typical projects were chosen and the strength of supporting concrete was detected by nondestructive drilling core method. The result shows that the strength is widely less than the design value. Furthermore, 4 projects of them were investigated by the ground penetrating radar (GPR) in order to evaluate the feasibility of GPR in the performance investigation of the roadway supports of a mine. The results indicate that ground penetrating radar is capable of measuring the thickness of the support, the distribution of rebars and the defects of the surrounding rock.

Abstract: In this paper，waveform is used to excite Lamb waves in the test plates during experimental testing. The optimal excitation frequency will depend on the test configuration. In order to select an excitation frequency, dispersion curves are first created to show what frequency range is best suited for Lamb wave excitation. According to dispersion curves were created for the aluminum test plates and it was concluded that a frequency below 1 MHz will be used in order to only excite the fundamental and modes. Experiments are performed on the aluminum test plates described. Experimental testing is first performed on undamaged plates in order to determine the path-to-path and test-to-test variability in Lamb wave measurements in the absence of damage. The admittance data is analyzed in order to determine if any of the PZT transducers need to be replaced because of poor bonding or mechanical failure. The sensor diagnostic technique is applied to each plate and used to ensure proper consistency between PZT transducers

Abstract: In this paper, the operating methods that the total station and the GPS as well as other equipments are employed to carry out the construction measure control have been briefly described, which have well met the needs of tower column, beams, supports and others as well as had the higher lofting precision and the obvious operating efficiency in the process of the pylon’s construction measure of Sutong Bridge. At the same time, they have also provided the technical reference for other similar projects.

Abstract: The existing concrete structures, especially hydraulic dams, in the cold areas of northern China have suffered from freeze-thaw damages to varying degrees in the small part or the vast areas of the projects. This paper will work out the performance deterioration index with the relative dynamic elastic modulus and the mass loss rate of the concrete. The test shows that there is a linear relationship between the concrete's relative dynamic elastic modulus and the increasing number of freezing-thawing cycles; the mass loss rate, however, varies with the water-cement ratio and displays different tendency of changes in the initial phase of the cycle, but the mass is decreased in the later phase. Besides, combining with the application, the writer will simulate the concrete's freezing-thawing process under actual operation conditions with the standard test data, in order to offer the presumption model of freezing-thawing durability and predict the residual freezing-thawing life of the concrete, thus providing theoretical basis for the structure's maintenance, repair, and dismantlement.

Abstract: Abstract. Corrosion of steel due to chloride ingress is a worldwide problem in reinforced concrete. In order to control such chloride-induced corrosion and evaluate the effectiveness of silane water repellent surface treatment on steel corrosion in concretes with different chloride ingress, two series of reinforced concrete specimens were used to investigate experimentally. In the first series, concrete was applied permanent migrating chloride from a reservoir of 3% NaCl solution which was placed on the top surface of each specimen. For comparison, the same concrete was made with silane water repellenet treatment correspondly. Tests were taken with half-cell potential and polarization resistance methods. Results show that steels in concrete without water repellent treatment have more negative half cell potential, higher mass loss ratio and bigger corrosion current density, and the effect of improvement through silane liquid surface treatment is evident. In the second series,concrete was same to the first one, but for wetting and drying cycle chloride ingress. Results indict that corrosion potentials decreased in negative little and later keep stable in the beginning period after water repellent treatment. Relatively for specimens without treatment, the value of corrosion negative corrosion potentials and corrosion current densities increase all the time.

Abstract: Based on finite-element analysis and some other theoretical analysis methods, the modal analysis of one pin masonry wall reinforced with the concrete wall have been researched with comparison, the results of two methods are well matched. The results showed that the modal analysis of brick walls reinforced with concrete wall could be analyzed with ANSYS software while the appropriate modle was chosen. Reference can be provided for the study of dynamic characteristics of the structure.

Abstract: Cross Correlation Function Amplitude Vector(CorV) is a method of damage detection which is based on random vibration .In this paper, CorV is introduced in the damage detection of historic timber structure according to the characteristics of structure and damage.Meanwhile,the research has been done. CorV of structural damage before and after the change has been expressed that is based on Cross Correlation function amplitude Vector Criterion(CVAC) .Results show that there is a remarkable decrease of CVAC among the CorVs between damaged and intact structures.Damage locations can be determined through the relative change of CorVs which is before or after the damage of the structure . A basis can be provided for the damage of buildings and the ancient structure protection through this paper.

Abstract: Calculation of structural course thickness is the primary task in pavement design. It will directly influence the mechanical properties, service life and the cost of pavement structure. Using BISAR3 of SHELL design method, the impacts of structural course thickness on the mechanical properties and service life of heavy load semi-rigid asphalt pavement structure were analyzed systematically. And the influencing laws of the thickness of surface course, base course and sub-base course on heavy load semi-rigid asphalt pavement service life were also discussed. According to the results of sensitivity analysis of structural course thickness and axle loads, a prediction model of service life of heavy load semi-rigid asphalt pavement was proposed. These achievements can contribute to determine the rational structural course thickness of semi-rigid asphalt pavement and ensure the service life of pavement consistent with the cost.

Abstract: In order to investigate the emergency capacity of the full prestress and A-class components under normal service conditions, vertical tensioned increment method was be applied to study the statistic discipline of effective prestress for existing PC bridges. The results showed that the statistical parameters of effective prestress obey normal distribution and ~N(0.97,0.09). On this basis, the stress-resisting probabilistic models of two kinds of components were constructed. The dead load effect probabilistic model and the vehicle load probabilistic model considering evaluation base period were established. Based on the research above, the assessment method of stress reliability for PC bridge under normal service conditions was presented.