Advanced Materials Research Vols. 446-449

Abstract: In this paper, based on the transient moving load equivalent radius, multiple non-point source within as multiple small non-point source, ground vibration amplitude for multiple small non-point attenuation stack, on the basis of considering the ground more than car parallel, will vehicle load simplified as parallel concentrated load, according to the harmonic waves equivalent radius, considering different soil types of geometric attenuation coefficient, gives a practical formulas with ring road of ground vibration attenuation caused by parallel vehicles. And through the comparison between the Xi’an bell Tower ring road traffic vibration decays monitoring and calculation results, the practical formulas are verified.

Abstract: In the paper, the conclusion on the effect of micro-crack damage on the chloridion permeability of concrete are drawn through the multi-direction splitting tests and the chloridion permeable tests for cracked concrete specimen. Limited units numerical simulation method are applied to simulate the whole process of concrete splitting and cracking and further analyse crack spreading rules to testify and explain the test results. Numerical simulation represents the complete process of concrete materials that include the initiation, propagation, and penetration of microcracks. It is feasible to simulate the cracking process of concrete because the analysis results on the patterns are consistent with testing results. At the same time, numerical simulation analysis results about transverse displacement, cracking process of microcrack can testify and explain testing results. Therefore, numerical simulation method is instructional for study of concrete durability.

Abstract: 12 RC columns specimens are divided 4 groups which have different eccentricities. Each group has 4 specimens, The first specimen was just made of reinforced concrete. The second was wrapped with 3 lays CFRP. The third had steel fibres added to it. The last was reinforced with steel fibres and wrapped with CFRP.The results showed that the introduction of fibres as well as wrapping the specimens with FRP improve the strength of concrete,especially its ductility.

Abstract: In the process of survey data processing, solving problem can usually be attributed to linear equations like Ax=b, but under some circumstances, the equations may be ill-conditioned, if conventional method of MATLAB still be used in programming, the solution worked out may not be the true one. To solve this problem, method of introducing symbolic calculation into programming has been proposed in order to make ill-conditioned feature of designed equations better and improve stability and accuracy of parameter, the superiority in GNSS elevation fitting has been proved by triple-order polynomial curve-fitting method.

Abstract: Chloride ion diffusion coefficient is an important indicator reflected the concrete durability in chloride erosion environment, and affects the service life of concrete structure directly. By the indoor test of chloride acceleration permeability, the chloride ions diffusivity is studied in the tunnel lining structure, and the variation law of the chloride content is tested with the change of penetration depth of different age specimen. Tests shows, with the increases of the penetration depth, the chloride content decrease gradually and finally tend to the initial chloride content of the specimen. Penetration time has a strong cumulative effect on the internal concentration of chloride ions in concrete, the high or low level of chloride ion concentration have a role of promotion or reduction for the chloride ion penetration in the concrete inside. The results provide an important basis for the predictions of service life of tunnel lining in chloride erosion environment.

Abstract: Analysis and calculation methods of reinforced concrete structure at present are based on test results of small-size component. This paper carried out test research on size effect of flexural capacity of RC cantilever beams. Sectional height of the biggest experimental specimen is 1000 mm. Obtaining detailed test data during different loading stage, such as carrying capacity, deflection, steel and concrete strain etc. Through observing test phenomenon and analyzing test data, verifying the safety to calculation formulas for ultimate bearing capacity of flexural members. Strength and ductility reserves show a growing trend with specimen size increasing.

Abstract: To study the bond behavior and the force transference of FRP plates adhered to masonry. In this paper, experiments of anchorage strength of FRP attached to masonry are done, a 100KN capacity hydraulic jack activated by a manual pump was used to load the specimen. The tensile strength was measured by using a loading transducer, and strain gauges were mounted directly onto the surface of the FRP composite to measure the strain during application of load. Besides the strain and bond stress development and distribution under every grade of loading were studied. Test results show that the maximum local bond stress is not influenced by the FRP bond length, instead it increases with masonry strength. At the same time, the local bond stress--slip curve is obtained. Based on the test results, two new bond stress-slip constitutive models between FRP and masonry were proposed and they turned out to be good matches to the experimental results, which indicate its valuable references for the corresponding codes and engineering applications.

Abstract: In order to solve structural damage identification problem, a damage identification method based on improved Particle Swarm Optimization (IPSO) is presented. First, structural frequency and modal strain energy are utilized to obtain damage information. Then, evidence fusion theory is utilized to integrate the information and preliminarily identify structural damage locations. After the damaged locations are determined, Particle Swarm Optimization (PSO) is used to identify structural damage extent. Some improved strategies are presented to enhance the search efficiency. The simulation results demonstrate that the proposed method can estimate the damage locations and extent with good accuracy.

Abstract: One of the main reasons for the damage of reinforced concrete is the expansion caused by corrosion of steel bar in concrete. In this paper, the equivalent circuit that inflects corrosion process of steel bars in reinforced concrete was analyzed, with the A.C.Impedance Spectrum method. And the effects of surface treatment of the bars on corrosion resistance of the reinforced concrete were investigated. Study results show that the surface coating (plating) on the built-in reinforcement can effectively prevent corrosion of steel bar, thereby enhancing the durability of concrete structures.

Abstract: Elevation control survey was the foundation of the surveying for ancient architecture profile and facade. The traditional survey method of closed leveling line had many defects such as its workload was big; its calculating office work was complex and so on. The new method used many control points existing in reality, then sublevel surveyed independently. The new method also used the traditional adjustment method and weighting adjustment method. It accelerated the survey progress and increased the survey precision.