Applied Mechanics and Materials Vols. 166-169

Abstract: According to the service environment of light rail transit and subway structures, in this paper experiments on the corrosion characteristics of reinforced concrete under single corrosion environment of stray current, single corrosion environment of chloride ions and joint corrosion environment of stray current and chloride ions were respectively carried out. Loading direct current electric field was used to simulate the stray current. The experimental results showed that, the corrosion growth process of the rebar in reinforced concrete under single environment of chloride ions was slow and stable, while that under single environment of stray current being separated two stages, i.e., rapidly increasing stage and stably varying stage. In addition, the rebar of reinforced concrete in stray current alone environment was corroded faster than that in chloride ion alone environment did; when stray current and chloride ion coexist, the stray current speeded up the chloride ion transportation, which gave rise to the increase of the corrosion rate of the rebar of reinforced concrete; the corrosion degree of the rebar depended on the chloride ion concentration, stray current strength and test time. The stronger the stray current strength, the longer the stray current corrosion period and the heavier the chloride ion concentration, the more the corrosion products of the rebar and thus the more serious the reinforced concrete deterioration.

Abstract: The accuracy of artificial boundary conditions plays an important role in the dynamic finite element analysis of unbounded media. By loading the solid skeleton an uniformly distributed triangular pulse on the approximate stress boundary and the original stress boundary respectively, the accuracy of the approximate artificial boundary is analysed. The calculation difference of radial displacement decreases with the increase of distance from artifical boundary to the scattering center, i.e. only when the artificial boundary are far enough can the accuracy be satisfied.

Abstract: Based on the test results of steel reinforcement high strength high performance concrete (SRHSHPC) frame beams, a new seismic damage model of SRHSHPC frame beams considered the strength and stiffness degradation was proposed, which was a non-linear combination of the deformation and accumulative damage. The results can more clearly reflect the laws of strength and stiffness degradation of SRHSHPC frame beams under reversed loading. The study results can supply the theory support for the seismic damage assessment and the establishment of damage-based earthquake-resistant design method of SRHSHPC members.

Abstract: Based on Newmark-β gradual integration method and elastic-plastic mechanical theory, numerical analyses of the effects of soft soil depth and thickness on the characteristics of seismic response of free bank field with soft soil layers are conducted by using finite element program Midas/GTS. The numerical results show that the high frequency components of seismic excitations can be filtered and the low frequency components are amplified correspondingly when seismic waves are transmitted through the free bank field from the bedrock.

Abstract: Several integrations of the plane wave functions frequently appearing in the scattering problems of elastic waves are considered in this study. In conjunction with the principle of superposition and the stationary wave function expansion, the exact solutions are obtained. As in the scattering problems of elastic waves and plane waves, the theoretical solutions can improve the convergence speed of the arithmetic and the computation precision. The analysis method and the analytical solutions can also be very helpful to solving other complex integrations in relation with the cylinder functions and plane functions.

Abstract: Recent earthquakes indicate that tunnels can not be considered as structures invulnerable to earthquakes, especially in areas crossing a fault. Seismic damage, such as falling, fissure and dislocation of the tunnel lining may happen at location of fault. Under the action of earthquake, two kinds of loads may occur, which are the fault movement and the function of seismic wave. In order to analyze the seismic damage to cross-fault tunnel, the seismic characters under each kind of load are studied by using finite element method. Some meaningful conclusions have been achieved. Under the condition of strike-slip fault, the stress of tunnel concentrated at the position of fault, and the stress in both active and driven plate is small. The influence degree of reverse fault is between the other two kinds of faults. By enhancing the lining materials stiffness, the displacement of tunnel decreased, but the peak acceleration and first principle stress of it increased and the position of max-displacement also changed.

Abstract: According to the investigation on historic structures in Zhaohua Ancient City, there are a total of 210 historic structures in the city, of which the historic timber structures account for 93.8%, namely 197 in total. In this paper, damage degrees of the historic timber structures have been determined, although the timber structures had not considered seismic design when they were built, nearly 60% of the historic timber structures are of relatively minor damage. Besides, based on the analysis on seismic damage of the historic timber structures, the failure modes of the timber structures have been concluded, namely the tenon pullout or tenon break-off, the pillar break-off, the pedestal slip and the retaining wall damage.

Abstract: The Taizang tower was the research object in this paper. The field of stress and displacement before and after reinforcement were calculated under seismic load. The dynamic response and variation regularity were obtained using dynamic finite element method (FEM). The results show that: Taking reinforcement measures, maximum displacement can obviously decrease and the distribution of stress tends to be uniformity. Reinforcement measures can improve the stability of the soil site.

Abstract: Basing on the characteristics of modernization of cities and requirements of seismic shelters for evacuation, the general principles and comprehensive evaluation methods based on multi-criterion for seismic shelters for evacuation were put forward. In addition, the evaluated indexes, choice methods, coverage ranges and area of responsibility problems of every shelter were also studied in this paper. In final, specific methods and steps for seismic shelters for evacuation were given using GIS.

Abstract: Structural destroy is a development process that damage is accumulated gradually under earthquake, and the partial destruction leads to the overall damage, even structural collapse finally. Based on the damage model of beam, column and shear wall, the damage is studied from the component level, the most important design parameters which include bending strength ratios of beam to column, xial compression ratio and stiffness characteristic value are researched. Then the finite element numerical analysis software ABAQUS is used to analyze the influence of various component damage on seismic performance of floor. Finally, this paper adopts Weighting Coefficient Method to establish a reasonable model for the floor damage evaluation .It proves that the model can reflect the relationship between component damage and floor damage.