Applied Mechanics and Materials Vols. 105-107

Abstract: The behavior of piles having a single defect which may be necking, bulging or of inferior concrete is simulated by an electrical model representing an electrical transmission line. The model successively simulated defective piles embedded in homogeneous soil. Through the interpretation of response curves supported by appropriate mathematical treatment it was possible to study piles having a single defect .The type of defect can be identified from the response curve by comparing the pile head stiffness of suspect pile with that of a similar but sound pile in the same site. The location of the defect can be determined by measuring the interval between resonating peaks at higher frequencies. For the same defect location along the shaft of piles in a given site, it can be differentiated between resonating large peaks for piles with bulging and necking.,The behavior of piles having a single defect which may be necking, bulging or of inferior concrete is simulated by an electrical model representing an electrical transmission line. The model successively simulated defective piles embedded in homogeneous soil. Through the interpretation of response curves supported by appropriate mathematical treatment it was possible to study piles having a single defect .The type of defect can be identified from the response curve by comparing the pile head stiffness of suspect pile with that of a similar but sound pile in the same site. The location of the defect can be determined by measuring the interval between resonating peaks at higher frequencies. For the same defect location along the shaft of piles in a given site, it can be differentiated between resonating large peaks for piles with bulging and necking.

Abstract: The stress intensity factors (SIFs) of biomaterial interface crack were analyzed using the Composite Grid Method (CGM). Two different scale grids were adopted: a coarse mesh for the whole area without considering interface crack and a fine mesh for the local singular area considering the impact of interface crack. It solved the global coarse mesh problem and the local fine mesh problem iteratively and obtained the final results. The calculation was carried out by CGM but without the demand of dense mesh near the crack tip and special crack tip elements compared with other methods. The numerical extrapolation method of determining the SIFs to avoid the oscillation singularity of asymptotic fields of elastic interface crack. Reasonable agreement was achieved and efficiency of CGM for such kind of problem was displayed.

Abstract: Rocks and other rocklike solid materials have inherent defects inside. The defects of rock will be evolved under loading. The evolution process and extent of defects can be described by the damage variable. But which physical or geometrical parameters can be used to define the damage, there has no consistent conclusion domestic and aboard. Moreover, limited by the method of experimental, it is difficult to obtain the parameters to depict the damage variable directly. In order to obtained the evolution law of the interior defects in the solid material, the non-conduct geophysical prospecting measure as AE (Acoustic Emission) will be the leading measure to prospect the interior defects and it’s evolution under outside loading. In the present paper, the AE method was used to obtain the AE parameters during the uniaxial compression process of coal and rock. Therefore, uniaxial compression and AE tests on coal and mudstone were conducted, and the curves among the AE energy accumulation, stress and strain were obtained after analyzing the results of tests data. Based on the principle of damage mechanics and thermodynamics, the damage evolution of coal and rock was deduced through analyzing the experimental results, the curves of damage and AE accumulation were obtained also. By analyzing and fitting the curves of damage and AE energy accumulation, the relation between the AE energy accumulation and stress-strain was obtained and verified through the experimental data.

Abstract: Based on modern ideas of thermomechanics, small strain dynamic dissipation function of Hardin-Drnevich model for soils is formulated using the assumptions of the beeline and the skeleton curve shift laws. Fundamentally, for cohesionless soils, two types of cyclic strain thresholds are identified: first threshold strain and second threshold strain represent boundaries between fundamentally different dynamic characteristics of cyclic soil behavior. Comparison between the two threshold shear strain values and dynamic degradation curves obtained on exactly the same soils, the results showed that the ratio of secant modulus and maximum dynamic shear modulus for the first threshold strain are almost 1.0, and the damping ratio is almost constant. When dynamic strain level exceeds the second threshold strain, the soil behavior is considerably at nonlinear, and the primary deformation mechanism is related to fabric changes during cyclic loading. The first and the second threshold strains are therefore essential for the understanding and solving soil dynamic problems.

Abstract: Based on the classical theory, and according to the structural features of SMA (stone matrix asphalt), this paper analyzes the road performance of SMA such as high-temperature stability, etc. The analytical result shows that good road performance of SMA comes from its structural characteristics. Through analysis of SMA design methods adopted in different countries, The tests are carried out in the following procedures: this paper has studied aggregate gradation to ensure which kind of coarse aggregates contributes more for high-temperature stability. The coarse aggregate of equal size is used as sample to do Marshall test (Asphalt compound test ) and rutting test. According to the analysis of test results, it is difficult to decide which kind of coarse aggregates does more contribution for high-temperature stability of SMA, and therefore, comprehensive analysis should be made on coarse aggregates of different grades so as to achieve satisfactory result.

Abstract: The delimitation is a frequent and danger failure in concrete-filled steel tube. The ultrasonic testing is an important method of NDT and it is usually used in detecting concrete-filled steel tube’s flaw .The ultrasonic signal include time parameter, frequency parameter, amplitude parameter and waveform parameter . At the present time the detection is mainly based on time parameter,not included the other parameters.The frequency parameter is sensitive to flaw in detecting.The artificial neural networks (ANN) is applied in order to enhance the detection's accuracy standard. Inputting the ultrasonic signal's time parameter and frequency parameter as characteristic number, through training and learning,we can indentify the failure's style. Though carrying out the combined diagnosing system into practical testing, the approving quantitative results is gained.

Abstract: AZ80 magnesium alloy was semi-continuously cast under different physical fields which were conventional direct chill (DC) casting, low frequency electromagnetic casting (LFEC), ultrasonic casting (USC) and electromagnetic-ultrasonic combined casting (ECUC), respectively. The effect of different physical fields on solidification structures of AZ80 alloys was investigated. The results show that compared with the conventional DC casting, structures of AZ80 alloys billets cast with LFEC and USC have been greatly refined. The effective refinement takes place in the edge of billets when LFEC is applied. However, the effective refinement takes place in the center of billets when USC is applied. When combination of low frequency electromagnetic and ultrasonic fields is applied during semi-continuous casting AZ80 magnesium alloy billet, structures of AZ80 alloys are refined significantly in the whole billets everywhere and more uniform.

Abstract: Abstract. In this paper, the elasto-plastic dynamic analysis on the steel spatial arch truss with 30 m span and 0.1 rise-span ratio is carried out under earthquake wave with SAP2000. In the analyses, the geometric and material nonlinear effects are considered at the same time based on the plastic-hinge theory. Under the action of EL wave with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL earthquake wave when applied in horizontal direction is 517 gal, and is 387 gal when applied in vertical direction; The ratio of its maximal node horizontal displacement and its structural height is 1/96, and its displacement ductility coefficient is 2.636; The ratio of its maximal node vertical displacement and its structural span is 1/589, and its displacement ductility coefficient is 1.08.

Abstract: As it involves the safety of flight and passenger’s life, requirement for intelligentized project construction of airport terminal is considerably high. We firstly analyze the basic structure of intelligentized project for airport terminal, subsequently make mainly research on the three sub-systems included in the dedicated civil aviation intelligence system, further analyze the latest developing trend of the current international intelligentized airport terminal system, and in the end, make strategic proposals with a view to solve the problem in the country’s terminal-junction airport intelligentized construction. This research will be sound reference for intelligentized airport terminal construction.

Abstract: Under the Guidance of Smart Growth Theory, the paper respectively discusses the spatial patterns including ecological network, waterfront accessible space and transit-oriented patterns through the analysis of project background and development conditions of Harbin Songbei New District Planning, and explores the functionally-integrated spatial layout patterns suitable for the development of Songbei New District through comparison and selection of various schemes, as well as analyzes the guidance and application of Smart Growth Theory in intensive urban development in order to propose reasonable measures and suggestions for the development planning of the New District.