Applied Mechanics and Materials Vols. 193-194

Abstract: Aroused by the differential stiffness of pile and soil, the upper load on subgrade is apt to be transferred to pile rather than soil among piles in pile supported embankment(soil arching effect), which optimizes the load-transfer path and effectively limits total settlement of the subgrade. In this paper the properties of soil arch under dynamic load have been investigated by performing numerical studies using the Finite Element Method. The influence of stiffness difference between soil and pile on the soil arch is also proposed in this paper. According to the calculation results, the softer the soil between piles is, the larger proportion of load imposes on pile. Dynamic load has negative effects on the static soil arch, but it does not ruin the shape of the arch. Simultaneously, the larger N (the ratio of dynamic modulus of pile to that of soil)is, the weaker the negative effects of dynamic load on static soil arch are. The static soil arch (soil arch formed when the model only bears static load) has optimized the load transformation path, leading more load undertaken by the pile. Besides, When the stiffness difference between pile and soil among piles is relatively small, the height of soil arch increases sharply with the decrease of N; while when the stiffness difference reaches some certain value, the further increasing of N has little influence on soil arch’s height.

Abstract: In this paper, according to the characteristics of near-fault earthquakes, combined with the strong ground motion attenuation law in China, the nonstationary power spectrum of bidirectional ground motion input is obtained through random vibration analysis. By introducing the pseudo excitation algorithm, the evolutionary power spectral density (PSD) of acceleration at the engineering bedrock is handled as the nonstationary pseudo input, and the Hardin-Drnevich hyperbolic model is utilized to take into account the nonlinearity of soil layer. On this basis, finite element method in the time domain and frequency domain are used for seismic response analysis of soil profile. Values including various time-varying power spectral density of the dynamic response, time varying RMS and time-dependent reliability at different threshold can be obtained by calculating, which provides a basis for the analysis of the foundation dynamic reliability assessment.

Abstract: An optimal design method for the maximum load of three-point bending concrete beam is proposed in this study. The statistics model is built according to the theory of GR resistance curve. With the help of least square method and Matlab® computing platform, the optimal design results are very similar of the experimental results, and thus a new criterion for unstable fracture in crack extension resistance curve theories is constructed. It can able to monitor safety and stability of specimens in engineering practice at any time.

Abstract: Full-scale of U-type and grooved-type slotted end plate (SEP) connections are tested to determine their failure modes and damage mechanisms under ultimate loading. Simulate on mechanical behaviors of U-type and grooved-type SEP connections under compression using finite element software ANSYS based on the experimental research. Obtain load-vertical displacement curves of the SEP connections, and compare with the experimental results to determine the validity of the model. On this basis, this paper provide the improved SEP connections, and contrast with the U-type and grooved-type SEP connections. The results indicate that finite element results are in good agreement with experimental data. Difference of the ultimate load between the test specimen and finite element model is less than 10%. The finite element can simulate mechanical behaviors of the SEP connections better. The ultimate bearing capacity of the UC-type SEP connected joints is significantly higher than the U-type and grooved-type, which shows the improved SEP Connections is reasonable and effective. SEP is the main factor of the U-type and grooved-type SEP Connections’ ultimate load, tube is controlling factor of the UC-type SEP connected joints.

Abstract: Polyethylene terephthalate containers (PET bottles) are recycled into fibers and sheets, but the complicated process requires a high level of technology and large cost resulting in a low recycling rate of PET. Weight reduction of concrete has been demanded for certain uses. In view of this, lightweight concrete embedding raw PET bottles is conceivable. It may be used for void slabs and lightweight wall panels for dwelling units. Also such bottles filled with functional materials can add a new function to concrete. In this study, the basic physical properties of lightweight multifunctional concrete embedding used PET bottles were investigated. A method of placing concrete with embedded PET bottles was examined. PET bottles fixed to the mold at their caps withstood the impact and the pressure during concrete placing with no deformation and the filling capability of concrete was confirmed. The weight reduction of the reinforcing concrete panel embedding PET bottles was approximately 16%. The strength properties of concrete embedding PET bottles were examined and the compressive strength of the specimen embedding bottles with the smallest intervals between bottles was 55% of that of the solid concrete specimen.

Abstract: Structural characteristics of tensile-compression prestressed concrete are introduced briefly in this paper. Firstly, with current concrete structure design code（GB50010）, requirements for materials used in tensile-compression prestressed concrete structure are put forward; and for prepressing stress steel pipe, strength value and basic types for structure design are determined. Secondly the calculation method of prestress loss is given during each work stage of tensile-compression prestressed concrete; and the basic measures of cracking control are concluded. Thirdly, bearing capacity formula of tensile-compression prestressed concrete structure and stress checking formula of menbers in construction stage are provided. Finally structure design of tensile-compression prestressed concrete is unified

Abstract: The suspension bridge contained damage was made as the object of study. Three different damage conditions for suspension bridge were calculated(conditions 1, the left midspan contains a damaged zone, condition 2, the left end bay contains two damaged zone, condition 3, both sides midspan contains a damaged zone). Using the wavelet analysis theory, solving strain modal parameters of the suspension bridge with cracks by means of Lanczos method. Then the cracks location of the suspension bridges could be identified by the maximum of wavelet coefficients. It can be concluded that the method using wavelet analysis of strain mode is more accurate and more effective through the calculation and analysis of the suspension bridge damage identification. The method can be useful in the suspension bridge damage identification and diagnosis.

Abstract: A numerical study is performed to investigate the stress concentration phenomenon in a piled embankment during high-speed train passage. In the numerical simulation, the loading of a moving train is first represented in the model as a series of time-varying equivalent concentrated forces vertically acting on the ballast surface, and the explicit finite element method (FEM) is then used to analyze the ballast-embankment-ground system subjected to the equivalent forces. The study shows that owing to the very high stiffness of the piles relative to the soft soil, a majority of the wave energy, which is generated by the passage of wheel axles, is concentrated to the improving piles and transferred down to the stiff soil stratum. By this stress concentration phenomenon, the soft soil surrounding the piles is subjected to less stress, and thus preventing undesirable dynamic effects that could be induced in the soft soil.

Abstract: In the rush for modernization, many of the Chinese cities are in the abrupt disappearance of character and identity of the unique places. Urban open space has lost its sense of place. This paper analyzes the applicability of group form theory within today’s dynamic environment by taking Maki’s Hillside Terrace complex as an example. The development of Hillside Terrace complex is resilient and adaptable to changes over time. It preserves the original spirit and character by creating urban open spaces for all kinds of human interaction. It provides inspiration for today's urban design.

Abstract: Based on theoretical research, waveform curve of shock wave and the pressure data of underwater group of satchel charges were measured by doing the monitoring test in the waterway dredging project of the second-phase construction in Gulei Xiamen. Characteristics and the law of its propagation of shock wave in water produced by the explosion were analyzed, the conclusion which the single dosage is 110 ~ 500kg while the total dosage is 730 ~ 4710kg and the blasting distance is from 74.5 to 220m was given. Semi-theory-semi-experienced formula of the shock wave on this condition was verified. Much valuable experience has been accumulated for the further research.