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Hou S.-N.,East China Architectural Design & Research Institute Co.
Yantu Lixue/Rock and Soil Mechanics

Based on the horizontal static load tests on 57 single-piles of 12 sites in Shanghai, the bearing capacity of single pile under the action of horizontal load is studied. According to the test data, the effects of different pile diameters, and different loading methods and grouted pile stress characteristics of prestressed hollow are explored. For the architectural engineering, the larger pile diameter or the pile diameter enlarging top within a certain range are suggested to optimize the design of horizontal bearing capacity of singe pile. The loading test is suggested by the single cycle constant speed horizontal loading method; the safety of prestressed hollow core can be used as filling pile top horizontal bearing capacity. The study results will be useful for the design of lateral bearing capacity of single pile. ©, 2015, Academia Sinica. All right reserved. Source

Zhang Y.,Tongji University | Wu J.-B.,East China Architectural Design & Research Institute Co. | Cai Y.-C.,Tongji University
Yantu Lixue/Rock and Soil Mechanics

Geddes's method is widely applied to estimate the settlement of pile group in China with its simple principle and easy realization. However, Geddes's method has its own obvious shortcomings. The influence of pile diameter is not considered in Geddes's method which can produce great stress concentration on the pile tip. Moreover, the distribution of shaft resistance of long piles under vertical working load is quite different from the suggested one of Geddes's method. In order to solve these problems, based on Geddes's method, a modified assumptions is presented, i.e. the end resistance uniformly distribute on the pile tip and the shaft resistance distributes on the side surface of the pile. Mathematical integration and Gauss integration are applied to estimate additional stress in the soil, which can significantly decrease the influence of stress concentration. Meanwhile, calculation formula of additional stress in the soil of bilinear distribution pattern is deduced by the combination of Geddes's method. Case studies show that the settlement predicted by modified Geddes's method is smaller than that predicted by Geddes's method. ©, 2015, Academia Sinica. All right reserved. Source

Wang Z.-F.,Shenyang Jianzhu University | Sui W.-N.,Shenyang Jianzhu University | Li G.-C.,Shenyang Jianzhu University | Wu Q.,East China Architectural Design & Research Institute Co. | Ge L.,Shenyang Jianzhu University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport

In order to investigate failure mechanism and seismic performance of partially concrete-filled steel (CFS) circular bridge piers, the elastio-plastic mechanical behavior experiment and numerical analysis of partially CFS circular piers were carried out under constant axial load and cyclic lateral load. At the same slenderness ratio and radius-thickness ratio, 8 specimens in two series had been examined to study the impact of the filled concrete height on the maximum strength and the ductility. And in order to study the stress distribution and deformation damage of specimens, these 8 specimens had been numerically analyzed by nonlinear finite element analysis ABAQUS package. The results show that through comparison with hollow steel tube piers, partially CFS circular piers behave better in seismic performance. As the filled concrete ratio ξ increases, the maximum strength and ductility of the pier are improved significantly. However it can be found that when ξ reaches 0.28, though the maximum strength of the pier (SC34-66 series) is improved as ξ increases, the ductility declines. It is found that stress concentration occurs at the root of steel tube and the distribution of equivalent plastic strain of concrete is large while structure fails through FEM analysis, which indicates that the steel tube and concrete together resist the external loads effectively. ©, 2015, Xi'an Highway University. All right reserved. Source

Ni H.,Zhejiang Industry Polytechnic College | Ni H.,Hohai University | Xu W.,Hohai University | Wang W.,Hohai University | And 3 more authors.
Arabian Journal of Geosciences

The study of scale effects plays an important role in the evaluation of mechanical properties of rock masses. There have been many studies on this topic; however, few have been able to effectively analyze relationships between size and deformation properties analytically. This paper presents an investigation of scale effects on deformation properties of jointed rock masses by using analytical and statistical methods. First, the analytical formula for Eeq (equivalent elastic modulus) of jointed rock with a parallel joint set was derived. This derivation is related to a geometrical parameter ρ’, defined as joint trace length per unit area. Second, model of a half-space rock with a parallel joint set was constructed and subsequently sampled to specimens with different locations and lengths. The expectation and standard deviation of the ρ’ of rock samples were derived to statistically describe scale effect of ρ’. Then, the scale effect of 1/Eeq (equivalent elastic compliance) was analyzed. The investigation shows that expectation of 1/Eeq is a constant with varying size and standard deviation of 1/Eeq decreases and periodically fluctuates with increasing size. The applicability of the conclusions was discussed, and some extended studies on stochastic jointed rock masses were made. Finally, representative elementary volumes of the rock model were determined according to the analytical solutions. © 2016, Saudi Society for Geosciences. Source

Shi G.,Tsinghua University | Zhu X.,East China Architectural Design & Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures

In the current Chinese steel structure design codes, there is only the design value for Q345 GJ steel. In order to complete the design values of other grades of GJ steel (mainly Q390GJ, Q420GJ and Q460GJ steels), this paper analyzes the reliability of domestic steel plates for building structures. Based on the statistical research on the material properties of Q390 GJ, Q420 GJ and Q460 GJ steels and the researches on the uncertainties of geometrical parameters and models of steel structures, the statistical parameters of GJ steel resistance uncertainty were calculated. Utilizing the check-point method, the partial factors for resistance of GJ steel under different load combinations were then obtained. Varying patterns of the partial factors for resistance were also analyzed. After comparisons and trials, this paper has suggested the partial factors for resistance and design values of strength of GJ steel under different circumstances. The reliability of the above design values was calibrated. The result shows that, the design values which are suggested in this paper satisfy the demands in the Unified standard for reliability design of engineering structures (GB 50153-2008) and have sufficient reliability. © 2016, Science Press. All right reserved. Source

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