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Shi G.,Tsinghua University | Zhu X.,East China Architectural Design & Research Institute Co.
Gongcheng Lixue/Engineering Mechanics | Year: 2017

The constitutive model of steel under monotonic loading is the basis for structure analysis. In order to calculate the response of high-strength steel structures and to analyze the member behaviour more accurately and to give some references to engineers when applying high-strength steel, this paper updated the parameters of the multi-linear constitutive model of high-strength steel and presented a nonlinear constitutive model based on the Ramberg-Osgood model by means of summarizing the experiment results and by carrying out lots of tensile tests. It has been proved that a nonlinear constitutive model could simulate the stress-strain relationship of high-strength steel under monotonic loading well by comparison with the experiment data. Moreover, to give a consideration to both accuracy and efficiency, a revised multi-linear constitutive model is proposed, which could present the nonlinear material property of high-strength steel and show the similarity in the meantime. © 2017, Engineering Mechanics Press. All right reserved.

Zhou J.-L.,East China Architectural Design & Research Institute Co. | Bao L.-J.,East China Architectural Design & Research Institute Co. | Qian P.,East China Architectural Design & Research Institute Co.
Gongcheng Lixue/Engineering Mechanics | Year: 2015

The economic design of super-tall buildings can be improved through three measures: reducing lateral loads on the structure, improving structural efficiency of lateral resistance, and selecting rational design indices. Firstly, in order to reduce lateral loads of the structure, a reasonable building shape and dampers should be considered to decrease the wind loading, and energy dissipation methods and high-strength, lightweight materials can be used to reduce the seismic loads. Secondly, in order to improve the structural efficiency, bracing structures, mega columns, and outriggers should be used. Finally, further research into several stipulated design indices of super-tall buildings is proposed so that the economy of the structure can be improved while still maintaining safety. ©, 2015, Tsinghua University. All right reserved.

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 | Year: 2016

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.

Shi G.,Tsinghua University | Zhu X.,East China Architectural Design & Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2016

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.

Zhou Y.,Tongji University | Miao C.,Tongji University | Yan F.,East China Architectural Design & Research Institute Co. | Liu Q.,East China Architectural Design & Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2015

Coupled shear walls with steel reinforced concrete (SRC) coupling beams have recently been applied in practical projects. Nonetheless, no clear requirement is specified in current codes on key parameters such as steel ratio of this technology. This research performed cyclic loading tests on coupled shear walls using SRC coupling beams with variable steel ratio. Finite element analysis with software of ABAQUS and variable parametric analysis were further conducted. The results of experiments and finite element analysis show that better failure mode and higher deformability, energy dissipation capacity and ultimate horizontal bearing capacity of shear walls with SRC coupling beams can be observed than those of shear walls with reinforced concrete (RC) coupling beams. And from the results of finite element analysis with ABAQUS, it can be concluded that the optimal steel ratio in the beams ranges from 4% to 8% and the web area of the steel should be increased. ©, 2015, Science Press. All right reserved.

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 | Year: 2015

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.

Hou S.-N.,East China Architectural Design & Research Institute Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

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.

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 | Year: 2015

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.

Gao C.,East China Architectural Design & Research Institute Co. | An D.,East China Architectural Design & Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2016

Theoretical and case studies were carried out for several outstanding issues in the engineering application of dissipative BRB. The main factors and technical parameters were discussed for the technology selection of this kind of BRB. The reasonable matching relationship between the yield capacity and axial rigidity of BRB, as well as the matching relationship between yield deformation and BRB's length were analyzed. The effective range of the two types of defined matching coefficients were given. The impact of BRB's yielding on the whole structural response index was analyzed. It was suggested that the possible structural performance degradation under rare earthquake be evaluated in the schematic design, and avoid considering the BRB's dual role of stiffness adjustment and energy consuming at the same time, or make the BRB reach yielding stage under design level earthquake. Through the calculation formula derivation of the additional damping ratio and the parametric analysis, the basic rule of the BRB's energy dissipation effect is clarified: the additional damping ratio is affected by both the structure itself and the BRB's parameters and the BRB's story shear ratio is the main controlling parameter. The additional damping ratio does not always increase with the increase of earthquake action, which has the maximum value corresponding to a seismic action. The problem about how to ensure the structure and BRB's safety in rare earthquake if the BRB reachs yielding stage from frequent earthquake is discussed, the deformation requirements in different systems and suggestions for devices improvement are given. The study results can provide theoretical reference for dissipative BRB's reasonable and efficient application in engineering. © 2016, Editorial Office of Journal of Building Structures. All right reserved.

Fang L.,East China Architectural Design & Research Institute Co. | Jin G.,Tongji University | Li J.,Tongji University | Wang Z.,Tongji University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2015

Based on the experimental results of eleven T-shaped RC short columns subjected to axial load and reasonable assumptions, the core concrete in T-shaped cross sections was divided into several regions. The analytic derivation of the effective transverse confined pressure was provided, and the equivalent uniaxial constitutive relationship was constructed for core concrete of the divided regions. The load versus strain curves of the specimens were calculated by the proposed constitutive relationship. The calculated results agreed well with the experimental results. The effects of the stirrup spacing, diameter, and yield stress of transverse reinforcement on lateral confinement were investigated in T-shaped cross sections. The results show that the stirrup spacing, diameter and yield stress of transverse reinforcement has significant influence on the axial load versus strain curves. The axial load, peak strain, and strain ductility increase, compared with the condition without the lateral confinement of transverse reinforcement. © 2015, Science Press. All right reserved.

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