Analytical Solutions of Deformation of Uplift Belled Group Piles considering Reinforcement Effect

Wenjuan Yao,Lu Xiao 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3

Up to now, the design method of uplift piles have still imitated the design of compressive piles, which results in that computation design theory is far behind of the engineering practice. As the interaction of piles has been very prominent and important in the deformation of pile groups, the deformation of the group piles has become the urgent issues in engineering applications. Based on the theory of elastic mechanics and principle of pile load transfer, it is derived that the nonlinear analytical expressions of deformation of uplift belled group piles considering reinforcement effect, and the specific calculation steps are given. The validity of the analytical method is verified through the comparison of the pictures, which consist of the calculated data of the analytical solution, the measured date of the model test and the results of finite element analysis. The results unveils that properties of soil, the expanded body of pile and the length of pile has impact on the deformation of uplift belled group piles considering the reinforcement effect significantly. With the increasing of elastic modulus of soil, the expanded body of pile and the length of pile, the uplift deformation of uplift belled group piles is reduced.

Nonlinear large deflection buckling analysis of compression rod with different moduli

Wenjuan Yao,Jianwei Ma,Jinling Gao,Yuanzhong Qiu 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.5

Many novel materials exhibit a property of different elastic moduli in tension and compression. One such material is graphene, a wonder material, which has the highest strength yet measured. Investigations on buckling problems for structures with different moduli are scarce. To address this new problem, firstly, the nondimensional expression of the relation between offset of neutral axis and deflection curve is derived based on the phased integration method, and then using the energy method, load-deflection relation of the rod is determined; Secondly, based on the improved constitutive model for different moduli, large deformation finite element formulations are developed and combined with the arc-length method, finite element iterative program for rods with different moduli is established to obtain buckling critical loads; Thirdly, material mechanical properties tests of graphite, which is the raw material of graphene, are performed to measure the tensile and compressive elastic moduli, moreover, buckling tests are also conducted to investigate the buckling behavior of this kind of graphite rod. By comparing the calculation results of the energy method and finite element method with those of laboratory tests, the analytical model and finite element numerical model are demonstrated to be accurate and reliable. The results show that it may lead to unsafe results if the classic theory was still adopted to determine the buckling loads of those rods composed of a material having different moduli. The proposed models could provide a novel approach for further investigation of non-linear mechanical behavior for other structures with different moduli.

Stability analysis of bimodular pin-ended slender rod

Yao, Wenjuan,Ma, Jianwei,Hu, Baolin Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

Many novel materials, developed in recent years, have obvious properties with different modulus of elasticity in tension and compression. The ratio of their tensile modulus to compressive modulus is as high as five times. Nowadays, it has become a new trend to study the mechanical properties of these bimodular materials. At the present stage, there are extensive studies related to the strength analysis of bimodular structures, but the investigation of the buckling stability problem of bimodular rods seems to cover new ground. In this article, a semi-analytical method is proposed to acquire the buckling critical load of bimodular slender rod. By introducing non-dimensional parameters, the position of neutral axis of the bimodular rod in the critical state can be determined. Then by combining the phased integration method, the deflection differential equation of bimodular pin-ended slender rod is deduced. In addition, the buckling critical load is obtained by solving this equation. An example, which is conducted by comparing the calculation results between the three of the methods including the laboratory tests, numerical simulation method and the method we developed here, shows that the method proposed in the present work is reliable to use. Furthermore, the influence of bimodular characteristics on the stability is discussed and analyzed.

Stability analysis of bimodular pin-ended slender rod

Wenjuan Yao,Jianwei Ma,Baolin Hu 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

Many novel materials, developed in recent years, have obvious properties with different modulus of elasticity in tension and compression. The ratio of their tensile modulus to compressive modulus is as high as five times. Nowadays, it has become a new trend to study the mechanical properties of these bimodular materials. At the present stage, there are extensive studies related to the strength analysis of bimodular structures, but the investigation of the buckling stability problem of bimodular rods seems to cover new ground. In this article, a semi-analytical method is proposed to acquire the buckling critical load of bimodular slender rod. By introducing non-dimensional parameters, the position of neutral axis of the bimodular rod in the critical state can be determined. Then by combining the phased integration method, the deflection differential equation of bimodular pin-ended slender rod is deduced. In addition, the buckling critical load is obtained by solving this equation. An example, which is conducted by comparing the calculation results between the three of the methods including the laboratory tests, numerical simulation method and the method we developed here, shows that the method proposed in the present work is reliable to use. Furthermore, the influence of bimodular characteristics on the stability is discussed and analyzed.

SP0454, A Putative Threonine Dehydratase, Is Required For Pneumococcal Virulence In Mice

WenJuan Yan,Hong Wang,WenChun Xu,KaiFeng Wu,Run Yao,XiuYu Xu,Jie Dong,YanQing Zhang,Wen Zhong,XueMei Zhang 한국미생물학회 2012 The journal of microbiology Vol.50 No.3

Increasing pressure in antibiotic resistance and the requirement for the design of new vaccines are the objectives of clarifying the putative virulence factors in pneumococcal infection. In this study, the putative threonine dehydratase sp0454 was inactivated by erythromycin-resistance cassette replacement in Streptococcus pneumoniae CMCC 31203 strain. The sp0454 mutant was tested for cell growth, adherence, colonization, and virulence in a murine model. The Δsp0454 mutant showed decreased ability for colonization and impaired ability to adhere to A549 cells. However, the SP0454 polypeptide or its antiserum did not affect pneumococcal CMCC 31203 adhesion to A549 cells. The sp0454 deletion mutant was less virulent in a murine intranasal infection model. Real-time RT-PCR analysis revealed significant decrease of the pneumococcal surface antigen A expression in the sp0454 mutant. These results suggest that SP0454 contributes to virulence and colonization, which could be explained in part by modulating the expression of other virulence factors, such as psaA in pneumococcal infection.

Non-salt roasting mechanism of V–Cr slag toward efficient selective extraction of vanadium

Zhichao Yao,Qing Zhang,Ling Wang,Wenjuan Zhang,Baozhong Ma,Chengyan Wang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

Developing a clean method for the sustainable utilization of reducing slag containing vanadium and chromium(V–Cr slag) is necessary, with the non-salt roasting method exhibiting considerable potential. Inthis study, we conducted a detailed analysis of the mechanisms driving non-salt roasting of the V–Cr slagby investigating phase transformations, valence transition, and redistribution of vanadium and associatedtransition elements. Based on our findings, we performed efficient selective extraction experimentsand revealed that spinel (Fe,Mn)(V,Cr)2O4, the carrier of vanadium, is converted to acid-soluble products,including VO2, Mg2V2O7, and Mn2V2O7, and acid-insoluble products, such as (Fe,Cr)2O3, TiO2, MnO2, andFe2TiO5 at a roasting temperature of 700 C; At roasting temperatures > 850 C, MnO2 is converted to halfMn2V2O7 and half (Fe,Cr,Mn)2O3. Vanadium is separated from Fe, Cr, Ti, Si, and half Mn via selective leaching. Under optimized conditions, the leaching efficiency of V reached 94.55%, and those of Fe, Cr, Ti, Si,and Mn were 0.71%, 0.50%, 0.44%, 0.23%, and 50%, respectively. This study provides a technical and theoreticalbasis for cleaner and safer utilization of V–Cr slag.

Analytical and numerical study of temperature stress in the bi-modulus thick cylinder

Jinling Gao,Peikui Huang,Wenjuan Yao 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.1

Many materials in engineering exhibit different modulus in tension and compression, which are known as bimodulus materials. Based on the bi-modulus elastic theory, a modified semi-analytical model, by introducing a stress function, is established in this paper to study the mechanical response of a bi-modulus cylinder placed in an axisymmetric temperature field. Meanwhile, a numerical procedure to calculate the temperature stresses in bi-modulus structures is developed. It is proved that the bi-modulus solution can be degenerated to the classical same modulus solution, and is in great accordance with the solutions calculated by the semi-analytical model proposed by Kamiya (1977) and the numerical solutions calculated both by the procedure complied in this paper and by the finite element software ABAQUS, which demonstrates that the semi-analytical model and the numerical procedure are accurate and reliable. The result shows that the modified semi-analytical model simplifies the calculation process and improves the speed of computation. And the numerical procedure simplifies the modeling process and can be extended to study the stress field of bi-modulus structures with complex geometry and boundary conditions. Besides, the necessity to introduce the bi-modulus theory is discussed and some suggestions for the qualitative analysis and the quantitative calculation of such structure are proposed.