Jiang X.,CAS Chengdu Institute of Mountain Hazards and Environment |
Jiang X.,Sichuan Agricultural University |
Cui P.,CAS Chengdu Institute of Mountain Hazards and Environment |
Wang Z.,Tsinghua University |
Heng W.,China Construction Steel Structure Co.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2016
In order to obtain the progress of longitudinal erosion and effects of different factors, 6 flume tests were conducted. The results indicated that the longitudinal erosion process included 3 stages. At stage I, the outflow was slow, and the suspended load was transports to downstream mainly during the process. At stage II, the depth of the breach changed rapidly. The bed load was transports fiercely due to backward erosion. At stage III, the velocity and rateof outflow decreases, armor layer is formed which protects the sediment under the armor layer from eroding. At last, dynamic equilibrium was achieved between the water phase and sediment phase. With inflow rate increasing, the breach time decreases and outflow discharge increased, leading to greaterstream power and highererosion rate. And the bottom of the breach become smoothly due to large inflow rate. The slope of the erosive characteristics curve become larger with the outflow discharge increasing. The shape of erosive curve changed from multi-peak curve to mono-peak curve with downstream slope increasing. The steepslope of downstream also increased the outflow discharge and erosion rate, and decreased the residual height of the dam. The factor J3 which was equal to the third power of tangent values of the bed slope and downstream slope's summation, could reflect the stability of soil particles in different downstream slopes. © 2016, Editorial Department of Journal of Sichuan University (Engineering Science Edition). All right reserved.
Chen W.,Hohai University |
Hu S.,Hohai University |
Hu S.,China Construction Steel Structure Co. |
Cai W.,Hohai University
Archive of Applied Mechanics | Year: 2015
This study proposes a dissipative acoustic equation in time-space domain including fractional derivative to describe the characteristic impedance and the propagation coefficient, which has been observed in an experimental study on the fibrous absorbent materials by Delany and Bazley. The parameters of characteristic impendence are obtained by fitting experimental data. The present fractional derivative model can be deduced by characteristic impendence, continuity equation, and state equation, of which the fractional order possesses clear physical meaning of the acoustical properties for porous materials. The attenuation and dispersion functions of the present model obey the Kramers–Kronig relation and agree well with the experimental results, where the fractional order is found to be 0.63 via data fitting. Finally, the proposed model is applied to normal incidence energy absorption aiming at investigating the effect of fractional order on the absorption coefficient with respect to the wave frequency. According to the power-law dissipative relationship, the fractional order in the present wave model ranges from 0 to 1. © 2015 Springer-Verlag Berlin Heidelberg
Cai J.,Chongqing University |
Sun J.,Chongqing University |
Xia L.,Chongqing University |
Xia L.,China Construction Steel Structure Co. |
Deng D.,Chongqing University
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2015
Based on ABAQUS software, a thermal-elastic-plastic finite element method (FEM) was developed to simulate welding temperature field, residual stresses and deformation for multi-pass joints. The residual stresses and deformation in Q345 butt-welded joint with 16 mm thickness were simulated through using the developed computational approach. Meanwhile, experiments were carried out to measure the welding residual stresses and angular distortion in the butt-welded joint. Through comparing the measured data and the simulated result, it is found that both the residual stress and deformation predicted by FEM are in good agreement with the experimental results. In addition, the results show that the angular distortion and transverse shrinkage increase with the number of weld pass. The numerical results also suggest that the region with high tensile longitudinal stress slightly decreases when the number of weld pass changes from three to five, while the peak value of longitudinal residual stress is not sensitive to the number of weld pass. © 2015, Harbin Research Institute of Welding. All right reserved.
Li G.,Tongji University |
Qu H.,China Construction Steel Structure Co. |
Yang T.,Tongji University |
Lu Y.,University of Edinburgh |
Chen S.,Tongji University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013
The characteristics of concrete-filled steel tubular columns (CSTC) were investigated by field explosion experiments on 12 CSTC specimens. A novel apparatus was designed and installed to apply and maintain a stable axial load on the columns. The actual front and rear pressure histories, as well as their distributions, were obtained along with the mid-span deflection and the strains at critical locations. The effect of difference explosive charge, explosive distance, axial compression ratio, concrete strength grade and steel ratio on the behavior of CSTC was also studied. Analysis of the test results shows that the rear pressure is considerably smaller comparing to the front pressure, and hence may be neglected. With the increase of axial compression ratio and the explosion charge, the maximum deformation increases. In general, the proportion of the plastic deformation in the total deformation increases with the increase of the maximum deflection, indicating a global-mode controlled response in these columns. Increase of the steel ratio and the concrete strength grade demonstrates a positive effect in reducing the column responses.
Niu B.,Tianjin University |
Liu X.,Tianjin University |
Chen Z.,Tianjin University |
Yang Z.,China Construction Steel Structure Co. |
And 2 more authors.
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2014
In order to investigate the influence of welding reinforcement process on mechanical behavior of steel beam and braces in load status, the process of welding reinforcement in Tianjin international trade center, was simulated by both the finite element analysis software ANSYS and welding test. The changing rules of stress and displacement of the beam and the bracing during the welding process were derived. The improvement of loading capacity of steel components by reinforcement and influence of welding residual stress on loading capacity was also investigated. Both the analysis and test results show that stress redistribution and additional displacement are caused by the local high temperature and heat affected zone during the process of welding, but the stress and displacement caused by welding are less, which mostly disappear at the end of the welding process. It shows that welding process has little effect on the safety of the structure during the service period and the safety of structure can be ensured.
Li Z.,Chongqing University |
Huang H.,Chongqing University |
Zhao N.,China Construction Steel Structure Co. |
Liu H.,Chongqing University |
Dai C.,Chongqing University
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2015
In order to investigate the stability performance of dual-angle combined section speciments, axial compression and eccentric compression tests were conducted. The influence of prameter of speciments on ultimate bearing capacity were researched. A formula for axial compression and eccentric compression component was given and compared with results of normal coded. The rusults showed that all of the speciments are flexural buckling, eccentric compression has great influence on ultimate bearing capacity, lateral suppot can reduce the slenderness ratio of speciments and the bearing capacity of such component can improved by appropriately increasing the angle specification and the number of filler plate. Eccentric compression has a negative effect on bearing capacity, especially for weak axis. On the premise of structural requirements, the rigidity and connection way of lateral support have little impact on bearing capacity of such component. ©, 2015, Editorial Department of Journal of Sichuan University. All right reserved.