Gao L.-Q.,Shijiazhuang University
Electronic Journal of Geotechnical Engineering | Year: 2014
It is an important problem that how to evaluate the active earth pressure in the geotechnical engineering. The classic theories of Rankine or Coulomb's method couldn't explain some new real tests, which above two theories didn't consider the soil arching effect. There is two key factors to decide the distribution of active earth pressure: the lateral coefficient of active earth pressure Kawn, and the average vertical stress σv. Assumed the circular arch in soil arching and new angles of slip surface, the lateral coefficient of active earth pressure Kawn of cohesive soil is derived. Using the horizontal differential element analysis method and transferring principle of the lateral coefficient of active earth pressure, the equation of average vertical stress is given. Finally, the new equations of distribution of active earth pressure and total earth pressure, moment of earth pressure from the retaining wall about the base from the clayey backfill were given. By comparing with the experimental results and other methods, the verity of proposed method is confirmed. Then, the key parameters which had a great influence on soil arching effect like c, δ/φ and φwere discussed. It shown that c, 7δ/φ and φ all had a positive influence on the soil arching effect. © 2014 ejge.
Wang Q.,Shijiazhuang University
European Physical Journal Plus | Year: 2014
Short-term synaptic plasticity in the Tsodyks-Markram model can lead to unpredictable and complicated network dynamics. In this paper, we present a new Tsodyks-Markram model with time delay as a parameter. The time delay plays a very important role for the dynamics of our model. We report on the existence of Hopf bifurcation in the model for fixed and varied release probability of available neurotransmitters. It is found that there are stability switches, and a supercritical or subcritical Hopf bifurcation occur when the delay τ passes through a sequence of critical values. We provide numerical results to illustrate our conclusion about stability and obtain the properties of Hopf bifurcation. Moreover, we find the large sensitivity to initial conditions in our model. © 2014 Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.
Chang Y.,University of Florida |
Ries R.J.,University of Florida |
Lei S.,Shijiazhuang University
Energy and Buildings | Year: 2012
Due to the lack of energy intensity data for building materials and the high integration of the construction sector in national input-output tables, applications of conventional process-based life cycle inventory (LCI) and input-output (I-O) LCI models are hindered in China. This study developed a process-based hybrid LCI model to calculate the embodied energy and emissions of a typical high-rise building in China, which has a frame-shear wall and reinforced concrete frame structure. The I-O model used for building materials manufacturing is based on the 2007 Chinese economic benchmark statistics. The process-based model uses the specific data of transportation and construction activities. Results show that the embodied energy of the case building was 309,965 GJ and, the energy intensity is 6.3 GJ m-2. The embodied energy is dominated by coal and the shares of diesel fuel and electricity in total energy were significant. The embodied emissions mainly derive from the electricity sector and gas and water production due to its intensive coal consumption. Results of the process-based hybrid model were moderately higher (5-13%) than the I-O model values. © 2012 Elsevier B.V. All rights reserved.
Liu Q.-K.,Shijiazhuang University
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2011
Multifunction boundary-layer wind tunnel is a necessary facility for wind engineering research. Based on the wind tunnel of Shijiazhuang Tiedao University, the technical requirement of this wind tunnel was introduced. Especially the aerodynamic design, accessory facilities design, structure design, construction mode, results of flow field measurement, and characteristics of the wind tunnel are explaned in detail. The measurement results of tunnel flow field show that the flow field is good. Basic research tests and applicational tests show that the wind tunnel is easy to operation and it meets the demand of special function such as rain-wind test, snow-wind test. All these prove that the aerodynamic and structure design are successful. This wind tunnel example provides a reference for the design and construction of similar wind tunnels.
Kong L.,Shijiazhuang University
ACI Materials Journal | Year: 2015
The chloride penetration and capillary water absorption of concrete with different water-binder ratios (w/b) and different sizes of coarse aggregate were studied as well as the microstructure of the interfacial transition zone (ITZ). The mechanism of the size effect of coarse aggregate on the permeability of concrete was explored. The results show that the negative effect of porous ITZ in concrete with a lower w/b is more significant, while a larger size of the coarse aggregate can decrease the volume fraction of the ITZ and reduce the content of harmful pores in concrete. Based on this study, the impermeability of concrete with coarse aggregates of 0.19 to 1.00 in. (4.75 to 25.0 mm) is optimal. Conversely, the tortuosity effect of aggregate in concrete with a higher w/b becomes prominent so that aggregate that is too large can shorten the permeation path, increase the porosity and macropore content and the trend of the orientation growth of calcium hydroxide (CH) crystals in the ITZ. Under this condition, aggregate with a size of 0.19 to 0.75 in. (4.75 to 19.0 mm) is preferred. Copyright © 2015, American Concrete Institute. All rights reserved.