Zhang Y.Y.,Chinese Research Institute of Highway |
Yu C.L.,Xian Highway Institute
Advanced Materials Research | Year: 2013
CFST Arch Bridge under pressure mainly stability is one of the key factors restricting its development. Most of the arch of instability belongs to the second type of instability, and that the non-linear deformation of the structure is nonlinear state, the mechanical properties of the structure also change from elastic state into nonlinear state. In this paper, based on nonlinear and stability theory and using the finite element software ANSYS, parameters of affecting the main arch stability were studied. By analyzing the geometric and material nonlinear factors on the structural stability, the parameters of influence on the stability of the main arch were discussed, including width-span ratio, arch-rib inside inclination, rise-span ratio and arch-axis coefficient. The influence law of these parameters were summarized and will be used to guide the actual project. © (2013) Trans Tech Publications, Switzerland.
Luo Y.-B.,Changan University |
Chen J.-X.,Changan University |
Duan X.-L.,Xian Highway Institute
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2012
At a road tunnel construction site, C20 shotcrete samples were made by using the spray large panel. The compressive strength and tensile strength of the samples which experienced different times of freeze-thaw cycles were tested by pressure testing machine to analyze the compressive and tensile strength variation of the shotcrete under freeze-thaw cycles, and the dynamic modulus of elasticity of the samples experiencing different times of freeze-thaw cycles were tested by resonance method and ultrasonic method to analyze the frost resistance durability. Besides, there were descriptions about the appearance of samples experiencing different freeze-thaw cycles. The result indicates that the freeze-thaw has a great influence on the tensile strength and compression strength of shotcrete, the degree of attenuation of tensile strength and compression strength increases gradually with the increasing cycles, the relative dynamic elastic modulus of the shotcrete gradually decreases linearly with increasing cycles, and the relative durability index of C20 shotcrete is 10.1% after 50 freeze-thaw cycles, which is lower than normal C20 concrete, so the frost resistance durability of shotcrete is worse. C20 shotcrete gets heavy spalling after 70 freeze-thaw cycles, which could not meet the freeze resistance demand of engineering.
Yu X.,Tongji University |
Wu X.,Xian Highway Institute
2nd International Conference on Information Engineering and Computer Science - Proceedings, ICIECS 2010 | Year: 2010
The mechanistic analysis presented in this paper is only a beginning of new approach for understanding the real joint load transfer capability on airport and highway concrete pavements. It gives up the two major assumptions those have been popularly adopted by hundreds of published papers: the load is transferred under a wheel with zero speed and with fixed position. The real load transfer in field is always under wheels with non-zero speed and with varied position at any moment. The objective of this study focuses on quantifying the dynamic effects of a moving wheel while it is crossing a joint on a pavement. The analysis is conducted using a model of two-slab system on Kelvin foundation under a moving wheel with variable speed ν, different pavement damping C s, foundation reaction modulus k and foundation damping C k. The dynamic joint load transfer efficiency is temporarily and empirically defined by the peak strain ratio LTE(S) on the two sides of a joint. The primary findings include: (1) The higher speed of a moving wheel leads to the higher LTE(S);(2) The larger the pavement damping Cs leads to the higher LTE(S);(3) The numerical ratio c(=LTE(S)dynamic/ LTE(S) static) varies in the range 1 to 2 mainly depending on speed ν and damping Cs;(4) The LTE(S)dynamic is not sensitive to foundation reaction modulus k and foundation damping Ck. Further researches are needed for appropriate applications of the new model in practice. ©2010 IEEE.
Fang M.,Xidian University |
Niu W.,Xidian University |
Zhang X.,Xian Highway Institute
Jisuanji Yanjiu yu Fazhan/Computer Research and Development | Year: 2012
The classification methods based on multiple attractor cellular automata can process the classification of two classes, and they are difficult to overcome overfitting problem. There are not yet effective methods for constructing a multiple attractor cellular automata which can process multi-classification and overfitting problem. The pattern space partition in the view of cell space is a kind of uniform partition which is difficult to adapt to the needs of spatial non-uniform partition. By combining the CART algorithm with the multiple attractor cellular automata, a kind of classifier with tree structure is constructed to solve the non-uniform partition problem and overfitting problem. The multiple attractor cellular automata characteristic matrix is defined, and the learning method of classifiers as a node in a tree is studied based on particle swarm optimization algorithm. The multiple attractor cellular automata classifiers built on this approach are able to obtain good classification performance by using less number of bits of pseudo-exhaustive field. The classifier with tree frame of multiple attractor cellular automata reduces the number of empty basin and restrains overfitting problem without lost accurate rate, and shorts the classification time. The feasibility and the effectiveness of the proposed method have been verified by experiments.
Xu T.,Beijing University of Technology |
Sun X.-D.,Beijing University of Technology |
He Y.-L.,Beijing University of Technology |
Wang W.-L.,Xian Highway Institute
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2010
Regarded curve sections of mountainous expressway as research object, setting method and procedure of advisory speed limit signs were studied. Speed information data from 8 curves were collected for one year. Speed difference concept was figured out and speed difference threshold was determined by linear model. The value of advisory speed limit was determined through considering operation speed and design speed. Finally, the advanced distance of advisory speed limit sign was determined considering drivers' visual characteristics and operation speed. Results show that when horizontal curve is small than 300 m, advisory speed limit sign should be set on horizontal curve for expressway.