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15 August 2011, Volume 33 Issue 4
2011, 33(4):  74-76.  doi:10.6052/1000-0879-lxysj2010-181
Abstract ( 1265 )   PDF (647KB) ( 785 )
Using the formula of the distance between two points , the deformation-displacement equation of axial force bars with small transfiguration is educed from the definition of bar's deformation. This equation has a pithy form, is easy to calculate, can be applied to solve the problems of small deformation of either linear or nonlinear materials, has no need to distinguish between statically determinate and indeterminate structure, can handle pedestal subsidence easily, thus is suitable for use to analysis truss structures widely.
2011, 33(4):  69-70.  doi:10.6052/1000-0879-lxysj2011-001
Abstract ( 1257 )   PDF (284KB) ( 887 )
Geometry deformation of unit graphics is used to obtained polar coordinate geometry equations for planar problems in the classic elastic mechanic courses. Analysis method is introduced to derive polar coordinate geometry equations for planar problems from Cartesian coordinate’s geometry equations.
2011, 33(4):  33-37.  doi:10.6052/1000-0879-lxysj2011-051
Abstract ( 1037 )   PDF (782KB) ( 381 )
Based on Goodman model, which is used for simulating the contact condition between beams, using Winkler foundation model upgraded as an elastic supporting body with horizontal and vertical forces, a set of differential equations and relevant theoretical solutions for bi-layer beams on the elastic foundation with the horizontal frictional resistance are obtained. Considering the vertical tension and compression and the horizontal shear of beams, a concept of the generalized reaction modulus for interlayer {\&} foundation isproposed and the corresponding formulas are obtained. The influence of the horizontal frictional resistance on the deflection, the total sectional moment and the maximum flexural stress of bi-layer beams is discussed. The results show that the influence of the horizontal frictional resistance can not be ignored.
2011, 33(4):  23-28.  doi:10.6052/1000-0879-lxysj2011-029
Abstract ( 1194 )   PDF (1083KB) ( 395 )
The incremental construction analysis is widely applied in the Finite Element Analysis of stress and deformation in the construction of earth-rock dams. The simulated displacement field may not be suitable for the use in the practice due to the new filling soil. Thus, the computed displacement field in the new filling soil should be modified. Based on the fact that the total displacement consists of the convected displacement and the relative displacement, the theoretical settlement solutions in the 1-D condition are obtained in two different construction cases. One is in a single lift and the other is in multi lifts. These solutions show that the convected displacement has a great effect on the total displacement. A new approach for modification is proposed, and a comparison with existing approaches is made for a typical example. The results indicate that the new approach is more accurate and effective to eliminate unrealistic features in contours of displacement.
CALCULATION METHOD FOR PPMT JOINT
Chen Zhiqiang Kong Xiangchen Hu Xiang Xue Weichen
2011, 33(4):  42-46.  doi:10.6052/1000-0879-lxysj2011-005
Abstract ( 1127 )   PDF (771KB) ( 417 )
In view of the construction of a precast prestressed municipal tunnel (PPMT) in the 2010 Shanghai Expo, a calculation method, to simulate the bending stiffness and the flexural capacity of PPMT joint, is proposed based on the internal force equilibrium and the deformation compatibility. The elongation of the prestressing tendons and the elastic modules change of the hydroswelling rubber-sealings are taken into consideration in the calculation method. The accuracy of the calculation method is shown by the experimental results. The results of this work has been applied in the PPMT in the 2010 Shanghai Expo.
2011, 33(4):  51-54.  doi:10.6052/1000-0879-lxysj2011-037
Abstract ( 972 )   PDF (625KB) ( 444 )
The problem of the nonlinear optimal design is reduced into a geometrical programming problem for the reinforced concrete frame beam, and the related formulas for the cross-section optimization design of reinforced concrete frame beams are derived. The numerical example shows that it is practical.
Extending method in conceptual mechanics analysis
Zhu Cimian Guo Zhigang Zhang Weiping
2011, 33(4):  61-62.  doi:10.6052/1000-0879-lxysj2011-096
Abstract ( 1012 )   PDF (529KB) ( 517 )
Extending method is developed after some previous methods for conceptual mechanics analysis, such as arousing factor method, major response method and extremely bounding method. The extending analysis process can be stated from a basic model for conceptual mechanics analysis and a series of problems with practical significance in engineering can be treated in the process. Conceptual analyses for two examples, bending moment and deformation analyses for pipes subjected to internal temperature increase and bending moment analyses for multi-stories frames subjected to uniform temperature decrease or floor loads, are performed using the extending process. Beside, extending method can be used in combination with the other basic conceptual analysis methods to surmount analysis difficulties, and further to define the basic response form of a loaded structure.
2011, 33(4):  47-50.  doi:10.6052/1000-0879-lxysj2011-090
Abstract ( 1117 )   PDF (669KB) ( 415 )
Concrete is the major material for infrastructures. A new, simple and inexpensive method to improve the seismic capacity of important structure components is to improve the damping capacity of concrete material. The damping capacity of the high damping concrete is frequency dependent, but the available viscoelastometer and other dynamic mechanical analyzers can not measure the shear damping capacity of a large scale material such as concrete materials. For the high damping shear-type plain concrete bar, using the damping model in complex variables, the shear vibration equations of motion are derived and then the steady displacement response under a simple harmonic load is obtained through the modal decomposition method. The testing formulae for measuring shear damping capacity of large scale materials are derived and the shear-type damping measuring instrument for large scale materials is thus designed. The suggested test theory and instrument can be used to study shear damping capacity and mechanism of high damping concrete materials.
Around the mechanics
2011, 33(4):  1-7.  doi:10.6052/1000-0879-lxysj2011-305
Abstract ( 1441 )   PDF (2502KB) ( 575 )
This paper discusses mechanics-related problems of saline disasters in western China concerning the development of the highway and railway systems, including studies of the damage effects of salt heave, dissolved subsidence, and corrosion of the saline soil and of engineering and mechanical properties of the saline soil. The mathematical model of the movement of water, salt and heat and an exploration of the coupling model of water, salt, heat and force by experiments and numerical simulations are reviewed. Finally some problems to be further studied are summarized.
2011, 33(4):  8-12.  doi:10.6052/1000-0879-lxysj2010-405
Abstract ( 1063 )   PDF (920KB) ( 388 )
The geometrically nonlinear finite element analysis for cylindrical shells is carried out using the 16-node curvilinear side isoparametric element. The analysis takes into accout of fully nonlinear kinematic relations so that the stable equilibrium paths in the advanced nonlinear regime can be accurately predicted. A general nonlinear displacement-based finite element formulation is established. The parallel strategies for the nonlinear finite element analysis based on the total Lagrangian formulation are presented and implemented on the workstation cluster. The geometrically nonlinear analysis for cylindrical shells is performed using parallel computing. The results show that the proposed algorithm can achieve better parallel speedup and efficiency under the cluster environment.
2011, 33(4):  13-16.  doi:10.6052/1000-0879-lxysj2010-446
Abstract ( 1003 )   PDF (723KB) ( 692 )
Though the constrained layer damping can reduce the vibration effectively, it increases the weight and the size of the structure. Thereby an optimization of the constrained layer damping treatment is necessary. In this paper, a new model of the partial stand-off constrained layer damping patch is established in the finite element software ANSYS. Based on modal strain energy principles, the modal loss factor of the proposed model can be found. An objective function related to the modal loss factors is constructed. Its design variables include the number, the length and the spacing between of damping patches, the thickness of the stand-off layer and the constrained layer. By using the multi-objective genetic algorithm of MATLAB, the optimization is carried out. The results of examples show that after the optimization the constrained layer damping can reduce vibration more effectively with less additional weight and attenuate the vibration of the structure in a shorter period of time than before the optimization.
2011, 33(4):  17-22.  doi:10.6052/1000-0879-lxysj2010-267
Abstract ( 1097 )   PDF (1001KB) ( 713 )
The concept of elastic support is defined in this paper, for the real contacts and constraints between structural bars, based on the concept of conventional support in structural mechanics. Two basic systems of elastic supports are established, with two feedback basic equations, and the basic formulas of the rod end constraint stiffness in both directions are obtained. The elastic support analysis method of structure mechanics is then formulated. The finite element equations for the elastic support analysis method are obtained. With the elastic support method, one step moment distribution method can be derived, which would improve the separated floor method and the $D$ value method a greatdeal.
2011, 33(4):  29-32.  doi:10.6052/1000-0879-lxysj2011-190
Abstract ( 990 )   PDF (682KB) ( 396 )
A method is proposed to obtain the compression strength and the peak strain of concrete by using the stress-strain curve before failure. The tests show that this method enjoys a good accuracy, and can be used to obtain the objective fatigue testing stress level. The compressive fatigue tests for hydro-concrete C15 were performed by using the MTS 810 TestStar material test system. By analyzing the results of this fatigue test, the evolution of the fatigue residual deformation, the criterion of fatigue failure, are obtained, together with an estimating formula for fatigue life and fatigue strength.
2011, 33(4):  38-41.  doi:10.6052/1000-0879-lxysj2010-407
Abstract ( 1192 )   PDF (672KB) ( 454 )
Experiments were carried out on the short CFST columns of different slendemess ratios. The test parameters, setups and methods are described. The curves of load vs. strain and deflection a obtained. The influence of the load slendemess ratio on the behavior of eccentrically-loaded CFST columns is analyzed. The ultimate bearing capacity is checked against related codes. Some suggestions are made for the application of the related structures in engineering. The results indicat that with the increase of load slendemess ratio, the confinement of steel tube to core concrete, and the ultimate carrying capacity of the column are decreased and the horizontal deformation is reduced, but with little effect on ductility. The longitudinal and toroidal strains in the compressive zone of the extreme compressive fiber at the ultimate load are increased.
2011, 33(4):  55-60.  doi:10.6052/1000-0879-lxysj2010-426
Abstract ( 1122 )   PDF (2009KB) ( 758 )
The automotive interior noise subjected to different road excitations was predicted with finite element simulation method, and acoustic contribution from the panel was also analyzed. Firstly, B and C grade road spectra were generated by MATLAB. Secondly, the frequency response results of body structure subjected to different road excitations were computed at 1$\sim$200\,Hz by NASTRAN. In LMS Virtual. Lab, the sound pressure level (SPL) around driver and passenger's ears was predicted by using Acoustic Transfer Vector (ATV) technology. Also, the impact of cavity structure surface impedance on the interior noise was discussed. Finally, the contributions of body panels to the noise levels around the driver's right ear were achieved via panel acoustic contribution analysis (PACA), key areas of structural optimization were identified. Analysis method discussed here is of a good reference to noise reduction and acoustic treatment.
2011, 33(4):  63-65.  doi:10.6052/1000-0879-lxysj2010-418
Abstract ( 862 )   PDF (745KB) ( 449 )
2011, 33(4):  66-68.  doi:10.6052/1000-0879-lxysj2010-242
Abstract ( 1172 )   PDF (464KB) ( 484 )
According to the basic concept of the axisymmetry, the planar axisymmetry problems can be classified as the axisymmetrical stress and the axisymmetrical displacement, and their basic equations are given, respectively. It should be noted that the planar axisymmetrical displacement is a special case of the planar axisymmetrical stress. The general solutions of the planar axisymmetrical stress and the planar axisymmetrical displacement are obtained by displacement method, respectively. The results indicate that the general body force can be considered when solution of planar axisymmetry problem in terms of displacement.
2011, 33(4):  70-72.  doi:10.6052/1000-0879-lxysj2010-442
Abstract ( 923 )   PDF (463KB) ( 361 )
2011, 33(4):  73-74.  doi:10.6052/1000-0879-lxysj2010-443
Abstract ( 986 )   PDF (281KB) ( 383 )
Analysis of the first prize model of Shandong structural design contest
Zhang Jia Wu Lixiang Peng Yangbo Qu Shuying Hou Xingming
2011, 33(4):  77-79.  doi:10.6052/1000-0879-lxysj2010-425
Abstract ( 1423 )   PDF (845KB) ( 658 )
2011, 33(4):  87-89.  doi:10.6052/1000-0879-lxysj2010-387
Abstract ( 2541 )   PDF (583KB) ( 1182 )
Shoulder-pole as a tool for carrying objects is widely used in China. As an elastic cantilever, it may make the load vibrate vertically for the shoulder up and down in the gait cycle. On the other hand, the carrier’s velocity changes periodically for he goes by feet alternately, which causes swing of the objects hanging with rope on the pole ends. Therefore the force acted on the shoulder-pole by the rope changes periodically, of which the vertical component may be amplified by the vibrating of shoulder-pole. A good shoulder-pole means that the carrier can take the step forward when the force on his shoulder is lower.
Around the mechanics
2011, 33(4):  90-91.  doi:10.6052/1000-0879-lxysj2011-052
Abstract ( 1540 )   PDF (1190KB) ( 722 )
This paper aims to conduct traffic safety education for drivers to avoid the car tire exploding, rolling over, drifting, "pushing head ", oversteering etc. signs of accidents when cornering. In the course of the study, to discover the laws, use real cars to do exercise in turn, ramp, snow and ice etc. complex road, repeatedly is needed. The law is concluded as followed, heavy brake in the corner will cause a tire blow up, or the car roll over, drift. Pedal to the accelerator in the corner will cause a car "push head" or oversteer. Stress analysis by multi-angle graphic solution method, and the method of displaying the visual image make it easier for novice to understand.
2011, 33(4):  92-92.  doi:10.6052/1000-0879-lxysj2011-306
Abstract ( 1274 )   PDF (154KB) ( 568 )
2011, 33(4):  92-93.  doi:10.6052/1000-0879-lxysj2011-307
Abstract ( 1307 )   PDF (514KB) ( 600 )
2011, 33(4):  79-80.  doi:10.6052/1000-0879-lxysj2011-175
Abstract ( 902 )   PDF (131KB) ( 358 )