Abstract:Based on the previous experimental results and a simulation loading test with 4 widths of the footing by employing the discrete element software of PFC2D, a study was made on the general law of scale effect and the causes of the scale effect. The result indicates that with the increasing of the width of the footing, bearing capacity factor decreases, and the amount of reduction decreases with the increasing of the width of the footing. Maximum curvature of p s curve (i.e., the curvature of the inflection point) decreases with the increasing of the width of the footing, and the overall shape of p s curve gradually gets smooth. In the discrete element method(DEM) simulation of net sand, the soil strength envelope is a straight line. When peak internal friction angle of particles remains as a constant with an increasing confining pressure, the scale effect remains on the bearing capacity of the foundation, which suggests that the strength envelope of nonlinear is not the fundamental cause of scale effect.

Abstract:According to the relationship between the material fabric and axis of major principal stress, the elliptic shape function was revised by adding a cross anisotropic term, and then a 3D cross anisotropic failure criterion was proposed based on the Mohr Coulomb criterion. The formula for calculating the peak stress ratio under different intermediate principal stress ratio condition was deduced, then the varying characteristics of peak friction angle with the intermediate principal stress ratio and the angle of major principal stress direction relative to material fabric were also obtained. A comparative study of a series of triaxial tests with different sample sedimentation angles and hollow cylinder tests shows that the predicted friction angle agrees well with the experimental results.

Abstract:According to the nodal displacement interpolation formulation in the finite element method, the interface degrees of freedom reduction technique for a free interface substructure was developed. Based on the basic transformation of the free interface modal synthesis method, the second coordinate transformation of the interface was completed, which effectively reduced the generalized degrees of freedom of the system, and the computation efficiency was improved. The modal analysis for a beam fixed at two ends was constructed as a numerical example, and the first ten main frequencies of the beam before and after the interface degrees of freedom reduction were compared. The result demonstrates that the proposed interface degrees of freedom reduction technique for the free interface substructure is reasonable and effective. In comparison with the modal reduction method for the interface degrees, the precision of the main computed frequencies obtained by these two methods are the same. However, the proposed method is more efficient and convenient when used in the engineering, though the latter has a better accuracy. Meanwhile, the influence on the calculation accuracy of the way to choose interpolation nodes was also discussed. The numerical results show that, the more the interpolation nodes involve in the modal analysis, the higher the calculation accuracy is. And when the interpolation nodes uniformly distribute on the interface, the accuracy is the highest.

Abstract:An adaptive mass proportional pushover(AMPP) analysis method is proposed for pushover analysis of aseismic bridges with cable sliding friction bearing. Compared with modal pushover analysis(MPA) and first mode pushover analysis(Po 1) method, the applicability and effectivity of AMPP method for seismic performance evaluation of aseismic bridges with cable sliding friction bearing are studied. It turns out that pushover analysis method can be applied to evaluate seismic performance responses of aseismic bridges with cable sliding friction bearing. Compared with Po 1 and MPA, AMPP can lead to the attainment of improved predictions of key response parameters. MPA provides a good estimation for internal forces of substructure elements.

Abstract:The reinforced concrete (RC) shear wall and composite shear wall is one of the predominant structural components used extensively in high rise buildings to resist lateral loads induced by earthquakes. How to simulate the hysteretic behavior of RC shear walls effectively under earthquakes is one of the key issues of seismic performance evaluation of high rise buildings. According to the features of elasto plastic responses of RC shear walls, several analytical models which could be classified into two groups, microscopic models and macroscopic models, were developed for RC shear walls. The theory of cyclic soften membrane model (CSMM) was introduced. Based on this theory, the modeling procedures for different kinds of shear walls were presented by using OpenSees program. The models were validated by comparing the calculated responses with the experimental results of 11 isolated walls with different failure modes and various steel encased profiles under cyclic loadings. Numerical simulation results indicate that such analytical method can predict effectively the global and local inelastic behavior (such as overall hysteretic behavior and local material strain) of the wall system, and it provides a reference to seismic performance assessment of high rise buildings.

Abstract:A kind of retrofitted bolt weld connection details and its corresponding design methods are proposed on the basis of the conventional RHS column joint with through diaphragm to meliorate structural robustness. With a view to material fracture and the path tracking after fracture, the numerical results indicate that the retrofitted bolt weld connection details can enhance the vertical deformation capacity of the beam column assemblies before the force transmission failure at the bottom of connection region, which is conductive to the development of catenary action by axial force in the beams. Therefore, the beam column assemblies can provide greater vertical carrying capacity and the connection details can be used in transforming structures against progressive collapse.

Abstract:Experiments were performed on 3∶1 rectangular prisms with various rounded corners (R/D=0, 5%, 10%, 15%) in low turbulence uniform flow to measure the surface pressures of four models for the testing Reynolds number ranging from 1.1×105 to 6.8×105. The aerodynamic forces were obtained by integrating the wind pressures on the model surface. Reynolds number effects on the aerodynamic force coefficients and their power spectrums are presented. The results show that drag coefficients of rectangular prisms with R/D=0 and 5% increase with the increasing Reynolds numbers, whereas sudden decreases of the drag coefficients root mean square(RMS) drag coefficients and RMS lift coefficients are observed for the rectangular prisms with R/D=10% and 15%. The power spectrums of drag and lift coefficients for rectangular prisms with R/D=0 and 5% change slightly with the increasing Reynolds numbers, whereas significant influences of the Reynolds number on the power spectrums of areodynamic force coefficients are found for the models with R/D=10% and 15%. Besides, Strouhal numbers of the 3∶1 rectangular prisms obviously increase with the increasing rounded corner ratio.

Abstract:Using the high strength mortar to pour into the hole prepared in the concrete bridge deck to fulfill the effective connection of steel girder and concrete. The shear bearing capacity of single stud obtained from single row stud push out test and that from multi row stud push out test are different in some degree. In order to test the shearing strength of the studs wrapped by the high strength mortar and compare the influence of group studs layout form on its shear strength, one group of single stud specimen and five groups specimens with different studs layout were carried out. The test results show that the connecting method by wrapping the studs with high strength mortar is reliable, and the shearing strength of the studs is high, and the average capacity of single stud is 197.2 kN. There are some influences on the shearing capacity of different group studs layout form. With the increase of stud row number the average single stud shear capacity is decline. The specimen N25 with the maximum stud numbers has the average single stud shear capacity of 160kN, which is 81% of the capacity of the single stud test. According to the load slip curves of multi row stud, the expression of load slip relation of multi row stud is proposed. Compared to testing results, the expression has a better match with the experimental values.

Abstract:1∶10 destructive model tests were carried out to investigate deformation characteristics, mechanical response, crack propagation and bearing capacity of pre maintenance of cracking lining. The entire failure of pre maintenance is controlled by ultimate bearing capacity of hance of lining. The mechanical process of the reinforced lining is as follows: loading, crack coalescence of lining crown, crack coalescence of umbrella arch, and failure test. Stiffness of structure declines with the load increasing. Sequences of failure at crucial positions are cracking of vault, brittle fracture of arch hance and ductile failure of arch. When the depth of crack reaches a third of lining thickness, the damage state should be deemed as favorite time of pre maintenance. Under different damage conditions, the catastrophe point of reinforcement with umbrella arch is unanimous. It can be deemed as control criteria for maintenance of umbrella arch. A simplified formula is put forward to show relationship between failure load and damage state. The deviation is 5% approximately between the calculation results and the model test.

Abstract:The Longfengtou Beach of Haitan Bay in Fujian Province of China had wide beach and fine sand. Since the end of last century, due to the construction of artificial seawalls, the beach has been eroded seriously, and the dry beach width got shorter. How to prevent the beach from erosion becomes very important. The nourishment trail project in Phase One was put into effect to solve beach erosion in 2011. After the nourishment project, the shoreline still retreated seriously, with an average erosion of 11m and the maximum of 31m in 4 months. In order to solve this problem, beach nourishment and some other engineering schemes are put forward. The evolution model of Longfengtou Beach based on Generalized Model of Simulating Shoreline Change(GENESIS) model is established and verified well with the measured shoreline changes of the nourishment project in Phase One. With this verified model, the shoreline changes with different new engineering schemes are predicted, compared and analyzed. The results indicate that both the north and the south nearshore breakwaters protect the beach, but the coastline still suffers a certain degree of erosion and the schemes should be combined with seasonal beach nourishment to keep the shoreline after the project.

Abstract:The solvent isotope effect was investigated with 1H and 2H NMR, LC MS and GC MS analyses on the reduction of H2O or CO2 with glycerine under alkaline hydrothermal conditions. The solvent isotope study results show that the H on the β C of lactate is almost exchanged by D2O, which suggests that the hydroxyl (—OH) group on the 2 C of glycerine is first transformed into a carbonyl (C=O) group and then is converted back into a —OH group to form lactate; a large amount of D is found in the produced hydrogen gas or formic acid, which shows that the water molecules act as a reactant; and D% in the produced hydrogen gas or formic acid is far more than 50%, which straight forwardly shows that acetol is formed in the first place as the most probable intermediate by undergoing a dehydration reaction rather than a dehydrogenation reaction.

Abstract:Taking the transformation of an impermeable pond in the north urban best practices area (UBPA) of Shanghai World EXPO as an example, a field infiltration study was conducted. The experiment before the engineering indicated a linear relationship between the infiltration rate and water level gap (i.e., pond water level versus groundwater table), which was further verified by the experiments within the transformed infiltration pond. With the measured dynamic infiltration rate, it is presented that adjusting the pond water level dynamically is a practical approach to enhance runoff infiltration, critical in achieving 17.6 mm UBPA runoff reuse or infiltration within three days, certified by LEED ND platinum grade.

Abstract:Setting times, mechanical strength and drying shrinkage ratio of Portland cement and calcium aluminate cement(less than 25%) blended systems were investigated, which were also characterized by means of calorimetry, X ray diffraction and environmental scanning microscopy. Results show that with the increasing of calcium aluminate cement, setting times of blended systems is shortened; the compressive strength first increases slightly (reach the utmost with 6% of calcium aluminate cement) and then decreases significantly, and the drying shrinkage grows continuously. In addition, except that the ettringite formation content increases slightly, lower content of calcium aluminate cement do not have obvious impact on the hydration of Portland cement; while higher content will delay the hydration of Portland cement prominently, furthermore, the ettringite formed at early age also transfer to monosulphoaluminate and the unstable calcium aluminate hydrates transfer to stable garnets, which does great harm to the microstructure.

Abstract:This paper studies the residual mechanical properties of engineered cementitious composites(ECC) specimens of different ages after high temperatures. The ECC specimens were cured for different ages (1, 3, 7, 28 d) and heated to different temperatures (200, 400, 600 and 800 ℃). After cooling, the mechanical properties of ECC were tested. Generally speaking, the strength and stiffness of ECC specimens after high temperature will decrease with the rising of temperature, but there are exceptions at 200 ℃; subjected to the same temperature, the strength and stiffness of ECC specimens increases with the increase of age, and those of the early age specimens increase very fast. The microstructure characteristics of the ECC specimens before and after high temperature can be analyzed by scanning electronic microscope (SEM) and mercury intrusion pores (MIP) test, which can well explain the residual mechanical property changes of ECC specimens of different ages after high temperature.

Abstract:A comparative study was made of the thaumasite formation speed of the specimen under the condition of electric pulse and the condition of common immersion. The erosion products generated by the two acceleration methods were analyzed by scanning electron microscope (SEM/EDS), X ray diffraction (XRD), and Fourier transform infrared spectroscope (FTIR) and appearance changes of the specimen were observed after different testing time. The results show that the electric pulse obviously accelerates the thaumasite formation of cementitious materials. There is a preparation period of the thaumasite sulfate attack(TSA) reaction in the specimen, when electric pulse act on it from the 90th day to the 120th day; abundant thaumasite is found in the erosion products after the 120thd. However, in the group of common immersion, there are some raw materials needed by the thaumasite formation in the specimen after the 1st year, and only a very small amount of thaumasite is found.

Abstract:A series of researches were made into the mortar specimens which were prepared with 50% of flue gas desulphurization (FGD) gypsum and metakaolin(MK), 50% of cement. The results show that 800℃ activated FGD gypsum is anhydrite with obvious cavity and crystal defect tested by transmission electron microscope(TEM). The dissolution rates of FGD gypsum in water after thermal activating at 400~800 ℃ during 10 min~7 d are different, and the dissolution rate of FGD gypsum activated at 800 ℃ is the fastest. The higher compressive strength is obtained with 800 ℃ activated FGD gypsum in condition of standard curing and the non activated FGD gypsum is preferred for steam curing. The molar ratio of CaSO4 in FGD gypsum and active alumina in MK range from 0.7 to 1.1 is good for compressive strength and volume stability simultaneously.

Abstract:The method of Computational Fluid Dynamics was applied to numerically simulation. Based on overlapping grid, the transient aerodynamic characteristics of the flow field around two vehicles were studied when simplified model were crossing each other in a curve. The change rules of six aerodynamic components were achieved. In the process of short meeting, side force and rolling moment as well as the yawing moment changed direction, quickly reached their positive and negative value. The side force, rolling moment and yawing moment of CAR 1 inside curve were slightly larger than those of CAR 2 outside curve. The lift force and pitching moment were changed on value and direction. All of these would bring some influence on vehicle driving stability. This study provided theoretical reference for the further study of curve crossing.

Abstract:A dimensionless thermodynamic model of single stage air refrigeration cycle was developed. Based on the model, analytical solution of the optimal pressure ratio at the maximum ε (coefficient of performance) was derived. So did the cycle key performance indices. Furthermore, numerical analysis using the analytical solutions was conducted to reveal the impact of operating conditions and component efficiencies on the cycle performance. The results show that bigger heat source temperature difference leads to higher optimal pressure ratio, higher cooling capacity, but lower ε. On the other hand, higher compressor/expander efficiencies result in less lower optimal pressure ratio, much higher ε and cooling capacity. Under the same conditions, the expander efficiency has more significant influence on the cycle performance than the compressor efficiency. The analytical solutions and corresponding conclusions are helpful in optimal design of air cycle refrigeration systems.

Abstract:A series of experiments with different charge aerosols were carried out to investigate the mechanism of static electricity attenuation for fibrous filter medium. DEHS and three different charge characters of KCl were used to challenge electrostatic fibrous filter medium. The surface potential and filtration efficiency were tested and morphology of medium was observed through scanning electron microscope (SEM) for different dust loading periods. The results of experiments show that surface potential of filter mediums challenged with charge KCl (Potassium chloride) has different variation trends with dust collection, however, the efficiency does not change obviously. Surface potential and efficiency of filter mediums challenged with diethyl hexyl sebacate (DEHS) decrease sharply. Both experimental results and SEM of medium challenged with different morphology show that the mechanism of electrostatic attenuation for filter medium is mainly due to electrostatic shielding effect.

Abstract:Two adjacent shuttle louvers were first taken as the research object, the calculation model of solar diffuse radiation transportation through shuttle louvers was established. Based on the model analysis, the calculation program of solar diffuse radiation was developed with the MATLAB to describe the shape, size, tilt angle, and surface optical properties of shuttle louvers. Then, the correctness of the calculation program was verified, and the sensitivity analysis was carried out on the partition number of shuttle louvers. Analysis results show that the relative error rate decreases with the segments, but changes no more if the partition number is over 8. Finally, a comparative study of the error by the proposed method and that by traditional methods with flat hypothesis model shows there exist the error increases with the tilt angle.

Abstract:The lifetime scaling law of time hopping impulse radio ultra wide band (TH IR UWB) sensor networks with multi source, multi destination is derived. We suppose that each source node transmits data packets to its nd destination nodes along the minimum energy dissipation route respectively. The results indicate that the upper bound on the lifetime of TH IR UWB sensor network is in proportion to the α/2 order of the node density λ. The results also reveal that the upper bound on the lifetime decreases with the number of source nodes ns and the number of destination nodes nd per source node, thus reducing the product of ns and nd can improve lifetime of network. Furthermore, as ns=n and nd=1, the upper bound on lifetime of TH IR UWB sensor network with multi source, multi destination becomes that of mutli source, single destination network in which Sink is the only destination node for all ns source nodes.

Abstract:The running of line side converter of alternating current(AC) drive electric locomotive and electric multiple units will generate current harmonic, and the frequency range of the current harmonic is wide. This will easily cause resonance between the train and the power supply grid. The harmonic characteristic of line side current in ideal conditions is analyzed; the problem about harmonic performance of usual transient current control strategy for multiple line side converters is discovered through comparison. In order to solve the problem, two optimal transient current control strategies based on average current feedback and primary current feedback are proposed. The simulation analysis and the line testing verify the validity of optimal control strategy. The total harmonic distortion(THD) for primary current fall to about 1%. The line side harmonic characteristic is improved visibly, and the resonance between the train and power grid is suppressed effectively.

Abstract:The paper presents, from the perspective of socially responsible investment, a multiple criteria decision making(MCDM) model based on the balanced scorecard, decision making trial and evaluation laboratory, and analytic network process(BSC DEMATEL ANP).Then, the decision making processes have been built about the investors, choice of the social organization which they want to invest. Finally, the key result of the empirical studies proves the feasibility and practicability of the BSC DEMATEL ANP model by using the established model and decision making proceses in a social organization.

Abstract:The labor market and housing market equilibrium models were established, and the empirical studies were made of the effect of productivity growth and industrial structure on the housing prices on the basis of the annually data for the 35 major cities in China from 2002 to 2012. Analysis results show that the productivity growth raises the housing prices, and the effect of the third industry is stronger than the second industry; the changes of industrial structure also raise the housing prices. Housing price rising is the inevitable result of the productivity growth and industrial structure changes, and the interventions, such as the accountability system for stable housing prices by the central government, are not in line with law of market. Government should focus on leading the industry and labor to the medium and small sized towns, and promote the balanced development of large cities and medium and small sized towns, for construction the long term mechanism of the housing market.