Abstract:According to frequency of vibration and vibration mode function of simply supported beam, the reliability functional function was established based on monitoring information. The reliability sensibility analysis method was used to study the influence of materials parameters and cross section geometry parameters on frequency of vibration. Theoretical analysis shows that the sensitivity of frequency of vibration on the reinforcement elastic modulus is lower than that on the concrete elastic modulus. The sensitivity of frequency of vibration on the moment of inertia of cross section of concrete is lower than that on the moment of inertia of cross section of reinforcement. The numerical example demonstrates that the sensitivity of frequency of vibration on the reinforcement corrosion is higher than that on the mid span damage. When the reinforcement corrosion degree and the damage severity are 5%, 10%, 15% and 20% respectively, the reinforcement corrosion caused by the first order frequency of vibration variation rate are 1.94 times, 1.85 times, 1.80 times and 1.74 times as much as that caused by mid span damage of the first order frequency of vibration variation rate.

Abstract:Little attention is usually paid to the fire safety problem of bridge structures in the plan and design stage. This paper established a complete bridge fire risk assessment system to realize the assessment and prediction of the potential bridge fire risk in the plan and design stage. First, a multilayer risk evaluation index system of bridge fire safety was proposed by risk identification process based on performance based and fire scenario analysis. Then by innovatively introducing fuzzy mathematics into the analytic hierarchy process, the AHP FCE method was presented for evaluating the risk probability and risk loss, integrating the advantages of traditional quantitative evaluation method and qualitative evaluation method. The weighting coefficients of the indexes were calculated using the analytic hierarchy process (AHP) while the fuzzy comprehensive evaluation (FCE) was used to realize the multilayer comprehensive evaluation. Finally, the risk level of bridge fire safety was obtained by using the 2 dimension evaluation model based on the computed values of risk probability and risk loss and the evaluation criteria; and the basic risk control principles were given. As an example of engineering application, the fire risk level of a partially cable stayed bridge was assessed by using the proposed fire risk assessment system.

Abstract:Based on the conventional bolt ball joint of gird structure, a novel gird structure joint——bolted ball cylinder joint which could be used on non purlin gird structure was created. Load bearing capacity experiments including 13 bolted ball cylinder joints were conducted. First, the experimental program was introduced in detail. Subsequently, the collapse phenomena of bolted ball cylinder joint were described. It is found that their failure modes mainly include flattening damage of cylinder wall, punching failure of cylinder wall, bolt pullout failure and weld strength failure. The cylinder wall is mainly subjected to hoop stress when the joint is under tension or compression. Setting stiffener can effectively increase the load bearing capacity and stiffness of joint.

Abstract:The problem of cylindrical cavity expansion in soil was analyzed with the unified strength yield criterion, strain compatibility equations in cylindrical coordinates and the associative flow rule. The theoretical relationship among the initial radius a0，expansion radius a and expansion pressure p of the cylindrical bore was derived by employing the basic displacement formula of plastic zone and the displacement changes of soil around the cylindrical bore. Then, the radius of plastic zone rpwas obtained by this theoretical relationship and the relative formulas about the radius of plastic zone rp. In addition, the closed form solutions of stresses, strains, displacements in the elastic and plastic regions were obtained in concrete problems of cavity expansion. Furthermore, the parameters of the unified strength theory and the soil were analyzed. Finally, an illustrative example was taken to analyze the change rules of stress and displacement fields, the radius of plastic zone a0 and expansion pressure p.

Abstract:A photoelastic experiment was conducted to analyze the evolution characteristics of force chain network and granule displacement in pentagons under a complete loading and unloading cycle. The results demonstrate that both contact force within the strong force chain and granule displacement show a visible “hysteresis” phenomenon during unloading; the area where granule displacement response is positive during unloading is larger than the area during loading. The displacement recovery ratio ηd((1<ηd<1) was defined to describe the movement locus of granules. Then the relationship between ηd and five types of movement locus were built. ηd increases along the depth. Evolution characteristics of both force chain and granule displacement show a critical level of superload. The residual contact force in granular material is at the state of stable equilibrium when superload is higher than the critical level while reaches the limit equilibrium state when unloading to the critical level. Further unloading will result in instant release of residual contact force as well as the redistribution of granules.

Abstract:The influence of the recycled coarse aggregate (RCA) replacement ratio, the amount of fly ash and slag powder on the cracking resistance of recycled aggregate concrete (RAC) during the early age was investigated by means of knife edge binding method in this paper. The total cracking area in flat of 1 m2 was applied as the main indicator to evaluate the cracking resistance for specimens. The results show that the total cracking area of RAC decreases with the increase of RCA replacement ratio. When the RCA replacement ratio reaches 100%, the total cracking area of RAC is 1.5 times that of natural aggregate concrete (NAC). The fly ash can effectively improve the cracking resistance of RAC. Compared to the control group without mineral admixture, the total cracking area of RAC specimens with fly ash accounting for 30% of the binder decreases by 72.1%. The effect of restraining the cracking area with slag powder is weaker than that with fly ash. However, the slag powder can decrease the discreteness of crack distribution.

Abstract:Based on the hypoplastic constitutive theory, this paper aimed to analyze the pressure of RC cylinder silo wall exerted by the granular material using the finite element method (FEM). The granular material inside the silo was modeled with the modified von Wolffersdorff’s hypoplastic constitutive model by Niemunis and Herle. In order to simulate the interaction between silo wall and granular material, the contact pair algorithm was used which could model pure master slave surfaces considering the Coulomb’s friction law. Using the ABAQUS finite element numerical model, the static interaction between RC silo wall and the granular material was analyzed，and the numerical results are compared to the codes of RC silos in China, Europe(ISO), USA, the classical theories of pressure exerted by the granular materials and the existing experimental data. Meanwhile, this paper also analyzed material parameters concluding a variety of granular materials, initial void ratio, critical friction angle, friction coefficient, granulate hardness and the granular strain. The analytical results show that the effects of initial void ratio, critical friction angle, granular strain, granulate hardness, and the variety of granular materials are more significant than any other material parameters.

Abstract:Salt solution and temperature fluctuation are predominant factors influencing the weathering performance of ancient bricks. This paper conducted laboratory test to explore weathering performance of ancient bricks in the Yellow River region. The experiment simulated brick freeze thaw cycle in fresh water and salt water, and used mercury intrusion porosimetry and five hours boiling in water to obtain pore structure characteristics and saturation coefficient. The experiment results show that the volume fraction of pore diameter of less than 1 μm decreases while that of 1 to 5 μm increases, and the saturation coefficient index is closely related to pore structure index. Pore structure index can replace saturation coefficient in evaluating the weathering performance.

Abstract:A structural failure index consisting of vulnerability index and damage coefficient was defined in this paper, which could be used to evaluate structural failure state after the occurrence of vulnerable scenarios. The estimation error of this index which is always induced by modal uncertainties can be derived with the eigenvector sensitivity method. By minimizing the estimation error of the newly defined index for all vulnerable scenarios, a optimal sensor placement mathematical model is presented and the algorithm, based on convex programming, for solving the proposed optimization problem is explained. The procedure was illustrated with a numerical example of a plane truss, and the mean and variance of the structural failure index was calculated using the simulated modal data yielded from three different sets of sensor locations. The results show that when evaluating the structural failure state, more accurate result can be obtained with the proposed approach than the other two traditional approaches.

Abstract:Real car experiments on eight urban underground roads in Shanghai Municipality were conducted in this paper. A total of one hundred and fifty six measured data were used to fit four presented characteristic and prediction models. The stepwise linear regression method was employed to predict the proper 85th percentile operation speed on urban underground road. Four regression models were used to investigate the relations between operating speed and corresponding roadway factors including lane width, slope grade, number of the lanes and speed limit, etc. The prediction made by using the presented models can meet real car experimental results on a ninth urban underground road very well, which indicates the applicability and reasonability of the models. In addition, the speed limit was found to have very small effect on the operating speed in underground roads. The models put forward in this paper are believed to be useful for operating speed prediction for urban underground road with four to eight lanes at a design speed of 40 to 80 km·h-1.

Abstract:Based on the urban transportation demand, this paper studied the dispatching problem of bus service frequency and bus size associated with urban transit to transport passengers. For the operation characteristics of dedicated line, optimization models of maximum passengers’ perception utility dispatching and average passengers’ perception utility dispatching were developed respectively with the algorithms provided. An application of the models to the case of K1 bus line in Jiangyin shows that the optimization models are practical and effective for reducing the cost of bus transit operation and improving the operating efficiency of bus transit system.

Abstract:This paper analyzed queue discharge characteristics of 11 straight ahead lanes at signalized intersections in Shanghai and Tianjin, China. The results show that the discharge process of queuing vehicles can be divided into three distinctive stages, i.e., the start up stage, the stable stage and the rising stage. The similarities and differences in queue discharge patterns were then compared with 17 straight ahead lanes in Nagoya, Japan. The results show that, in China, the average saturation headway was 0.05s larger, the average saturation flow rate was 80 pcu·h-1 lower, the average start up lost time was 0.83s shorter, and the passenger car equivalent was 7% larger. However, the headways compression phenomenon and the distribution of discharge flow factors were found to be similar in the three cities. Finally, one typical intersection in Shanghai was selected as the test site to analyze the impacts of different queue discharge patterns on signal timing and operational efficiency.

Abstract:The degree of freedom (DOF) of the motion system does influence driving behavior. This paper established two free driving scenarios under clear weather and foggy weather to investigate the impacts of 8 DOF and fixed based driving simulator on the driving behaviors of acceleration, deceleration and desired speed. The results show that the DOF of driving simulator has less impacts on the acceleration behavior and desired speed, yet it has significant impacts on the deceleration behavior, especially at foggy weather conditions. The visibility of weather conditions has significant impacts on the driving behaviors.

Abstract:In order to improve the residue in shield construction, slump tests for watered sandy stratum in Shenzhen were conducted by using foam, bentonite and polymer. Based on the results of field test, laboratory tests including electron microscope scanning, permeability test and compression test were performed. The variation of soil sample properties as meso structure, the seepage and squeezing were analyzed. Based on the tested data, the effects of additives on improving plasticity fluid and capability of retaining water of sandy strata as well as the balance mechanics of shield work face were discussed in detail. As reasonable proportion, bentonite with mass ratio of 1∶7, incorporation 8% to 10% were determined providing valuable experience for shield construction in the similar strata.

Abstract:In order to reasonably classify the line grade and distribute limited resources of maintenance, fusing detection data sources of geometrical status which were obtained by existing means, the track geometry comprehensive index (TGCI) was proposed, the initial weights of parameters of TGCI were determined by AHP, and a weight sensitivity analysis for parameters of TGCI was conducted by using the perturbation method. The quantitative study on the relationship between changes in weights of parameters and percentage of different line grades, and initial weights were modified. The results show that changes in weights of TQI has the most significant effect on line grade classification. The weight range of TQI should be no less than 0.2, the weight range of data overrun of dynamic detection should be no more than 0.45, and the internal weight distribution ratio of each parameter is 1∶1 and 3∶2. The weight of vehicle detection should be less than 0.3, and the weight of locomotive shaking monitor meter should not be less than 0.1.

Abstract:This paper proposed a Monte Carlo based method to quantify non storm water flow entries into storm drains, in conjunction with mass balance of marker profiles between sources and exit. The proposed model was applied to a separate storm and sewer system in Shanghai, China. The sanitary sewage, semiconductor wastewater and groundwater with inappropriate entries into storm drains were quantified using acesulfame and total nitrogen, fluoride, total hardness as marker species respectively. Compared with the traditional deterministic approach, the proposed approach is able to account for the measurement errors and the impact of variability of the source marker profiles resulting from the spatial heterogeneities and therefore presents reliable source flow components that add up to 100%. Good precision was found between simulated and measured data, with a relative error of less than 10% in this case. The guideline to establish data library of marker species was also presented.

Abstract:Effluent qualities of pilot scale green roof facilities with different substrate compositions were evaluated and compared with runoff qualities of an asphalt roofing, the blank control roof and rain water for total 20 rainfall events. The results show that the concentration of TP, NH4+ N and COD in effluent of the facility using commercial green roof medium are 0.95, 1.66 and 115 mg·L-1, respectively, which are higher than those of runoff from asphalt roofing and control facility effluent. The effluent quality of the experiment facility using light inorganic medium and the cheap medium made of brick scrap and sand are better than the effluent of control facility. Considering runoff volume reduction effect, the pollution loads of different green roof facilities are not pollution source for every monitored pollutant compared with the load of asphalt roof and control facility, for NH4+ N load the green roof facilities can even reduce the load of rain water. The aboveground biomass of green roof is positively related to the effluent quality, and the facility using commercial green roof medium presents a better growth status than those using media emphasizing effluent water quality. Application of water treatment residual as component of the medium, the leaching of P from commercial green roof medium is significantly reduced and the growth of vegetation is not affected.

Abstract:Pyrite Cinder（PyC）supported Ce by optimized incipient wetness impregnation was prepared to enhance the catalytic activity of PyC in ozonation. TOC removal efficiency of O3/Ce PyC was kept at about 80 % in the pH range of 3 to 10 in the degradation of aqueous Reactive Black 5（RB5）which was quiet different from the case of traditional ozonation. The kinetic analysis showed that the TOC removal rate constant of O3/Ce PyC was 7.22 times higher than that of O3 alone in the degradation of RB5. Moreover, the fact that more than 75 % of TOC removal efficiency while the catalyst was reused for the third time indicated stable catalytic activity of Ce PyC. Surface hydroxyl groups were the key to catalytic activity of PyC while supported Ce enhanced its catalytic activity for its effectiveness in decomposing O3 into HO·. Ce PyC showed its potential application value in wastewater treatment considering the low cost.

Abstract:The algorithm of AEB (autonomous emergency control) was analyzed based on driver behaviors and effectiveness of different collision avoidance maneuvers. The results show that the current emergency braking algorithm cannot well adapt to driver behaviors under emergency conditions and the potential of collision avoidance is also limited. Therefore, in this paper an autonomous emergency control (AEC) algorithm, which integrated braking and steering control, was proposed. In this algorithm the driver is always in the loop and the information of driver model, while the vehicle model and road environment model are integrated to determine the appropriateness of the driver’s behavior. The resulting corrective control input, which added to the driver’s input, is then used to correct the driver’s inappropriate behavior.

Abstract:To improve the lubrication characteristic of slipper pair, the thermal clearance formula of slipper pair was proposed based on thermodynamic principles considering the heat conduction relationship between slipper pair and oil film. The laws of effect of different cylinder pressure, cylinder speed and inlet oil temperature on thermal clearance of slipper pair were discussed. The results show that the thermal clearance of slipper is inversely proportional to the linear expansion and thermal conductivity of material, which reduces the resistance capacity of material to deformation and matching performance of friction pair. Thermal expansion of slipper and swashplate are caused by surface temperature, which remarkably reduces the thermal clearance of slipper pair, and is positively proportional to cylinder pressure, speed and inlet oil temperature. Therefore, the high linear expansion and thermal conductivity of material is used as slipper in order to reduce surface wear, which is just the opposite to material selection of swashplate.

Abstract:Let Zn={0,1,…,n} be the additive group of integers modulo n and let Z*n=Zn＼{0}. For an inverse closed subset AZ*n，let Gn(A) be the Cayley graph on vertex set Zn, in which {x,y} is an edge if and only if |x－y|∈A. We compute the independence numbers for triangle free Cayley graphs of orders up to 258, which improves the known lower bounds for Ramsey numbers r(3,q) for 27≤q≤38.

Abstract:The generators and relations of little qSchur algebra uq(2,r) were mainly obtained in the 6th root of unity. The algebra was defined by generators and the relations for each case were defined, too. Moreover, that the algebra is isomorphic to little qSchur algebra uq(2,r) is proved. Furthermore, a basis for little qSchur algebra uq(2,r) is obtained.

Abstract:A quality choice model was established to analyze the enterprise’s quality choice considering both immediate and long term interests and the change tendency of quality level. By using formula deduction and numerical verification, it is concluded that there exists an optimal quality choice. The relationship between price and quality level, customer expected profit ratio and quality level , credit mean and quality level, cooperative willingness degree and quality level, cooperative willingness degree and credit mean was analyzed.

Abstract:The industry structural factor, the economic strength factor, the technological capacity factor, and the market environment factor were summarized as the competitiveness of construction industry evaluation indexes. The competitiveness of construction industry evaluation model was established based on optimal combination weight. Finally, China’s competitiveness of construction industry in 2012 was analyzed.