Abstract:

Abstract:As for the local buckling of aluminum bending members, a finite element analysis of the stability of aluminum plates under bending was performed. Compared with the results of codes’ method and finite element method, the advantages and disadvantages of existing codes were discussed. Base upon the results of simulation, the relevant design formula in Code for design of steel structures (GB50017) were modified with the reference of existing foreign codes. And the design methods were proposed for buckling strength and postbuckling strength of aluminum plates under inplate bending. It was found that the results of proposed methods were in high accuracy and safer condition, and suitable for the stability design of aluminum plates under inplate bending.

Abstract:A nonlinear finite elements analysis was carried out to investigate the failure modes and the ultimate strength of gusset plate to CHS KKjoints. The effects of web loading proportion, geometric parameters and axial stress in chord on the ultimate strength were considered. It was found that the ultimate strength of gusset plate to CHS KKjoints was greatly decreased with the increase of web loading proportion when the proportion value was positive; however, the web loading proportion had less effect on the ultimate strength when the proportion value was negative. And with the varying of web loading proportion, the effect of the axial stress in chord on the ultimate strength of KKjoints had a complex effect on the joint mechanic behavior. Based on the regression analysis, a formula was proposed for predicting the ultimate strength of gusset plate to CHS KKjoints.

Abstract:The relative alteration of WignerVille Distribution crossterm statistic was proposed for damage detection of guyed masts. And numerical analysis and experimental study were carried out with the case of the aeronavigating guyed mast in Fuling District. It was found that not only the shaft’s damage of different location and degree, but also the local damage of different type could be identified with the relative alteration of WCS accurately. The accuracy and sensitivity of the identification can be improved by increasing the guy’s initial pretensions. The damage identification test can quantify the damage extent of simulation. And it was indicated that the WCS index can identify the local damage of guyed mast and the results of damage identification were in good agreement with those of numerical analysis.

Abstract:Aiming at the low servicelife and bad durability of the traditional concrete structure and concrete cover, the highdense concrete cover (HDC) was produced with the optimization of interfacial transition zone in meso scale(50100μm) between cement mortar and aggregate of the ordinary concrete. Moreover, some properties of HDC were studied, including the impermeability, the anticorrosion behavior, antiacidic gas corrosion and freeze resistance. It was shown that the impermeability of HDC was excellent with very low permeability. Compared with ordinary concrete, the anticorrosion behavior of HDC was remarkably strengthened. And under the condition of erosion accelerated by CO2 and SO2, the freeze resistance such as the appearance after freezing and thawing, mass loss and relative dynamic modulus of HDC was better than that of ordinary concrete and neutralization depth of 90day was less than 1 mm. On the other hand, the results of Scanning Electron Microscope (SEM) experiment indicated that the size of interfacial transition zone of HDC was effectively reduced and the microstructure compactness of concrete was increased. Therefore, it was found that the special producing technology and characteristics of HDC can improve the durability, and then the servicelife of structure was increased effectively.

Abstract:As a new kind of supporting member, a prestress selfbalanced cable truss has been widely applied in pointsupported glass curtain walls. The free and forced vibration behaviors were analysed. Taking the temperature effect and geometric nonlinearity into consideration, the nonlinear vibration equation was derived with continua theory for prestress selfbalanced cable truss support system in pointsupported glass curtain wall. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation and then solved with LP method and KBM method. With the case study, the effects of temperature, amplitude, and exterior excitation on the nonlinear vibration were discussed. And it was found that the frequency would decrease with increase of temperature and the nonlinear vibration showed the characteristics of hard spring.

Abstract:The effects of the restraint stiffness ratio, the axial load ratio and the column slenderness on the buckling temperature and failure temperature of a restrained Hsection steel column under axial load in fire were studied with a calibrated finite element method (FEM) model. And the calculation methods of buckling temperature and failure temperature were proposed. The effect of the restraint stiffness ratio on the buckling temperature and failure temperatures could be expressed with an exponent curve while polynomial functions was appropriate for the effects of the axial load ratio and the column slenderness. The results of the proposed method were in good agreement with those by FEM method and on the safe side.

Abstract:Taking into account the influence of the internal micro cracks on the strength and deformation of concrete, a fourphase composite material model was proposed, in which it included mortar, aggregate, interface and random defects. Mesoscale unit in concrete was subjected to elasticplastic damage constitutive of increments form in strain space. With the simulation of mesh concrete crack growth by damage elimination, the damage processes of concrete under 3D uniaxial compression and the elastoplastic damage process of concrete under uniaxial tension with heterogeneous specimen were obtained. It was shown that the proposed fourphase model added the simulation of random defects, with which it was more appropriate to the actual situation in concrete forming. The percentage of random defects in volume was the key to determine the weakening degree of macrostrength of concrete. The cracks occlusion was obvious for the lower homogeneous uniaxial tension specimen and the fracture was clearer for higher homogeneous specimen. The simulation results was in good agreement with test results.

Abstract:Aiming at the fact that parameters in support vector machine(SVM) model were difficult to be identified, a genetic algorithm SVM(GASVM) was proposed to avoid the blindness in parameter choosing and improve the estimation ability of SVM, in which the parameters in SVM and kernel function were searched by genetic algorithm. And it was then applied to the classification for the swell and shrink grade of expansive soils. Five indexes including liquid limit, total swellshrink ratio, plasticity index, water contents and free expansive ratio were adopted as discriminated factors. And the four grades of the expansive soils were the outputs correspondingly. Classification function was obtained through training a large set of expansive samples. And it was shown that the classification method of GASVM was effective and with high accuracy.

Abstract:Under the external loads, the volume of soft clay decreases with the time and several subsidence phases could be classified with the during development characteristics. And the compression indicators should develop gradually. With the soft clay samples taken from representative soft base before and after geotechnical process in some express highway area of the Pearl River delta, indoor consolidation tests were carried out under different pressure levels. With the data analysis, quantitative relation formulas were obtained for the compression modulus of silt soil with pressure and time. Consequently, dynamic evolution pattern of compression modulus was obtained.

Abstract:In order to study aging behavior and antiaging performance of asphalt, aging tests were carried out with rolling thin film oven test(RTFOT) and oven aging test at 60℃, and aged asphalt was extracted from pavements of different service life. Viscosity of asphalt samples was fitted with nonlinear differential dynamic model. With parameter study, property changes, aging rate of asphalt and the difference of aging mechanism were analysed under different aging conditions. It was shown that the nonlinear differential dynamic model can simulate asphalt aging process in the laboratory or onsite effectively. At the same time, model parameters(L and r) can quantify aging state and aging rate. Asphalt had its limited aging state corresponding with different aging temperature. Ultimate aging degree of RTFOT and field aging were about 4~5 times of that of oven aging test at 60 ℃. And aging effect of RTFOT for 6h was about equivalent with that of field aging for 6 years. Thus timedelay RTFOT can simulate longterm aging of pavement asphalt.

Abstract:The long term deflection behavior of longspan continuous rigid frame bridges has often attracted the attentions in engineering field. Based on the moisture diffusion theory, the calculation method of differential shrinkage deflection was proposed for PC boxgirder bridges. Finite Element Method(FEM) model of 2D moisture field were established for typical cross sections of a case bridge. And the distribution law and the timevariation characteristics of moisture field were analyzed. Through the deformation coupling condition of moisture field, the drying shrinkage deflection of the bridge was calculated and analyzed. It was found that the differential shrinkage deformation was significant and great error would be with the conventional method. When considering the effect of differential shrinkage, the deflection in midspan was 3.1cm larger than that of the conventional method. Thus, the differential shrinkage was the main reason for long term deflection of longspan continuous rigid frame bridges.

Abstract:In order to explore the mechanism of low temperature construction and influence of additives on the high temperature performance of the asphalt concrete pavement, the viscosity at 110 ℃, 120 ℃ and 135 ℃ and softening point were measured for SBS modified asphalt and base asphalt with different additive content of ADZ, ADW or ADS, respectively. The additives can reduce viscosity of asphalt and realize construction of asphalt concrete in low temperature. The experimental results showed that: To some extent, three kinds of additives can reduce the viscosity of base asphalt or SBS modified bitumen. In contrast, at lower temperature (120 ℃or 110 ℃), the viscosity of SBS modified asphalt and base asphalt with ADW or ADS were obvious smaller than that of ADZ. With the increase of the three types of additive content, the softening points of base asphalt also increased. However, the softening points of SBS modified asphalt with lower additive content of ADZ, ADW or ADS were smaller than those without ADZ, ADW or ADS.

Abstract:Based on the analysis of seismic damage effect and induced secondary disasters on urban gas piping systems, the seismic damage characteristics and influencing factors were discussed, such as seismic intensity, geologic conditions and piping system characteristics. Moreover a series of earthquake disaster mitigation approaches were proposed for urban gas piping system, including:(a)aseismatic design of urban gas facilities; (b)erosion monitoring and replacement of old pipelines;(c)automatic gas shutoff system and district gas supply; (d) gas supply recovery after fault finding and treatment of damage pipelines; (e)establishment of realtime seismic data acquisition and rapid pipeline damage estimation system; (f)establishment of emergency response management system; (g)establishment of urban gas network seismic disaster risk assessment and simulation system.

Abstract:Under the traditional static protection mode that advocates controlling and stresses no change to the original, the central historic block in Baoding is facing some new problems such as the setting back of physical environment, isolation from the urban development and imbalance of the regional economical development. Based on investigation and analysis, the goals and dynamic conservation strategy were proposed for central historic block. The strategy took the dynamic conservation theory, in which the holistic protection and sustainable development were the features, as theoretic tool. And from urban planning, urban administration, society economic growth, urban space design and historic buildings protection aspects, the relationship between protection, renaissance and development were studied with the dynamic conservation strategy.

Abstract:The river watersource heat pump system is an important technique to utilize renewable energy in Chongqing and heat exchanger can influence overall energy efficiency of system obviously. A test was carried out to study the heat transfer efficiency of doublepipe heat exchanger with semicircular reentrant tube. It was found that the heat transfer efficiency would increase while curvature of semicircular reentrant tube rose. And when the ratio of R to r was five, heat transfer efficiency for semicircular reentrant tube would be increased 2.5% than that of straight doublepipe heat exchanger. Flow, temperature field and heat transfer process of semicircular reentrant tube were simulated with computational fluid dynamics(CFD) tool to study the heat transfer mechanism. The modified RNG κε Turbulence Model was adopted to ensure the accuracy of simulation analysis under the situation of rotary flow and great curvature. Thus, it was indicated that there was obvious secondary flow vertex in reentrant tube. And disturbance of vertex on boundary layer was the main reason for which heat transfer efficiency of double pipe heat exchanger would increase as curvature of semitoroidal reentrant tube rose. Based on the experiment and simulation, the recommended curvature for reentrant tube was proposed with the consideration of sediment in riverwater and heat transfer efficiency of heat exchanger.

Abstract:Conceptual design is one of the most important stages in building design, and energy efficiency analysis is one of the key issues in building conceptual design stage. The existing energy efficiency analysis methods and tools require inputing large number of parameters. However, the detail information of most parameters is not identified at the stage of conceptual design. And the current prevailing energy consumption simulation methods and tools are not appropriate at the stage of conceptual design. The proposed method can be used to compare the energy efficiency of multistrategies at the conceptual design phase. Minimum data were required to be input for achieving the optimal building design scheme. The method can provide a solution to the gap between the rapid building design cycle and the sustainable development demand in China.

Abstract:The influencing relationship equation of humidity distribution on the characteristics and extent of cross diffusion was proposed based on the nonequilibrium thermodynamic theory. With the parameters of temperature, humidity and contaminant gas concentration, a further study on the relationship was employed. It was showed that the temperature grads and the contaminant gas mass grads were less than zero when the humidity grads and additional diffusion coefficient were both positive/negative, otherwise the two grads were more than zero. Moreover, the higher the initial temperature and contaminant gas concentration were, the greater the absolute values of temperature grads and contaminant gas mass grads were, with the same humidity grads and additional diffusion coefficient. Whereas the influence of initial temperature was limited, and that of initial contaminant gas concentration was obvious.

Abstract:Fuzzy PID controller was applied in variable air volume system. The task was to control the temperature of supply air and the temperature of airconditioned room (the return air temperature) close to their respective targets. The fuzzy PID control system of supply air temperature and return air temperature was designed respectively. The supply air temperature was controlled through adjusting the valve opening of chilled water. And the indoor temperature was controlled through adjusting the rotational speed of variable frequency ventilator. The supply air temperature and the indoor temperature (return air temperature) were controlled online by fuzzy PID controller. Thus, it was shown that the design of fuzzy PID controller was reasonable and the effect of fuzzy PID control was well.

Abstract:Sludge is a very good fertilizer source and has higher value in use as nutrients for greening, whereas sludge also contains higher concentration of heavy metals, with which urban underground water would be suffered secondary pollution. A test of greening with sedium lineare and modified fly ash passivation sludge was carried out to study the impacts of different mixture ratio and dosage of modified fly ash on the plant’s growth and leachate. It was shown that 20% mixture ratio of modified fly ash was the optimum for sludge treatment and 80% of heavy metals pollution can be removed.

Abstract:The phosphate removal mechanisms of Calcite were investigated with the tests of Xray diffraction (XRD) analysis, transmission electron microscope (TEM) measurement, fourier transform infrared spectroscopy (FTIR) analysis , specific surface area by BrunauerEmmettTeller(BET) method and pole size distribution by BarrettJoynerHalenda(BJH) method. The main influencing factors on phosphate removal were investigated and the removal mechanism was approved. It was shown that phosphate removal efficiency was significantly influenced by reaction time, temperature, pH value and dosage of calcite. And with BET, BJH and TEM tests, no porous materials, less than 16.0 m2/g for the specific surface area and below 0.085 cm3/g for total pore volume, were found during the reaction process so as to prove that absorption was not the main way of phosphate removal. And based on XRD and FTIR tests, it was found that chemical precipitation was the main way of phosphate removal which contained two steps: the formation of CaHPO4·2H2O(DCPD) and its transformation to ACP, and the controlling step was DCPD’s transformation to ACP.

Abstract:Productive commissioning of treating sewage in plateau region has the features of low temperature, low atmosphere pressure and low oxygen concentration. The CASS process was applied in the expansion of wastewater treatment plant in ShangriLa. Aiming at the low air temperature and low atmosphere pressure and the low concentration of influent, several approaches, such as adjusting the aeration mode compatibly, controlling the contents of dissolved oxygen and cultivating active sludge with warm maintenance, were studies for system stable operation under the condition of mismatch between design parameters and operation mode. With the field test, when the water quality of influent was: CODCr:50.0~164.0 mg/L, SS:30.0~123.0 mg/L, TN:7.0~82.6 mg/L, NH3N:1.9~39.2 mg/L, TP:0.6~3.2 mg/L, the quality of effluent was: CODCr:10.0～49.0 mg/L, SS:5.0～22.0 mg/L,TN:3.4～22.7 mg/L, NH3N:0.9～11.1 mg/L, TP:0.1～1.8 mg/L, in which the standard of the level B in class I were achieved according to Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).

Abstract:In order to investigate the variation of sludge nitrification activity before and after microbulking with low dissolved oxygen(DO), with mean DO value of 0.6mg/L-0.9 mg/L，the sequence batch reactor (SBR) was employed to test the oxygen consumption velocity curves before and after microbulking. The results showed that COD removal ability increased, whereas the ammonia nitrogen removal effect was decreased with microbulking of sludge. The oxygen consumption velocity curves before and after microbulking showed that the total activity of activated sludge was 67.72 mgO2/gVSS·h before microbulking, of which nitrification activity was 43.12 mgO2/gVSS·h, that is, 63.67% of the total activity. And the total activity of activated sludge was 90.49 mgO2/gVSS·h after microbulking, of which nitrification activity was 23.98 mgO2/gVSS·h, that is, 26.51% of the total activity. The low DO value was the limited substrates for microorganism growth. When activated sludge was in the state of microbulking, the filamentous bacteria were the dominant bacteria, whereas the nitrification bacteria were subordinate. Thus the total nitrification activity of activated sludge decreased.

Abstract:The mechanism and kinetics of parathion degradation was investigated under high frequency ultrasonic irradiation in aqueous solution. The pseudofirstorder kinetic model and the response surface methodology (RSM) were proposed to evaluate the effect of ultrasonic frequency, power and initial concentration on sonochemical degradation of parathion. With the response surface experiments and quadratic fitting model, it was clearly indicated that the quadratic model was significant (P=0.000 2) and the lace of fit was not significant (P=0.113 6). The R2 of the model was 0.973 3. Ultrasonic power, initial concentration and the square of ultrasonic frequency were significant items for the model. And it was also indicated that there was an optimal frequency for parathion degradation with the operating conditions and the degradation rate of parathion was found to decrease with increase of initial concentration and decrease of power.

Abstract:Scanning Electron Microscope and Energy Dispersive Analysis (SEMEDS) were used to study the elements of particles in drinking water treatment effluents, to conduct the distribution characteristics of particles and distribution probability of main elements, and to analyse the possible structure of individual element in the Granular Activated Carbon(GAC) effluents particles. It was indicated that there were more elements in particles at GAC inlet and outlet, in which the major elements were Ca、Fe、Al 、Si 、C、O. And the concentration of nonmetal elements was absolutely higher than that of metal elements. The shapes of particles were various, in which most of them were irregular and very few were baculiform, spherical or flocculent. The molar ratio of (C+O) to (Ca+Fe+Al+Mg) in particles had a wide range, from 1.0 to 40, in eight samples, in which ratios of two samples were 1.0-3.0 and five were over 7.0.