Abstract:To explore the secondary moments on the columns and beams in steel braced frame arising from the reaction introduced by the gusset plates of bracing members with the developing story drift, and to obtain this unwanted effects on the frame members, a series of diagonally braced frames (one-story and one-span) where the braces are connected with gusset plates are simulated by using shell elements in ANSYS program. By considering two conditions in which the brace is compressed or tensioned respectively under story drift, the secondary moments in the columns and beams influenced by the key factors such as gusset plate thickness, length of gusset plate, axial compression ratio of columns, and yield strength of steel used in the frames are investigated. It is shown that the secondary moment increases with the increase of story drift, and can even form plastic hinges in both the beam and the column if a stronger gusset plate is employed. At elastic limit state of the braced frames, the tensioned brace can cause smaller secondary moment than the compressed one. The axial compression ratio of columns can slightly decrease the secondary moment. Based on the statistic results of the parameter analysis, reasonable values of the secondary moments are suggested for the engineering design of the columns and beams.

Abstract:Bond behavior of FRP rebars and concrete at elevated temperature are present in this paper. Commercially produced GFRP and BFRP rebars with sand coatings surface treatments were cast in concrete for the pullout tests, and the degradation of bond strength and bond-slip curve at the temperature ranging from 20-350 ℃ were obtained from the test. Experimental results indicated that the bond strength declined significantly during the glass transition temperature zones of epoxy resin, and a bond strength decay model at elevating temperature was proposed based on two controlled parameters of the glass transition temperature T_g and the decomposition temperature T_d of matrix. The model shown good agreement with our experimental results and other researcher's, and the model is also suitable for FRP bars with different fiber types and matrix materials. The bond failure of pullout specimens at high temperature is caused by the deboning of FRP core section and sand coatings. Based on the bond performance, the paper proposes a four stage bond-slip theoretical constitutive relationship model for FRP rebar with sandcoating surface and concrete at high temperature. The τ-s constitutive model at high temperature is based on the CMR and mBEP model, and the parameters in the model are proposed from the τ-s test results. The bond-slip constitutive relationship model at elevate temperature can be used for the analysis of fire performance of FRP reinforced concrete members.

Abstract:To solve the problem that the existing effective width formula of the equivalent strut mode does not apply to steel frame structure with light enclosure wall panels, in this paper, re-fitting the effective width formula of the equivalent strut model for steel frame structure with light enclosure wall panels is obtained by parameter analysis method. Considering the key parameters influencing lateral stiffness of steel frame with light enclosure wall panels on the applicability of formula, the validity of the formula was proved by using the test data in the literature. The results show that the fitted formula are applicable in different cross-height ratio, axial load ratio, wallboard thickness and wallboard holes. In different width wallboard, it can be multiplied by the width coefficient KB to regulate the influence of the formula by panel width.

Abstract:To predict the cracking pattern of masonry under uniformly and laterally load more simply and more accurately, a support vector machine (SVM) method was developed. Firstly, the feature of the cracking patterns of tested wall panels was extracted, and the priority knowledge of these panels was obtained. Secondly, the feature of these panels to form the characteristic data was quantitatively described and the SVM model to study the characteristic data was built. Finally, the cracking patterns of new panels were predicted using the SVM model above. To testify the SVM model, the panels with three simply-supported edges (hereinafter referred to as “the trilateral support”) and a top free edge, the panels with four simply-supported edges(hereinafter referred to as “support on four sides”), and all the panels above were studied. The result indicated that the developed SVM method could predict the cracking patterns of masonry wall panels in a better precision than traditional methods.

Abstract:To understand the changes and influencing factors of on-way resistance in sludge transportation pipelines, the influence effects of sludge concentration, temperature, drag reduction agent dosage and mean velocity on on-way resistance were investigated and the mechanisms were analyzed using the sludge concentrated in storage basin in a wastewater treatment plant in Changchun City as object. The results showed that the sludge concentration significantly affected the on-way resistance, and when the concentrations were 2.38％, 3.94％ and 5.39％, the resistance increased as the concentration increased, therefore, to achieve the best conveying effect, the sludge concentration should be controlled less than 2.38％ during transportation process. Temperature has significant effect on the on-way resistance, therefore, appropriate heating or insulation measures will be beneficial to the reducing of resistance; Drag reduction agent dosage significantly affects the on-way resistance. The drag reduction effect will both be reduced when the drag reduction agent dosage is too low or too high, therefore, the drag reduction agent optimum dosage should be calculated in the actual use, and the best dosage for 3.94％ concentration sludge is 0.588％; The mean transportation velocity of sludge should be slightly higher than the non-deposition velocities under turbulent conditions which are determined to be 1.35-1.45 m/s,1.20-1.30 m/s and 1.10-1.20 m/s for 2.38％, 3.94％ and 5.39％ concentration sludge respectively.

Abstract:An integrated approach of potassium permanganate composites and polymeric ferric sulfate was used to strongthen the effect on the removal of simulated thallium and antimony combined pollution in surface water. Jar tests and micro-travelling experimentation platform tests were used to optimize the operation conditions, then the main factor for removing thallium (Tl) and antimony (Sb) combined pollutants was discussed. The results show that the initial water containing 0.21-0.35 μg·L-1 (2-3 times) thallium(Tl) and 15-20 μg·L-1 (3-4 times) antimony (Sb) can be treated to satisfy the Chinese drinking water quality standard, simultaneously the corresponding operation condition are as follows: the pH value of raw water should be adjust to 5.7-6.3, the dose of PPC was higher than 3 mg·L-1 and a dosage of PFS was higher than 40 mg·L-1. And furthermore, the dosage of potassium permanganate composites(PPC) was the key factor for thallium(Tl) removal,while the dosage of polymeric ferric sulfate(PFS) and pH of raw water were the key factors for antimony(Sb) removal.

Abstract:As for the application of ultrafiltration in water treatment process, one of the key points is the selection of suitable threshold flux. Based on the needs of ultrafiltration in water works, four kinds of water sources including raw water, water during coagulation, water after sedimentation and water after sand leach were used. The effects of different pretreatment on threshold flux obtained from flux cycling method were compared and analyzed. The irreversible threshold flux of raw water was 11 L/(m²·h), which was due to high organic maters and turbidity. The irreversible threshold flux of water after sand leach was higher than 55 L/(m²·h), which was similar to that of water after sedimentation. It is suggested that the ultrafiltration membrane system can be installed after sedimentation.

Abstract:To improve the selective reduction of nitrobenzene to aniline in biocatalyzed electrolysis system (BCES), glucose, as the co-substrate, was employed into the biocathode. The enhancement of nitrobenzene reduction efficiency and selectivity by adding co-substrate was observed. Cyclic voltammetry revealed nitrobenzene reduction peak was positively shifted by 70 mV with the present of co-substrate, indicating the enhanced performance was caused by not only the extra electrons donated by glucose but also the improvement of bioelectrocatalytic activity. To avoid the excess increase of COD in wastewater, the suggested concentration of co-substrate was 200 mg·L-1, which resulted in aniline formation efficiency over 97 ％ at all tested applied voltages (0.15-0.25 V), and increased the apparent first-order kinetic constant by (52 ± 6)％ compared to that without co-substrate.

Abstract:Electrocatalytic hydrodechlorination (ECH) is an efficient method for dechlorination of chlorinated organic pollutants. Preparation of working electrode used in ECH is of great importance. Dopant ions doped in polypyrrole had effects on Pd/PPY/Ni composite electrode. The influences of dopant ions on morphology and ECH performance of composite electrode were investigated. The removal rates of 2,4-DCP for Pd/PPY(PTS)/Ni electrode reached 91.1％, higher than others, especially than that of Pd/PPY(NaClO₄)/Ni. The effects of strongly adsorbed anions (ClO₄-, Cl-) in catholyte on electrochemical hydrodechlorination activity of the composite electrode via removal of 2,4-DCP were studied. 

Abstract:To reduce fermentation costs and achieve continuous fermentation of bio-flocculant, the immobilized fermentation to produce bioflocculant was used. The performances of the carriers including activated carbon, pllyurethane foam and mycelial pellets were contrasted by comparing the carrier stability, bio-flocculant production and bio-flocculant activity. The solid-liquid ratio of activated carbon and mycelial pellets were optimized. The results show that the activated carbon, polyurethane foam and mycelial pellets could adsorb bioflocculant-producing bacteria F+ and retain high flocculanting activity for long time. The yields of activated carbon and mycelial pellets were higher than that of polyurethane foam. The adsorption rate of mycelial pellets in 24 h was higher than that of granular activated carbon. Under the optimized conditions (solid-liquid ratio 1.0 g/L; the fermentation time 24 h), the crude bio-flocculant yield of immobilized fermentation by mycelial pellets (2.234 g/L) increased 14％. The shake flask experiments show that the three carriers could produce bioflocculant more than 15 batches. The solid-liquid ration was optimized as 1.0 g/L by considering the flocculation rate and cost.

Abstract:The thermal response psychology experiments were conducted for college students wearing winter clothes in three experimental conditions, overall slightly cool, overall neutral asymmetrical cold radiation and overall neutral uniform. The environmental and physiological parameters were recorded. Meanwhile, the subjects were asked to fill in the questionnaires on five local and overall thermal sensation and thermal comfort. The results show that, in the slightly cool and neutral asymmetrical cold radiation conditions, the head and back thermal sensation have no significant difference; while the hand, arm, lower leg and overall thermal sensation are different. In the neutral non-uniform condition, overall thermal sensation votes were lower than those in the uniform condition, although the mean indoor temperature of the former condition was higher. The temperature difference between head and foot increased for the subjects near the exterior window and wall because of cold radiation, which led to the people felt cold at their legs and the overall thermal sensation and comfort decreased. In the slightly cool and neutral conditions with cold radiation, overall thermal sensation followed the thermal sensation for cooler parts, and overall thermal comfort followed the most uncomfortable parts, following the “complaint” modes. In the uniform condition and asymmetrical cold radiation environments, overall thermal sensation votes and thermal comfort votes have good linear correlation. The air temperature for the lower body such as lower legs should be increased, which led to leg local thermal sensation improved, and overall thermal sensation and thermal comfort would be improved.

Abstract:To provide theoretical basis for determining reasonable maximum speed limit value and lighting parameter at crosswalk, and ensure crossing pedestrian safety at nighttime, considering driving speed and average illuminance of street lamp, the change rule of driver recognition distance for crossing pedestrian was studied. Single and statistic pedestrian with dark clothes at six crosswalks were regarded as recognition object, and eight drivers′ recognition distance data at nighttime were recorded. With the collected data, several regression models were established to capture the relationship among the variable of recognition distance, driving speed, and average illuminance. The result shows that the driver recognition distance at nighttime decreases with the raise of driving speed and there is negative relationship between them, and it increases with the raise of average illuminance and there is positive logarithm relationship between them.

Abstract:To understand salt spray corrosion behavior and corrosion mechanism, the resistance of salt sprays corrosion for a Fe-based alloy 30Cr2Ni4MoV used in ship had been studied in the paper. The surface and section of samples corroded for different times, the corrosion products, the corrosion weight loss and corrosion ratio had been analyzed. The result showed that after corrosion 400 h, the surface of samples had been covered with corrosion products, and some corrosion products had separated from the substrate. The main component of corrosion product was FeO(OH). The corrosion of 30Cr2Ni4MoV started form the corrosion pits, and then extended. While the corrosion extent of samples tended to be same, new corrosion pits appeared, and corrosion continued. In the first 100 h, the corrosion rate changed greatly.

Abstract:Based on the similarity principle, a reduced scale test model of steel-concrete joint section of The Xiamen Maxin Bridge is designed to investigate the mechanical behavior of steel-concrete joint section of hybrid beam cable-sayed bridges. The test model is loaded with design load and 1.7 times design load, and the variations of stress and deformation of control sections and main members with loading history are obtained. Combining test results with numerical simulation results, the load transfer mechanism of steel-concrete composite joint section is researched. As shown in the results, the stress of steel, concrete and PBL connector of the joint section is small, and there is enough safety capacity in the joint section. The relative slip between steel box and concrete is small, the steel box and concrete work together well, and the load from steel is smoothly delivered to concrete. The load distribution of load-transmission members is proper. It is proved by the test that the lattice with post-bearing plate and PBL shear connectors is reasonable for steel-concrete composite joint section.

Abstract:To comprehensively evaluate the seismic performance of precast concrete shear wall with vertical reinforcements grouted in holes and spliced indirectly in horizontal connections, two fabricated and a cast-in-place concrete shear wall with full scale specimens were tested under low cyclic loading. The test results show that the concrete interior shear wall specimens (JN) is basically the same as the cast-in-place specimen (XJ) in failure modes, but the concrete exterior shear wall specimen wall (JW) is different with the XJ. The hysteresis curve of the specimen is full, the trend of the skeleton curve is basically the same and the capacity of the energy dissipation is close. The ultimate displacement angle of each specimen is 1/56-1/49 and the displacement ductility factor are 4. The initial stiffness of JW, JN are lower than the XJ, and the force behavior is improved in exterior wall specimens (JW) with the setting position of horizontal connections moved up.

Abstract:To evaluate and predict the strength of backfilling body, a new method is provided to establish a model of the relationship between backfilling body strength and influence factors. The modified BP neural network algorithm is used to establish the model based on 18 groups results of the compressive strength tests of the backfilling in laboratory. The structure of the model is 5-7-1 type, that is to say 5,7 and 1 neurons are the input, hidden and output layers respectively, where the input is including the cement-sand ratio and quantity of the cemented material and the output is the 28 days compressive strength of the backfilling body. The results show that BP neural network model exhibits excellent prediction ability for the prediction of the strength of backfilling body, the prediction model speeds up the convergence rate of BP network and improves the training accuracy. The maximum relative error between the predicted results and the test data is 4.23％.

Abstract:In order to study the temperature rise in the steel components exposed to fire, experiment was carried out in one large space building and a theoretical model was built in which the influence of flame radiation on the temperature rise of steel components was taken into consideration. The calculation methods for the thermal radiation from the flame and temperature development in steel were proposed, and the calculated results agree well with the experimental data.

Abstract:To provide base isolation design theory support of vertical storage tank, based on existing elastic theory seismic model,introducing the base isolation measures, the base isolation mechanical model was established,which was convenient to engineering design staff, at the same time,base isolation mechanical model was compared to elasticity theory three-mass tank isolation mechanical model which was author put. For 1.5×10⁵ m³ vertical storage tanks, isolation layer using the equivalent linear model, selecting 0.40g El-Centro seismic wave as the ground motion input, the equations of motion using numerical integration method, the model parameters and seismic response were analyzed. The results showed that: several elastic theory tank isolation model mass and height parameters were similar,storage tank design could be compared with reference to calculation. Convective mass of several models more than 70％ total mass,it should be give attention. Isolation reduces the earthquake response of elastic impulse component, while long period convective component plays a leading role. From the actual situation, elasticity theory three-mass tank isolation mechanical model of author was feasible and applicable.

Abstract:For the purpose of appropriate nitrate dosage, experiment was conducted to evaluate the performance of control of acid volatile sulfide(AVS) with calcium nitrate and to investigate the changes of related properties including total organic carbon(TOC), redox potential(ORP), pH, water content, ammonia nitrogen and bioactivity. Injection dosage of nitrate-nitrogen at 1.27 g/kg fresh sediment can obtain 97％ removal of AVS in 14 days. There was no affect of increase of nitrate-nitrogen dosage on removal efficiency of AVS, and higher nitrate-nitrogen dosage could keep treatment effect stable for a longer time. ORP increased significantly to -100 mV when injection dosage of nitrate-nitrogen was more than 1.58 g/kg fresh sediment. The nitrate-nitrogen dosage more than 2.53 g/kg fresh sediment resulted in significant decline of pH value, and the nitrate led to increasing in ammonia nitrogen and decreasing in sediment micro-bioactivity. The appropriate range of nitrate-nitrogen dosage is from 1.58 to 2.22 g/kg fresh sediment (0.70-0.98 g/g S).

Abstract:To analyze the effect of bicycle flow caused by curb parking on segregated bicycle lane, this paper analyzed the group and compression characteristic of bicycle flow. Then based on airflow analysis method, we put forward the model of bicycle compression wave to describe the state of cycle deceleration-following and stop under the influence of parking process of vehicles. By means of the model, the maxim queuing position is calculated when the situation caused by curb parking is the worst. Furthermore, the shortest distance between curb-parking space and upper intersection is calculated. Based on the field data measured at Dongzhongshi Road in Suzhou city, comparing the calculated results with the real stop wave rate, the average value of relative error is less than 8.57％. By controlling the interference time of bicycle and density of bicycle flow, the phenomenon that queuing bicycles extend to upper intersection can be reduced effectively, so that the traffic congestion can be relieved and the traffic hidden danger can be reduced.

Abstract:To increase system uptime with limited energy, this paper discussed the influencing factors of threshold selection in timeout policies from the point of view of timeout policies in dynamic power management. After investigating domestic and overseas principles of dynamic power management strategies, analyzing principles of dynamic and fixed threshold policies in timeout policies and completing analyses of influencing factors of threshold selection in the present dynamic threshold policies, the paper drew a conclusion of the following three influencing factors on threshold selections, which were energy consumption during hibernating and awakening of system, batteries′ discharge voltage and system′s application environment, respectively. At last, this paper confirmed that comprehensive consideration on threshold influencing factors would be a shortcut in finding optimal threshold.

Abstract:According to the ill-conditioned Z transformation disadvantage of the LLL algorithm(A.K.Lenstra,H.W.Lenstra,L.Lovasz)for GPS integer ambiguity decorrelation,a modified LLL algorithm is proposed in the paper. The modified LLL algorithm applies the repaired Gram-Schmidt orthogonalization and row vector inner product adjustment matrixes to decorrelate integer ambiguity covariance matrixes, improve the performance of the low-dimension matrixes decorrelation applying the LLL algorithm and achieve high-dimension matrixes decorrelation.Taken the condition number as the criterion for judging the degree of matrix correlation,the performance of the LLL algorithm and the modified LLL algorithm are compared by applying 200 integer ambiguity covariance matrixes derived from random simulation. Results show that the modified LLL algorithm has better performance in decreasing the condition numbers of integer ambiguity covariance matrixes and reducing the correlations of covariance matrixes. Thus,the modified LLL algorithm is better for searching and solving GPS integer ambiguity.