Abstract:According to our current bridge seismic design codes, the bridge tower is explicitly required to remain almost elastic even under the excitation of occasionally happened earthquake. To achieve this seismic performance objective, usually the steel ratios of tower base and strut are required to satisfy the static loading demand and increase by a large margin as well in most engineering practices which leads to engineering inefficiency as well as a rising seismic demand for the substructure. Therefore, the structural design parameters including the location, the stiffness and the constrain condition of the strut with respect to the tower column of H shape tower were studied to explore their effect on the transverse seismic responses of cable-stayed bridge tower, Moreover, the effect of yield intensity of the strut on the seismic responses of the tower column is also studied. The results show that the location and the stiffness of the strut have a slight effect on the seismic responses while the transverse seismic demands of the bridge tower decrease drastically when the constrain condition between the cross beam and the tower column changes.

Abstract:Premature debonding between CFRP and concrete commonly occurs in RC beams strengthened with CFRP sheets. U-wrap anchorages installed at the ends of CFRP sheets or along the entire beams are currently well accepted for preventing the debonding failure in engineering practice. Three schemes of CFRP strengthening beams without U-wraps, with U-wraps at CFRP ends and along the entire beam are numerically studied. The loading capacities and deflections of the beams, bond-slips in the interfaces and strains of CFRP sheets in the three cases are compared under different loading levels. The result shows that the strength and stiffness of the strengthened beams are effectively improved with the clamping of U-wraps. After the yield of steel reinforcement, U-wrap anchorages along entire beam are more effective for preventing the debonding failure than those at CFRP ends and lead to the uneven strains of CFRP sheets as well At the ultimate state，CFRP can rupture locally at the places of high strain concentrations leading to decrease in the loading capacity compared to the beam anchored at two ends of CFRP.

Abstract:The emergence of large-span bridge and extreme weather attract much more attention of researchers on the bridge buffeting problem. One of the most important factors that affect bridge buffeting response is wind velocity spectrum. In the precious investigations, wind velocity of various frequency has impact on the bridge buffeting response. While Proper Orthogonal Decomposition(POD)method is proposed to decompose the wind velocity to solve the above problem and a cable-stayed bridge was used to investigate the contribution of effective model to bridge buffeting response. The result showed that not all frequency ranges of wind velocity spectrum contributed to the response which had relationship with both structural self-vibration mode and turbulence effective mode coefficient.

Abstract:The internal force would vary largely with different load ratio for steel arches under combined full-span with half-span loads. However, most relevant formulas on in-plane stability capacity of steel arches were obtained by studying the stability under a single load. Thus, it lacks full considerations of the applicability of bearing capacity formulas under a combined full-span load with half-span load. To overcome this shortcoming, the two-hinged parabolic steel arch was used to compare the results of bearing capacity of arches with different load ratios, rise-span ratios and sections calculated by several methods, The method proposed in the current Chinese design specification of steel arch structure and the finite element method based on the perfect arch and the consistent imperfect arch were included. The results showed that the method in the specification for designing a steel arch would be conservative with a large ratio of the full-span load to the total loads while unsafe with a large ratio of the half-span load to the total loads.

Abstract:In order to satisfy the demand of the double-deck traffic in city, a concrete box girder model with rectangular web openings was designed with ratio of 1:6. Experimental study was carried out to investigate the flexural capacity of the model girder with double uniformly distributed load. The finite element model was established based on the experiment and the results agreed with measurement results. The effect of the web openings on the girder was explored. The results demonstrated that the deflection caused by load on bottom plate of box girder was 9.7% more than that of load on the top plate. The deflection of girder with web opening is 22.9%~28.1% greater than that of girder without web opening. Compared with girder without web opening, the shear lag of girder with web opening increased, of which the maximum value was 62.0% in various working conditions. simply-supported concrete box girder with web openings under double uniformly distributed load affect the flexural capacity.

Abstract:Construction risk for water piers and foundations with double-wall steel cofferdam was analyzed by the fuzzy fault tree theory. An evaluation method of construction risk for water piers and foundations with double-wall steel cofferdam was proposed. Fuzzy fault tree of construction risk for water piers and foundations with double-wall steel cofferdam was established based on Yingwuzhou Yangtze River Bridge. 31 bottom events were considered in fuzzy fault tree model according to 2 water pier and foundation with double-wall steel cofferdam. Key process of construction risk was obtained and risk prevention measures were proposed.Results showed that fuzzy number of construction risk probability for water piers and foundations with double-wall steel cofferdam was(0.05015,0.05278,0.05542). Construction risk of 2 water pier was highest. And weld leakage, pile broken and sand boiling were the key processes with higher construction risk. There fore appropriate prevention measures would be taken to reduce the construction risk for water piers and foundations with double-wall steel cofferdam.

Abstract:In the process of damage identification for high-order nonlinear structure such as cable-stayed bridges by the standard genetic algorithm, premature convergence would appear. In order to avoid this, an improved hierarchic genetic algorithm was proposed. The cable force change was used to establish the optimization function and threetypes of standard genetic algorithm were combined with variable fine-tuning and hierarchic strategy.To establish a hierarchical genetic algorithm with catastrophe characteristics A single-tower cable-stayed bridge model was used in the numerical simulation and the result showed that the probability of premature convergence was reduced in the improved hierarchic genetic algorithm and and the cable-stayed bridge damage was identified effectively. The anti-noise performance was better.

Abstract:To study the bearing behavior, failure mode and mechanical behavior of different structural forms of steel-concrete joint of hybrid girder, based on the hybrid girder of Jiujiang Yangtze River Highway Bridge with 818-metre main 8pan, select a pressure-resistant shear-transferred steel-concrete joint, redesign a shear-transferred only joint for contrast, carry out two scale 1:2 model specimens bearing behavior experiment, measure the strain and relative slip of steel and concrete. The results show that:the bearing capacity of the pressure-resistant shear-transferred specimen is twice than the other；the bearing plate carries about 62.5% of the axial load, the force transmission of the bearing plate reduces the steel stress、steel-concrete relative slip and the force transmission ratio of connectors, makes the load transferred more effectively.

Abstract:Reasonable choice of rock strength criteria is crucial for stress and displacement prediction and support design in tunnel engineering. Based on Mogi-Coulomb strength criterion and elastic-perfectly plastic model, analytical solutions of stress and displacement for surrounding rocks around a circular tunnel were derived The intermediate principal stress coefficient was used to present the intermediate principal stress effect. The results in this study were compared with the current solutions in the literatures and the influence of intermediate principal stress and shear strength parameters of surrounding rocks was discussed. The results showed extensive applicability and the Mohr-Coulomb strength criterion and Matsuoka-Nakai criterion are two special cases; when the intermediate principal stress coefficient b was equals to 0.5, the results indicated that the intermediate principal stress effect and its range for rock strength; the influence of cohesion and internal friction angle on the plastic radius and tunnel wall displacement was significant; Care should be taken to the effects of intermediate principal stress and shear strength parameter variations of surrounding rocks on tunnel design and construction.

Abstract:Based on settlementation control design, CFG pile-raft composite foundation was used in the Shanghai-Nanjing intercity railway embankment test. To explore the settlement control mechanism and bearing characteristics of the CFG pile-raft composite foundation，embankment settlement, pile-soil stress distribution and the dissipation of excess pore water pressure were observed to obtain data through field testing. Composite foundation settlement, lateral deformation of subgrade soil， pile-soil stress distribution along the lateral base and excess pore water pressure changes with time under embankment were analyzed. The change pattern of pile-soil stress ratio and load sharing ratio were studied. Field test results provide the experimental basis for the further theoretical studies and optimized practial design of the soft foundation treatment in the CFG pile - raft structure in the high-speed railway project.

Abstract:The process of valley-type solid waste landfill sliding was simulated in centrifugal model test using container rotated during the centrifuge flight In the test, the displacement of the slope was measured and analyzed. The results showed that large deformation occured in the shoulder of the slope when the front slope angle and the back slope angle reached 40 degree and 45 degree respectively at centrifuge acceleration of 40g. The overall sliding appeared when the front and back slope angels were 51.6 degree, 56.6 degree respectively, and the interface slope angle at the bottom was 11.6 degree. With the increase of rotation angle of the model, the trend of overall sliding was accelerated and there was a large deformation of landfill body as well. The deformation perpendicular to the bottom of the slope was larger than that parallel to the bottom. When the model rotated 26 degree with the front and back slope angel of 66 degree, 71 degree, respectively，the interface slope angle at the bottom was 26 degree, and the failure mode changed from sliding inside the landfill to sliding along the internal interface slopes. The process of waste body sliding along the liner interface was recreated in the test and this process supported the method of choosing liner parameters in stability analyses. Based on measured data, the deformation and destruction characteristic were analyzed, and the main influence factors in selecting the waste shear strength parameter were discussed.

Abstract:The Falling Weight Deflectometer(FWD)test, Portable Falling Weight Deflectometer(PFWD)test and Dynamic Cone Penetrometer(DCP)test in field as well as indoor repeated loading test were carried out with three types of subgrade, clay, sandy and earth-rock mixture. The regression relationship of the parameters observed of these three different types of subgrade in field was investigated respectively. The indoor dynamic modulus changed along with different water contents and the relationship waspresented as well as the empirical relationship of the on-site and indoor dynamic The results indicate that in the three different subgrade conditions,a double logarithmic regression relationship between dynamic modulus(EP and EF)and average penetration rate(DP)and a parabola regression relationship between indoor dynamic modulus and water content exist. The regression relationship between field index and indoor dynamic modulus was significant as well.

Abstract:The advantages and disadvantages of existing methods of foundation treatment were analyzed. The “vortex squeeze expansion mechanism” was proposed and tested in the laboratory. The self-designed vortex squeeze expanding environment box and steel casing were used to implement the vortex squeeze expanding experiment. The vortex pressure blade in the steel casing can squeeze the flowing concrete into the surrounding soil medium smoothly. The expanded diameter ratio was defined. The expanded diameter ratio conditions of sandy soil and clay under different torque and the ultimate torque were presented. The concrete flow analysis model and dynamics model of concrete in the vortex pressure chamber was established based on the analysis of flow patterns that occurred during the vortex compressed concrete. The results indicate that it's feasible to use the method of vortex squeeze expansion to handle foundation, it have strong applicability. Vortex squeeze expansion mechanism will bring new vitality for the foundation treatment methods.

Abstract:A mathematical model was established by using the transfer matrix based on Winkler elastic subgrade and spring supports in Newmark method. In simplification for subgrade reaction with discrete spring supports, the unequal displacements of two ends for pile section were included in the model. Lateral displacement and cross-section angle of the pile were determined by lateral static load test and the values of parameters of multiple subgrade reaction models were calculated by computer programming. By identifying the stability of long pile in different subgrade reaction models, the change patterns of three factors were analyzed, including effective length of long pile, restrictions on pile top and extensive length on the ground.

Abstract:Pile supported embankment has been widely used in road, airport and dam engineering due to effective construction and economic advantages which can effectively control the settlement and differential settlement. The soil aching effect is a key factor in the load transfer mechanism of pile supported embankment. Based on the current laboratory model test, a series of numerical simulations were conducted with the particle flow code PFC2D to study the contact force, principal stress, vertical and lateral displacements in embankment. The embankment fill and subsoil were simulated by the Disk,andthe pile and model box were simulated by the WallThe multi-layer compaction method was used to establish the Discrete Element Method models. The micromechanical properties of the embankment fill and subsoil were obtained from numerical biaxial compression test and simple compression test, respectively. The simulation results indicated that the soil arching in pile supported embankment was composed by multiple hemispherical arches with different centers, and the height of arching was about 5(s-a)/6. Within the soil aching height, the deflection of principal stresswas obvious, and the vertical and lateral displacements were significant.

Abstract:The samples contaminated by heavy metal were taken from tailing pond and landfill site of wastes The different heavy metal contamination samples with different incorporation ratio are respectively mixed with the undisturbed soil. The content analysis of heavy metal, direct shear test and unconfined compression strength test are carried out in order to study the strength properties of the heavy metal pollution. The results of test and analysis show that: the heavy metal pollution has a very strong impact on the strength properties of soil. With the increase of concentration of heavy metal pollutants i, c-value gradually increased and φ value decreased. Under the same water content, the unconfined compression strength is reduced with the increase of heavy metal content. The strength will decrease by approximately 35%～60%. The characteristics of the diffuse double layer and the thickness of the water film between the soil particles will change when the heavy metal contaminants the soil, the balance relationship between cationic and anionic on the soil surface will also be broken. Therefore, the strength properties of the contaminanted soil will change.

Abstract:In order to control the water eutrophication, microorganism agents with high capability of denitrifying phosphorus accumulation are required. A denitrifying poly-phosphate accumulating organisms(DNPAOS), B8(Pseudomonas putida sp.)was isolated from activated sludge in oxidation ditch of Anhui Tianchang wastewater treatment plant. Intracellular polyphosphate granule(Poly-P)dyeing method was used to optimize the culture conditions of Poly-P-producing Pseudomonas putida strain B8 seed liquid. The results showed that the appropriate culture conditions were as follow: pH value and temperature ranged from 6.5 to 7.0 and 30~32 ℃m respectively. The saturation values of dissolved oxygen varied from 70% to 88%(when velocity was in range of 120~140 r/min), 15~20 h proved to be the cultivation time. The seed liquid produced by B8 showed high phosphorus uptake rate in the processes of anaerobic-anoxic and anaerobic-aerobic in wastewater(89.73% and 94.09% respectively)In the anaerobic-anoxic process, the highest nitrate removal efficiency was 53.48%. Extracellular polymeric substances(EPS)extracting method and analysis of phosphorus removal characterization revealed that phosphorus removal was mainly caused by intracellular uptake, rather than by extracellular biological adsorption.

Abstract:Ferulic acid(FA)was one of important auto-toxic chemicals leading to continuous cropping obstacle for many crops. A bacterium strain AWS4B was screened out and identified preliminarily as Staphylococcus sp.,named as AWS4B. The degradation characteristics was studied and the pathway of the degradation was discussed. The results showed that the degradation rate reached 99.97% in 72 h when the initial FA concentration in the inorganic salt urbane liquor was 100 mg/L. The degradation of FA followed first-order reaction kinetics model and the thermal degradation activation energy was 19.88 kJ/molThe rate constant(k0)was 3.26×10 -4and equation for strain AWS4B prediction model was proposed in this paper. Many compounds provide strain AWS4B with carbon and enery. The influence of different nutrient substrates added in the degradation experiments was also investigated. Degradation pathway was likely to be that FA was degraded into Vanillin, Vanillic acid and protocatechuic acid through non-oxidative decarboxylation, oxidation and demethylation.The protocatechuic acid was depredated through benzene ring cleavage and water and carbon dioxide were produced finally and FA was degraded by strain AWS4B.

Abstract:The mechanical properties, phase change energy storage, environmental protection, and recycling of building materials are extensively studied, but few studies focus on the mercury adsorption of different building materials. Five types of cement brick powder including foam concrete, red brick, aggregate and gravel as well as several standard concrete blocks were exposed to gaseous mercury in constant temperature to determine most vulnerable building material to mercury contamination and the contamination depth of concrete blocks.Results showed that small particle contributed to large mercury adsorption, however different performance was found amongvarious materials. Red brick was the likely to have strong adsorption capacity followed by foam concrete and gravel. For concrete block,the pollution mainly concentratedat the 0~1.5cm of the surface. As a result, for some seriously mercury polluted factories and workshops, mercury pollution can be removed by peeling the skin of the buildings before demolition, renovation process.