Abstract:In order to investigate the basic mechanical performances of the composite girder under the fire loads, three typical experimental models including simple-support T-section girder, simple-support box-section girder, and continuous box-section girder, were built. After establishing a detailed experimental plan, a fire experiment loaded on three sides was conducted in a laboratory fire furnace. The comparative study on the material characteristics of steel between the models before and after the fire loads showed that the yield and limit strengths decreased by 10%~20 % after fire loads with the 700~900 ℃.The elastic modulus of the steel girder only slightly changed with the increase of temperature. The influence on the concrete material during the fire could be almost ignored; however, 5% decrease of the concrete material strength could be found after cooling off. The results provided good experimental and theoretical foundation for determining the basic material characteristics in the anti-fire design of the composite girders.

Abstract:In order to reveal the size effect meso-heterogeneity mechanism of concrete strength, the meso-element equivalent heterogeneity model was established. Tension and compression tests were simulated for different size meso-heterogeneity models. The results showed that the size effect of concrete is rooted in the meso-heterogeneity mechanism of materials. With the increase of model size, the variation coefficient of meso-element elastic modulus increases and meso-heterogeneity of concrete heightened. Also, more low-strength units or defects were discovered in the large-size model. As a result, the tension and compression strength of concrete and the ultimate strain decreased and the brittleness of concrete strengthened. Concrete damage region extended from the concentrated area to multiple non-penetrating crack zones.

Abstract:The restraint ring test is used to assess the restraint stresses development and cracking potential for early-age cement based construction materials. An analytical expression is presented to estimate the time-dependent residual stresses of the restraint mortar ring considering the synthetic effects of hydration heat, autogenous shrinkage, drying shrinkage, creeping and restraint by the steel ring. The relative stiffness of the steel ring to the mortar ring is discussed. The tendency and age of cracking of the restrain mortar ring is predicted by introducing the cracking tendency factor. The present analytical method demonstrates significant agreement with the restraint ring test and numerical simulation by FEM.

Abstract:Taking the Dougong of Tianwang palace in Baosheng Temple, Luzhi as a case, experimental study was carried out on shaking table tests of the full-scale pine Dougong model. Analysing the acceleration and dynamic magnification coefficient trends, the process of displacement characteristics of Dougong in response to changes of vibration, and the rotary and sliding displacement values of Dougong and each component at the biggest deformation moments. Major conclusions are as follows, Seismic acceleration indicates the response of seismic intensity, instead of the maximum deformation of the Dougong specimens. Vibration frequency has important influence on the degree of rotation deformation, while amplitude has decisive effect on the sliding displacement of each component. The maximum deformation of Dougong and each component all have a strong correlation, among which the rotary displacement of Ludou and Huagong occupies a dominant position. Huagong with xia-ang, which is a special part of Dougong, is mainly for decoration and it's weak on connection node position during the shaking table tests. So more attention and relevant reinforcement measures should be taken on this part in the maintenance and conservation of cultural relics.

Abstract:12 strong-motion stations are selected and based on 584 seismic records recorded during the 2010-2012 Canterbury earthquake sequences, New Zealand, a systematic variability analysis of the deep-soft site response (SAF, i.e., site amplification function) in Christchurch city area is conducted with a reference outcropping station LPCC. Thereafter, influence factors including ground motion intensity roughly measured by PGA, magnitude Mw, hypocentral distance Rhypo and azimuths on the variability of SAF are analyzed. The results show that: 1) ground motion intensity PGA has weak effect on mean lg(SAF) values except that PGA tends to strengthen amplification effect for long period components; while under different PGA subdividing bins, the standard deviations of lg(SAF) for bins with PGA greater than 0.6m/s2 are considerably larger than those for PGA less than 0.6m/s2 bins, indicating possible subsoil non-linearity tends to increase the site response variability; 2) seismic magnitude shows little influence on the variability of site response and the means and standard deviations of log10(SAF) for different Mw dividing bins demonstrate similar patterns; 3) hypocentral distance is an another important influence factor on site response variability, that is, the variability of SAF with Rhypo less than 5km is larger than that with Rhypo were larger than 5km; 4) the variability of SAF is basically independent of source azimuths to stations which means the uncertainty of SAF remains closely similar in different azimuth bins.

Abstract:Straight-wall arches have been widely applied in civil engineering. Considering displacements at the arch springing, the arch model was assumed as elastically supported horizontally. Distribution of the bending moments was deduced using classical force method. The distribution and the inflection point of the bending moment were studied under uniformly distributed, triangular and concentrated loads, respectively. Central angle corresponding to zero bending moment at the springing was calculated, which decreased when the load changed from uniformly distributed load, triangular load to concentrated load. Horizontal constraint from the side wall was assumed as elastic support and the equivalent spring stiffness was deduced. With the increase of the straight-wall height, bending moment at the crown increased while that at the springing decreased. When the moment at the springing was zero, anti-flexural capacity at the crown and anti-shearing ability at the springing were improved. Straight-wall height and central angle should be selected to make the moment at the springing zero.

Abstract:A denoising and enhancing method based on frequence domain filter was developed aiming at two main noise in cement pavement image: groove noise and longitudial stripe noise. Firstly, the spectral features of the two kinds of noise were analyzed. On this basis, the position of groove spectral peaks in the frequency domain were deduced according to the groove period in spatial domain. Then, a series offilters were designed to elimiante these peaks in the frequency domain. Moreover, aiming at the longitudianl stripe noise belonging to the low frequency components, a filter of which parameters were optimized through experiments, was designed to eliminating this disturbance by suppressing low frequency and enhancing high frequency. Finally, the experimental results showed that this proposed method can eliminate the two kinds of noise and enhance the constrast of cracks, which provided a foundation for crack recognition in cement pavement.

Abstract:The coupling effect of consolidation caused by the waste and the cover, and the solute transport has been widely studied in the field of environmental civil engineering. Based on Biot consolidation theory and solute transport theory, a three-dimensional coupled model of consolidation and solute transport is thus developed and in the modeltheporosity is thecoupled parameter and consolidation equations is linked with transport equations.The influence of consolidation on solute transport parameters is taken into consideration as well.. Then, the 3D model coupling the consolidation and solute transport is establishedusing the finite elementsoftware COMSOL Multiphysics.The numerical results show that consolidation deformation retards the transport process of solute leading to decrease in contaminant plume and the transport depth in vertical direction and has a strong and long-term influence on the transport of soluteThe transport distance decreasing rate increased over time and reache27.75% in 20 years ; the transport distance in the horizontal direction of contaminant concentration increases with the increasing of lateral hydraulic gradient.

Abstract:The bearing capacity of circular shallow footings subjected to combined loading composed of vertical component V, horizontal component H and moment M on sand is explored through three dimensional finite element numerical analyses. The sand is assumed to be purely frictional and obey elasto-perfectly plastic relationship following the Mohr-Coulomb failure criterion. The capacity of circular footing under centrally vertical load is computed, and the calculated results agree well with those derived from slip-line field theory. Then the influence of soil friction angle on the failure locus in the V-H and V-M load plane and V-H-M load space is investigated. The results show that the shape of failure envelopes of shallow foundations on sand is different from that on undrained clay, whilst normalization of the failure envelope on the V-H and V-M load plane by the pure vertical bearing capacity allow it to be generalized for varying conditions. Based on finite element analyses, the equation of failure envelope in the V-H-M three dimensional load space is proposed, which can be used to evaluate the general stability of circular footings on sand under combined loading condition.

Abstract:Considering the impact of sand state on its critical state line, a constitutive model for anisotropic sand is established in the method of macro-micro incorporation. The novel anisotropy state variable is introduced into critical state equation of the model, the influences of anisotropic parameters, stress state and the relationship between stress and fabric direction on the equation is added and the state-dependent concepts of sand is extended. With the changes of stress state and the relationship between stress and fabric direction, the shape and the position of phase transformation-state, peak-state and critical-state of model is changed inartificially on the direction of hydrostatic pressure. The more degree of anisotropy, the further offset from the axes of hydrostatic pressure and the greater change in shape. The hardening law and dilatancy equation of model are the function of anisotropy state variable. The description of sand dilatancy and hardening law are refined and quantified with the change of microscopic quantification parameter. One set of model constants can describe the strength-deformation responses of sand under a large scale of confining pressures and densities.

Abstract:The conformal transformation and elastic theory of complex function are used to derive the analytical expression of surrounding rock stress distribution of vertical wall archy roadway. The distribution laws of roadway boundary surrounding rock stress and the stress along horizontal line are analyzed. Also the impact of different aspect ratios of roadway cross-section and different lateral pressure coefficients on stress field of surrounding rocks are studied. The results showe that: with different aspect ratios of roadway cross-section and different lateral pressure coefficients, three locations of vertical wall archy roadway surrounding rocks are main stress concentration area concentrated . The three locations are the basic angle at bottom of vertical wall,the location near midpoint of archy roof and the center of floor. Under different aspect ratios of roadway cross-section, the distribution laws of stress along horizontal line of vertical wall archy roadway are the same basically. When the lateral pressure coefficient is greater than one, roadway is stable with aspect ratio of roadway cross-section less than one. While,when the lateral pressure coefficient is not greater than 1,roadway is stable with aspect ratio of roadway cross-section greater than one.

Abstract:physical model and field experiments which consists of pullout test and strain monitoring on bolt-grout interface were conducted on wood bolts fully grouted by natural hydraulic lime and quartz sand slurry in rammed earth to study anchor capacity，failure mode，shear stress distribution and transfer along the bolt-grout interface .were studied on its Experimental results shows that ultimate anchor force in laboratory (30 kN~45 kN) is larger than that in field (16.2kN~19kN). Anchor system has strong ductility. In the process of loading, single-peak or double-peak stress distributes along bolt-grout interface and interfacial stress transfers toward anchor end, meanwhile, compressive stress mainly emerges at middle-end of anchor segment. With considerably physical and mechanical compatibility to rammed earth, the anchor system is suitable to conserve rammed earth heritages.

Abstract:The hydraulic characteristics of the variable primary flow system with on-off valves under temperature difference control is investigated, and the nonlinear heat exchange coupling property of fan coil units and rooms is combined to further explore the applicable conditions of temperature difference control and setting procedures of temperature difference value(TDV). The result indicates that the temperature difference control in the system with on-off valves at the terminal is also applicable when the pipe network's load is equally distributed and the load changing rule of each opening user is similar. In this case, the system's hydraulic disorder has smaller impact on the indoor temperature and humidity. When adopting variable temperature difference control, setting TDV piecewise according to different total load rates cannot have good control of indoor temperature and humidity. Therefore, it is recommended to set TDV according to ensure fan coil's dehumidification capacity and indoor dry-bulb temperature preferentially, compared with current methods, the stability of indoor temperature can be guaranteed under the same fluctuation of the indoor relative humidity.

Abstract:Experiment is conducted to study The heat characteristics and moving regulation of phase change interface in the progress of water flowing along icicle under forced and mixed convection The mapping relationship between the experimental data and the heat transfer coefficient in phase change interface of icicle is established. With various initial dimensions of icicle, initial temperatures in icicle, velocities and temperatures of water, moving regulation of phase change interface of icicle is recorded using industrial cameras The results show that, The variation trend of each location of phase change interface is similar with different velocities, and the location of phase change interface decreases with time in a form of power function; the average convective heat transfer coefficient increase over time with the increase of velocity and temperature of water,with different velocities and temperatures of water, at first Nu increases steadily with Gr/Re 2, however it witnesses a fall trend after reach to the peak point. Empirical correlation ofNu、 Gr、Re、Prand Ste is established.

Abstract:Two cities located in cold zone, Lanzhou and Zhengzhou were selected to study the relationship between the building envelope properties and the building heating and cooling load.Under the condition of energy efficient rate 65%, four types of walls, three types of windows and four window-to-wall ratios were assembled into 48 types of office building envelopes as the calculating rooms. The annual heating and cooling loads of the calculating rooms were obtained and the influence of thermal performance on building load was analyzed. The energy saving ratio and the optimal building envelope for each city were determined by comparing with the annual total load of baseline room,.

Abstract:New-built rural residential buildings in Guangdong province have the tendency of multilayer and courtyard disappearance, resulting in the change of the indoor thermal environment. Three typical buildings are selected to measure the parameters of indoor thermal environment in order to understand the status quo of indoor thermal environment in new-built rural residential buildings in Guangdong. It's found that there are several defects count against indoor thermal environment on the basis of comparative analysis. Thus, optimizations were made for design strategies such as shading, insulation and natural ventilation in low-rise buildings with/without patios. There are effective measures to improve the indoor thermal environment in summer of low-rise buildings with patios like the shading roof，increasing height of skylight and skylight placed under the wind direction. Numerical analysis was conducted to quantify the energy and comfort performance of these design strategies. Stilt floor was found to be a good way to build semi-open spaces in low-rise buildings without patios.

Abstract:Reduction of CO2 to fuels and industrial chemicals with bioelectrochemical system has been widely studied. This review focuses on recent development in methane production from CO2 with bioelectrochemical systems, which includes the functional microbe used in cathode, the mechanism of conversing CO2 to methanewith bioelectrochemical systems, and the influence factors of the conversion of CO2 to methane as well as the reactors of bioelectrochemical systems. After that, problems of conversing CO2 to methane with bioelectrochemical system are analyzed, and the directions of future research are also discussed. This review aims to motivate and inspire further research for the conversing CO2 to methane with bioelectrochemical systems.

Abstract:The electro-fenton process was employed in the advanced treatment of Mature landfill leachate．Power，initial pH，and initial ammonia-nitrogen concentration were selected as the variables and CODCr removal efficiency were used as the response in the central composite design (CCD) ．Response surface methodology (RSM) was used for the analysis of the experimental results． A second-order polynomial regression equation was developed to describe the CODCr removal efficiency and was validated by variance and significance test．The optimum reaction conditions were determined by calculate inverse matrices of regression equation．The results showed that under the optimum reaction conditions (power dosage of 23.26 Ah/dm 2，initial pH value of 3.58 and initial ammonia-nitrogen dosage of 56.78 mg/L) ，the CODCr removal efficiency was 96.5%，which was highly consistent with value predicted by the model equation，with a deviation of 4.45%．GC-MS method was used in analysing landfill leachate treated by electro-fenton，comparing with landfill leachate treated by conventional treatment process, it is indicated that the electrolytic Fenton technology can effectively degrade the refractory organics in landfill leachate. The result showed that electrolytic Fenton technology was effective advanced treatment.

Abstract:The inactivation efficiencies of Synedra sp. by NaClO and KMnO4 oxidation were investigated. The results indicated that in the range of 0~5 mg/L in the neutral condition, the inactivation efficiencies increased with the increase of NaClO dosage and the optimun dosage was 3 mg/L. Meanwhile NaClO showed a better degradation ability in acidic condition. The degradation ability of KMnO4 was not significant, indicating that KMnO4 had no effect on inactivation. Chlorination was effective for Synedra sp. inactivation, and however led to cell disintegration and organic matter release, thus endangering the safety of drinking water.

Abstract:To reduce the hardness in the water, the new-style granulation reactor with gravel packing is utilized. The reactor operates at 20°C. During the experiment, the content of absorbed calcium carbonate crystal in the gravel packing is measured by changing pH value, the diameter of the gravel packing, hydraulic condition and reacting time to investigate the performance of the reactor. Experimental result demonstrates that when the pH value is over 12, the diameter of the gravel packing was 0.2~0.5 mm; the feed water flow of raw water was 10~35 mL/s; the reactor has the optimal treatment efficiency. With the progress of the granulation reactor,it is found that the calcium carbonate crystal absorbed in the surface of the gravel padding gradually accumulates. When the reactor operates for about 15 days, the content of absorbed calcium carbonate crystal reaches saturated state, and the old packing could be replaced with new one. The reactor removed 58%~67% of the hardness in raw water.and the water quality of the effluent is good.