Abstract:The multi-branch tunnel has multiple routes for smoke extraction and air supply, consequently its ventilation and smoke control modes could have multiple solutions owing to the competitive effects of buoyancy and fan power. For the smoke control of a multi-branch tunnel, the mass and energy balance equations for every possible flow pattern were established, and the corresponding multiple solutions were obtained using mathematical methods. The results demonstrate that, even though the exhaust ventilation mode and fan type have been determined in accordance with the anticipation, multiple states of exhausted flow remain and the operation point of the fans will drift away from the design accordingly. This could cause a totally different direction of smoke route from the anticipated one. It is also shown that the type of fan has significant effects on the existence of multiple solutions.

Abstract:The complicated architectural layout and form within urban area lead to the phenomenon of multiple-reflection radiation in the urban area. And this multiple-reflection radiation directly affects the thermal environment in urban areas. This paper is based on the theoretical basis of multiple-reflection between the buildings and converts the problem of urban integrated reflectivity into geometrical parameters which are relevant to the urban spatial structure. At the same time, a case study was taken to obtain an integrated reflectivity which had taken the structure of urban space into account. The results show the integrated reflection is lower 32.4% than the normal situation.

Abstract:In the simulation of building energy consumption and solar energy system design, hourly direct and diffuse radiation is one of the most important basic parameters.While, due to Chinese solar radiation data missing, it is difficult to obtain hourly direct and diffuse radiation data. Many domestic and foreign scholars has studied and put forward several diffuse radiation models. 2009-2011 year's measured data of total solar radiation and diffuse radiation were scleted and five typical separation models, that is Erbs model, Orglill and Hollands model,stochastic climatic model, Zhang Qingyuan model，were put to analyze and compare the measured data and the simulation data between the correlation coefficient, root mean square error and relative error. Found that Erbs model predicts diffuse radiation with the highest accuracy, followed by the Zhang Qingyuan model and Orglill and Hollands model, Clearness index Kt can be used as the main influence factor.

Abstract:Its rationality of temperature and water vapor partial pressure as driving potential for coupled heat and moisture transfer was demonstrated based on non-equilibrium thermodynamics. As water vapor partial pressure is a function of moisture content and temperature, mathematical model of coupled heat and moisture transfer for multilayer wall were established according to the theory of total differential. The approximate expressions between humidity content and relative humidity of air used in Budaiwi method could be avoided. The coefficients of mathematical model were simplified and could improve efficiency of solution. Its validation was illustrated by contrasting and analyzing the simulation results of a multilayer wall.

Abstract:In the generation of the typical meteorological year（TMY）for building energy consumption simulation, the traditional Finkelstein-Schafer statistical method given fixed weighting factors to the meteorological parameters, but the relevant studies showed that there was debate for the curing of weighting factors of meteorological parameters due to the different regional meteorological resources. Aiming at the weighting factors of metorological parameters unity or not in selection of TMY and the impact of building energy consumption simulation, Beijing and Lhasa on behalf of the cold region in building thermal partitions, based on the methods of FS and principal component analysis（PCA）was analyzed. The results showed that the FS statistical method is suitable for the similarity characterization of meteorological parameters for a long time and suitable for the solar energy rich area, there is too much weight given to solar radiation parameters across the country; and the PCA method is suitable for the essential characteristics of the local meteorological resources, choice of meteorological parameters is particularly important when using this method.

Abstract:Flowing dynamic characteristics and its temperature dynamic characteristics of a three-level sewage pipe network in Chongqing were analyzed. A mall's building whole year load was simulated. In the adverse condition of wastewater flow, the market construction peak discharge heat was compared with the sewage heat load, the balance between the most adverse flow and the building demand was found. Explored supply and demand matching method between urban sewage and city building load in flow adverse condition to take full advantage of the urban sewage cold and hot resources. the composite system was adeptcd to make up the most unfavorable flow time of sewage average heat load and the construction load difference; it also puts forward principle of load sharing and control strategy aimed at compound system.

Abstract:Compling a program by matlab to investigate closed heat source tower operating under spraying conditions. The numerical results of the spray solution temperature, the refrigerant temperature, air enthalpy value were compared with the experimental ones. The program was used to calculate the distribution of the spray temperature, refrigerant temperature, air enthalpy in the closed heat source tower under spraying conditions. Some results were obtained. The air enthalpy is linear distribution and upper fin heat exchanger heat transfer effect is better than the lower part.The center of the tower is firstly frosting. The air dry bulb temperature is above 5.1 ℃and relative humidity is above 75%. The closed heat source heat pump system is without risk of frost, so stopping the spray pump is viable in order to reduce the energy consumption of the operation of the heat pump system.

Abstract:The indoor thermal conditions of residential buildings during the plum rain season in East China (Nanjing for example) were obtained and the accuracy of three different building energy consumption models (whole building heat, air and moisture model HAM, conduction transfer function model CTF, effective moisture penetration depth model EMPD) were analyzed. The numerical model was implemented into Matlab-Simulink and was validated using measured data from a field survey. Then the validated model was used for simulation analysis using typical weather data of plum rain season.The results from the survey showing the indoor temperature was higher than 28℃ and the indoor relative humidity was higher than 70% in most time of the plum rain season of 2013. Simulation results showed that there was not much difference when using the three models for thermal simulations, however, using CTF model for moisture simulation would result in large inaccuracy. During the plum rain season in Southeast China, when the room ventilation rate is less than 2 ACH, the moisture buffering effect of building envelope is obvious and the choice of proper hygroscopic materials can save up to 30% of building energy consumption.

Abstract:Based on central air conditioning system of Xi'an-Xianyang international airport, energy efficient utilization with life cycle theory and analytic hierarchy process was conducted. Firstly, the application of life cycle and analytic hierarchy process to building energy was deeply studied. Secondly, life cycle inventory analysis was conducted combined with the practical cases data. And the data resource is related to the proposed model. Thirdly, On basis of analytic hierarchy framework model and analysis of energy consumption as well as potential environmental impact on air-conditioning project, the study on how to evaluate energy-consumption project with the use of life cycle impact assessment is done. Based on the life cycle assessment of practical cases data, a new hierarchical evaluation model of energy utilization is put forward. And in view of the model， several suggestions are given such as establishing energy utilization process monitoring and evaluation from the point of whole life cycle assessment. This provides a theoretical basis for policies about enormous quantity of building energy and energy saving of air conditioning system.

Abstract:Angle factors between enclosure structural surfaces, or between human body and enclosure structural surfaces are the basic parameters to calculate radiant heat transfer in a radiant air-conditioned room. At present, the angle factors between the human body, radiant panels, windows and doors are usually quite difficult to solve. Therefore, we derived the angle factor expressions of two rectangular surfaces in the positions both mutual perpendicular and mutual parallel by using curve integral formula of angle factor, instead of using conventional surface integral formula. Meanwhile, angle factors between human body and enclosure structural surfaces by simplifying a seated person as a rectangular solid were acquired. The results were shown to be efficient and practical, and were free from the limitation of envehpe sizes and relative positions.

Abstract:In order to quantify the WLED's impact on color of Chinese traditional calligraphy and painting, and explore the practical applicability of using WLED as display lighting, an experiment was carried out on the RYGB type of WLED irradiated models of calligraphy and painting. And the color parameters was tested periodically to make curve charts of color coordinate and luminance over time. The impact of the WLED on hue, saturation, brightness was quantified based on the carve to provide evidence of application of WLED.

Abstract:The water retention capacities of commonly used roof greening matrices, concluding ceramsite, peat and super absorbent polymer, under fully saturated, cyclic wetting-drying and natural evaporation conditions were studied. The saturated water retention capacity of matrices were obtained by vacuum saturated test. It showed that the fully measured saturated degree of saturation of mixed matrix was greater than that calculated by the combination of all components. The reason which increases the water contents to porous skeleton was analysed. In cyclic wetting-drying tests, the water retention capacities of ceramsite and peat were almost unchanged. However, due to the main molecular chain broken under drying in relatively high temperature, the water retention capacity decreased rapidly after several wetting-drying cycles. In natural evaporation tests, the evaporation rates of ceramsite, peat, super absorbent polymer and free water were almost identical in the condition of high water content. As the water content decreasing, the evaporation rate of the matrix which had lower water retention capacities decreases faster. The matrix with a reasonable proportion of super absorbent polymer can remarkably improved its water retention capacity.

Abstract:Concrete cover cracking induced by corrosion of steel reinforcement is a major influencing factor for durability and serviceability of reinforced concrete structures. In order to investigate the cracking process of concrete cover induced by rebar corrosion, the heterogeneity of concrete meso-structure and non-uniformity of rebar corrosion are accounted for. The undamaged concrete is assumed to be a three-phase composite material composed of aggregate, mortar matrix and the interfacial transition zone (ITZ). And a concrete random aggregate structure is established for the study on the mechanical behavior of the non-uniform radial corrosion expansion. In the present simulations, non-uniform radial displacement is adopted to simulate the non-uniform corrosion of the rebar; the plasticity damaged model is used to describe the mechanical behavior of the mortar matrix and the ITZ, and the aggregate is assumed to be elastic. The cracking of concrete cover due to the non-uniform corrosion of the middle located rebar is numerically simulated. The comparison of the analysis and the test result on failure pattern of cover concrete shows fairly good agreement. And then the failure patterns under uniform corrosion and non-uniform corrosion obtained from the macro-scale homogeneous model and the meso-scale heterogeneous model are compared. Furthermore, the influences of concrete cover thickness and rebar diameter on the failure pattern of concrete cover, the expansive pressure and the corrosion rate of the rebar when cover concrete cracks are investigated.

Abstract:The temperature distributions were measured in hardening concrete slabs, determining final set time of concrete; the calculation methods of built-in temperature difference and the effective temperature difference were provided to determine the corresponding values of the slabs constructed during spring and fall, respectively. Finally, the influence of built-in temperature difference on slab curling and stress were evaluated based on finite element analysis. The results show that negative built-in temperature differences were found in both spring and fall construction which will lead to loss of slab support in the mid-slab position during the most time of a day, and larger tensile stress generates at the slab bottom. However, small size slab will minimize this negative effect from built-in temperature difference and at the same time reduce fatigue damage.

Abstract:In order to study the mechanical behavior of corroded reinforced concrete beams strengthened with bolted steel plates, this paper designed 12 reinforced concrete beams. These beams were corroded by using accelerated electrochemical corrosion method with a designed corrosion ratio of 10%. The pre-compression experiments were performed for all RC beams before strengthening and the maximum crack width was controlled as 0.2 mm. According to the thickness of concrete cover, the beams were divided into 3 groups. Each group was composed of one comparative beam and three tested beams strengthened by steel plates bolted with study according to the thickness of steel plates which were 3 mm, 4 mm and 5 mm, respectively. It was shown that the strain distributions along the height of the strengthened beams at middle-span were in good agreement with the plain section assumption basically. The serviceability performances of corroded RC beams were significantly improved and these ultimate bearing capacities increased obviously. The steel plate bolted with stud effectively reduced the crack width and the extension height of reinforced concrete beams. It was indicated that an increase of steel plates with 35 mm resulted in a decrease of deflection by 13%51% when beams had the same thickness of concrete cover and corrosion ratio. Influence of the thickness of concrete cover on the ultimate bearing capacity was not obvious.

Abstract:In order to simplify the analysis of thin-walled open-profile bars, a method is presented in which the analysis is split into two parts, dominated by in-plane and out-plane loading effects respectively. This article focuses on the out-plane loading effects. Based on bending theory of thin plate with small deflection, each slab or strip is analyzed separately and the results are integrated into vectors, in which, the deformation shapes and equilibrium conditions are simplified appropriately, thus leading to the slabs' out-plane bending resistance system of thin-walled bars, which reflects the properties of the bar's distortion and torsion. By composing the slabs in-plane tension-bending resistance system and the slabs' out-plane bending resistance system, deformation equations of thin-walled open-profile bars considering distortion are deduced. In order to set up the finite bar element method, stiffness equation and equivalent nodal forces of internode loadings are deduced. Comparative analysis with finite shell element method indicates the high efficiency and accuracy of this method.

Abstract:The flat steel box girder is commonly used for long-span cable-stayed bridges. the structural complexity, construction details and manufactures cause damage to the bridge and the damages seriously grow overtime. The main reason for these damages is that welding technology of flat steel box girder with thin plates and rib elements produces residual stress and strain fields during the welding process, and further more welding cracks commonly appear. In this study, thermal-structural couple methods was adopted to numerically simulate the welding high temperature fields and the stress fields at the joint of U rid and decks of a flat steel box. The welding residual stress distribution was studied as well for further analyzing on the structural damage and strengthening design strategies.

Abstract:Hydrolyzed polymaleic anhydride (HPMA) and polyethylene glycol monomethyl ether(MPEG) synthesized a kind of polycarboxylic grinding aid, the esterification was prompted by the mechanical force during the process of cement grinding. The effects on cement grinding and mortar property were tested from HPMA, MPEG, the mixture of HPMA and MPEG, and the resultant of HPMA and MPEG. The results showed that the mixture of HPMA and MPEG and the resultant of HPMA and MPEG had better grinding performance than HPMA and MPEG, and which can improve the fluidity and early strength of cement mortar. Laser Raman spectrum tests showed that the resultant of HPMA and MPEG had a similar Raman shift spectrum with the mixture of HPMA and MPEG, when they were adsorbed on the cement particle surface after co-grinding.

Abstract:According to the structural characteristics of bridge engineering, the mix optimization design method of bridge fair-faced concrete was presented, and C30~C50 concrete with high cohesion and package, outstanding fluidity and excellent mechanical properties were prepared. Through the test of air content of fresh concrete, micro hardness and micro structure in different parts of hardened concrete specimens, effects of viscosity-modifying admixtures on homogeneity of concrete were discussed. The results showed that the composition of bridge fair-faced concrete were relatively homogeneous, and the microstructure were relatively dense. When C30 concrete mixed with 5 × 10 -5 cellulose ether or 6% silica fume (mass fraction of cementitious material), air content of fresh concrete were less than 2%, and slurry viscosity values were between 1 900 and 2 000 MPa·s. Also, the micro hardness values in different parts of hardened concrete specimens were closed. The results were applied in practical bridge engineering, which generally meets the apparent quality requirements of bridge fair faced concrete.