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Shi X.,Nanjing Southeast University | Shi X.,State Key Laboratory of Subtropical Building Science | Burnett E.,RDH Group
Journal of Building Physics | Year: 2013

In residential buildings, a typical rainscreen exterior wall system often incorporates an exterior membrane mechanically fastened to an exterior sheathing. This thin and flexible membrane is an important component of the wall system and performs multiple functions. Under a negative air pressure differential, that is, wind suction, the exterior membrane can deform or balloon. The membrane ballooning has important implications on many performance issues in the rainscreen exterior wall system. That the membrane ballooning changes the air cavity volume and therefore affects rainscreen pressure equalization is one important implication. Since the 1980s, many theoretical pressure equalization models have been proposed. This article takes a unique viewpoint and focuses on reviewing how the theoretical screen pressure equalization models consider the effect of membrane ballooning. It is believed that such a review is essential for future study on how to incorporate the membrane ballooning into the pressure equalization model. © The Author(s) 2013.

Wang J.,State Key Laboratory of Subtropical Building Science | Zhang Z.,Agilent Technologies
Advanced Materials Research | Year: 2012

It is a common view to build up a sustainable development world, and greening/ecological residence is becoming more and more popular. So an efficient assessment system is so important for all the shareholders to assess a residence project and certificate an authoritative, rational and impartial level of the project. A test is designed in this paper to illustrate relevance to efficiency of greening residence assessment system and the scalar of criteria, and claim the efficiency is extremely low of a fat criteria system based on the test results. © (2012) Trans Tech Publications, Switzerland.

Jin X.,State Key Laboratory of Subtropical Building Science | Luo X.,Guangzhou Building Materials Institute Co. | Luo X.,South China University of Technology | Meng Q.,State Key Laboratory of Subtropical Building Science
Advanced Materials Research | Year: 2011

In this paper, a research was performed which considers the material characteristics of autoclaved aerated concrete (AAC) blocks and the weather characteristics in Pearl River Delta region. The AAC blocks laws of absorption and desorption and its thermal conductivity under different equilibrium moistures were measured. The experimental results show that equilibrium moisture content (EMC) is 6.27% for AAC blocks with a B07 density in hot and humid areas in the Pearl River Delta region including the city of Guangzhou, and the correction coefficient of the thermal conductivity is 1.5. Autoclaved aerated concrete (AAC) blocks have excellent thermal insulation, and are light and easy to be processed. They are one of light wall materials that were utilized earliest and most widely in China[1,2]. At present, the thermal conductivity in the dry state is used as the only index for measuring the energy-saving effect of AAC blocks. However, this parameter cannot reflect the thermal conductivity of light wall materials when they become moisturized during use. It has been shown that AAC blocks are generally loose and porous. When used for engineering projects, they are more likely to absorb moisture and become damp[3~5]. A fairly large disparity in thermal conductivity arises when the AAC blocks become damp compared to that when they are dry. If a designer bases his/her energy-saving design of a building only on the dry-state thermal conductivity of AAC blocks, it will be less likely to guarantee the thermal insulation effect of the walls. This problem is particularly serious in areas with wet climate[6,7]. Therefore, it is very necessary to study the characteristics of moisture absorption and desorption for AAC blocks, measure the thermal conductivity in the equilibrium moisture, and propose a correction coefficient of the thermal conductivity for projects in the Pearl River Delta region, such as the city of Guangzhou. The characteristics of absorption and desorption and the thermal conductivity in different moisture equilibrium were researched in this paper. The moisture contents of a group of AAC blocks with the density grade of B07 after one year of outdoor natural curing were measured. The concept of equilibrium moisture content (EMC) of AAC blocks in the Pearl River Delta region including Guangzhou is proposed. The correction coefficient of the thermal conductivity for B07 AAC blocks, which are used to build self thermal insulation systems in projects in the Pearl River Delta region, such as the city of Guangzhou, is determined. © (2011) Trans Tech Publications.

Li W.,South China University of Technology | Li W.,Guangdong Electric Power Design Institute | Fang Y.,South China University of Technology | Mo H.,South China University of Technology | And 5 more authors.
Tunnelling and Underground Space Technology | Year: 2014

In order to explore the immersed tunnel foundation treated by sand-flow method, modeling principles for the full-scale model test of sand flow were put forward. In addition, a sand-flow test model was built, which consisted of model system, equipment system and measurement system. The situation of sand-deposit expanding and the water pressure in the foundation trench were evaluated through the model test. The results show that a semi-closed space was formed between the model board and the expanding sand deposit, which made the water pressure in it rising with little range of volatility. The sand deposit gradually became non-circular truncated cone which shaped with its expanding radius, and the difference of the water pressure increased at each direction. The water pressure in crater had a linear increase with the sand-deposit radius, with a maximal value of 0.015 2. MPa. The volatility of the water pressure under the tunnel board and the water pressure value in the crater could be used as bases of construction control. © 2013 .

Song Z.Y.,South China University of Technology | Fang X.S.,State Key Laboratory of Subtropical Building Science
2011 International Conference on Multimedia Technology, ICMT 2011 | Year: 2011

With the national implementation of the western development strategy in China, Southwest campus construction have been more and more attention. The main difference between the southwest campus and traditional campus is that the former more emphasizes on the efficient design and construction of land suitability, pursuit of harmony between man and nature, try to achieve ecological balance and sustainable development. Based on the design practice in new campus planning of Zunyi Medical College, the article explored the regional design strategy by taking full account of topography and climate characteristics. © 2011 IEEE.

Fang Y.-G.,South China University of Technology | Fang Y.-G.,State Key Laboratory of Subtropical Building Science | Li B.,South China University of Technology
Mechanics of Materials | Year: 2016

Soil medium is the research focus of soil mechanics. Soil is a mutiphase geological material consisting of soil particles and structures at various scales. The mechanical behaviour of soil involving the interaction of multiscale particle and structure has an important influence on its macroscopic mechanical properties. The present work mainly analyse the particle and structural characteristics of soil and the physical and mechanical mechanism of the mutiscale coupling properties of them. In addition, the mutiscale problems in the deformation process and the nonlinear phenomena associated with deformation localisation, parameter sensitivity and catastrophe are discussed. Furthermore, a new energy criterion for the division of particle scales and multiscale soil cell element model are established. Moreover, approaches to the mutiscale problems, such as fractional-step coupling, particle size effect analysis and multiscale nested model analysis methods, are proposed. © 2016 Elsevier Ltd

Liu H.-L.,South China University of Technology | Cai J.,South China University of Technology | Cai J.,State Key Laboratory of Subtropical Building Science
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2013

In this paper, first, a uniaxial stress-strain relation of the core concrete is proposed for the finite element (FE) analysis of the square concrete-filled steel tubular (CFST) stub columns with binding bars. Then, based on the ABAQUS FE platform, a USDFLD subroutine is presented by considering the Poisson ratio changes and the nonlinear constitutive relation of many materials in the loading process, and a FE model is then established to simulate the square CFST stub columns. Finally, the mechanical behavior of the square CFST stub columns is discussed in terms of the stress-strain relation and the confined effect among the steel tube, the core concrete and the binding bars, as well as of the longitudinal stress distribution of the core concrete. The results show that (1) the computation results obtained through the proposed FE model accord well with the test results; (2) the binding bars can delay the local buckling of the steel tube and thus make the steel tube yield before the ultimate strength of the specimen occurs, and they can also improve the concrete confinement of the corner and central regions and thus increase the longitudinal stress of the core concrete, so that the bearing capacity and ductility of the specimen can be improved; and (3) the concrete confinement of the corner and the central regions increases with the decrease of the spacing between the binding bars.

Guo J.-L.,South China University of Technology | Cai J.,South China University of Technology | Cai J.,State Key Laboratory of Subtropical Building Science | Chen Q.-J.,South China University of Technology | Chen Q.-J.,State Key Laboratory of Subtropical Building Science
Gongcheng Lixue/Engineering Mechanics | Year: 2016

A numerical model based on the explicit finite element package LS-DYNA was proposed to investigate the pancake collapse response of a 9-story steel frame under seismic action. The numerical model was validated by a shaking table collapse test for a spacial slab-column structure, and then the pancake collapse process of the steel frame was simulated and analyzed. It is found that the drift angle of the weak story expanding larger than 1/10 leads to pancake collapse, then the upper part of the structure moves downwards and collides with the lower part of the structure, and causes a large axial force in the sub-story column, which expands the P-Δ effect and leads to progressive collapse of the steel frame. The dynamic increase factor of the sub-story column may be larger than the proposed value in the code. It is indicated that the pancake collapse can be prevented by enhancing the lateral stiffness of the weak story, and the collapse would not happen by a reasonably design if the drift angles of the story converge though larger than the code limit. © 2016, Engineering Mechanics Press. All right reserved.

Liu H.L.,South China University of Technology | Cai J.,State Key Laboratory of Subtropical Building Science
Applied Mechanics and Materials | Year: 2013

The constitutive model of core concrete was proposed, which was suitable for finite element (FE) analysis of rectangular concrete-filled steel tubular (CFST) columns with binding bars. Based on the ABAQUS FE platform, the USDFLD subroutine was compiled, which could consider the changing of Poisson ratio of many materials in loading process. A FE model was developed and used to simulate the rectangular CFST columns with binding bars. The mechanical behavior were analyzed for stress versus strain relationship curves, confined effect among steel tube, core concrete and binding bars, longitudinal stress distributions of core concrete. The results show that the FE results simulated by using constitutive relationship of core concrete of this paper are in good agreement with test results. The local buckling of steel tube is delayed which can make the yield of steel tube occur before ultimate strength of specimens, the concrete confinement of the corner regions and central regions is improved, the longitudinal stress of concrete is increased and the capacity and ductility of specimens are improved, by setting binding bars and decreasing the binding bars spacing. © (2013) Trans Tech Publications, Switzerland.

Yan X.-Q.,South China University of Technology | Yan X.-Q.,State Key Laboratory of Subtropical Building Science | Fang Y.-G.,South China University of Technology | Fang Y.-G.,State Key Laboratory of Subtropical Building Science | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The micropore structure characteristics have significant influence on permeability of the soil, and bentonite is high anti-seepage material, which is added into the soil to reduce the peamiability by changing the pore-scale distrbution and pore characteristics of the soil. The micropore structure characteristics of the soil added with different bentonite contents are measured by the mercury intrusion porosimetry (MIP). The test results show that just adding a little bentonite can reduce the quantity of the large pore abruptly. With the increase of bentonite content, the pore-scale distribution changes gradually, the quantity of the middle pore increases, the quantities of the small pore, the micropore and the supermicro-pore increase gradually, and the pore size distribution density function changes from three-model to bi-model while the pore diameter size corresponding to the peak decreases. It is proved that the pore characteristics of the same void ratio are various according to the test results, so the void ratio which is a macroscope parameter can not represent the pore characteristics of the soil perfectly and it is necessary to introduce other microscope parameters to describe the pore characteristics of the soil. The conclusions have certain referential value for the design and construction of the anti-seepage (infiltration) projects.

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