[Objective] The aim was to calculate the safe straw volume using Frank- Kamenetskii Model to provide method for fire protection in forage farm. [Method] Frank-Kamenetskii Model was used to measure Tacr and improved by...[Objective] The aim was to calculate the safe straw volume using Frank- Kamenetskii Model to provide method for fire protection in forage farm. [Method] Frank-Kamenetskii Model was used to measure Tacr and improved by marginal tem- perature which was adjustable. In addition, effects of water content and density of baled straws on Tc were explored using the improved model. [Result] Size of straw bales was the key factor determining whether spontaneous combustion would occur. For baled straws with water at 15.27% and density at 285 kg/m3, Tc was 85-88 ~C and safe diameter of baled straws maximized 8.2 m. In addition, straws should be stacked from south to north （or north to south） to avoid sunshine and certain space should be kept between straw bales for heat dissipation. [Conclusion] The research is of significance for safe management of forage farm.展开更多
The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Base...The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Based on an exponent model, the testing coefficients of straw bale were estimated using Levenberg-Marquardt Method. The results of test showed that the relation between failure density and loading ability and compressing energy was linear in the phase of high density. The loading ability of straw bale could meet the building bill.展开更多
Loading ability of straw bales was tested by using an Electronical Testing Machine. Linear regression models were proposed to describe the loading ability as a function of failure density and compressing energy. Based...Loading ability of straw bales was tested by using an Electronical Testing Machine. Linear regression models were proposed to describe the loading ability as a function of failure density and compressing energy. Based on an exponent model, the testing compression coefficients of straw bales were estimated by using the Levenberg-Marquardt Method. Results showed that the relation among failure density, loading ability and compressing energy was linear in the phase of high density, Loading ability of straw bales could meet the requirement for building bills .展开更多
Dwellings in a Mediterranean climate, such as that of Chile’s Central Valley, must provide hygro-thermal comfort both during the cold winters, and the hot days and cool summer nights. Straw, once a material common in...Dwellings in a Mediterranean climate, such as that of Chile’s Central Valley, must provide hygro-thermal comfort both during the cold winters, and the hot days and cool summer nights. Straw, once a material common in Chile’s indigenous and vernacular architecture, could meet these demands when coupled with sufficient thermal mass in the form of earth renders and floor finishes. This article presents measurements of dry bulb temperatures and relative humidity, both in physical test chambers and Chilean straw bale homes. The results of these measurements confirm that straw bale construction could provide hygro-thermal comfort with heating demands 28% less than those of constructions that meet the Chilean thermal building regulations. Straw bale, therefore, could provide a viable solution for comfortable, energy efficient, rural dwellings in Chile’s Central Valley. Whilst over 40 private straw bale projects have been completed in Chile to date, restrictions applying to projects receiving government subsidies prevent this technology being available to those who need it most.展开更多
Straw bale construction offers a renewable,sustainable and proven alternative to mainstream building methods;still,little is known about its airflow characteristics.To this end,the intent of this paper is to evaluate ...Straw bale construction offers a renewable,sustainable and proven alternative to mainstream building methods;still,little is known about its airflow characteristics.To this end,the intent of this paper is to evaluate airtightness of fully constructed and plastered straw bale walls as well as individual plain straw bales.The first experiment entailed measuring the influence of straw bale orientation on airflow characteristics with the finding that straw bale considered alone has poor air flow-retarding characteristics and that plaster is the primary air barrier.A second experiment involved thirty plastered straw bale specimens using three different plaster types.From this experiment,a crack grading system was developed and is herein proposed as a tool to evaluate plaster performance as an air barrier.A third experiment validated the crack grade system through application on four fully constructed straw bale walls.Practical use of the crack grading system was demonstrated on a case study straw bale house in Radomlje,Slovenia,where the predicted air tightness results were validated through comparison to results of blower door tests.展开更多
Experimental studies on full-scale straw-bale walls have demonstrated the adequacy of straw-bale wall systems for resisting lateral loads from wind or seismic actions.Critical to the performance of the wall system is ...Experimental studies on full-scale straw-bale walls have demonstrated the adequacy of straw-bale wall systems for resisting lateral loads from wind or seismic actions.Critical to the performance of the wall system is the anchorage of mesh reinforcement to the bottom plate and to the roof bearing assembly or top plate.Reported in this paper are the results of experiments examining mesh strength,anchorage strength,and failure mode for a variety of reinforcement meshes(steel,plastic,and hemp)and anchorage details.Because of the potential for new wood preservative pressure treatments to cause corrosion,stainless steel staples driven pneumatically into pressure-treated sill plates were tested in addition to electro-galvanized staples driven pneumatically into untreated sill plates and a heavier gauge staple driven manually into an untreated sill plate.Recommended anchorage details are identified,considering not only the test results but also the many other factors that must be considered in developing reliable,economical,and constructible details.展开更多
This paper describes the hot-box testing(based on ASTM C1363-11)of seven straw bale wall panels to obtain their thermal conductivity values.All panels were con-structed with stacked bales and cement-lime plaster skins...This paper describes the hot-box testing(based on ASTM C1363-11)of seven straw bale wall panels to obtain their thermal conductivity values.All panels were con-structed with stacked bales and cement-lime plaster skins on each side of the bales.Four panels were made with traditional,2-string field bales of densities ranging from 89.5 kg/m^(3)-131 kg/m^(3) and with the bales on-edge(fibres perpendicular to the heat flow).Three panels were made with manufactured high-density bales(291 kg/m^(3)-372 kg/m^(3)).The fibres of the manufactured bales were randomly oriented.The key conclusion of this paper is that within the experimental error,there is no difference in the thermal conductivity value for panels using normal density bales and manufactured high density bales up to a density of 333 kg/m^(3).However,because of lack of precision of the hot-box,no conclusions can be made on the true thermal conductivity of the high density bale panels.In addition,the panels tested were found to have significant voids between bales,and this is believed to have con-tributed to higher measured thermal conductivity values compared to those reported in the literature for normal density bale panels.Thermal properties may be affected for bales with higher densities than 333 kg/m^(3),therefore further testing is suggested.展开更多
The search for more sustainable construction methods has renewed interest in straw-bale construction.Rectangular straw bales stacked in a running bond and plastered on the interior and exterior faces have been shown t...The search for more sustainable construction methods has renewed interest in straw-bale construction.Rectangular straw bales stacked in a running bond and plastered on the interior and exterior faces have been shown to have adequate strength to resist typical loads found in one-and two-storey structures.The straw bales provide excellent insulation,while possessing low embodied energy compared to conventional insulation materials.The structural behaviour of a load-bearing plastered straw-bale wall subject to uniform compressive loading has been the focus of a number of studies reported in the literature.However,in a typical building wall,there will be numerous locations(such as around window and door openings)where the load paths produce areas of concentrated stress.The behaviour in these regions cannot necessarily be predicted using tests from uniformly loaded wall assemblies.This paper describes experiments on plastered single bale assemblies subjected to three-point bending.These assemblies develop shear and flexural stresses,and so simulate the stresses that exist around door and window openings in a wall.The specimens were rendered with lime-cement plaster,and were either unreinforced,or contained steel“diamond lath”mesh embedded within the plaster.The specimens were pin-supported at various centre-to-centre distances(L)ranging from 200 mm to 500 mm.The height(H)of all specimens was constant at 330 mm.This gave a range of H/L values of 0.66 to 1.65.Two distinct types of failure were observed.For tests with H/L<1,failure was due to flexural tension cracks in the plaster which propagated through the depth of the plaster skin.For tests with H/L>1,failure was due to crushing of the plaster in compression under one of the loading points.It was shown that models based on simple mechanics were able to adequately predict the assembly strength.In particular,analysing the assemblies with H/L<1 as simple beams,and using the transformed section concept to deal with the straw and steel mesh,was adequate for predicting their strength.The results suggest that current practice for straw bale construction is generally appropriate.To avoid tensile cracking of plaster due to flexure,regions around doors,windows,and other openings should be designed such that H/L>1.In regions where H/L<1,the use of steel reinforcing mesh can increase the plastered bale strength by 30%on average.展开更多
基金Supported by Fund for Philosophy&Social Sciences of Jiangsu Provincial Department of Education(2011SJD820013)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Scientific Research Fund of Jiangsu Police Institute(11Y03)~~
文摘[Objective] The aim was to calculate the safe straw volume using Frank- Kamenetskii Model to provide method for fire protection in forage farm. [Method] Frank-Kamenetskii Model was used to measure Tacr and improved by marginal tem- perature which was adjustable. In addition, effects of water content and density of baled straws on Tc were explored using the improved model. [Result] Size of straw bales was the key factor determining whether spontaneous combustion would occur. For baled straws with water at 15.27% and density at 285 kg/m3, Tc was 85-88 ~C and safe diameter of baled straws maximized 8.2 m. In addition, straws should be stacked from south to north （or north to south） to avoid sunshine and certain space should be kept between straw bales for heat dissipation. [Conclusion] The research is of significance for safe management of forage farm.
基金Supported by the Returnee Foundation of Ministry of Education and Project (1054hz023)Supported by the Key Research Foundation of Ministry of Science in Heilongjiang Province
文摘The loading ability of straw bale was tested by Electronical Testing Machine. The linear regression equations were proposed between failure density and loading ability, and failure density and compressing energy. Based on an exponent model, the testing coefficients of straw bale were estimated using Levenberg-Marquardt Method. The results of test showed that the relation between failure density and loading ability and compressing energy was linear in the phase of high density. The loading ability of straw bale could meet the building bill.
基金Supported by National Natural Science Fund(50675071)Specialized Research Fund for Doctoral Program of Higher Education(20060564009)
文摘Loading ability of straw bales was tested by using an Electronical Testing Machine. Linear regression models were proposed to describe the loading ability as a function of failure density and compressing energy. Based on an exponent model, the testing compression coefficients of straw bales were estimated by using the Levenberg-Marquardt Method. Results showed that the relation among failure density, loading ability and compressing energy was linear in the phase of high density, Loading ability of straw bales could meet the requirement for building bills .
文摘Dwellings in a Mediterranean climate, such as that of Chile’s Central Valley, must provide hygro-thermal comfort both during the cold winters, and the hot days and cool summer nights. Straw, once a material common in Chile’s indigenous and vernacular architecture, could meet these demands when coupled with sufficient thermal mass in the form of earth renders and floor finishes. This article presents measurements of dry bulb temperatures and relative humidity, both in physical test chambers and Chilean straw bale homes. The results of these measurements confirm that straw bale construction could provide hygro-thermal comfort with heating demands 28% less than those of constructions that meet the Chilean thermal building regulations. Straw bale, therefore, could provide a viable solution for comfortable, energy efficient, rural dwellings in Chile’s Central Valley. Whilst over 40 private straw bale projects have been completed in Chile to date, restrictions applying to projects receiving government subsidies prevent this technology being available to those who need it most.
基金supported in part by the Slovene Research Agency,No.252256-1/07the Slovene Human Resources Development and Scholarship Fund,No.11012-47/2012.
文摘Straw bale construction offers a renewable,sustainable and proven alternative to mainstream building methods;still,little is known about its airflow characteristics.To this end,the intent of this paper is to evaluate airtightness of fully constructed and plastered straw bale walls as well as individual plain straw bales.The first experiment entailed measuring the influence of straw bale orientation on airflow characteristics with the finding that straw bale considered alone has poor air flow-retarding characteristics and that plaster is the primary air barrier.A second experiment involved thirty plastered straw bale specimens using three different plaster types.From this experiment,a crack grading system was developed and is herein proposed as a tool to evaluate plaster performance as an air barrier.A third experiment validated the crack grade system through application on four fully constructed straw bale walls.Practical use of the crack grading system was demonstrated on a case study straw bale house in Radomlje,Slovenia,where the predicted air tightness results were validated through comparison to results of blower door tests.
文摘Experimental studies on full-scale straw-bale walls have demonstrated the adequacy of straw-bale wall systems for resisting lateral loads from wind or seismic actions.Critical to the performance of the wall system is the anchorage of mesh reinforcement to the bottom plate and to the roof bearing assembly or top plate.Reported in this paper are the results of experiments examining mesh strength,anchorage strength,and failure mode for a variety of reinforcement meshes(steel,plastic,and hemp)and anchorage details.Because of the potential for new wood preservative pressure treatments to cause corrosion,stainless steel staples driven pneumatically into pressure-treated sill plates were tested in addition to electro-galvanized staples driven pneumatically into untreated sill plates and a heavier gauge staple driven manually into an untreated sill plate.Recommended anchorage details are identified,considering not only the test results but also the many other factors that must be considered in developing reliable,economical,and constructible details.
文摘This paper describes the hot-box testing(based on ASTM C1363-11)of seven straw bale wall panels to obtain their thermal conductivity values.All panels were con-structed with stacked bales and cement-lime plaster skins on each side of the bales.Four panels were made with traditional,2-string field bales of densities ranging from 89.5 kg/m^(3)-131 kg/m^(3) and with the bales on-edge(fibres perpendicular to the heat flow).Three panels were made with manufactured high-density bales(291 kg/m^(3)-372 kg/m^(3)).The fibres of the manufactured bales were randomly oriented.The key conclusion of this paper is that within the experimental error,there is no difference in the thermal conductivity value for panels using normal density bales and manufactured high density bales up to a density of 333 kg/m^(3).However,because of lack of precision of the hot-box,no conclusions can be made on the true thermal conductivity of the high density bale panels.In addition,the panels tested were found to have significant voids between bales,and this is believed to have con-tributed to higher measured thermal conductivity values compared to those reported in the literature for normal density bale panels.Thermal properties may be affected for bales with higher densities than 333 kg/m^(3),therefore further testing is suggested.
文摘The search for more sustainable construction methods has renewed interest in straw-bale construction.Rectangular straw bales stacked in a running bond and plastered on the interior and exterior faces have been shown to have adequate strength to resist typical loads found in one-and two-storey structures.The straw bales provide excellent insulation,while possessing low embodied energy compared to conventional insulation materials.The structural behaviour of a load-bearing plastered straw-bale wall subject to uniform compressive loading has been the focus of a number of studies reported in the literature.However,in a typical building wall,there will be numerous locations(such as around window and door openings)where the load paths produce areas of concentrated stress.The behaviour in these regions cannot necessarily be predicted using tests from uniformly loaded wall assemblies.This paper describes experiments on plastered single bale assemblies subjected to three-point bending.These assemblies develop shear and flexural stresses,and so simulate the stresses that exist around door and window openings in a wall.The specimens were rendered with lime-cement plaster,and were either unreinforced,or contained steel“diamond lath”mesh embedded within the plaster.The specimens were pin-supported at various centre-to-centre distances(L)ranging from 200 mm to 500 mm.The height(H)of all specimens was constant at 330 mm.This gave a range of H/L values of 0.66 to 1.65.Two distinct types of failure were observed.For tests with H/L<1,failure was due to flexural tension cracks in the plaster which propagated through the depth of the plaster skin.For tests with H/L>1,failure was due to crushing of the plaster in compression under one of the loading points.It was shown that models based on simple mechanics were able to adequately predict the assembly strength.In particular,analysing the assemblies with H/L<1 as simple beams,and using the transformed section concept to deal with the straw and steel mesh,was adequate for predicting their strength.The results suggest that current practice for straw bale construction is generally appropriate.To avoid tensile cracking of plaster due to flexure,regions around doors,windows,and other openings should be designed such that H/L>1.In regions where H/L<1,the use of steel reinforcing mesh can increase the plastered bale strength by 30%on average.
