[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four ty...[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four typical forest stands in Jinyun Mountain of Chongqing was explored, including conifer-broadleaved mixed for- est, evergreen broad-leaved forest, bamboo forest and shrub forest. [Result] The re- sults showed that the order of saturated water storage capacity of soil in four forest stands was shrub forest （266.48 mm） 〉 conifer-broadleaved mixed forest （190.40 mm） 〉 evergreen broad-leaved forest （186.80 mm） 〉 bamboo forest （174.80 mm）; the order of maximum water-holding capacity of litter was shrub forest （8.06 mm） 〉 conifer-broadleaved mixed forest （4.71 mm） 〉 evergreen broad-leaved forest （4.32 mm） 〉 bamboo forest （3.34 mm）; the order of canopy interception in various forest stands was conifer-broadleaved mixed forest （16.15%） 〉 evergreen broad-leaved for- est （14.70%） 〉 bamboo forest （12.64%）. [Conclusion] The study had great signifi- cance to rational manage forest resources, improve water environment and realize scientific management and use of water resources.展开更多
This paper shows consideration of decrease in cross-section stiffness in commonly used in practice RC （reinforced concrete） beams and slabs in cases when only reinforcing bars or only concrete compressed zone, which...This paper shows consideration of decrease in cross-section stiffness in commonly used in practice RC （reinforced concrete） beams and slabs in cases when only reinforcing bars or only concrete compressed zone, which is subjected to fire. Analyses were based on： （1） standard fire curve [EN 1991-1-2]; （2） 500℃isotherm method assumptions [EN 1992-1-2]; （3） mechanical properties of reinforcing steel heated up to high temperature. Afterwards, based on estimated decrease of cross-sections stiffness, the redistribution of bending moments was calculated in some cases of two-span RC beams and slabs subjected to fire from their bottom face. Due to the bending moment redistribution, one could expect a reduction of bending moments in span cross-sections and an increase of support bending moment. As a result of this phenomenon, the ultimate limit state of the structural multi span elements might occur after shorter fire duration than it could be expected when redistribution of bending moments is neglected.展开更多
基金Supported by"Twelfth Five-Year"National Scientific and Technological Support Project(2011BAD38B0602)~~
文摘[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four typical forest stands in Jinyun Mountain of Chongqing was explored, including conifer-broadleaved mixed for- est, evergreen broad-leaved forest, bamboo forest and shrub forest. [Result] The re- sults showed that the order of saturated water storage capacity of soil in four forest stands was shrub forest （266.48 mm） 〉 conifer-broadleaved mixed forest （190.40 mm） 〉 evergreen broad-leaved forest （186.80 mm） 〉 bamboo forest （174.80 mm）; the order of maximum water-holding capacity of litter was shrub forest （8.06 mm） 〉 conifer-broadleaved mixed forest （4.71 mm） 〉 evergreen broad-leaved forest （4.32 mm） 〉 bamboo forest （3.34 mm）; the order of canopy interception in various forest stands was conifer-broadleaved mixed forest （16.15%） 〉 evergreen broad-leaved for- est （14.70%） 〉 bamboo forest （12.64%）. [Conclusion] The study had great signifi- cance to rational manage forest resources, improve water environment and realize scientific management and use of water resources.
文摘This paper shows consideration of decrease in cross-section stiffness in commonly used in practice RC （reinforced concrete） beams and slabs in cases when only reinforcing bars or only concrete compressed zone, which is subjected to fire. Analyses were based on： （1） standard fire curve [EN 1991-1-2]; （2） 500℃isotherm method assumptions [EN 1992-1-2]; （3） mechanical properties of reinforcing steel heated up to high temperature. Afterwards, based on estimated decrease of cross-sections stiffness, the redistribution of bending moments was calculated in some cases of two-span RC beams and slabs subjected to fire from their bottom face. Due to the bending moment redistribution, one could expect a reduction of bending moments in span cross-sections and an increase of support bending moment. As a result of this phenomenon, the ultimate limit state of the structural multi span elements might occur after shorter fire duration than it could be expected when redistribution of bending moments is neglected.
