To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristi...To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.展开更多
Wind-driven rain(WDR)has a significant influence on the hygrothermal performance,durability,and energy consumption of building components.The calculation of WDR loads using semi-empirical models has been incorporated ...Wind-driven rain(WDR)has a significant influence on the hygrothermal performance,durability,and energy consumption of building components.The calculation of WDR loads using semi-empirical models has been incorporated into the boundary conditions of coupled heat and moisture transfer models.However,prior research often relied on fixed WDR absorption ratio,which fail to accurately capture the water absorption characteristics of porous building materials under rainfall scenarios.Therefore,this study aims to investigate the coupled heat and moisture transfer of exterior walls under dynamic WDR boundary conditions,utilizing an empirically obtained WDR absorption ratio model based on field measurements.The developed coupled heat and moisture transfer model is validated against the HAMSTAD project.The findings reveal that the total WDR flux calculated with the dynamic WDR boundary is lower than that obtained with the fixed WDR boundary,with greater disparities observed in orientations experiencing higher WDR loads.The variations in moisture flow significantly impact the surface temperature and relative humidity of the walls,influencing the calculation of cooling and heating loads by different models.Compared to the transient heat transfer model,the coupled heat and moisture transfer model incorporating dynamic WDR boundary exhibits maximum increases of 17.6%and 16.2%in cooling and heating loads,respectively.The dynamic WDR boundary conditions provide more precise numerical values for surface moisture flux,offering valuable insights for the thermal design of building enclosures and load calculations for HVAC systems.展开更多
Wind-driven rain(WDR)constitutes a significant source of moisture for building facades,which poses considerable challenges to both the thermal insulation performance and long-term durability of walls.Prior studies hav...Wind-driven rain(WDR)constitutes a significant source of moisture for building facades,which poses considerable challenges to both the thermal insulation performance and long-term durability of walls.Prior studies have contributed significantly to the understanding of fluid behavior and moisture response of WDR upon impacting walls.However,the quantification of absorbed rainwater by the wall remains elusive.To address this gap,this study focuses on comprehending the dynamic WDR absorption behavior of various exterior finishing materials.Specifically,nine types of finishing materials were selected as research objects and conducted field measurements.The findings reveal that WDR absorption ratio is influenced by physical parameters of materials,surface waterproofing and the cumulative WDR.Leveraging multiple regression fittings,we established an empirical WDR absorption ratio calculation mode.This model serves as a valuable reference for determining building simulation parameters regarding dynamic moisture boundary conditions on the exterior surfaces of walls.By providing empirical insights into WDR absorption,our research contributes to a more comprehensive understanding of moisture behavior in building envelopes,thereby aiding in the development of effective strategies for enhancing building performance and durability.展开更多
To address the limitations of current urban building energy modeling(UBEM),which often neglects moisture effects,we developed a comprehensive roadmap for modeling urban heat and moisture flows.This effort included dev...To address the limitations of current urban building energy modeling(UBEM),which often neglects moisture effects,we developed a comprehensive roadmap for modeling urban heat and moisture flows.This effort included developing an urban-scale whole-building heat and moisture transfer(HAMT)model that considers wind-driven rain,integrated with a microclimate model known as Urban Weather Generator(UWG).The proposed model was validated through analytical and comparative cases of whole-building hygrothermal performance analyses from the Annex 41 Project.The integrated whole-building and microclimate HAMT models were applied to a real urban building to assess the impact of moisture on annual energy predictions in a hot-humid region of Shanghai.The results show that incorporating moisture effects into the UBEM increases the annual cooling energy demand by 22.11%(5.92% owing to latent heat loads)and the annual heating loads by 6.06%,resulting in a 19.73%increase in the total annual energy loads.Additionally,the outer wall surface temperature decreases during and after rainfall events,with maximum decreases of 3.23℃ in winter and 8.80℃ in summer.Therefore,integrating moisture effects into UBEM is crucial,particularly in humid regions.展开更多
基金Projects(20B062,19B054)supported by Excellent Youth Program of Hunan Education Department,ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation of ChinaProject(kq195004)supported by Changsha Science and Technology Bureau Project,China。
文摘To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.
基金The work described in this paper was financially supported by the Shanghai Municipality Natural Science Foundation(No.21ZR1434400).
文摘Wind-driven rain(WDR)has a significant influence on the hygrothermal performance,durability,and energy consumption of building components.The calculation of WDR loads using semi-empirical models has been incorporated into the boundary conditions of coupled heat and moisture transfer models.However,prior research often relied on fixed WDR absorption ratio,which fail to accurately capture the water absorption characteristics of porous building materials under rainfall scenarios.Therefore,this study aims to investigate the coupled heat and moisture transfer of exterior walls under dynamic WDR boundary conditions,utilizing an empirically obtained WDR absorption ratio model based on field measurements.The developed coupled heat and moisture transfer model is validated against the HAMSTAD project.The findings reveal that the total WDR flux calculated with the dynamic WDR boundary is lower than that obtained with the fixed WDR boundary,with greater disparities observed in orientations experiencing higher WDR loads.The variations in moisture flow significantly impact the surface temperature and relative humidity of the walls,influencing the calculation of cooling and heating loads by different models.Compared to the transient heat transfer model,the coupled heat and moisture transfer model incorporating dynamic WDR boundary exhibits maximum increases of 17.6%and 16.2%in cooling and heating loads,respectively.The dynamic WDR boundary conditions provide more precise numerical values for surface moisture flux,offering valuable insights for the thermal design of building enclosures and load calculations for HVAC systems.
基金Shanghai Municipality Natural Science Foundation(Grant No.21ZR1434400)Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,Chongqing University,China(Grant No.LNTCCMA 20210103)National Natural Science Foundation ofChina(Grant No.51778358).
文摘Wind-driven rain(WDR)constitutes a significant source of moisture for building facades,which poses considerable challenges to both the thermal insulation performance and long-term durability of walls.Prior studies have contributed significantly to the understanding of fluid behavior and moisture response of WDR upon impacting walls.However,the quantification of absorbed rainwater by the wall remains elusive.To address this gap,this study focuses on comprehending the dynamic WDR absorption behavior of various exterior finishing materials.Specifically,nine types of finishing materials were selected as research objects and conducted field measurements.The findings reveal that WDR absorption ratio is influenced by physical parameters of materials,surface waterproofing and the cumulative WDR.Leveraging multiple regression fittings,we established an empirical WDR absorption ratio calculation mode.This model serves as a valuable reference for determining building simulation parameters regarding dynamic moisture boundary conditions on the exterior surfaces of walls.By providing empirical insights into WDR absorption,our research contributes to a more comprehensive understanding of moisture behavior in building envelopes,thereby aiding in the development of effective strategies for enhancing building performance and durability.
基金support from the National Natural Science Foundation of China(52478031).
文摘To address the limitations of current urban building energy modeling(UBEM),which often neglects moisture effects,we developed a comprehensive roadmap for modeling urban heat and moisture flows.This effort included developing an urban-scale whole-building heat and moisture transfer(HAMT)model that considers wind-driven rain,integrated with a microclimate model known as Urban Weather Generator(UWG).The proposed model was validated through analytical and comparative cases of whole-building hygrothermal performance analyses from the Annex 41 Project.The integrated whole-building and microclimate HAMT models were applied to a real urban building to assess the impact of moisture on annual energy predictions in a hot-humid region of Shanghai.The results show that incorporating moisture effects into the UBEM increases the annual cooling energy demand by 22.11%(5.92% owing to latent heat loads)and the annual heating loads by 6.06%,resulting in a 19.73%increase in the total annual energy loads.Additionally,the outer wall surface temperature decreases during and after rainfall events,with maximum decreases of 3.23℃ in winter and 8.80℃ in summer.Therefore,integrating moisture effects into UBEM is crucial,particularly in humid regions.
