The behavior of cold⁃formed steel(CFS)stud⁃to⁃sheathing connections at elevated temperatures is an important parameter for the fire resistance design and modeling of mid⁃rise CFS structures.In this paper,three kinds o...The behavior of cold⁃formed steel(CFS)stud⁃to⁃sheathing connections at elevated temperatures is an important parameter for the fire resistance design and modeling of mid⁃rise CFS structures.In this paper,three kinds of sheathings,namely,medium⁃and low⁃density calcium⁃silicate boards and oriented strand board,were selected for double⁃shear experiments on the mechanical properties of 253 screw connections at ambient and elevated temperatures.The effects of the shear direction,screw edge distance and the number of screws on the behavior of the connections were studied.The results showed that the shear direction and the screw edge distance more significantly influenced the peak deformation,while their impacts on the peak load varied with the type of sheathings.Compared with the single⁃screw connections,the peak loads of the specimens with double⁃screw connections obviously increased but did not double.Finally,a simplified load⁃displacement curve model of stud⁃to⁃sheathing connections at elevated temperature was generated first by establishing the prediction formula for characteristic parameters,such as the peak load,the peak deformation and the elastic stiffness,and then by considering whether the curves corresponded to stiffness increase phenomena.The present investigation provides basic data for future studies on the numerical modeling of CFS structures under fire conditions.展开更多
A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effe...A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone considerably increase due to the latent heating,especially in the lower troposphere.A thermally direct cross-front ageostrophic circulation.forced by frontogenesis,is found better developed and organized in the moist case than in the dry case.This cross-front direct ageostrophic circulation,particularly its ascending branch,is considerably enhanced by latent heating due to increased frontogenetical forcing and reduced effective static stability in the rising motion region where condensation occurs.One important feature in most observed cold fronts is the presence of an intense rising cell just above their leading edge.This intense rising cell is well simulated in the moist case but is less clear and much weaker in the dry case,indicating the important contribution by the la- tent heat release to the formation of this intense updraft above the surface cold front.展开更多
基金the National Natural Science Foundation of China(Grant No.51978655)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20201347)+1 种基金the Xuzhou Science and Technology Project(Grant No.KC20175)the China Postdoctoral Science Foundation Funded Project(Grant No.2019M652007).
文摘The behavior of cold⁃formed steel(CFS)stud⁃to⁃sheathing connections at elevated temperatures is an important parameter for the fire resistance design and modeling of mid⁃rise CFS structures.In this paper,three kinds of sheathings,namely,medium⁃and low⁃density calcium⁃silicate boards and oriented strand board,were selected for double⁃shear experiments on the mechanical properties of 253 screw connections at ambient and elevated temperatures.The effects of the shear direction,screw edge distance and the number of screws on the behavior of the connections were studied.The results showed that the shear direction and the screw edge distance more significantly influenced the peak deformation,while their impacts on the peak load varied with the type of sheathings.Compared with the single⁃screw connections,the peak loads of the specimens with double⁃screw connections obviously increased but did not double.Finally,a simplified load⁃displacement curve model of stud⁃to⁃sheathing connections at elevated temperature was generated first by establishing the prediction formula for characteristic parameters,such as the peak load,the peak deformation and the elastic stiffness,and then by considering whether the curves corresponded to stiffness increase phenomena.The present investigation provides basic data for future studies on the numerical modeling of CFS structures under fire conditions.
文摘A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating on the structure of cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone considerably increase due to the latent heating,especially in the lower troposphere.A thermally direct cross-front ageostrophic circulation.forced by frontogenesis,is found better developed and organized in the moist case than in the dry case.This cross-front direct ageostrophic circulation,particularly its ascending branch,is considerably enhanced by latent heating due to increased frontogenetical forcing and reduced effective static stability in the rising motion region where condensation occurs.One important feature in most observed cold fronts is the presence of an intense rising cell just above their leading edge.This intense rising cell is well simulated in the moist case but is less clear and much weaker in the dry case,indicating the important contribution by the la- tent heat release to the formation of this intense updraft above the surface cold front.
