Composite one-way concrete slabs with profiled steel sheeting as permanent formwork are commonly used in the construction industry. The steel sheeting supports the wet concrete of a cast-in-situ reinforced or post-ten...Composite one-way concrete slabs with profiled steel sheeting as permanent formwork are commonly used in the construction industry. The steel sheeting supports the wet concrete of a cast-in-situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel sheeting is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the longitudinal shear capacity of each type of steel decking using full-scale tests. This paper presents the results of the short-term testing up to failure of two types of profiled steel decking that are commonly used in the construction industry in Australia. Fourteen full-scale, simply-supported slabs were tested in four-point bending with shear spans of either span/4 or span/6. Four slabs were tested at age of 28 days and the other 10 slabs were subjected to drying shrinkage and various levels of sustained loads for a period of at least 6 months prior to testing to failure. The effects of creep and drying shrinkage on the load carrying capacity and deformation of the slabs at ultimate loads are presented and discussed. The bond-slip relationship of each slab is determined from the test data and the values of maximum longitudinal shear stress calculated using different methods are described and compared.展开更多
Objectives: During visual stimulation, the elevated metabolism rate will coupl e with increase of blood flow velocity(BFV) in posterior cerebral artery(PCA). T his study with TCD was aimed to investigate whether the c...Objectives: During visual stimulation, the elevated metabolism rate will coupl e with increase of blood flow velocity(BFV) in posterior cerebral artery(PCA). T his study with TCD was aimed to investigate whether the coupling might change ac cording to the different vasoneuronal conditions. Methods: Ninety-nine voluntee r s including 24 hypertension(HT) patients and 2 patients suffering from both HT a nd diabetes mellitus(DM) were enrolled in this trial. BFV and pulse indexes(PI) in P2 segments of PCA on both sides were monitored during visual stimulation. Re sults: In all subjects, Mean BFV increased and PI went down in response to visua l stimulation. The percentages of changes (ΔV and ΔP) of both mean BFV and PI we re larger in young group(<55 years old) than in old one(≥55 years old). There w a s significant positive correlation between ΔV and ΔP. Multivariated re gression a nalysis did not show HT and DM, but age related to ΔV(ΔP). We did not find signi ficant difference of ΔV(ΔP) between left and right sides. Conclusions: Blood flo w velocity in PCA P2 segment increased due to decreased cerebrovascular resistan ce during visual stimulation and the response weakened with aging of the patient .展开更多
文摘Composite one-way concrete slabs with profiled steel sheeting as permanent formwork are commonly used in the construction industry. The steel sheeting supports the wet concrete of a cast-in-situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel sheeting is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the longitudinal shear capacity of each type of steel decking using full-scale tests. This paper presents the results of the short-term testing up to failure of two types of profiled steel decking that are commonly used in the construction industry in Australia. Fourteen full-scale, simply-supported slabs were tested in four-point bending with shear spans of either span/4 or span/6. Four slabs were tested at age of 28 days and the other 10 slabs were subjected to drying shrinkage and various levels of sustained loads for a period of at least 6 months prior to testing to failure. The effects of creep and drying shrinkage on the load carrying capacity and deformation of the slabs at ultimate loads are presented and discussed. The bond-slip relationship of each slab is determined from the test data and the values of maximum longitudinal shear stress calculated using different methods are described and compared.
文摘Objectives: During visual stimulation, the elevated metabolism rate will coupl e with increase of blood flow velocity(BFV) in posterior cerebral artery(PCA). T his study with TCD was aimed to investigate whether the coupling might change ac cording to the different vasoneuronal conditions. Methods: Ninety-nine voluntee r s including 24 hypertension(HT) patients and 2 patients suffering from both HT a nd diabetes mellitus(DM) were enrolled in this trial. BFV and pulse indexes(PI) in P2 segments of PCA on both sides were monitored during visual stimulation. Re sults: In all subjects, Mean BFV increased and PI went down in response to visua l stimulation. The percentages of changes (ΔV and ΔP) of both mean BFV and PI we re larger in young group(<55 years old) than in old one(≥55 years old). There w a s significant positive correlation between ΔV and ΔP. Multivariated re gression a nalysis did not show HT and DM, but age related to ΔV(ΔP). We did not find signi ficant difference of ΔV(ΔP) between left and right sides. Conclusions: Blood flo w velocity in PCA P2 segment increased due to decreased cerebrovascular resistan ce during visual stimulation and the response weakened with aging of the patient .
