Objects that would become triggers of perceptions of building vibrations by visual sensation are not necessarily seen in actual environment of building. Vibration perception only by visual sensation in consideration of length of time that visual cues are seen is examined. Furthermore it is compared with probability of vibration perception by body sensation. It is found that a situation between vibration perception by visual sensation and vibration perception by body sensation is much different in each range of vibration frequency and that of vibration amplitude.
The present paper discusses the peak wind force coefficients for designing the cladding of free-standing canopy roofs with ceiling, based on a series of wind tunnel experiments. Wind pressures are measured simultaneously at many points both on the upper and lower surfaces in a wind tunnel. The internal pressure between the roof cladding and ceiling is estimated from the external pressures on the lower surface, assuming that there are many small openings uniformly distributed on the ceiling. The net wind force coefficients on the roof cladding and ceiling are given by the difference between the external and internal pressure coefficients. The characteristics of the net wind force coefficients as well as of the internal pressure coefficient are investigated. The method for evaluating the peak wind force coefficients on the roofing and ceiling is discussed based on the correlation between the external and internal pressures.
The properties of internal pressures induced by wind are very important for evaluating the wind loads of exterior materials and structural frames in buildings. This paper describes the properties of internal pressure in nominally sealed but leaky low-rise buildings induced by wind. The internal pressures in the low-rise building models with the apertures are measured in a wind tunnel experiment. The internal pressure fluctuations in the nominally sealed but leaky low-rise buildings have also been simulated using the leak-flow model and the fluctuating external pressures obtained from the wind tunnel experiment. The relationship between external pressures and internal pressures in the low-rise building models with the apertures are also shown by normalized power spectra, coherence and phase spectra.
Aerodynamic force and base pressure on axial cylinders as well as flow fields around them were measured at 100,000 of Reynolds number based on their diameter with the JAXA 60cm magnetic suspension and balance system (MSBS), a digital telemeter system, and a particle image velocimetry (PIV). The models were suspended by the MSBS without any support interference. The fineness ratio of them ranged from 1.27 to 1.79. The flow fields were measured in the cross section of the wake perpendicular to the model axis and were also measured in the parallel section including model axis. The test results showed that these three devices could be used concurrently. At the JAXA 60cm MSBS, estimated unsteady aerodynamic force less than about 15Hz could be evaluated successfully. A peak in the power spectrum of the drag fluctuations was observed at about
1.5 Hz (Strouhal number of approximately 0.012) which corresponded to a peak in the power spectrum of the base pressure fluctuations, but absent in the side force spectrum. This is considered to be caused by the axial oscillation of the recirculation region. The Strouhal number of the main base pressure fluctuating frequency was 0.34 which corresponded to large scale vortex shedding. Numerous longitudinal vortices were observed in the unsteady cross sectional flow field of the wake perpendicular to the cylinder axis and they moved widely in the field. Any sting mount of an axial cylinder would have interfered with the flow field to make such observations.