Shuyang Cao

Experimental Study on Tornado-Induced Wind Pressures on a Cubic Building with Openings

AbstractWind pressures acting on a cubic building with openings exposed to stationary tornadolike vortices were studied experimentally. The effects of opening ratio, single central opening azimuth,...

A comparison study on gust factor considering non-stationary effects under typhoon and monsoon conditions:

This article studies the feasibility and effectiveness of a non-stationary model using field measurements. Gust factors are compared for both typhoon and monsoon winds whose maximum 10-min mean wind speeds were all greater than 20 m/s using non-stationary models. Wind speeds were recorded by three-dimensional anemometers by the Structural Health Monitoring System of Xihoumen Bridge. The study focuses on the dependences of gust factor on gust averaging time, sample duration, and mean wind speed for both typhoon and monsoon climates. The gust factor curve and the relationship between gust factor and turbulence intensity are also studied. The results suggest that a non-stationary model is more suitable for actual turbulence flow, particularly under typhoon conditions. The article also compares resulting gust factor curves with those obtained in former studies and shows that accurate gust factor curves can be obtained by field measurements for monsoon wind. It is thus recommended that gust factor research should differentiate between typhoon and monsoon winds.

Investigation of Spatial Coherences of Aerodynamic Loads on a Streamlined Bridge Deck in an Actively- Controlled Wind Tunnel

Two-dimensional flow fields were simulated in an actively-controlled wind tunnel by using multiple fans and active-vibration grids. On coming flow features and aerodynamic loads on a streamlined bridge deck section model were measured simultaneously. Experimental result shows that the spatial coherences of on coming flows and aerodynamic loads are both influenced by on coming flow features. Longitudinal and vertical flow features have different effects on spatial coherence of aerodynamic loads. The shape of the spatial coherence function versus frequency curve does not always satisfy an exponential law, but sometimes shows an inverse form in the low-frequency region. A new empirical model is proposed and compared with the traditional exponential one. This new model shows good performance in reflecting spatial coherences of both oncoming flows and aerodynamic forces under different flow conditions.

Shielding Effects of Surrounding Buildings on Wind Loads on Low-Rise Building Roofs

Low-rise buildings are often built in groups, and their wind loads differ from those on isolated buildings. In this study, the wind pressures on flat roofs of low-rise buildings surrounded by similar buildings were measured with a series of wind tunnel tests. The general properties of the shielding effects of surrounding buildings were discussed. The effects of area density, relative height, and arrangement patterns of the surrounding buildings on the shielding factors of the smallest minimum negative extreme wind pressure coefficients and of the largest peak uplift force coefficients on the whole roof of the shielded building for all wind directions were analyzed. For practical purposes, both shielding factors were expressed as equations of the building area density and the relative height of the surrounding buildings based on the wind tunnel test data, which can cover most of the test results.

Area-Averaged Characteristics of Wind Loads on Roof-Mounted Solar Arrays

With the increasing use of solar photovoltaics, wind-induced loads on rooftop solar arrays have become a problem. A series of wind tunnel experiments have been performed to evaluate wind loads on solar panels on flat roofs, mainly focusing on their area-averaged characteristics such as mean and negative peak force coefficients, and peak factors. Solar array models were fabricated with pressure taps installed as densely as possible to identify the area-averaged characteristics. Design parameters of solar arrays including panel position, tilt angle and distance between arrays have been considered. Although values for unfavorable mean and peak differ for different tilt angles, the variation tendencies and peak factors are similar. The results were also compared to Japanese Standard (JIS C 8955) which correctly estimates negative mean module force coefficients but not peak values.