This report describes wind pressures acting on prestressed concrete egg-shaped digestion tanks in various arrangement. Egg-shaped digestion tanks are the sludge digestion facilities in sewage treatment plants and have been widely constructed in Japan since 1980's. After the passing of the typhoon T9719, the cladding of the tank in Miyazaki City was damaged. Therefore, the wind tunnel tests were conducted to clarify the reasons of the damage and to evaluate the design load of the cladding for the future construction. The results of the wind tunnel tests are reported in this paper.
Immediately after the Typhoon 9119 which caused severe damages in the transmission lines in western Japan, electric power utilities asked Central Research Institute of Electric Power Industry (CRIEPI) to carry out the studies on the local wind resistance design of transmission tower-conductor systems. To promote this study, CRIEPI organized a committee and three sub-committees (the Wind observation sub-committee, the Wind simulation sub-committee, and the Wind-resistance design sub-committee). This paper describes the investigation results by the Wind observation sub-committee, which conducted to observe the topographic effect to the local wind and to understand the space-time structure of the high wind.
Immediately after the No. 9119 typhoon which caused severe damages in transmission lines in West Japan, electric power utilities asked Central Research Institute of Electric Power Industry (CRIEPI) to carry out the studies on the local wind resistance design of transmission tower-conductor systems. To promote the studies, CRIEPI organized a committee and three sub-committees (Wind observation sub-committee, Wind simulation sub-committee, and Wind-resistance design sub-committee). The purpose of this paper is to describe the investigation results by the Wind-resistance design sub-committee, which conducted to observe the dynamic behavior of the 500kV proto-type power transmission lines by measurements and numerical simulation under severe wind condition and to develop a new aspects on the current wind-resistance design standards.
This paper describes the comparison between analysis and measurement of aerodynamic admittance functions for lift and moment. Sears' function which is a theoretical expression for the aerodynamic admittance for a thin airfoil is conventionally applied to the gust response analysis of long span bridges. Comparing to the experimental results of the aerodynamic admittance function for deck sections, the measured aerodynamic admittance functions are different from Sears' function and some experimental formulas have been suggested. However, these formulas are not sufficient to apply to various sections. Then we propose new prediction method of aerodynamic admittance functions for lift and moment utilizing flutter derivatives and these functions obtained by our method have been compared with the measured ones and verified to be accurate.
Blast fences are used at airports to protect humans from jet blasts. As pertinent design data are too scarce, model experiments were conducted at a scale of 1/6. In a preliminary experiment without a fence, we simulated the spatial mean wind speed distribution due to the jet blast, which previously had been measured at an airport. Then various configurations of fences were studied. A number of interesting results were obtained, one of which is the following. When a long fence was placed perpendicular and symmetrical with respect to the oncoming jet at a distance of 50m (full scale) from the engine, the fence lifted the jet up into the air, and no significant reattachment of the jet to the ground surface was observed. This pattern occurred for all fence types studied.
A numerical investigation on the turbulent flows over a steep hill is presented. The numerical model developed for the present work is based on the finite volume method and the SIMPLE algorithm with a collocated grid system. Standard κ-ε model and Shih's non-linear κ-ε model are tested for the validation of the prediction accuracy in the 2-D and 3-D separated flows. Comparisons of the mean velocity and turbulence profiles between the numerical predictions and the measurements show good agreement. The Shih's non-linear κ-ε model is found to predict mean flow and turbulence better than the Standard κ-ε. Flow patterns have also been examined to explain the difference in the cavity zone between 2-D and 3-D hills.
Multiple-fan wind tunnels have been developed in our laboratory to investigate the effects of turbulent wind on large structures, such as high-rise buildings, long-span suspension bridges, etc.. In the previous report, coherence of turbulence between laterally separated points as well as many other statistical parameters, was reproduced in the tunnel by assuming a randomly distributed phase-lag. The vertical profiles of the coherence, the phase-lag and cross-correlation coefficient in an atmospheric boundary layer were investigated and presented in this paper. First, target of these parameters were determined by analyzing observed data on a meteorological tower. Second, the reproduction of these parameters was examined in the methods of numerical simulation and experiment in the wind tunnel. As the result, the profiles of these parameters were obtained closely to each target.