Search

In this paper, the aerodynamic admittance or the dynamic lift function of long spannedbridges with plate like structural section are discussed, and the deflectional response of afew sectional models due to random vertical gust is analized by numerical calculationmethod evaluating Duhamel's integral and by analog simulation method.Experimental results of dynamic lift function in wind tunnel test are simulated approxi-mately by the modified quasi-steady theory or the Sears function.By using with these dynamic lift functions, the calculating results of numerical analysisand analog analysis for the deflectional response due to vertical gust show the goodagreement with the experimental results.

In this study, the effects of turbulence on galloping were investigted from the frequencyeffect of turbulence point of view. Two 2-D rectangular cylinders with slenderness ratios 1 (B/D=1, B: chord length, D: height of section) and 2 (B/D=2) were used and the steady lift forceand an aerodynamic response were measured in grid-turbulent flow and a pulsating sinusoidalflow. As a result, it is sujested that the higher frequency fluctuating components of turbulenceintensifies the entrainment effect of separated shear layer around the body, and the comparativelylow frequency fluctuating components of turbulence which is correspponeding to "shear layer in-stability enhancement frequency region" which would generate a vortices on a body side surfacewhich sometimes interact with Karman vortices, have few significant effect on steady lift forceand galloping response.

In this study, human-response against bridge vibration was investigated in the frequencyrange 0.2 Hz-1.0 Hz and in the amplitude range 1.0 cm-10.0 cm in order to evaluate serviceabilitylevel for pedestrian to the bridge vibration. Approximately 100 persons were tested on OhshimaBridge and vertically oscillating stage.Furthermore, the evaluation procedure of the extreme distribution of wind speed in considera-tion of Typhoon effect in various wind directions was developed and failure probability of severallong span suspension bridges due to strong wind were calculated. Finally the conceptional prob-abilistic approach of bridge design method against strong wind was shown in standing on a fai-lure probability.

This study aims to clarify the aerodynamic effects of the "corner cut" for the sake of themitigation of aerodynamic instability of the tower like structure. Two-dimensional rectangularcylinders with various cutting of their corners were tested in a wind tunnel, and their re-sponse, stationary pressure and stationary aerostatic force were measured in smooth flow. Be-sides flow visualization in water flume was carried out in order to visualize the effect of "cor-ner cut" to the flow pattern.Finally, the optimum size of corner cut was discussed by use of the elastic full scalemodel of tower of a long spanned cable-stayed bridge.

In order to anticipate various aspects of local scouring phenomena around abridge pier, a dynamic and flexible model will be necessary which reflects theessence of the phenomena. Such a model was constructed considering tractive forcedue to horseshoe vortex, geometrical similarity of scour hole and mass balance ofsediments in the scour hole. The model explained the feature of scouring processwhich has been observed in flume experiments under oscillatory flow conditions, such as scouring and deposition of scour hole associated with the change of flowdirection. The model was considered useful for rough estimation of maximum scourdepth at least.

The effect of vehicle loading on the seismic load of highway bridges isdiscussed. Urban expressways that are subjected to frequent traffic congestions areof primary concern. For this purpose, it is assumed that a bridge is loaded withheavy trucks at the moment of earthquake occurrence. The subject is dealt with asa dynamic interaction problem between bridge structures and vehicles. Bridge-vehicle systems are analyzed in terms of complex eigen-value problem and responsetime-history analysis. The vibration modes pertinent to the effect of vehicle loadingare identified. The result of earthquake response analysis is examined extensivelyby comparing the responses of bridge-vehicle systems and those of bridge-alone forvarious conditions of input earthquake motions and truck weight. From theseresults, the effect of vehicle loading on the seismic loads is made clear. On thisbasis, some coments are made on bridge desigh.

Hydraulic characteristics around various types of flow obstructions is a problem of continuinginterest. Many investigators have published results on the various aspects of this problem inthe past, particularly on the local scour around bridge piers.The present study is concerned with local scour around single cylindrical pier or plural cylin-drical piers arranged in various types under the condition of clear water scour. In the case ofsingle cylindrical pier, the variation of scour depth with time is investigated experimentally toobtain a formula. On the other hand, in the case of plural cylindrical piers, the effect of arrange-ment of piers on the scour characteristics is investigated mainly.

This study is concerned with the bluff body aerodynamics, I.e. the vortex-induced oscillationand galloping.Aerodynamic effects of separated vortices generated by body movement to torsional vortex-induced oscillation has been investigated by changing rotational axis of two dimensional rect-angular cylinder. Furthermore, the Karman vortex effect to these self-movement vortex-in-duced oscillation has been experimentally clarified by arrangement of splitter plate in a wakeof cylinder.The galloping investigation for simplified box girder section and the fundamental considera-tion of its aerodynamically stabilizing mechanism have been done by pressure measurement, static force measurement and flow visualization.

This paper concerns with an experimental investigation of the hydraulic characteristics ofthe flow behind two circular cylinders arranged latetrally. The study deals with the flow fieldnear cylinders. The vortex shedding properties are analyzed on the basis of the data obtainedby the propeller flowmeter, and the characteristics of vortex shedding process in ralation to thespacing between two cylinders are investigated from various viewpoint. The instantaneousstreamline pattern is also described by the use of flow visualization technique.

In this study the aerodynamic improvement for the coupled flutter oscillation of the bridgeroad deck box section of super long-spanned suspension bridge was experimentally investigated.The mitigation of the aerodynamic instability by installing "air gap" on the deck was target-ed here, besides the effects of the geometry shape of the edge fairing of the box girder werebliefly discussed. The unsteady pressure distribution on the box girder in a state of coupledflutter oscillation was measured, then it was clarified the pressure difference between upperand lower flange near the leading edge was significantly mitigated by the installment of "airgap", consequently this could sufficiently and aerodynamically stabilize the box girder.

Se estudia sistemáticamente la geometría y la topología de variedades de Kahler indefinidas. Se da un primer capítulo de ejemplos de estos espacios. En el capítulo segundo se estudia su curvatura en el tercero se utiliza este estudio para hacer una clasificación de cierta familia de estos espacios. El cuarto capítulo estudia la topología desde dos puntos de vista: tipo homotópico y cálculo de números de Betti de estos espacios, Univ. Granada, Facultad de Ciencias. Leída el 17-12-1982