Field measurement of strong wind characteristics is of great significance for the development of bridge wind engineering. Located in east China, the Runyang Suspension Bridge (RSB) with a main span of 1490 m is the longest bridge in China and the third longest in the world. During the last four years, the RSB has suffered from typhoons and strong northern winds on more than ten occasions. To determine the strong wind characteristics of the RSB, wind measurement data obtained from field tests during strong winds and data from the wind environment monitoring subsystem of the structural health monitoring system (SHMS) of the RSB were combined to analyze the wind speed and direction, variation in wind speed with height, turbulence intensity, turbulence integral length, wind friction speed and the power spectrum. Comparative studies on the characteristics of these different strong winds were carried out based on the current wind-resistant design specification for highway bridges. Results showed that some regularity in wind characteristics can be found in these different typhoons passing through the RSB. The difference between a strong northern wind and a typhoon is relatively clear, and in summer the typhoon is the dominant wind load acting on the RSB. In addition, there were some differences between the measured strong wind characteristics and the values suggested by the specification, especially in respect to turbulence intensity and turbulence integral length. Results provide measurement data for establishing a strong wind characteristic database for the RSB and for determining the strong wind characteristic parameter values of this coastal area in east China.
A 3D finite element model for the Taizhou Yangtze River Bridge,the first triple-tower long-span suspension bridge in China,is established based on the nonlinear finite element software ABAQUS,and the dynamic characteristics of the bridge are analyzed using the LANCZOS eigenvalue solution method. The study focuses on the effects of the vertical,lateral and torsional stiffness of the steel box girder,the rigid central buckle and the elastic restraints connecting the towers and the steel box girder on the dynamic characteristics of the triple-tower suspension bridge. Our results show that,in general,the dynamic characteristics of the triple-tower suspension bridge are similar to those of two-tower suspension bridges. The vertical,lateral and torsional stiffness of the steel box girder have different effects on the dynamic characteristics of triple-tower suspension bridges. The elastic re-straints have a more significant effect on the dynamic characteristics than the central buckle,and decreasing the stiffness of the elastic restraints results in the appearance of a longitudinal floating vibration mode of the bridge. Also,rigid central buckles have a greater influence on the dynamic characteristics of triple-tower suspension bridges than on those of two-tower suspension bridges. The results obtained could serve as a valuable numerical reference for analyzing and designing super-long-span triple-tower suspension bridges.
As a cable-stayed bridge with the longest main span, the Sutong Bridge faces the threat of typhoons every year. Based on field measured data measured at the top of the tower and at the mid-span by anemometers, Typhoon Muifa is analyzed in detail to obtain the wind characteristics, including the mean wind speed and direction, turbulence intensity and gust factor, power spectral density and integral scale of turbulence, etc. The correlated mean wind speeds at the two heights show the reliability of recorded wind data as well as the variation of wind speed with height. Turbulence inten- sities and gust factors fluctuate in a similar way. The values of inte- gral scales are sensitive in different case. The measured power spec- tra are particularly compared with Kaimal spectrum, Teunissen spectrum, Harris spectrum, and Davenport spectrum. The results show that the measured spectra cannot fit the code-suggested spectra very well, which exhibits the demand of more accurate spectra. Conclusions obtained in this article can provide references for wind resistance desima of suoer-long-soan cable-staved brides.
A new multi-functional bridge seismic isolation bearing(MFBSIB) is designed and its mechanical model is developed in this paper.Combining an upper sliding device and a lower energy dispassion isolation device effectively,the new MFBSIB can adjust the deformation caused by temperature,vehicle breaks,and concrete creep,etc.,in addition to dissipating energy.The switch of 'slide-isolation' is achieved and the efficiency of both upper and lower parts is validated through experiment with a model.The shear performance curve established in this paper is verified to be efficient in describing the mechanical characteristics of the bearing through experiment.It is proved through both numerical calculation and experimental analysis that the new MFBSIB is endowed with enough vertical rigidity,good energy dissipation ability,stable overall performance,and good realization in expected goals.Its performance is slightly influenced by shear stress,while affected by vertical pressure,loading frequency,slide limit,etc.,diversely.The results could provide reference for study and application of the new MFBSIB.
