Case Study
109. The Winds of Time: a Case Study on 250 West 55th Street
This paper discusses model, design, and application of viscous dampers in one the skyscraper in New York City.
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This paper discusses model, design, and application of viscous dampers in one the skyscraper in New York City.
Adding damping with various energy dissipating devices has become an accepted method to reduce wind induced vibrations in tall buildings. An example of a 39-story office tower is presented where large projected accelerations generated by the vortex shedding of an adjacent existing 52-story building are reduced by a passive system composed of viscous dampers and a motion amplification system. A description of the damping system and its analytical complexities are discussed. Non-linear analysis of the tower, using time history forcing functions derived from the wind tunnel is presented. Cost data for the damper system is also presented.
Fluid Viscous Devices have been found to be a highly effective protection system for bridges. Introduced to China in 1999, the Taylor Devices damper systems have been successfully installed or will be installed in both large and super large bridges in China for protection from earthquake, wind, vehicle and other vibration. Seventeen different bridge projects include the Sutong Yangtze River Bridge, the longest cable stayed bridge in the world, the Nanjing 3rd Yangtze River Bridge, the fifth longest suspension bridge in the world, and the Xihoumen across Sea Bridge, the second longest suspension bridge in the world. The performance of the bridges and dampers have been reported as “very good” during the May 12, 2008 Wenchuan earthquake. All of the dampers produced have been subjected to rigorous static and dynamic testing, which show the dampers will perform well for the next 50 years and possibly much longer.
Pangu Plaza, located at Beijing close to 2008 Olympic main stadium, is a 191 meter, 39-story steel high rise building. It was analyzed under earthquake and wind loads with both Fluid Viscous Dampers (FVD) and Buckling Restrained Braces (BRB or UBB) as the seismic protection system. The complete seismic response on the horizontal and vertical directions showed that the Fluid Viscous Dampers are highly effective to reduce the structural response, as well as the secondary system response. A comparative analysis of structural seismic performance and economic effect was considered, by the traditional method of increasing steel columns and beams size; by using BRB’s and by using FVD’s to absorb the seismic energy. Structural response analysis showed that using FVD’s to absorb the seismic energy made the structure satisfy the Chinese seismic design code for the “rare” earthquake and also greatly improved the seismic performance. Economic analysis showed that FVD’s were the most economic approach for both one-time direct investment and long term maintenance.
Viscous dampers can protect structures against wind excitation, blast and earthquakes. Viscous damper technology originated with military and aerospace applications. Approximately 20 years ago it was found that the same fluid viscous dampers that protect missiles against nuclear attack and guard submarines against near miss underwater explosions could also protect buildings, bridges and other structures from destructive shock and vibration. This paper describes fluid damper technology, analysis considerations, installation methods and development work in progress.
Structural control of large buildings using tuned mass damper systems has gained wide acceptance in recent years. Significant structural performance improvements during wind storms have been realized using both active and passive systems. Disadvantages of employing active systems include high engineering and implementation costs, high maintenance costs, unnecessary system complexities, and the requirement for a continuous and non-interrupted power supply. A design for a passive tuned mass damper system is presented with analytical simulations and component test results. These demonstrate the effectiveness of using a tuned mass in conjunction with a maintenance free, hydraulic damper, having frictionless flexural seals to successfully attenuate the response of a high rise building subject to severe wind inputs.
Adding damping by the use of various damping devices has become an accepted method to reduce wind induced vibrations in tall buildings. An interesting example of a 39 story office tower is presented where large projected accelerations are the result of vortex shedding of an adjacent existing 52-story building. Viscous dampers and a toggle brace type motion amplification system are used to suppress the anticipated accelerations. A description of the damping system and its analytical simulation are discussed. This paper includes a nonlinear analysis of the tower, with time history forcing functions derived from wind tunnel testing. Cost data for the damper system is also presented.
Light poles at Rich Stadium in Orchard Park, N.Y., were showing incipient failure of their hold-down bolts, due to wind excitation. This paper describes the measures used to alleviate this problem, including the addition of viscous dampers between the stadium structure and a point around one third up on the light poles.
This specification, prepared jointly by TY Lin and Imbsen Associates, describes the requirements for the viscous dampers to be used in the retrofit of the Golden Gate Bridge. The specification includes wind excitation as well as seismic, and also describes testing requirements.