Tuned massed damper (Contrapeso en un rascacielo - Taipei 101)

Taipei 101

Thornton-Tomasetti Engineers along with Evergreen Consulting Engineering designed a 660 tonnes (728 short tons)steel pendulum that serves as a tuned mass damper. Suspended from the 92nd to the 87th floor, the pendulum sways to offset movements in the building caused by strong gusts. Its sphere, the largest damper sphere in the world, consists of 41 circular steel plates, each with a height of 125 mm (4.92 in) being welded together to form a 5.5 m (18 ft) diameter sphere.Another two tuned mass dampers, each weighing 6 tonnes (7 short tons),sit at the tip of the spire. These prevent damage to the structure due to strong wind loads.

[from wikipedia}

 BUILDING BIG :BRIDGES BASICS

There are more than half a million bridges in the United States, and you rely on them every day to cross obstacles like streams, valleys, and railroad tracks. But do you know how they work? Or why some bridges are curved while others are straight? Engineers must consider many things -- like the distance to be spanned and the types of materials available -- before determining the size, shape, and overall look of a bridge.

Since ancient times, engineers have designed three major types of bridges to withstand all forces of nature.

 

Read more in  BRIDGES