The Making of Mega Pall Friction Dampers for Torre Cuarzo Office Tower in Mexico City

Abstract eng:
The 600 feet (183 m) high steel frame tower is founded on piles. The preliminary time-history dynamic analysis by the project structural engineers, WSP Group in New York, have shown that higher modes influence to excite the structure above 11th floor, resulting in large story drifts. Introduction of supplemental damping by incorporating passive energy dissipation devices was considered to be the most economical solution. Pall Friction Dampers® (PFD) were chosen because they possess both stiffness and damping and are best suited to control story drifts. Beside their low cost, they are maintenance free and can be easily modified to suit site conditions. The architectural constraints allowed limited number of braced bays. Therefore, dampers of very high slip loads up to 1950 Kip (8700 kN) were needed to control large displacements. This big capacity damper has not been manufactured so far. Generally, the demand for damper is up to 350 Kip (1500 kN) capacity. Therefore, the manufacturing / testing equipments are geared to damper size in demand. Upgrading the equipment is expensive and economically not justified. The making of Mega damper was therefore a challenge. Making an assembly of group of PFD units, in parallel, was thought to be a right solution for Mega dampers. The compact size of PFD units, made it possible to build an assembly up to 8 units. The desired design slip loads were achieved with assemblies of group of 2, 4 and 6 units. The architects have liked the appearance of PFD assembly and have boldly exposed Steel bracing with Mega Pall Friction Dampers to view - a showcase of The Art of Structural Engineering. This paper describes the history of development of Pall Friction Dampers, from an idea to real application. The paper will also discuss challenges in the making of Mega Pall Friction Dampers and show the construction details. Hopefully, the development story will inspire young engineers to continue advancement of their innovative ideas for a better and safer world.

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