Structural Analysis of Calder's Mountains and Clouds

Mountains and Clouds, installed in the Hart Senate Office Building Atrium in 1986, was the last work of Alexander Calder (1898-1976), one of America's greatest twentieth-century sculptors. This sculpture, his only work with a separate mobile and stabile, consists of four organically shaped clouds hanging from a single shaft suspended from the roof. The largest cloud is 42.5' long and weighs approximately 2,000 pounds; the total weight of all four clouds is 4,300 pounds.

The clouds, which were lowered to the ground in December 2014, have been assessed to determine their structural integrity. X-ray analysis, 3-D laser imaging, a pull test analysis and a computer finite analysis have been performed to predict the static, dynamic, and seismic effects of potential stresses on the clouds.

A worker preparing a cloud for X-ray analysis; The sculpture with clouds in place before being lowered.

With the structural safety analysis of the Calder Clouds complete, the construction compound used to support that effort was removed, and the Hart atrium has been restored to its beautiful, spacious appearance.

Since the structural safety analysis identified the clouds as unsafe for reinstallation due to significant structural defects, the Architect of the Capitol, in consultation with the Calder Foundation, has determined that the best course of action is to refabricate the clouds to the artist's original intent.

This project was completed in 2016.

The original clouds have been disassembled and new clouds will be refabricated and reinstalled when funding becomes available.