Last week's lift of the Assembly Building roof structure was a delicate operation that required close-to-perfect alignment between the vertical columns and the connexion plates on the roof structure.
And close-to-perfect it was. Despite the relative flexibility of the steel structure, real-time metrological measurements showed that only 4 (out of 66) connexions ended up slightly misaligned. As a consequence, 4 new plates (1 m x 20 cm) will be machined to compensate for the slight misalignment.
Working at a height of nearly 60 metres, workers are now placing and tightening 3,000 connexion bolts (out of 85,000 for the whole steel structure). This operation, along with the removal of the temporary structures that held the hydraulic jacks and cables, will take about two weeks to complete.