Following the agreement for reconstruction of the roof of SESAME’s experimental hall signed on 20 April 2014 with the contractor who built the SESAME building, considerable work has been carried out on the roof.
During the first two weeks of May 2014, the steel structure of the roof was fully dismantled, and the designer (and contractor) has since prepared a new design for the roof under the supervision of two international experts, one from PSI (Paul Scherrer Institute) in Switzerland and the second from Elettra Sincrotrone Trieste S.C.p.A in Italy. In both cases, expenses related to the experts were generously covered by the experts’ respective home institute.
Some features of the new design of the roof differ from those of the roof that was in place (see figures (a) and (b) below), namely:
- The slope of the roof has been increased from 9% to 15% to reduce the possibility of snow accumulation and/or to facilitate the removal of accumulated snow.
- Since the slope was increased by connecting the upper cord of the secondary truss to the top cord of the spine truss, there are no skylight windows in the new design.
- The two concrete columns supporting each end of the main truss have been connected with a concrete beam. These columns have in addition been cladded with a 10 mm thick steel envelope.
The other supporting concrete columns that were damaged by the collapse have been repaired.
No parts of the spine truss of the previous roof have been used in the new truss, but some parts of the secondary truss have been used in the new roof.
The roof has again been designed to withstand a snow load of 175 kg/m2. This is about double that called for in the Jordanian National Building Code.
Since SESAME wished to have every step in the design approved by the two international experts, completion of the roof is slightly behind schedule. Thus, although most parts of the new roof have been manufactured, the new roof will be fully in place 6-8 weeks later than the deadline that had been set (20 October 2014).
Notwithstanding the removal of the caved-in roof, the SESAME staff have been able to continue their normal activities in their offices and laboratories at SESAME. Moreover, work at SESAME has been able to progress well and, as mentioned in SESAME’s press release of 3 September, after having successfully stored electrons from the 20 MeV Microtron in the Booster in July 2014, on 3 September 2014, the SESAME team succeeded in accelerating the electrons in the Booster to their final energy of 800 MeV.
The SESAME Safety Committee has been working closely with the safety officer of the contractor to ensure a safe work environment for the staff, and will continue to do so.