Design Review of the D0 Central Calorimeter Module Assembly to Fermi National Accelerator Laboratory

Abstract

The D-Zero Central Calorimeter Module Assembly is a segmented ring structure consisting of an assemblage of trapezoidal modules. It is housed inside a vessel containing liquid argon. The modules contain specialized equipment for use in particle physics experiments. The design review of the D-Zero Central Calorimeter Module Assembly evaluated all major structural elements for adequacy for their design loads. They were evaluated in accordance with applicable specifications from Reference 1. The allowable stresses of the Specifications provide an approximate safety factor of 2.0 or more on failure and 1.67 on serviceability of the structure. This margin is typical of buildings, bridges, and other large structures executed in steel. To the extent that calculated stresses are less than the allowable stresses, the margin is proportionately greater. For additional conservatism to account for inherent uncertainties in estimating design loads, an arbitrary load factor of 1.25 was also applied. Design loads were calculated for deadwe1ghted plus thermal expansion, neglecting the effects of friction, and for deadweight only, considering postulated effects of friction. All of the major structural elements were found to be provisionally acceptable for their intended service and the predicted design loads. The provisions are as follows: (1) That the connect pinsmore » be fabricated of Inconel 718 or functional equivalent, instead of the originally specified Type 304 stainless steel; and (2) That conditions on bearing surfaces be modified to effectively reduce the potential coefficient of friction. The affected bearing interfaces include those between the CH, FH, and EM rings, and between the CH ring and its support members. The D-Zero Central Calorimeter Module Assembly is a segmented ring structure consisting of an assemblage of trapezoidal modules. It is housed inside a vessel containing liquid argon. The modules contain specialized equipment for use in particle physics experiments. The assembly design was reviewed to verify structural integrity and adequacy for service. Components that were evaluated were the main support beams, main support straps, module endplate brackets, module endplates, endplate connection pins, and transition pieces. Loading conditions considered were deadweight and differential thermal expansion due to specified temperature gradients. The American Institute of Steel Construction Specifications for The Design Fabrication and Erection of Structural Steel for Buildings Eighth Edition, referred to hereinafter as the AISC Specifications, were the primary acceptance criteria, where applicable. Other guidelines and engineering judgment were applied as appropriate.« less