D0 Silicon Upgrade: Upgrade Piping Loads on Cleanroom Roof

Abstract

The proposed piping layout for the DO upgrade will run along the south wall of DAB. The cryogenic service pipe runs above the upper and lower cleanroom roofs and will need to be supported by the roofs beams. Calculations were done to determine the stresses in the I-beams created by the existing and additional loads due to the upgrade. Refer to drawing no. 3823.115-ME-317283 for drawings of the piping layout. Figure 1 shows the 'plan view' portion of this drawing. The weight of the individual lines were calculated in figure 2 assuming a pipe density of O.28 lbm/in{sup 3} for stainless steel (0.12% C) and a fluid density (assuming LN2 at 1 atm) of 0.03 lbm/in{sup 3}. The weights of the corrugated steel flooring, assembly hall feed cans, support beams, and roof hatch were also included in the analysis. These loads are calculated on pgs. 5-6. A floor load of 50 lbf/ft{sup 2} was also added in order to maintain the existing floor load limit in addition to the added piping loads. Measurements of the dimensions of the I-beams determined that the nominal sizes of the beams were W8 x 21 for the lower roof and W14 x 26 for the upper roof. Pipe lengths were determined from the drawing for each of the lines on pgs. 1-2 of the calculations (refer to all piping by line numbers according to figure 2). A total weight was calculated for lines 3-9 along the south wall and lines 1-2 running along the north wall of the lower cleanroom roof. To simplify the calculations these weights were assumed to be evenly distributed on the 5 I-beam supports of the lower cleanroom roof 2.5 feet in from the south wall. The stress analysis was done using FrameMac, a 2-D finite element program for the Macintosh. Beam 3 was not included in the analysis because it is structurally equivalent to beam 1. The program outputted maximum values for shear stress, bending stress, shear force, and moments in each of the beams analyzed. These values were then compared to the allowable stresses as per the specifications and codes stated in the AISC: Manual of Steel Construction. The stresses on the roof beams needed to be determined in a number of different places. The first was in the beam itself which included the flange and web sections. The second place was at the ends of the beams where the flanges were removed to make the perpendicular connections to the other beams on the lower roof. The final point was the framed beam connection which included the bolt analysis. FrameMac calculated stresses only for the beams which included the sections where the flanges were removed to make the end connections. To analyze the connections, the allowable bending and shear stresses were solved for allowable shear and moments. This was done because FrameMac does not have the capability to analyze the dimensions for the bolts and angles used in the connections were known and the program outputted values for reaction forces and moments at the ends of the beams. Multiplying the allowable shear stress for the bolts and angle connections by their respective areas gave the allowable shear force. The allowable moment for the angle connection was calculated by multiplying the section modulus of the angle by the allowable bending stress. These allowable loads are calculated on pgs. 7-8. The allowable and maximum calculated stresses by FrameMac are summarized in a table. In conclusion, the cleanroom roofs will be able to safely support the weight of the upgrade cryogenic piping, feed cans, corrugated flooring and a 50 lbf/ft{sup 2} floor load with the addition of diagonal braces at the ends of beams 1,2,3,4, and 8. The location and size of these diagonal braces are shown in fig. 4. Also, the piping supports and feed cans will all need to be placed directly above the I-beam supports. These supports will consist of unistrut structures that will be detailed and specified separate to this analysis. The output and input data from FrameMac and the drawings used in the analysis follow the calculation pages.