27-05-2011, 01:57 AM
Attached is the Excel worksheet which computes the weight of the facade steel. I've revised the graphic in the previous post adding more weight to the tree columns and making their wall thickness 5".
Methodology:
Although the facade were 36' tall x 10' wide pre fab panel assemblies I broke out the columns by floors. Therefore the column length is given as 12" and for the mechanical floors it is 14'. The mech floor facade panels were actually 42' tall. The corner assemblies were 24' tall (two floors) and 10' wide with with there spandrels bent at 45° to joint to the facade panels. The spandrels were treated as a separate item.. 10' x 4.25' for all but the mech floors which were 10'x5' and were assumed to be thicker.
The facade panels not only incremented in wall thickness and weight, but were assembled in an offset pattern beginning and ending at each mechanical floor section. This meant that there would be panels of two different wall thicknesses spanning three floors as the wall thickness "transitioned". So the panels just above and below the mech floors would have a 1 floor high panel, a two floor high panel then a 3 floor high panel and repeat symmetrically about the center. Refer to the graphic to see how the wall thicknesses were "mesh" and transitioned over 3 floors
The increment for wall thickness was .125 with the thinnest wall being .25" at the top floors and the thickest at floor 10 being 2.375". These thicknesses made the total facade cross sectional area and weight about 20% greater than the core columns. The facade did support about 10% more of the axial loads than the core and it also had to be stronger because of the wind shear.
The core columns decremented by .125 wall thickness as they went up and so the approach was the reverse... increment the thickness beginning at .250 at a similar rate. However, if the rate of change was less, the wall thickness at the bottom columns on floor 10 would be less than 2.375" and the weight less for the entire facade steel. The scheme presented makes sense... but the RATE of decrement could be different... yielding a lower overall mass.... but not by much. It HAS to be larger than the core... and we KNOW the core column sizes which are published online.
To compute the weight if a facade assembly... find the column weight at the floor chosen and multiply it by 6 then add 3 times 1,100 pound for the spandrels.
Example: How much did the facade panel weight at floor 96?
1 - 12' column weighs 1,151#
1 spandrel weighs 1,116#
1,151 x 6 = 6,906#
1,116 x 3 = 3,348#
6,906 + 3,348 = 10,254#
total weight of one 36' tall x 10' wide face panel at flr 96 = 10,254# = 5.127 tons (short)
Methodology:
Although the facade were 36' tall x 10' wide pre fab panel assemblies I broke out the columns by floors. Therefore the column length is given as 12" and for the mechanical floors it is 14'. The mech floor facade panels were actually 42' tall. The corner assemblies were 24' tall (two floors) and 10' wide with with there spandrels bent at 45° to joint to the facade panels. The spandrels were treated as a separate item.. 10' x 4.25' for all but the mech floors which were 10'x5' and were assumed to be thicker.
The facade panels not only incremented in wall thickness and weight, but were assembled in an offset pattern beginning and ending at each mechanical floor section. This meant that there would be panels of two different wall thicknesses spanning three floors as the wall thickness "transitioned". So the panels just above and below the mech floors would have a 1 floor high panel, a two floor high panel then a 3 floor high panel and repeat symmetrically about the center. Refer to the graphic to see how the wall thicknesses were "mesh" and transitioned over 3 floors
The increment for wall thickness was .125 with the thinnest wall being .25" at the top floors and the thickest at floor 10 being 2.375". These thicknesses made the total facade cross sectional area and weight about 20% greater than the core columns. The facade did support about 10% more of the axial loads than the core and it also had to be stronger because of the wind shear.
The core columns decremented by .125 wall thickness as they went up and so the approach was the reverse... increment the thickness beginning at .250 at a similar rate. However, if the rate of change was less, the wall thickness at the bottom columns on floor 10 would be less than 2.375" and the weight less for the entire facade steel. The scheme presented makes sense... but the RATE of decrement could be different... yielding a lower overall mass.... but not by much. It HAS to be larger than the core... and we KNOW the core column sizes which are published online.
To compute the weight if a facade assembly... find the column weight at the floor chosen and multiply it by 6 then add 3 times 1,100 pound for the spandrels.
Example: How much did the facade panel weight at floor 96?
1 - 12' column weighs 1,151#
1 spandrel weighs 1,116#
1,151 x 6 = 6,906#
1,116 x 3 = 3,348#
6,906 + 3,348 = 10,254#
total weight of one 36' tall x 10' wide face panel at flr 96 = 10,254# = 5.127 tons (short)