Attachment 0011 Floor Study Report.pdf

US Army Corps of Engineers Rock Island District

Structural Analysis of the Third Floor of

Rock Island Arsenal Building 104

18 January 2013

Table of Contents

Summary

History and Background Information

Phoenix Iron Company

Intent of Floor Analysis

Site Visits

Site Visit 20/12/2012

Figure 1. Typical layout of decking, stringers, and beam

Figure 2. Typical brick masonry arch condition and stringer clearance

Figure 3. Typical beam – arch interface

Figure 4. Roof hatch leak

Figure 5. Typical 5 flange Phoenix column, drop ceiling, mechanical, and insulation on the bottom of the third floor

Site Visit 3/1/2013

Figure 6. Location where the floor panels were removed to examine the leak and the column

Figure 7. General beam condition directly underneath the leak

Figure 8. Typical beam – girder connection at a column

Figure 9. Girder connection detail

Figure 10. Beam connection detail

Calculations and Assumptions

Conclusions

Reference Documents

Appendices

Summary

• The recommended live load over the entire floor area is 50 psf.

• The recommended loading of the rack system is 12 boxes per rack for all racks excluding the two outside rows. These outside rows shall be loaded with only 8 boxes per rack.

History and Background Information All historical information can be found in A History of the Rock Island Arsenal from Its Establishment in 1863 to December, 1876.

Rock Island Arsenal Building 104, originally known as Shop C, was constructed between September 1867 and June 1873. It was built concurrently with Building 60, originally known as Shop B.

Building 104 was the second building finished and the first to be equipped for manufacturing. Cooper & Hewitt of New York furnished the 15 inch I-beams (stringers) for the first and second floors and all of the 12 inch I-beams (joists) for the second floors. The date of contract was April 21, 1868. The Union Iron Mills of Pittsburgh, Pa. furnished all 12 inch I-beams (joists) for the first floor. The date of contract was May 8, 1868. The Phoenix Iron Company of Philadelphia furnished all the 12 inch I-beams (stringers) and all the 9 inch I-beams (joists) for the third floors, all the wrought iron columns and cast iron column caps and bases required for both shops, and the wrought iron roof frames for both shops. The date of contract was May 20, 1868.

Phoenix Iron Company The third floor girders are built up of the stock 170 lbs per yard Phoenix Iron Co. No. 55 beams.

The actual girders are made up of two beams fastened together at the individual beam – girder and column connections. See Appendix 3, page 6 of Designs of Wrought Iron Manufactured by the Phoenix Iron Co. for section details.

The 9 inch beams are Phoenix Iron Co. No. 5. The No. 5 beams are originally specified to be 84 lbs per yard, but, according to the Phoenix Iron Co., can be increased by up to 10% if desired. The actual beams in Building 104 have been increased up to 90 lbs per yard. See Appendix 3, page 6 of Designs of Wrought Iron Manufactured by the Phoenix Iron Co. for the stock section details.

The 2nd floor columns are specified as 5 – segment “Mark D” Phoenix Columns. The actual columns have an additional 1/4” thick plate between the segment flanges. This will increase the diameter of the section. See Appendix 3, page 15 of Designs of Wrought Iron Manufactured by the Phoenix Iron Co. for the stock section details.

Intent of Floor Analysis The original plans specified a 100 psf live load. Sometime later, the allowable floor load was reduced down to 80 psf. The intent of this floor analysis is to recommend a new safe live load that can be placed uniformly on the floor. A second objective of the analysis is to recommend a rack loading plan for the current tenant that occupies the third floor space. The rack loading plan would recommend the arrangement of racks as well as the number of boxes per rack in order to maximize box storage.

Site Visits Yogi Patel and Kirk Atwater of the US Army Corps of Engineers met with Mike Panilo of the US Army Garrison Rock Island Arsenal Public Works on December 20, 2012 and January 3, 2013. In addition, Kirk Atwater met with the tenant, MSG Ivan Meskimen, Operations NCO on January 3, 2013.

Site Visit 20/12/2012 The purpose of this site visit was to view the current existing conditions and general layout of the 3rd floor of Building 104. Prior to this date, Mr. Panilo had a portion of the 3rd floor decking removed in order to access a typical beam. The decking was removed just outside the tenant’s secured area. The tongue and groove oak decking is 1.5” thick and placed on top of wood stringers. The wood stringers are 4.75” wide (depth) by 2.5” thick, and spaced at 16” on center.

Figure 1. Typical layout of decking, stringers, and beam.

The brick vault arches that span between the beams were originally intended to be used for fire protection of the 3rd floor. The bricks are finished with a plaster covering on both the top and bottom. The arches are completely supported by the flanges of the beams. The top of the arch is located about an inch below the bottom of the wood stringers. There is enough clearance between the top of the arch and the wood stringer so that the wood stringers do not transfer any load to the arch. The arches appear to be in good overall condition for their age.

Figure 2. Typical brick masonry arch condition and stringer clearance.

Figure 3. Typical beam – arch interface.

During the site visit of the area outside of the tenant’s location, a leak was found beneath a roof hatch. The roof hatch appears to have been leaking for some time, and it was deemed necessary to have the floor decking removed in this area to determine how much deterioration the leak has caused in this area. The decking was removed for the January 3rd site visit.

Figure 4. Roof hatch leak.

We were also able to view the second floor columns during this visit. These columns are 5 flange built-up Phoenix Columns. They have an additional 1/4” thick plate between the segment flanges which will increase the diameter of the section. A drop ceiling panel was removed by the maintenance staff to allow viewing of the underside of the 3rd floor. The original design did not incorporate any drop ceiling panels, mechanical, electrical, plumbing, or insulation. The CMEP and insulation were added when the second floor was converted to office space.

Figure 5. Typical 5 flange Phoenix column, drop ceiling, mechanical, and insulation on the bottom of the third floor.

Site Visit 3/1/2013 The purpose of this site visit was to view the deterioration of the structure underneath the roof hatch leak and to view a typical beam and girder column connection. In addition, Mr. Atwater met with MSG Meskimen to view the floor physical condition and loading in the tenant’s secure area.

Figure 6. Location where the floor panels were removed to examine the leak and the column.

The area where the leak occurred was generally in good condition. If water does get past the decking, the arches will funnel and hold the water directly at the web of the beams. The beams in this location appeared to be in good overall condition for their age, and did not show section loss. This indicates that the tongue and groove decking does a reasonable job of keeping the water away from the beams.

Figure 7. General beam condition directly underneath the leak.

The column connection area is in good condition overall. The deck opening allowed us to take measurements and determine which exact Phoenix Iron Co beams were used for both the girders and regular beams. The girders are made up of two Phoenix Iron Co. No. 55 beams, while the regular beams are Phoenix Iron Co. No. 5 beams. The two beams that make up the girder are connected to each other where each beam frames into the girder. At the column connections, a cruciform section extends up from the column cap and is connected to both girders as well as the two beams that frame in at the location.

The beam connection is different at the columns than it is where the beams frame into the girders. The beam – column connection has only one plate, the cruciform, on one side of the web. The beam – girder connection is made up of two angles, one on each side of the web. There is one bolt that goes through both angles and the web of the beam. Each angle has a bolt that goes all the way through both girder beams and as well as the angles that connect the beam on the other side of the girder. At outside locations, such as the stairwells, where there is only one beam that frames into the girder, the angle support bolts still go through both girder beams. It does this to ensure that both girder beams stay connected together.

Figure 8. Typical beam – girder connection at a column.

Figure 9. Girder connection detail.

Figure 10. Beam connection detail.

During Mr. Atwater’s meeting with MSG Meskimen, Mr. Atwater inspected the floor for visible signs of damage. This was done to determine if any specific areas would need to be investigated in greater detail. The floor was in good condition for its age, and did not show any signs of significant past water leakage or other damage. MSG Meskimen confirmed that the actual maximum loading of the boxes is between 30 – 35 lbs per box rather than the estimated 50 lbs initially given. The initial estimated weight is a maximum possible box weight when the boxes are fully loaded with densely packed reams of paper, which is not applicable in this case. The racks are also equipped with water proof covers to prevent the boxes from soaking up and holding water in the event that the fire protection sprinklers are activated.

Calculations and Assumptions There are several general assumptions that were necessary to complete the calculations. These assumptions are mainly due to the lack of original information known about the building.

• The beams and girders are assumed to be in good condition and free of defects. Determining the exact condition and corrosion level of the beams and girders is beyond the scope of this floor analysis.

• The beam and girder wall supports are assumed to be in good condition and free of defects.

Determining the exact condition and corrosion level of every beam and girder support is beyond the scope of this floor analysis.

• All of the beam, girder, and column connections are assumed to be in good condition and free of defects. Determining the exact condition and corrosion level of each connection is beyond the scope of this floor analysis.

• The unit weight of the wood decking is assumed to be 40 pcf. The unit weight of wood is highly variable and changes with moisture content. The 40 pcf was taken as a standard design value.

• The drop ceiling, MEP, and insulation weights are assumed to be 2 psf, 5psf, and 3psf, respectively.

• The unit weight of the brick masonry arches is assumed to be that of a common brick.

• The beam connection bolts is assumed to be A307, non-high strength bolts. The strength of these bolts can be found in AISC Table J3.2.

• The thickness of the brick arch is assumed to be 4” thick. This corresponds to the thickness of a common brick. The actual dimension is unknown without drilling through the arch.

• The beams are assumed to be simply supported and completely braced by the brick arches.

• The girders are assumed to be simply supported at the columns.

• The weight per box is assumed to not exceed 35lbs. See above for the verification of this self weight.

• The racks are assumed to have a water proof cover which prevents the boxes from getting wet in the event that the fire protection sprinklers are activated.

• The self weight of the racks is assumed to be approx. 16lbs. This is lower than the original estimate of 32lbs per rack. The picture of the shipping box of the racks from the inspection package indicates a gross weight of 32lbs. However, the box also indicates there are 2 racks per box.

• The north wall of the tenant’s secure area is assumed to not influence the loading of the tenant’s floor. The detailed information for this wall is unavailable and is outside the scope this floor analysis.

The structural hand calculations can be found in Appendix 2.

Conclusions The recommended uniform live load of the entire floor area is 50 psf. This is lower than the historical 80 psf allowable loading. The reduction is from our conservative assumptions listed above as well as the addition of the 2nd floor CMEP and insulation. A more in-depth analysis of the brick masonry arches and the beam/girder supports and connections would be needed to justify increasing the allowable uniform floor load above 50 psf.

The recommended loading of the rack system is 12 boxes per rack for all racks excluding the two outside rows. These outside rows shall be loaded with only 8 boxes per rack. The rows of racks shall be evenly spaced across the floor with at least 2’ to 2’ – 6” of clearance between the outside rows and the walls. There should be approximately 6’ – 4” of clearance between the south end of the rows and the southern wall face. See Appendix 1 for the rack layout and loading diagram.

Reference Documents

1. A History of the Rock Island Arsenal from Its Establishment in 1863 to December, 1876 and of The

Island of Rock Island, The Site of The Arsenal, From 1804 – 1863. Prepared under the instructions of Brig. Gen. Stephen V. Benet, Chief of Ordnance, U.S. Army. By Major D. W.

Flagler, Ordnance Department, Brevet Lieutenant Colonel, U.S. Army. Washington: Government Printing Office, 1877.

2. Designs of Wrought Iron Manufactured by the Phoenix Iron Company, Prepared by the Phoenix Iron Company, Van Ingen & Snyder Engravers, Philadelphia, Pa., 1869.

Appendices

Appendix 1: Rack Layout and Loading

Appendix 2: Structural Calculations

Appendix 3: Designs of Wrought Iron Manufactured by the Phoenix Iron Company

Appendix 4: Initial Inspection Package provided by the US Army Garrison Rock Island Arsenal Public Works

Appendix 5: Third Floor Modification – Construction of Secure Document Storage Area Package provided by the US Army Garrison Rock Island Arsenal Public Works