05/23/1988 Meeting - Laserfiche WebLink

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e e e Jim Robertson presented information regarding the possible use of the Bon and Sears buildings for a library. Mr. Robertson said he had looked at two issues: size of the structures, and structural capabilities of the building for accepting the loads required by libraries. He discussed the Bon build- ing, noting that it is four-story structure including a basement, ground floor, and two upper floors. Each floor is approximately 25,000 square feet for a total of 102,000 square feet, which meets the size requirements of the proposed library. Calculations of the bearing capacity of the floor system, beam system, and column system showed that the floors are designed for 75 pounds per square foot of live load. The UBC requires that floors be de- signed for 125 pounds per square foot for book stacks. Where stacks are not located, the floors must have 50 pounds per square foot live load capacity. Mr. Robertson said the only place stacks could be located in the Bon building is in the basement. The ground floor and the two upper floors would not accommodate book stacks. This means that the bookstacks would need to be spread out or partial-height bookstacks could be used. This would mean that the library would need more square footage to house the same number of books. These constraints would also affect the flexibility of the building. Re- sponding to a question from Mr. Holmer, Ms. Decker said 45,000-50,000 square feet were identified as necessary for bookstacks. Mr. Miller asked about the feasibility of reinforcing floors for bookstacks. Mr. Robertson said the existing Bon building is a cast-in-place concrete beam and slab system. It is possible to put in a series of secondary beams underneath the existing beams and add columns. However, this would reduce the head height necessary for mechanical systems and add to the number of columns within the building. Mr. Robertson said such a project would be possible if the City has enough money to do it. Most of the ceiling heights are eleven to twelve feet, while the ground floor has a ceiling height of thirteen feet. Beams would remove some of the ceiling height. Mr. Robertson said he did not have the precise figures on how much such a renovation would cost. He said that his engineer, John Herrick, did not feel that resupporting the existing system was cost- effective. Mr. Robertson discussed the Sears building, noting that it is a cast-in-place concrete flat slab system using drop panels and round columns. The building is 73,200 square feet and is a three-story structure. The square footage does not meet the necessary square footage required for the library. Mr. Robertson said the Sears building is more stout than the Bon, and the floors were designed for 100 pounds per square foot live load. However, this is the only part of the structural system designed for 100 pounds per square foot. The code requires that builders design floors to take 100 pounds per square foot, but allows a reduction factor on secondary members like beams and columns. This reduction means the columns and beams in the Sears building were only designed for 68 pounds per square foot. That system could be reinforced to carry the loads to a new foundation below. The only place currently within the building capable of taking the stack loads is the base- ment. Mr. Miller asked if it would be cost-effective to gut a building such as the Sears or Bon building and start over as opposed to new construction. Mr. Robertson said no. Mr. Rutan clarified that the two buildings would be as MINUTES--Eugene City Council May 23, 1988 Page 4