Historic Steel Beam Reuse: A Case Study of a 100-year-old Warehouse

Abstract

The production of steel accounts for approximately 9% of global C0₂ emissions today. The reuse of existing steel sections could drastically decrease this percentage. However, a lack of information about the material properties of existing steel sections can prove a barrier to steel reuse, especially for historic sections. This thesis explores coupon testing and full-scale beam testing as a way to obtain information about the ductility and strength of historic steel beams produced in the United States between 1894 and 1911. Four historic steel beams were obtained from the MIT Metropolitan Warehouse, located in Cambridge, Massachusetts. During full-scale beam testing, the steel beams were simply supported and a distributed load was applied at their center. The displacement of the beam’s bottom flange was measured throughout the test and the yield strength, ductility, and failure mode of the beams were determined. During coupon testing, three coupons were taken from the web of each beam and were subjected to tensile testing. The yield strength, ultimate strength, and ductility of the beams were determined. Finally, the beams’ experimentally determined allowable stresses were calculated and compared with the allowable stress values specified in historic building codes.

All four beams have values for elastic modulus, yield strength, and ultimate strength that are comparable to those of A36 steel produced today. All the beams have an elastic modulus of about 29,000 ksi, indicating the beams are adequately ductile. The beams’ yield strengths vary between 34.8 ksi and 41.5 ksi, while the beams’ ultimate strengths vary between 55.5 ksi and 62.7 ksi. Additionally, the four beams have experimentally determined allowable stresses that are 35% to 55% higher than the allowable stresses specified in the historic building code. Using these experimentally determined allowable stresses instead of assuming the allowable stresses specified in the historic code could significantly decrease the amount of strengthening necessary during renovations. Finally, the load capacity of the floor system in the Metropolitan Warehouse was determined. It is estimated that the floor system can carry between 800 psf and 1,530 psf of distributed live load, in addition to its self-weight. The low estimate assumes no composite action between the steel beams and concrete slab, while the high estimate assumes complete composite action. Even if composite action is neglected, the floor system can carry eight times the standard distributed live load value of 100 psf used for design today.