Miami Art Museum hanging garden failure

Forensic consulting case (Tom retained by general contractor). 20-ton reinforced concrete cantilevered beams in a Miami building, hung by two three-quarter-inch threaded rods in tension, originally specified in 410 martensitic stainless. Tack welds caused delayed hydrogen cracking; beams fell in August and November 2012. Material substitution to 316 austenitic stainless raised chloride stress corrosion cracking concerns at the marine site; Tom refused to sign off as PE, sent a written notice to general contractor, who forwarded it to the owner. Final resolution: duplex stainless steel. Litigation pending as of recording (Summer 2014).

Six-story hanging garden 100 yards from Biscayne Bay. 410 martensitic stainless steel tension bolts failed during construction (low fracture toughness + tack welds). 316 proposed; Tom warned of SCC. Settled on 2205 duplex (Sandvik recommendation), no weld details. Cost increase 7–8M on a 60M building. Tom refused to sign off as engineer of record. Used to teach martensitic vs duplex stainless steels, stress corrosion cracking, and consulting liability.

If we want to talk about stainless steels and corrosion resistance, we can talk about the Miami Art Museum, which is a fun story. So Miami's building an art museum, about a hundred yards from Biscayne Bay, and it's a hanging garden. Some guy in Switzerland is designing this, and up six stories in the air they have these big concrete beams. Since mold and green things grow all over in Miami, they decided to make it part of the architecture. This is supposed to be like the Babylonian Hanging Gardens — people could sit out there in the verandah and sip their mint juleps or whatever, with these concrete beams shielding them from the sun.