Abstract: A stainless steel beam includes first and second substantially parallel plates, first and second substantially parallel webs extending between the first and second plates, and a plurality of laser-fused welds connecting the first and second plates with the first and second webs. A platform assembly includes a first steel beam having first and second substantially parallel plates with a first web extending therebetween and a first sidewall extending from a first edge of the first plate away from the second plate, and concrete overlying the first plate and abutting the first sidewall.