A full seismic retrofit was required for ecology-minded Urban Ore, a Berkeley based recycling company, to use this existing steel industrial building for their new Eco-Park. The objective was to minimize cost and construction time while utilizing a green approach to the strengthening work. The retrofit solution consisted largely of new steel tie-rods fastened to existing structural elements. The tie-rods could be handled easily without specialized equipment, and allowed for the greatest strengthening in proportion to the amount of materials added. In many cases, the rods were fastened directly to the existing column flanges, without new plates or welds. To balance the loads and to meet the strength requirements, pairs of rods were sometimes used.
By adding bracing to the existing roof trusses, we were able to utilize the trusses as part of the seismic system, allowing for much less extensive steel and foundation work (the retrofit steel quantity was measured in pounds, not tons). No shoring was required for the project, and existing foundations were strengthened, instead of being replaced. The use of minimal amounts of new materials conformed well to the project’s ecological objectives. In addition, the concrete used for the project used high amounts of fly ash, an industrial byproduct that, when used in lieu of a portion of cement in concrete, can result in greater strength and reduced cracking.