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Steel is Sustainable Construction

Outdoors Inside By Beth S. Pollak

The Oregon Department of orest, water, wildlife, and pro- quality. Among cantilevered eaves tection from fires are the basic and high, sloping roofs, a recycled Forestry’s new Operations elements of The Oregon Depart- wooden roof deck showcases Douglas Fir ment of Forestry’s (ODF) juris- timbers salvaged from several decon- Building combines structural diction—and its new Operations structed buildings on the site. Long FBuilding is designed to reflect them. Lo- bring daylight in- steel and re-sawn timber to cated in a forested area on the banks of side, where it is reflected off the wood create attractive offices. Mill Creek in Salem, OR, the new steel surfaces. The desire for long, clear spans, structure combines a natural setting with wide bays, a sustainable design, and seis- sustainable design and innovative con- mic resistance made structural steel the struction to avoid harmfully impacting best solution for the building. the serene surroundings—and to ensure that the building remains standing in a Seismic Challenge fire- or earthquake-emergency situation. ODF required a high level of reliability With long, horizontal lines and a from the Operations Building to improve gabled roof, the two-story, L-shaped chances of maintaining a functioning fa- 34,000-sq.-ft Operations Building reflects cility after an earthquake. The building the contemporary practices of forest the ODF’s fire operations, dis- management and 21st century “green” patch, and coordination sections. As a re- design. ODF wanted an open workplace sult, the building was designed as an that allowed extensive daylighting, and essential facility under the Uniform that used renewable products. The build- Building Code, with seismic performance ing features recycled products, including equal to that required for emergency-re- exposed structural steel. Structural steel sponse facilities like hospitals and fire sta- has a recycled content near 100% and can tions. To meet this challenge, Degenkolb be recycled repeatedly without losing its used a special concentric braced-frame Photos this page © Rick Keating Photography

Modern Steel Construction • June 2004 system that reduces steel tonnage and performs well under cyclic earthquake loading. Eleven special concentric braced frames are hidden in the building walls. A split-X configuration, where a beam runs through the middle of the two-story X- brace, creates chevron braces on the lower floor and V-braces on the upper floor. The braces are 5”-square HSS, with welded connections. Floor beams typically are W14×26 and girders are W16×26. Columns are ex- posed 8”- square HSS and bays are 21’ by 25’. Connections are single-tab shear con- nections, with slotted shear tabs through the HSS members. Standard AISC toler- ances are used. The building is sprin- klered, so no fire-protective coatings are The ground floor is slab-on-grade construction. required for the structural steel. The foun- dations are concrete spread footings, and the first floor is concrete slab-on-grade. Multi-level roofs with overhanging eaves, hips, varying slopes, and cleresto- ries create a complex roof configuration that required a high level of coordination between the architect, engineer, and steel detailer. The geometry of the roof created engineering challenges, and the intercon- nection between reclaimed timber deck- ing and structural steel in the roof added complexity. “There were different pitches, differ- ent directions, and many slopes, so you had to deal with all of the hips,” said Jake Stept, P.E. project engineer for Degenkolb Roof overhangs are typically 4’. Recycled wood decking was covered with a layer of plywood to Engineers. “The roof overhangs were create a shear diaphragm. typically 4’ eaves. In one area, the clerestory is offset from a column line. In some places we had to use horizontal X- bracing to drag the shear loads from the roof diaphragm into the braced frames.” Roof beams were W14×22s, and roof assembly was facilitated by welding threaded studs on the top flange of the steel beams. Wooden nailers were bolted to the studs, and then the recycled wood decking was installed. An additional layer of plywood on top added di- aphragm shear strength. Sustainable Design Sustainable elements include the reuse of the already developed site, re- duction of paved areas, restoration of creek riparian zone, daylighting, natural ventilation, use of well-managed forest products, no- or low-maintenance mate- rials and finishes, recycled and recyclable products, and products with no or low toxicity. The use of structural steel espe- cially contributed to the building’s sus- Lateral forces are resisted by special concentric braced frames. Braces are typically HSS mem- tainable design: steel’s recycled content is bers.

June 2004 • Modern Steel Construction Smaller windows on the building’s south side bring in daylight but block direct penetration of sunlight. Larger windows are placed on the northern exposure to capture cooler air for natural ventilation. Photo © Rick Keating Photog- raphy near 100%, and it’s a material that can be The new facilities consume 30% less en- Owner recycled repeatedly without losing its ergy than Oregon’s energy code requires. State of Oregon, Department of quality. Rather than relying on air condition- Forestry, Salem, OR The operations center is oriented to ing, the new building takes advantage of protect the ecological and historical char- natural ventilation for maintaining com- Architect acter of the site. The design incorporates fortable temperatures. Windows in the SRG Partnership, Inc., Portland, OR materials, shapes and forms that are con- clerestory in the high at the cen- Structural Engineer sistent with those of the original timber ter of each building are motorized, and Degenkolb Engineers, Portland, OR buildings on the site. from the de- windows in private offices and open constructed buildings were reused as roof areas have manual controls. When the in- Mechanical Engineering decking in the new buildings. Beams and ternal temperature of the building PAE Consulting Engineers, Portland, OR columns from the deconstructed build- reaches a predetermined temperature Landscape ings were used to build outdoor benches range (between 66° and 73°), computer Walker-Macy, Portland, OR located around the campus. Air quality controls automatically open the was enhanced by using natural materials clerestory windows. Cool air then enters Geotechnical Engineering that emit few, if any, volatile organic com- the lower areas and pushes warm air out Foundation Engineering, Inc., pounds (VOCs). Wood surfaces were through the to encourage just Corvallis, OR used where possible, as well as materials the right amount of air circulation. General Contractor like linseed-based linoleum flooring in- The orientation of the buildings also Pence/Kelly Construction, LLC, stead of vinyl flooring. helps this process. Smaller windows that Salem, OR The new ODF building takes advan- are shaded by broad eaves on the south tage of natural light whenever possible side of the buildings bring in daylight but Engineering Software and uses artificial light strategically. block direct penetration of sunlight with RAM Structural System Work areas are located in open spaces its radiant heat. Larger windows are where windows, and clerestory placed on the northern exposure to cap- For more information on the use of struc- openings provide ambient natural light ture cooler air. tural steel in sustainable design, please during the day. Task lights provide the Building design began in 2000, and visit www.aisc.org/sustainability or view bright light required for working at a the entire project was completed in June the article “Structural Steel Contributions TM desk. At night, indirect lighting provided 2003.  Toward Obtaining a LEED rating” in by fixtures that reflect light off the the May 2003 issue of Modern Steel Con- uses less energy to provide ambient light. struction, available online at www.mod- ernsteel.com.)

Modern Steel Construction • June 2004