We are honored and thrilled that the Q21 mixed-use project in NW Portland was a recent recipient of the Structural Engineers Association of Oregon (SEAO) 2017 Excellence in Structural Engineering Award for a New Building Over $10M. Designed by YBA Architects and constructed by Andersen Construction Company, Nishkian Dean served as the Structural Engineer of Record on the project.
SEAO is a nonprofit organization that works to educate the design industry and the community at-large on structural engineering topics, and provides a valuable forum for structural engineers to interact throughout Oregon.
“We would like to thank SEAO and the awards committee for this honor and we appreciate the continuous efforts of the organization to educate our members and strengthen our industry. We also want to thank the entire Q21 project team and especially YBA Architects for selecting us as the Structural Engineer for such a fun and challenging project.”
Rob Aman, Associate, Nishkian Dean
Located adjacent to the Conway District at NW 21st & Quimby in Portland, the 7-story, 202,200-SF project provides 162 living units, a courtyard, offices, parking, and ground-floor retail. The mixed-use project consists of two 3-story wood-framed residential buildings separated by a courtyard, all of which is situated above a two-level post-tensioned concrete parking structure that is partially below-grade.
The two buildings are connected directly to a seven-story post-tensioned concrete structure that includes residential units at the upper levels, an office floor level, and retail spaces at the ground floor. The concrete structure’s lateral force-resisting system consists of reinforced concrete shear walls, and a seismic joint was detailed to separate the wood and concrete buildings where they adjoin.
A one-story retail space extends off the north side of the structure, and 8 two-story townhomes occupy the ground level along the building’s south side. The project is highlighted by three-story double-tapered steel columns at the main entrance that form an “XXI” shape to symbolize the project name and street number location. These specialty steel columns were constructed with two tapered dodecagon (12-sided) steel sections welded together at the column midpoint to form a double-tapered member. A tapered cantilevered post-tensioned concrete beam spans the top of the steel columns to support four stories of structure above.
One of the most unique and challenging aspects of the project included preserving and modifying the 35-foot tall existing concrete tilt-up wall panels from the existing warehouse building on the site. The team incorporated the panels into the architectural and structural design as a non-structural exterior wall element to preserve the heritage of one of the early buildings that Andy Andersen, the founder of Andersen Construction, constructed and to promote the conservation of materials. This effort was significant and meaningful for Andersen Construction now that the family-owned business is being led by its third generation.
The existing concrete wall panels were cut, reinforced with steel backing and fiber reinforcement, and temporarily braced during construction. A few of the panels were lowered and transported to off-site storage to allow for site access during construction. Nishkian Dean provided full engineering support for this entire process during the initial phase of construction.
“The project afforded many opportunities for creative solutions to meet an ambitious and innovative vision. It was an honor to be a part of the cutting-edge design team on one of the first two-story podium structures in the City of Portland. We are very proud to receive such a prestigious award and grateful to SEAO for establishing a platform to recognize excellence in structural design.”
Dave Beh, Project Engineer, Nishkian Dean
Robert Aman, PE, SE (email@example.com) is an Associate with Nishkian Dean a structural engineering consulting firm in Portland, Oregon.
Dave Beh, PE (firstname.lastname@example.org) is a Project Engineer with Nishkian Dean a structural engineering consulting firm in Portland, Oregon.
Xylia Burros, (Xylia.email@example.com) Marketing Consultant, provided copy and editing for this article.
A challenge of constructing larger and larger projects in dense urban environments is placing those buildings on sites with sub-optimal soil conditions. These sites may include soft compressible layers of native or fill materials, soils that may be subject to settlement during an earthquake due to liquefaction, sites that may be subject to lateral spreading during an earthquake, or conditions that require a high capacity foundation system.
DDC design and construction was performed by Farrell Design-Build Inc. for U.C. Berkeley’s Maxwell Family Field and Garage project in Berkeley, California. The site sits directly adjacent to the Cal Memorial Stadium, the Greek Theatre, and the Haas School of Business.
Traditionally, 2 options have been used to mitigate these conditions:
Both of these options have impacts on the project schedule and cost. Over-excavation requires heavy earthwork equipment, a large site for material storage and creates significant environmental conditions that must be addressed. Installing drilled piers or driven piles can be expensive, time consuming, and loud. Driven piles require traffic considerations and adequate storage, agreements with neighbors, and other environmental considerations.
A new term that has become more prevalent in soils reports and foundation design is Ground Improvement. This has become a generic term for a variety of methods that can be used to mitigate these soft soil sites without over-excavation or deep piers or piles. Ground improvement allows for a shallow foundation system to be used which will save costs and time.
Ground improvement comes in several forms, these include: deep soil mixing, drill displacement piers, and deep dynamic compaction. Deep soil mixing uses augers and other heavy equipment to pump grout and mix it into the existing soil. Deep soil mixing can be spread over a site to support a mat foundation, or can be closely spaced to support concentrated loads. These drilled elements can vary in diameter and depth and produce small amounts of spoils. Another type of deep soil mixing uses vertical blades to cut a trench in existing soil while mixing in a cement slurry. This is called cutter soil mixing with machinery that has blades that can cut through in situ soil up to 130 feet in depth. These improved trenches can be used as stiffen vertical support elements, retaining walls and to restrain liquefiable soil. Deep dynamic compaction uses rams or deep soil vibrators to consolidate and stiffen existing soil or existing soil with added aggregate. Adding grout to the existing soil increases the shear strength, lateral stiffness, and bearing capacity and allows for use of shallow foundation systems on top of the improved subsurface. Since each of these methods involves a specific type of specialized heavy machinery, the exact type of ground improvement will depend on the contractor selected. The result is that ground improvement is typically provided on a design-build basis.
Nishkian Engineers have utilized ground improvement techniques on several recent projects to provide less invasive and more cost-effective foundation solutions. One recent project is The Encore residential development in Redwood City, CA. This 6-story building of concrete and wood frame construction does not have huge foundation loads. However, approximately one third of the building footprint had a subgrade layer of soft material that had a high potential for liquefaction settlement. Ground improvement of this select area was a cost- and time-effective solution to mitigate these conditions in lieu of other, more costly options.
Nishkian worked with Regis Builders, the general contractor, and Farrell Design Build, the ground improvement contractor, to develop the system to support this building. Farrell quickly mobilized their equipment on the prepared site and utilized Drill Displacement Columns (http://www.farrellinc.com/services/foundation-systems/auger-cast-column-drill-displacement-column) up to 30 feet in length to provide support in compression for the foundation and ground floor slab in the soft zones. Farrell also installed displacement ground anchors for tensile resistance under lateral elements. After this quick process the shallow spread footing foundation system was excavated and installed.
Another relevant project is the Maxwell Family Field and Garage which sits directly adjacent to the California Memorial Stadium on the University of California Berkeley campus. Long ago, the site was once a creek bed. During the development of the campus, the creek was turned into a set of large culverts, and filled in to provide a flat surface. This type of loose fill makes building a seismically safe structure more difficult. Similar to the challenges of building on bay mud in San Francisco, the ground could liquefy during an earthquake, resulting in amplified forces on the structure. This condition is exacerbated by the presence of the Hayward fault, which runs just a few hundred feet away from the site. Although there are many ways to improve the soil, the best option for the Maxwell Family Field and Garage project was Drill Displacement Columns (DDC). DDC design and construction was performed by Farrell Design-Build Inc. as well.
Ground improvement installation by Farrell Design-Build Inc. for the Maxwell Family Field and Garage project at the University of California Berkeley campus.
In a previous blog post, building noise and vibration mitigation was discussed as it pertains to tenant improvements (TI) in existing buildings and how the building code sometimes falls short concerning client parameters. As described in the previous post, this is often the case with fitness clubs that move into mixed-use spaces below residential or offices that are sensitive to sound and building vibrations, but the need for vibration mitigation goes well beyond fitness clubs.
The previous blog post examines how performing a finite element analysis of an existing floor system can determine its natural frequency and the natural frequency of a modified, stiffer system. The American Institute of Steel Construction (AISC) has previously put forth a “Design Guide” to design and account for vibrations in new buildings of typical framing. The Design Guide provides for determining perceived floor accelerations that change based on the natural frequency of the floor system. It is of particular note to avoid systems with frequencies that would match those of the space occupied to avoid resonance, where the amplitude of the motions would become very large. These accelerations are compared against recommended peak floor accelerations for human comfort which is dependent on the type of occupancy; offices and residences have a lower threshold than shopping malls and gymnasiums.
However, another increasingly prevalent challenge is the need to design for truck loading on ground floors that serve as drive aisles or emergency access. Conditions can occur where a heavier truck loading is adjacent to retail, office, or residential spaces, or at times, below these spaces either during construction or the lifetime of the structure. Special considerations must then be made to account for the excess vibration that may be encountered as a result of these potentially larger forced vibrations and to design for a higher level of vibration serviceability.
Owners of new buildings typically have two main concerns when considering the effect of adjacent parking or trucking; the transmission of noise and vibration into the sensitive adjacent tenant areas, whether retail, residential, mixed-use, etc. Careful measures and criterion must be developed to mitigate the noise and vibration from the loaded areas from propagating into the more sensitive areas of the structure and disturbing the other building tenants.
In collaboration with an acoustic/vibration consultant, recommendations for the comfort level of all the building tenants will typically determine what treatments need to be made, but the structure itself must be prepared to receive the treatment. Nishkian Chamberlain works with the acoustic/vibration consultant to determine a course of action to be taken and works toward providing a solution to achieve the desired performance.
Nishkian Chamberlain engineers provide building owners, property management organizations, and tenants with a level of confidence that their tenants will be able to cohabitate in a comfortable environment. Should you have any questions about an upcoming or ongoing project, do not hesitate to contact any of our offices. You can also send an email directly to Craig Chamberlin at firstname.lastname@example.org.
By Edwin T. Dean, PE, SE
Having completed the initial designs for the innovative CoreFirst system, we at Nishkian Dean believe that it is a viable alternative to doing nothing and accepting fate when it comes to the next earthquake that may devastate Oregon buildings and put occupants in harm’s way. There is little argument that a full seismic strengthening of a building is the best solution, but for many building owners, it is simply not an expense that they can afford. If a full seismic upgrade is not a financially viable option, an alternative that would potentially provide a robust sanctuary to shelter occupants as the building around them shakes apart during a seismic event is a good one.
The CoreFirst system functions as a seismic shelter erected within an existing building, providing improved life safety during a seismic event without the need to retrofit the building to current seismic standards. Coupled with an earthquake early-warning system that can provide more than 60 seconds to evacuate, CoreFirst both alerts building occupants and provides a safe place to congregate during an earthquake.
Composed of a one or two-story steel special moment frames oriented in both principal directions, the CoreFirst system includes a steel grating plank platform at each level to provide protection from debris and existing building failure. The moment frames are isolated from the existing structure, ensuring that they only resist load generated by the seismic weight of the CoreFirst shelters. While the moment frames are not tied to the building’s existing seismic-force-resisting system, they are designed with a large reserve capacity for additional lateral load, with the added benefit of potential use as a component of a future comprehensive seismic upgrade of the building.
The shelters are designed so that their floor levels are located below the floor structure of the existing building. These floor levels are framed out with infill gravity framing supporting steel planks or channels that form a debris shield, preventing debris from falling through the floor of the existing structure into the shelter’s protective zone. The platforms are designed for a floor live load of 100 psf, a roof live load of 20 psf, and a vertical seismic load of 50 psf (representing both the dynamic load of debris falling on the platform and the static load of accumulated debris). Ultimately, all the gravity load is supported by the moment frames.
The moment frames are designed to the requirements of a Risk Category IV structure, which primarily impacts the drift limit, or the typical governing limit state for steel moment frames. Based on the seismic weight of the frames and grating platforms, seismic loads are generated for the frame per the equivalent lateral force procedure of ASCE 7. To enable the potential use of the frames as a component of a future full seismic upgrade of the building, additional seismic load is assigned at each level of the moment frames. It is not always possible to predict what shape a future seismic upgrade would take, and what loads the moment frames might need to carry, but a conservative load is estimated by assuming that a certain tributary area is assigned to the moment frames based on their location in the building. The total lateral load the frames are designed for is indicated on the construction drawings for future reference.
Footings are also designed for the additional seismic load described above. Because the frames are isolated from the main structure, they have very little dead load to resist overturning. As a result, there are three footing options:
1) Very large isolated footings with enough weight to prevent overturning
2) A mat footing designed to resist overturning
3) Small isolated footings/pile caps utilizing helical piles to resist uplift and downforce
The seismic gap required around all interfaces between the shelters and the existing structure is determined by estimating the maximum seismic drift of the building (based on the drift limits for the building’s structural system at the time it was constructed), determining the maximum seismic drift of the moment frames, and calculating the resulting maximum drift in any direction for both cases by combining the maximum drift in one direction with 30% of that drift in the orthogonal direction. The sum of the two maximum drifts is the minimum required seismic gap.
We believe that building owners could benefit from this affordable system. If you have any questions about CoreFirst, please contact us at the Nishkian Dean office or visit the CoreFirst website. We are happy to discuss this innovative system!
Edwin T. Dean, PE, SE is Vice President and Managing Principal of Nishkian Dean a structural engineering consulting firm in Portland, Oregon.
580 Anton | Costa Mesa
The 250-unit, luxury apartment building project in Costa Mesa, CA is nearing structural completion and set to open in the near future. Work began in February of 2016 to demolish the existing 24,000-square-foot strip mall, built in 1990.
As construction is just about complete for this luxury apartment building project, the residence offers one of the best locations in Orange County, providing immediate access to the incomparable performances at Segerstrom Center for the Performing Arts as well as to a panoply of gourmet dining options and couture fashion at the South Coast Plaza.
The structure includes three stories of parking with five stories of wood framing on a concrete post-tensioned podium slab, all founded on a concrete mat foundation. Collaborative, creative engineering solutions eliminated all exterior shearwalls providing limitless design opportunities for the building’s façade.
The units themselves will feature top of the line finishes, and residents will be able to enjoy the many offered community amenities, including a landscaped courtyard with barbecues and fire pits, a spacious pool, and multiple indoor and outdoor common areas.
For more information about this project and for availability announcements, visit http://www.580anton.com/
Sheraton Los Angeles San Gabriel | San Gabriel
Scheduled to open in early 2018, the Sheraton San Gabriel is a 288-key hotel located on Valley Boulevard in San Gabriel, CA. The hotel is adjacent to retail and dining destinations in the San Gabriel Valley, and a stone’s throw from many of SoCal’s major tourist attractions.
The main hotel structure is five stories of above-grade and three levels of below-grade parking. The lobby level offers large meeting rooms, several dining options, and banquet/conference space in the attached, 30-foot tall open by 112-foot clear span in a 11,500 square foot ballroom. The Hotel will feature an American steakhouse and Chinese restaurant, as well as high tea service in the lobby area and a full-service Starbucks café on site. A well-appointed fitness center, luxury day spa, terrace garden and recreational pool deck can be found on the second level.
The building is primarily composed of special concrete shear wall construction, and utilizes post-tensioned slabs for levels 2 thru roof. The ballroom boasts a long clear span constructed with a steel truss roof system capable of supporting operable partitions for dividing up the large ballroom area. Lateral loads are supported in the Ballroom space by buckling-restrained braced (BRB’s) frames to resist wind and earthquake forces.
Significant savings in time of construction and materials was realized by Nishkian Chamberlain, after inheriting the project from another structural engineering firm. Nishkian Chamberlain introduced post tensioned slabs, in lieu mild-steel reinforced slabs, resulting in a reduced slab thickness, building mass, reduced footings and overall shear wall reinforcement.
For more information about hotel amenities, please visit http://www.sheratonlasangabriel.com/
The building boom sweeping Bozeman is hard to miss, between giant holes in the ground and construction crews closing down streets, there is a lot of development on all fronts. Early this summer a new restaurant called Sidewinders American Grill opened on the west side of town. The building features 8,000 square feet of space with a large bar and rooftop seating. Thomas Bitnar Architects has designed the restaurant building collaborating with general contractor Langlas & Associates, and structural engineers Nishkian Monks.
The structure was built at a level site. Above grade, the exterior and interior walls are of light-framed metal stud construction with thin set brick veneer at the exterior walls. The roof framing was accomplished with pre-engineered gang-nailed trusses by Simkins-Hallin, Inc. of Bozeman. The building includes a partial basement, upper level deck, kitchen and restaurant area, and is founded on conventional concrete strip and spread footings with a slab-on-grade at the ground level.
The Sidewinders building is the first commercial structure to be completed at Ferguson Farm, a 19-acre, B2 Zone development on the north side of Huffine Lane between Cottonwood Road and Ferguson Avenue. Developed by Delaney & Company, the new neighborhood commercial center will include restaurants, a bank, coffee shops, retail, professional offices and lodging.
For more information about Sidewinders, visit http://sidewinderstavern.com/home/.
Photo Credit: Zakara Photography
Nishkian Dean is proud to have served as the structural engineer on the recently opened 10 Barrel Brewing brewpub in the Maker’s Quarter district in San Diego’s East Village. The restaurant and social gathering place, situated in a converted warehouse, offers guests a chance to view many different aspects of the brewing process. Each level of the building incorporates different brewing equipment that is visible to guests, with a grain silo on the roof, brew tanks on the interior mezzanine, and fermenters on the ground floor, adding points of visual interest.
At roughly 10,000 square feet and with three separate levels, the brewpub and restaurant has ample space for dining and events. The main level incorporates a dining room and bar connected to an outdoor patio through roll-up industrial doors. The exterior mezzanine deck and rooftop patio bar provide additional space for patrons to the enjoy the sights of the surrounding bustling residential area.
The space, converted from an existing warehouse, required substantial seismic upgrades due to the change in occupancy and extensive improvements made to the building façade. New lateral-force-resisting elements include concrete masonry shear walls at portions of the building perimeter, and steel-braced frames to support the interior steel mezzanine that houses the brew equipment. The existing roof framing required strengthening to support the increased loading from the rooftop patio.
Due to poor soil conditions on the site, a network of grade beams at the ground level was used to support the new brew mezzanine and rooftop deck. These grade beams are supported by deep cast-in-drilled-hole concrete piles to minimize settlement.
It was a pleasure to have teamed with Scott|Edwards Architecture and general contractor Bergman KPRS on this exciting new project.
If you have any questions about an upcoming commercial or hospitality/restaurant project, do not hesitate to contact any of our offices. We’d be happy to assist you.
This past Saturday August 12th, Nishkian Menninger employees gathered at a foggy Crissy Field in San Francisco for the summer company picnic. Having an opportunity to just relax with friends (whom you also just happen to work with) is invaluable. The Nishkian firms recognize how important this is – and we work hard to facilitate reconnection through events like these. We had a great turnout with many friends and family in attendance. Kevin and Kim Menninger orchestrated an outdoor cooking setup complete with a well-engineered wind screen. Everyone took turns stirring the pot in between games of ladder ball and frisbee.
The event also served as a baby shower for senior engineer Bethany Jones-Kent. She is expecting a baby boy in September. We wish her, and her husband Brandon, all the best!
Building codes require that buildings be classified based on the risk to human life, health, and welfare associated with their damage or failure. Minimum design loads, maximum allowable story drift criteria, and lateral force resisting system limitations are derived based on this classification. Building codes in the U.S. generally reference the ASCE 7 provisions for appropriate building classification criteria.
The idea of designing different types of buildings to different seismic force levels based on their “risk” is not new. The Building Code utilized increased Importance Factors for schools and hospitals for many years to provide a greater degree of resilience in certain structures. In the early 2000’s the first edition of ASCE 7 utilized the term “Occupancy Category” to define a buildings classification. However, the term “occupancy” is primarily used with fire/life safety issues and only implicitly defined risks associated with structural failure of a building. Consequently, the 2010 version of ASCE 7-10, introduced the term “Risk Category” in lieu of “Occupancy Category” to distinguish between the two considerations. Per commentary section C1.5.1 in the ASCE 7-10:
“The Risk Categories in Table 1.5-1 are used to relate the criteria for maximum environmental loads or distortions specified in the ASCE 7 to the consequence of the loads being exceeded for the structure and its occupants.”
Table 1.5-1 the ASCE 7 defines four distinct Risk Categories:
Risk Category I
Structures that are normally unoccupied and would result in negligible risk to the public should they fail. These include structures such as barns and storage shelters.
Risk Category II
This category contains all buildings and structures not specifically classified as conforming to another category. The majority of structures such as residential, commercial, and industrial buildings are included in this category.
Risk Category III
This category includes buildings and structures that could pose a substantial risk to human life in case of damage or failure. Structures under this category include:
Careful assessment of the Risk Category for a new project is required prior to design. Minimum design loads for snow, ice, and seismic considerations are greatly influenced by the importance factors defined in Table 1.5-2 of the ASCE 7 for different Risk Categories:
Additionally, buildings located in regions with high seismicity are particularly sensitive to Risk Category classifications. Per Chapters 11 and 12 of the ASCE 7 Risk Category selection has major impacts on:
For this reason it is important to note that changing a buildings occupancy can result in significant changes to gravity (in snowy/icy regions) and lateral designs. Careful consideration must be given to projects involving existing structures whose occupancy change triggers a bump from a lower Risk Category level to a higher one. The existing lateral and gravity systems may require retrofits to accommodate stricter structural system limitations, increased load demands and stricter allowable drift criteria.
In addition to ASCE 7, individual states have further defined and clarified Risk Categories for different buildings and each state’s Building Code should be considered and referenced when determining a buildings Risk Category. It is also helpful to work with a design professional such as an Architect when determining number of occupants in complex buildings made up of multiple occupancies and where total number of occupants may require different Risk Categories. In fact different Risk Categories can be specified within the same building structure in special conditions.
The Nishkian team has years of experience with thousands of projects across all Risk Category types. Should you have any questions on an upcoming or current project, please do not hesitate to contact any of our offices.
What once was a car wash and auto detail shop along El Camino Real off Shoreline Boulevard in the Silicon Valley is now turning into a luxury condominium community developed by Regis Homes Bay Area LLC. 1101 West, the new condominium building located at 1101 West El Camino Real in downtown Mountain View, is nearing completion and will hit the luxury property market this summer. The forthcoming 75,700-square-feet development is poised to bring 52 condominium units comprising of 6 studios, 18 one-bedroom, 17 two-bedroom, and 11 three-bedroom residences featuring spacious floor plans, refined finishes and sustainable design elements. Community amenities include an elegant lobby, landscaped courtyard with barbecues and fire pit, a bike pavilion with secure bike storage and workshop, a pet-friendly area and electrical vehicle charging stations available for every homeowner.
The structure includes a full story of below grade parking supported by continuous and spread footings with a concrete podium slab at grade creating a landscaped patio for the residents, and supporting four stories of traditional wood framing. The structure is set back from the street to promote foot and bike traffic. There is also a new bus stop in front of the building. With a Walk Score of 79 out of 100 in the Miramonte-Springer neighborhood in Mountain View, 1101 West’s location is very walkable so most errands can be accomplished on foot. Nearby parks include McKelvey Park, Eagle Park and Pioneer Park.
Regis Homes Bay Area with Van Tilburg, Banvard & Soderbergh (VTBS Architects), and Nishkian Monks of Bozeman worked together on this transit-oriented, urban-infill, luxury condominium building project to help with the Grand Boulevard Initiative, a collaboration of more than 30 different San Francisco Bay Area cities, agencies and other organizations working together to attract new development, retail, transit, employment, services and housing along the El Camino Real corridor which is one of the Bay Area’s major thoroughfares.
For availability announcements and more information about this project, visit http://www.1101w.com/