Megan Crawford, Kevin Doyle
Beautiful Burnished Block Provide Shear Wall Support
Construction manager AUCH Construction not only celebrated its 110th year in 2018 of providing planning, preconstruction and construction services in southeast Michigan but also moved into new corporate headquarters at the eastern gateway to downtown Pontiac MI, Woodward Avenue and University Drive, leading to Oakland University.
Knowing that AUCH Construction intended to make this new headquarters to serve future generations, Harley Ellis Devereaux (HED) strived to provide a structure that conveyed permanence, longevity, durability and had a significant presence at its prominent location. To that end, masonry was the clear choice.
Masonry Plays More Than One Role
Through the design process, masonry presented itself in many ways: Black Diamond utility wire cut velour brick with 97A Super Black pigmented mortar depicts a successful sophisticated corporate icon with 100+-year longevity. Beautiful charcoal burnished 8″ block carry the lateral shear load and add thermal mass as they enclose the insulated cavity wall. Great efficiency is gleaned when masonry plays more than one role.
Cost effective CMU is essential to provide redundant structural support for cavity walls. Masonry cavity wall construction also contributes thermal mass for energy optimization, acoustic benefits of sound isolation, resilience to disasters such as high winds and fire, durability and requires less maintenance less often. Because the insulated masonry cavity wall system plays so many roles without requiring additional materials, its efficiency results in considerable cost and schedule savings.
More than one-third of the project’s CMU has a burnished face, dual-purposed to serve as a resilient and rich interior finish. Two of the masonry shear walls are exposed burnished CMU within public areas, three are exposed painted CMU in utility rooms.
Steel Braced Frames for Open Design Depend on Masonry Shear Walls
For the program of the building, AUCH envisioned large open spaces with plenty of collaborative areas for employees to easily work together. Therefore, for the structural system, HED instinctively began with steel columns and girders with open web steel joists to support the gravity loads and steel moment frames or braced frames to support lateral loads. Steel moment frames would provide the open spaces and large windows that AUCH was envisioning, however they are more costly than a steel braced frame due to the higher material and labor costs and heavier connections.
Therefore, steel braced frames were considered as a more economical design. However these would need to be strategically located to provide the openness AUCH was desiring. Working with such knowledgeable partners as we had with AUCH, the question came up if we could use CMU we already had on the project as part, or all, of the lateral force resisting system. With this suggestion, the HED structural team was able to analyze the structure using some of the CMU walls that were already planned for the perimeter of the building as the majority of the lateral force resisting system.
Since masonry was already being heavily used, we were able to reduce costs by capitalizing on its multiple roles and functions while reducing construction time by eliminating unnecessary steel components
Additionally, we were able to work with AUCH to strategically place some interior CMU shear walls in the portion of the building where interior walls were already planned to make up the remainder of the lateral force resisting requirements. This still allowed for a large portion of the building to be open to meeting their objectives, while adding walls where they were already required around burnished block conference rooms.
Reducing Materials, Costs and Schedule
Use of CMU shear walls in this application provides many benefits compared to a steel lateral system. Because of the increased stiffness of a CMU shear wall compared to a steel moment frame system, we were able to use fewer lateral elements, concentrating them around the perimeter of the building, which provided the opportunity for open spaces desired. Additionally, since masonry was already being heavily used, we were able to reduce costs by capitalizing on multiple roles and functions, with minimal adjustments to provide the required structural capacity, and reduce construction time by eliminating unnecessary steel components.
If shear walls were not used for this building, in each location where there is a CMU shear wall, there would have been a steel brace and gypsum wall in its place. CMU was able to achieve both the structural lateral support as well as the required architectural wall in one element, thereby reducing costs and construction time. Based on cost models prepared by AUCH throughout the construction process, it is estimated that we were able to reduce the steel cost by approximately 10% by replacing moment connection with steel braced frames. Minimal changes were required to ensure the CMU walls had sufficient strength to resist the lateral loads. This was simply increasing the amount of vertical reinforcement in the CMU shear walls.
Furthermore, when steel braces or moment frames are used as the lateral resisting elements, it is typically necessary to add large concrete footings to provide mass to counteract the large uplift forces typically experienced with steel lateral systems. Another advantage to CMU shear walls is that the wall itself provides mass and helps to reduce the size of pad footings required to resist the uplift.
Setting a Dramatic Tone
In addition to the use of CMU shear walls for the structure, masonry was used in various other locations, providing a dominant appearance for the building prominently located on the Woodward Loop while also conveying the longevity that AUCH wanted. Masonry was used as a brick façade with CMU backup for the exterior walls. The façade incorporates black brick contrasting against nearly full height windows, providing a dramatic appearance and striking presence.
The use of exposed charcoal burnished CMU on the interior carries the feeling of strength throughout. More than one-third of the CMU has a burnished face, dual-purposed to serve as a resilient and rich interior finish. Of the six masonry shear walls, two are exposed burnished CMU within public areas, three are exposed painted CMU within utility rooms.
CMU was able to achieve both the structural lateral support as well as the required architectural wall in one element, thereby reducing costs and construction time
Using masonry for the site wall around the mechanical yard connected to the north elevation rather than galvanized steel again provides a durability to the structure, especially in an area where work will be occurring and the potential for damage to a less durable material would be likely. Furthermore, CMU requires little maintenance over its lifetime rather than what would be required with steel.
Masonry Offsets Glass in Meeting Energy Code
Because of the project’s total vertical fenestration area, the Building Envelope Trade-Off Option was used to demonstrate compliance with the applicable Energy Code, for Climate Zone 5. Even with dual low-e insulated glass units (U-0.20) and thermally broken curtain wall framing, the project glazing system has a U-factor of only 0.38. The masonry wall assembly, comprised of utility face brick (R-0.44) over 8″ normal weight CMU back-up (R-2) with 2 1/2″ Dow CAVITYMATE Ultra rigid insulation (R-14) on a fluid-applied air/vapor barrier and a 1 1/2″ air space, has a U-factor of 0.055. Coupled with a roof assembly having a U-Factor of 0.034, the high performing masonry wall assembly offsets the glazing, from an energy perspective.
The team’s desire to incorporate building components that would tell a story played a significant role in meeting AUCH’s goal.
Best in Class
Founded in 1908 in Detroit, AUCH moved to Pontiac in 1985, continuing their best-in-class construction services and focus on customer satisfaction and employee support. Ongoing repeat business and dedicated employees have been the main ingredients in the company’s longevity. The investment in the new headquarters signifies the company’s commitment and service to revitalizing Pontiac and its surrounding community. Employees are using the new ergonomic work environment with an open floor plan and abundance of natural daylight to communicate and collaborate, employing state-of-the-art construction technology systems to better serve clients.
AUCH hosts and supports organizations and events by sharing their new work-space with industry and community groups. The company is active in local workforce development through Pontiac and Oakland Schools and is active in the ACE Mentor Program of Southeast Michigan.
The use of a significant amount of masonry provided the performance, appearance and feeling AUCH was envisioning while still allowing for the layout and program plan they desired on the interior of the building. HED was able to work collaboratively with AUCH to determine the most efficient structural system for the building, which in the end reduced cost and construction time. The team’s desire to incorporate building components that would tell a story played a significant role in meeting AUCH’s goals for their new HQ. The durability of this structure will allow AUCH to call this new building in downtown Pontiac home for many years to come.
Megan Crawford, PE, is an Associate and structural engineer in Harley Ellis Devereaux’s (HED) Detroit office. With almost a decade of experience, Crawford’s thorough knowledge of structural design and engineering techniques brings positive impact. An alumni of The University of Western Ontario and a certified Professional Engineer in the State of Michigan, Crawford’s experience ranges from large STEM and engineering buildings for leading universities to healthcare facilities and highly technical workplaces in Canada and the US. Crawford is a member of the Structural Engineering Association of Michigan. email@example.com | 248.262.1500
Kevin Doyle, AIA, LEED AP, is an Associate Principal and architect in Harley Ellis Devereaux’s (HED) Detroit office. With nearly 25 years in the construction industry, Doyle’s professional background includes architectural service through all project phases within the healthcare, higher education, commercial and industrial market sectors. Doyle is a licensed architect in the State of Michigan and received his Bachelor of Science in Architecture, Master of Architecture and Master of Science in Engineering from the University of Michigan. firstname.lastname@example.org | 248.262.1500
AUCH Construction Pontiac MI
Architect and Engineer Harley Ellis Devereaux (HED) | Southfield
Construction Manager AUCH Construction | Pontiac
Mason Contractor Rosati Masonry | Redford
Mason Suppliers BASF | The Belden Brick Company DOW | Grace | Grand Blanc Cement MasonPro | Royal Stone Solomon Colors | St Marys Cement
20,000 sf | $6 million project budget Completed July 2018 | LEED Silver Design
RACER’s Edge Award for redevelopment excellence designed to maximize energy efficiency and minimize environmental impact for epitomizing their mission