[design '96]


Swenson Say Faget

The recent opening of Kreielsheimer Place by A Contemporary Theater combined the excitement of a new facility and an important Seattle landmark rescued and restored. The elegance and beauty of the historic Eagles Auditorium has been rediscovered after years of neglect and abandonment.

Behind the stately restoration and elegant new ACT is a hard working structure that set the stage for dramatically reconfigured spaces. The design team and contractor worked behind the scenes in a tightly orchestrated and technically challenging performance.

Demolition and restructuring satisfied the new space requirements, preserved the historic interior plasterwork, acoustically isolated the two theaters and did not exceed a limited budget. The renovated structure represents "state of the art" for seismic retrofit.

A Seattle original

Originally designed as Aerie #1 for the Fraternal Order of Eagles by Henry Bittman in 1924, The Eagles Auditorium is recognized for its terra-cotta ornamentation and Romanesque style. Seattle architects and engineers experienced in the renovation of existing buildings recognize Bittman as a prominent architect and structural engineer during Seattle's formative years.

The complicated original building had seven stories above grade with an additional two levels below grade. The lowest level contained a two-story billiard room, restaurant and gymnasium as well as a storage vault. A two-story lodge room with a balcony and stage occurred over the billiard room. Over the lodge room was the grand ballroom which extended four stories to an ornate plaster ceiling above. Four levels of apartment units surrounded three sides of the upper ballroom. Surrounding the main rooms of the lower levels was a labyrinth of discontinuous levels and passageways.

Bittman's construction drawings of the Eagles Auditorium are unusually detailed, and reveal a complex and sophisticated structure.

Below it's illustrious surface, the original Eagles Hall was composed of reinforced concrete pan joists supported by a
ACT's arena theater takes center stage at Kreielsheimer Place, with the meticulously restored grand ballroom as a backdrop. The second-level ballroom was large enough to contain the 390-seat arena theater, but a large portion of the original floor was dropped to accommodate the recessed seating tiers and stage.
Photo by Steve Keating for Callison Architecture

super-structure of reinforced concrete and concrete encased steel. The ballroom roof was held up by steel trusses ten feet in depth and seventy feet in span length. The ballroom floor was supported by steel plate girders spanning fifty feet. While the principal interior columns were built-up steel encased in concrete, the exterior columns were concrete with a double spiral pattern of bar reinforcement.

A new lease on life

The Eagles Auditorium had been virtually unoccupied for more than a decade when A Contemporary Theater and the Seattle Housing Resource Group collaborated to renovate the landmark structure.

The program requirements were complex. The building was to accommodate two independent theater spaces with separate lobbies and public spaces, administrative offices, rehearsal rooms, shops, storage areas and a future third theater. In addition, the building was to provide affordable housing for downtown residents. A performance goal of the program was to acoustically isolate the theater spaces.

Callison Architects soon discovered the Eagles Auditorium was too small to accommodate the program requirements. A number of options were explored, including retaining ACT's building on lower Queen Anne for administrative offices and shops, before it was decided to add an additional story to the top of the structure. The new penthouse was carefully designed to minimize it's visual impact and preserve the appearance of the south and west facades fronting Union Street and Seventh Avenue.

Although the grand ballroom on the second level was large enough to contain the 390-seat arena theater, a large portion of the original floor was dropped to accommodate the recessed seating tiers and stage. The arena seating and central stage now occupy the upper part of the former Lodge Room, which was originally sandwiched between the ballroom and the billiard room below.

The 390-seat thrust theater below the arena theater required more aggressive restructuring measures. To accommodate the new theater and lobby, most of the basement mezzanine, first floor, and first floor mezzanine had to be cut away. A row of columns supporting the ballroom floor above also had to go. The trap below the stage and associated vomitory required removal of the basement slab and considerable excavation.

The demolition and restructuring had to be accomplished in a manner which simultaneously satisfied the space requirements, preserved the historic interior plasterwork, acoustically isolated the two theaters and did not exceed a limited budget. In addition, the earthquake resistance of the entire structure needed to represent the "state of the art" for seismic renovation of existing structures.

Surgical intervention

Swenson Say Faget met the structural challenge presented by the Eagles Auditorium renovation with a creative application of conventional methods and innovative solutions.

The seismic resistance of the structure was improved through the addition of concrete shearwalls pneumatically placed against
Design section of the Eagles/ACT renovation.
existing masonry walls. Pneumatically placed concrete was also used to strengthen the areaway retaining wall below the Seventh Avenue sidewalk. The height of the wall was essentially doubled when the basement mezzanine was removed to accommodate the thrust theater lobby.

The diverse space needs at each floor level did not allow vertical alignment of the shearwalls. The existing floor diaphragms were therefore strengthened with steel plates and steel drag struts and chords were added to transfer seismic loads between the discontinuous walls. Existing columns supporting the discontinuous shearwalls were strengthened by jacketing the columns with steel. This enabled the structural utilization of the unreinforced concrete cover originally intended as fire protection of the encased steel column.

Other seismic improvements include "strong-backing" of the interior hollow clay tile walls to prevent their collapse during a seismic event. Although these walls are not required to support the structure, their collapse would present a considerable hazard to the building occupants.

The new penthouse presented a number of structural challenges. The additional mass placed on top of the structure increased the seismic and gravity demand on the structure below. While the penthouse protected the arena theater below from outside ambient noise, the shops, administrative areas, mechanical rooms and rehearsal room housed within the penthouse had to be acoustically isolated from the supporting structure to prevent the transmission of noise from the penthouse level above.

The existing roof trusses spanning seventy feet over the arena theater required strengthening to support the additional load of the penthouse as well as a suspended fly grid and light grid for the theater. The trusses also required repair to replace steel lost to corrosion by water infiltration during the time the Eagles Building was unoccupied.

The trusses were repaired and strengthened by welding additional steel to the truss members. The additional steel was minimized by utilizing an analysis technique known as "limit state" design.

The penthouse was acoustically isolated from the supporting structure by utilizing neoprene bearing pads at all connections. The pad density was controlled to be stiff enough to support the load but soft enough to dampen vibrations.

Similar bearing pads were used to separate the thrust theater structure from the surrounding building structure. To alleviate noise due to vibration transmission through the structural frame, attachments between the thrust theater structure and the surrounding building structure were minimized. Where attachments were unavoidable, the connection components were isolated by neoprene pads. The thrust theater is, in essence, an independent structure constructed within the Eagles building.

New steel floor trusses were designed to span seventy feet over the thrust theater and support the arena theater above. The trusses flank the trap below the arena stage and form the vomitory space below the arena seating. The trusses were designed in three pieces to allow installation within the existing structure.

The truss installation represented a significant milestone in the construction schedule. The extensive demolition and reconstruction had to be carefully sequenced in order to maintain the overall stability of the structure throughout the process.

Sellen Construction rebuilt the Eagles Auditorium from the middle. The arena trusses were erected after demolition of the upper floor levels but before demolition of the lower floor levels. Other key components of the new structure were installed in conjunction with the demolition. Once demolition was complete the remaining structural components were installed. The work was sequenced to simultaneously occur above and below the arena trusses.

The success of the Eagles Auditorium renovation was in large part due to the close coordination and cooperation of the design team and contractor. The unique complexities presented by the project required more of the team members than mere technical expertise. A strong spirit of teamwork was also required. The spirit of teamwork was established early in the design process and was carried through the end of construction. All of those involved have reason to be proud.

Paul Faget is a structural engineer and principal with Swenson Say Faget.

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