The Don Knabe Wellness Center highlights the first phase of a $460 million state-of-the-art renovation at Rancho Los Amigos National Rehabilitation Center, one of the nation’s top hospitals for rehabilitative medicine. The new Wellness and Aquatic Center is equipped with a therapy swimming pool that has an underwater treadmill, weight-lifting room, dance studio, cardio and yoga room. This center was recognized by state legislators and was officially dedicated and named after Donald R. Knabe, former member of the Los Angeles County Board of Supervisors, Fourth District.

IMEG provided design-build structural engineering services to Phase 1 of the campus-wide project, which encompassed a major renovation of existing facilities and construction of new patient care and support buildings, including the LEED Gold Certified, 12,000-sf, one-story Wellness and Aquatic Center at the heart of the campus. All structures were designed and constructed based on the 2013 edition of California Building Code.

The gravity system of the Wellness and Aquatic Center building consists of three-inch corrugated metal decking with 3-1/4” light-weight concrete fill for a total thickness of 6-1/4”.  The decking in all instances is supported by steel wide flange purlins spaced no more than 9’-6” on center. The beams include welded shear studs at the top flange to engage the concrete deck for composite action. The steel purlins are supported by wide flange steel girders, which in turn are supported by wide flange steel columns.

The lateral force resisting system (LFRS) of the one-story structure consists of the concrete on metal deck that acts as the horizontal diaphragm transferring lateral forces to the vertical lateral load resisting elements, which consist of reduced beam section (RBS) steel special moment frame (SSMF) system in each orthogonal direction. A 3D structural analysis model of the outpatient structure was created using RAMSTEEL for the gravity and lateral design. A dynamic response spectrum analysis was performed for the lateral analysis and design of the structure. W24x beams and columns were used for the SSMF. The foundation system for the gravity columns consists of individual spread footing and 30”Wx36”D grade beams supported by starter footings at the frame column location. The fixity of the SSMF column was obtained by embedding the columns into the grade beams and by welding grade beam reinforcement to the frame column flange.

A decorative screen structural feature makes the Wellness and Aquatic Center building — and the adjacent outpatient building — stand out from its surroundings. The decorative screen with perforated scrim is located on the south and southeast corner of the building. The challenging part of the screen structure design was the 25-foot cantilever from the main structure. IMEG engineers created a 3D structural analysis model in ETABS for the analysis and design of this screen. The frame was carefully designed to be compatible with the movement of the building in the event of an earthquake. Tube steel members were used for the screen frame. HSS14x10 and HSS8x8 outriggers were provided from the building columns and beams to support it and horizontal bracing with HSS4x4 were provided to control the excessive movement from the seismic force. The vertical surface of the frame consists of HSS6x4 and HSS4x4 elements to support the perforated screen.

As this was a design-build project, all structural details were closely coordinated with the contractor (McCarthy Construction) to speed up the steel fabrication process, and IMEG worked closely with the contractor and architect from the design phase to the end of construction to track the project construction budget. That early involvement of the construction team in this project led to a smooth handoff from the architect/engineer to the construction manager, ensuring a seamless transition from design to construction. Due to the coordination of the structural details with the contractor and the steel fabricator, the construction process was smooth and successful.