Our Lady of the Angels Cathedral

Awarded:

• 2006 Applied Technology Council/ENR Award for Top Seismic Project of the 20th Century

Multiple Performance Levels by Design

Matching Client Expectation with State of the Art Technology “500 Years”

Owner’s Performance Objectives:

• A sacred edifice and a place of refuge after major disasters for 500 years
• Artistic / architecturally exposed walls providing strength, stiffness and longevity

Challenge: “Robust design preserving function and integrity of sanctuary within budget.”
With the use of advanced analysis/design methods and materials sciences technology NYA developed creative solutions and methodology to transform these performance goals into quantifiable engineering parameters.

Creativity: “Influencing the design form and integrating its inherent attributes.”
Although the building is essentially two stories, 150’ tall, it has multiple roof diaphragm levels and shapes.  The architectural features of the design (i.e. exposed concrete, tall slender walls and abundance of alabaster glass) placed exceptional demands on the structural design and construction.

Response modification using different isolation systems.  Global finite element models and nonlinear time history analyses were performed to study the global response. 

For the concrete walls (BIAX) moment curvature analysis was performed to assess cracking at DBE displacement and several different stress-strain models for concrete tension behavior were created. Rational interpretation of code requirements for B/E detailing considering response modifications of non-linear wall behavior of this unique system provided in-depth understanding and considerable cost-savings.

Quality Control:  “Mitigating concrete cracking by design”

• A concrete mix was developed to reduce long-term deterioration
• Polypropylene fibers added to interrupt propagation of cracking
• Concrete mock-ups to simulate different aspects of the walls

J. Paul Getty Villa & Museum – Addition & Historic Renovation

Awarded:

• 2006 California Construction “Best Restoration” Award
• 2005 American Concrete Institute Charles J. Pankow Award

New Building Design
Architects Machado and Silvetti designed an arrangement of new buildings into a hill
side in Pacific Palisades that represents an archeological excavation harmonizing
modern architecture with the Villa’s original Roman-style house.  The Getty Villa project involved a transformation in excess of $150 million to convert the existing site into a new center for the study of classical antiquities, archeology, and comparative ancient cultures. One of the goals of the new construction was to create outdoor plazas and indoor spaces resulting from an excavation of the existing museum, revealing layers of earth, or strata that formed the basis of design.  The aesthetic desire was to create concrete walls and floors that appeared as if they were part of a stratum.  

The visual continuity of horizontal and vertical elements would reinforce a monolithic appearance, emphasizing the building as a structure carved from the earth, delineated by different concrete mixtures, textures, and decorative aggregates.

Existing Villa
At the existing Villa, the combined desire for seismic strengthening of the reinforced concrete structure and more natural light to the interior was one of several challenges.

Artwork Seismic Protection
Other challenges included preservation and strengthening of exterior detailing work and the important artwork also needed seismic protection as it included sizeable relics both along the walls and on the floor. To this end, NYA designed wall mounting devices and floor stands as isolated seismic support systems.  

Los Angeles Convention Center Hotel (LACCH)

“Seamless Seismic Energy Dissipating System”

A seamlessly integrated, highly efficient seismic energy dissipating structural system.
At the forefront of mixed-use high-rise buildings in downtown Los Angeles, the 55-story Los Angeles Convention Center Hotel stands alone as a profound success of the application of performance-based structural design at its highest level.  Not only modern in its architectural form, the hotel tower takes full advantage of a leading edge structural steel lateral force resisting system, comprised of unstiffened thin steel plate shear walls (SPSW), moment frames, Buckling Restrained Braces (BRB) , mid-height outriggers and cap trusses.

The design process exemplifies a successful collaboration of performance-based engineering and rigorous peer review by a panel of noted experts in each structural system type.  The result minimizes the cost and construction schedule while maximizing the interior space available for architectural programming.

UCSF Institute of Regeneration Medicine Laboratory

The UCSF Stem Cell Research building will be located at the UCSF Parnassus Campus on the site of the previous Medical Research Buildings 1 & 2.    The building is serpentine-shaped in plan, spanning over 600 ft in length, with floor plates that step up one-half floor every 120 ft to loosely match the existing uphill grade.   NYA developed an elegant scheme consisting of a steel space frame to limit impact on the existing site.   This very unique building completely supported high off the ground by long-span steel box trusses bearing on tall concrete piers to give the architectural impression that the building is “floating” in space.  A pedestrian bridge, spanning 150 ft, located 80 ft above grade, connects the laboratory building with the existing hospital tower.  Base isolation was incorporated and was an ideal seismic system, due to the relatively few contact points with the ground, the building’s “natural moat”, and the enhanced performance desired by the client.

Westfield San Francisco Centre

Awarded:

• 2007 SEAOC Excellence Award For “Best Historic Preservation”

The Westfield San Francisco Centre is a $460 million, 1.5 million sf mega structure, spanning a full city block in downtown San Francisco. The project involved the redevelopment of the Emporium building, originally constructed in the late 1800’s, and includes eight new stories of mixed-use construction with over 200 specialty shops, a dining level, an entertainment complex and three levels of office space, resulting in the largest urban retail centre on the west coast. The project included a number of interesting challenges requiring creative structural solutions. They include:

1. Incorporation of historic dome and façade.
2. Long-span pedestrian bridges.
3. Expansive, disparate floor openings at every level.
4. 15,000 sf Column-free loading dock.
5. Multitude of site challenges/constraints.
6. Linear and nonlinear analysis.

Lifting of Historic Dome:
The job of lifting the 250 ton historic and fragile dome intact required considerable analysis, experience, collaboration, and nerve. Using the original shop drawings as a guide, 3-D computer models were developed and analyzed for effects of lifting, variations in levelness, consistency while lifting, and evaluation of the structure to withstand wind and seismic forces as required by the current Code, and as a result the main arches and ring beam of the dome were strengthened.

Seismic Preservation of the Historic Façade:
Another challenge was to incorporate the massive, Colusa sandstone façade into the modern structural system.  To accomplish this task, the façade was first strengthened with a new ductile reinforced “shotcrete” frame, again threading it within the confines of the existing structure.  Temporary steel shoring towers with micropile foundations were installed to support the façade out of plane once the remaining structure was demolished. At this phase, the façade stood independently, some 145’ above the basement and foundation excavation.  The shotcrete frame now served as a temporary strong-back in addition to being a permanent component of the modern lateral system and allowing for an easier attachment of the new structural system.