Resilient steel structures
By questioning the status quo, we’ve developed improved approaches for the design of steel structures that provide better seismic performance with no cost premium. Through iterative design and decades of research and development, we reconceived the approach to seismic bracing to create a more resilient system. By introducing an elastic mast to an otherwise conventional braced frame, we’ve been able to improve the performance of steel structures and make them more damage resistant with minimal cost and architectural impact.
At 1951 Harbor Bay Parkway, the team devised an innovative approach for seismic bracing that provides improved performance and cost-effectiveness over conventional braced-frame systems. A mast-frame system uses BRBs, in conjunction with a vertical mast or strong-back, to reduce drift, eliminate weak stories, and increase redundancy. The yielding BRBs work in tandem with an elastic mast frame to create controlled rocking behavior that provides improved resiliency and protection for the building frame, cladding, and interior construction. The mast-frame occupies the same footprint and extent of a conventional frame, but uses fewer BRB members. The mast effectively forces all of the BRB’s in the system to work together to resist movement at any story, which fully mobilizes the BRB elements’ deformation capacity and increases the system’s inherent redundancy.
Resilient concrete design
We’ve improved on the inherent strength and stiffness of concrete shear walls by introducing vertical post-tensioning that gives the ability for the structure to recenter after an earthquake. This “self-healing” capability significantly improves the resilience of concrete structures by limiting movement and protecting critical components. This simple, innovative, and cost-effective approach has been effectively applied in a number of projects in the commercial, academic, and institutional sectors.
At 270 Brannan, a seven-story office building, the vertical post-tensioning system in the shear walls allows the building to recenter after a major earthquake, reducing downtime and repair costs for both structural and non-structural components. With weak soils within the San Francisco urban site, Deep-Soil Mixing (DSM) combined with micropiles emerged as the most cost-effective solution to support the vertical post-tensioned shear walls, while addressing the ground conditions.
At Tipping, we employ custom tools and advanced analytics to design structures that not only meet the minimum life-safety objectives prescribed in the building code, but also provide enhanced post-earthquake resilience that reduces potential harm, economic losses, and overall construction costs. By harnessing the insight from our data-driven process, we pioneer innovative strategies for seismic protection that lead to unconventional approaches—our powerful suite of custom designed tools has allowed us to be at the forefront of major innovations in seismic design including BRB mast frames, post-tensioned walls, and seismic isolation.
The 680 Folsom team created a unique lateral system—unprecedented in modern engineering—that saved $4 million on a $110 million project and provided enhanced seismic performance. Inspired by Japanese pagodas, the design solution was founded on the shinbashira, or central pillar, of the centuries’ old Japanese pagoda. The team invented a modern shinbashira in the form of a concrete core-wall system resting on a single friction-pendulum slider bearing that pivots within its base. Harnessing the strength of the existing moment frame, the system acts as a mode-shaping spine that improves the drift pattern and spreads yielding throughout the frame’s height, thus redistributing seismic deformations throughout the structure and preventing the formation of a weak-story mechanism.
Innovative structural approaches, communication, and iterative collaboration allow us to meet discerning architects’ most ambitious design visions with structural solutions that are smart, efficient, and integrate seamlessly into the overall project plan. Our custom in-house tools allow us to better understand structural behavior, so we can create cost-efficient solutions that support the overall architectural design, such as long column-free spans, dramatic cantilevers, thin structural members, unconventional shapes or volumes, and complex facade systems.
San Francisco Conservatory of Music’s Bowes Center is a unique twelve-story tower that blurs the lines between musical education, communal space, three distinct state-of-the-art performance venues, and apartments for 400 student-musicians and guest performers. With this wide variety of elements, wide column-free spans, acoustics, and seismic performance were top priorities for the high-rise structural design. A tailored concrete structural system was used to meet the needs of the architectural program. Thin post-tensioned slabs minimize floor assemblies, aid in acoustic isolation, and accommodate glass curtain walls for transparency and views. Expressive long cantilevers, an unconventional shape, and thin structural elements highlight the structure’s main performance space at the top of the structure.