Novel Methodology to Reduce Tendon Steel and Keep Performance: Responsive Tendon Patterns – PT Optimization

Session: Track D: Structural Engineering Award: Part 2 & Innovation Award, Part 1

Mark SarkisianRicardo HenochProject image

Mark Sarkisian
Partner of Structural and Seismic Engineering, Skidmore, Owings & Merrill
San Francisco

Ricardo Henoch
Associate, Structural Engineering, Skidmore, Owings & Merrill
San Francisco

Post-tensioned (PT) flat-plate gravity framing systems are highly efficient and reduce embodied carbon when compared to conventional reinforced concrete framing systems. PT flat-plate gravity framing systems are useful in reducing slab thickness, improving construction efficiency, and reducing seismic mass in many building applications. A novel approach to determining PT tendon arrangements has been applied to several buildings informed by topology optimization results. Topology optimization is a method that determines optimal load paths in a finite element continuum. By orienting PT tendons along optimal load paths -- suggested by topology optimization, it has been shown that 25% or more of PT quantities can be reduced while maintaining the same mild steel reinforcement.

Responsive tendon patterns have been applied to a high-rise luxury residential development located in San Francisco, California. The building achieved quality indoor and outdoor living spaces through a well-integrated structural layout with unit configurations. The superstructure consisted of a special reinforced concrete shear wall core and perimeter gravity columns with PT flat-plate gravity framing system.

This design methodology has been applied to several buildings and addresses code requirements, constructability, and material efficiency. Each application revealed new patterns which were determined to be specific to the project's unique support conditions. Through multiple applications and detailed studies with contractors a fully realized design methodology has been developed. The application of this methodology could save significant amounts of tendon steel in tall buildings applications while maintaining the performance of regular pattern layout PT tendons.