Related Links: Main Story: Tensioning Eases Stress on a 13-Story Sustainability Showcase Tipping Mar's vertically post-tensioned concrete shear walls in the 164-ft-tall San Francisco Public Utilities Commission Headquarters is the most ambitious—and tallest—example to date of a family of lateral-load-resisting structures designed to minimize damage in a major earthquake and allow immediate reoccupancy. U.S. structural practitioners and researchers have been developing the self-centering systems, modeled after PT bridge construction, for about a decade.Self-centering structures, when designed in structural steel, have become known as "rocking frames." In addition to concrete systems, there are examples of self-centering PT structures in precast concrete
The market is generally healthy and steadily growing, and margins are up for large specialty contractors. Further, advances in design tools and owner demand for collaboration are giving subcontractors a seat at the table early on in projects.