Review of Transverse Reinforcement Requirements for Precast Load-Bearing Wall Panels with Large Openings under Compression

Precast concrete load-bearing wall panels have been used for decades with unparalleled success due to their architectural versatility, thermal insulation, ease of production and erection, and structural performance. According to the current building code, structural walls do not need transverse ties if the vertical reinforcement ratio is less than 1% or when vertical reinforcement is not required as compression reinforcement. Also, minimum reinforcement requirements do not apply to structural walls with an average effective prestress of 1,551 kPa (225 psi) or greater. Elimination of transverse ties in structural precast walls simplifies the production of the panels. The presence of large openings in precast walls is very common in the design of modern buildings. This results in a significant reduction of the panel cross section. Most designers tend to design the remaining portion of the panel cross section as a column and not a wall, which requires minimum transverse ties according to the current building code in the United States. The requirement could complicate wall detailing and reduce the efficiency and economy of panel fabrication. This paper summarizes the literature review conducted to determine when precast load-bearing walls should be designed as columns/walls with respect to transverse reinforcement. The requirements of transverse reinforcement in walls and columns in various building codes were studied, and design recommendations were made.