Reinforcement Concepts for 3D Concrete Printing and Modular Construction in Tor Alva

Tor Alva is a 30-meter-high tower and, at this point, the tallest structure in the world constructed using Reinforced 3D Concrete Printing (R3DCP). The building system is modular and prefabricated, using branching columns that are stacked and connected with bolts and grout. It is designed for easy disassembly and reuse. Each structural component follows a common typology: a precast base, a 3D-printed segmented column with varying numbers of branches, and a precast capital. Within the 3D-printed section, a combination of reinforcement strategies is employed—including inter-layer stainless steel reinforcement, vertically embedded conventional steel bars bonded via grout, and unbonded post-tensioning rods. These possible reinforcement strategies are applied in different components of the tower, depending on structural design and construction requirements. This paper presents the steps taken from stay-in-place 3D-printed formwork to fully R3DCP. It also discusses how each reinforcement strategy was constructed by focusing on the implications of each technique on the fabrication workflow. The findings show how hybrid reinforcement methods in R3DCP can support broader architectural and structural uses, making concrete 3D printing suitable for load-bearing applications.