Tie rods are integral in structural engineering, primarily for transmitting traffic loads and alleviating compression forces within a structure. These slender components, resembling cables or metal bars, offer seamless integration into a space, lending themselves to visually appealing designs through repetition. They have applications ranging from furniture design to large-scale urban infrastructure projects, including suspension and cable-stayed bridges.
In contrast to trusses, which undergo both tensile and compressive forces, tie rods predominantly serve as structural elements within a framework. Typically, they are integral to portal systems and are primarily responsible for handling normal forces. They operate without being subject to bending moments or shear forces, offering a wide range of applications for architects and engineers. These applications include creating extensive spans, supporting facades, efficiently distributing wind loads, shaping structural support, and even serving aesthetic purposes. Below, we have gathered eight Brazilian projects that use this technique on different scales.
When Teresa Mascaro designed the kitchen table integrated into the living room of the Higienópolis Apartment, she created a reinforced concrete countertop in situ. This countertop has an "L" shape, beginning at a height of 90cm in the kitchen area, and as it extends into the living room, it gradually descends by 15cm to reach standard table height. It stretches over 3 meters without any support on the floor; instead, it is suspended by two steel bars anchored to the ceiling slab. These steel tie rods also support a linear iron plate luminaire that appears to float above the table.
In the Niterói Contemporary Art Museum, the Rio de Janeiro-based office gru.a created the Riposatevi Installation. It occupies the 400m² of the museum's main hall. For its execution, a horizontal steel cable grid formed by equilateral triangles was necessary, fixed 2.5 meters above the floor. From it, 13 vertical tie rods are fixed to the bases of the building's beams, connecting the steel cable system to the reinforced concrete structure of the museum. Hooks were strategically installed at each tie rod point to suspend the 30 nets that occupy the space.
As a result of a handmade assembly process carried out by a team of four people, the Acaiacá House, designed by Gui Paoliello Arquiteto, had the support of a single metal scaffold that was moved for the manual assembly of the six portal beams. These beams are approximately 20cm diameter logs and were reinforced with a steel cable tie rod, forming a wagon beam with a total length of 12 meters to span a central span of 8 meters.
In the micasa vol.C project, studio mk27 effectively spans almost 15 meters using a series of laminated glued timber portals. To maintain structural integrity, steel tie rods for bracing have been positioned between each pair of modules on the upper level.
In the Líder Store, the São Paulo-based FGMF office aimed to highlight the typically underutilized upper level in commercial spaces. To achieve this, they introduced a significant mezzanine, suspended by merely six slender tie rods in the main area. This innovative design distinctly characterizes a mixed structure that impressively spans 15 meters.
To span large spans and help establish the steel structure that supports the roof of the Immersive Vivarium at Animália Biopark, which has upper openings that promote light permeability, AM2 Arquitetura also adopted tie rods for greater structural efficiency.
In even more daring engineering, master João Filgueiras Lima (Lelé) created the Exhibition Center of the Administrative Center of Bahia, which remains entirely suspended five meters above the ground. For this, two identical lateral towers support the tie rods that stabilize the building, which develops in symmetrical balances of inverted volumes.
Finally, one of the most iconic examples of tie rods in urban infrastructure is the Octávio Frias de Oliveira Bridge, designed by architect João Valente Filho. Here, the tie rods are called stays, in homage to the technique used in boats that refers to the adopted structural solution, and they give the name to the cable-stayed bridge. In this example, there are 144 stays, formed by bundles of steel cables - covered by a yellow polyethylene tube for protection of the structural material - that suspend two 900-meter-long lanes over the Pinheiros River.
