Developed "Folded Plate Buckling Restrained Brace (FP-BRB®)"

Three companies, TOA Construction Corporation (Head Office: Shinjuku-ku, Tokyo; President: Tsuyoshi Hayakawa), Aoki Asunaro Construction Co., Ltd. (Head Office: Minato-ku, Tokyo; President: Hisayuki Mochizuki), and Meiko Sekkei Co., Ltd. (Head Office: Nagoya-shi, Aichi Prefecture; Representative: Tomonori Otani), have jointly developed a new seismic damping brace, the "Folded Plate Buckling Restrained Brace (FP-BRB® - Registered Trademark No. 6679723)" (hereinafter referred to as "this brace"). This brace is composed entirely of steel and can be manufactured without the need for special processing or welding methods.

This brace has obtained structural performance evaluation from Japan ERI Co., Ltd. (ERI-K25001). (Patent pending)

Background of Development

In the construction of logistics warehouses, the most cost-effective structural form is a moment-resisting frame structure with braces (Note 1). Therefore, buckling restrained braces (Note 2), which offer stable performance in both compression and tension, are widely used as seismic damping braces (Figure 1).

Figure 1 Overview of Moment-Resisting Frame Structure with Braces

Note 1: A structure that ensures building strength by adding diagonal members (braces) in addition to the frame structure (moment-resisting frame structure) constructed with columns and beams.

Note 2: Steel braces are strong against tensile deformation but weak against compressive deformation, and they bend sharply (buckle) when they reach their limit. Buckling restrained braces are strong against tensile deformation, and when subjected to compressive deformation, buckling is restrained by a buckling restraint material such as a steel pipe, allowing them to exhibit performance equivalent to tensile deformation.

Various types of buckling restrained braces have been put into practical use, differing in the shape, material, and manufacturing method of the core and restraint materials. However, with the rising cost of construction materials, development of a new seismic damping brace was initiated to achieve further cost reduction.

Overview of This Brace

The "Folded Plate Buckling Restrained Brace (FP-BRB)" is a new seismic damping brace that utilizes a folded mechanism (Figure 2). In this mechanism, multiple steel plates arranged in parallel are joined end-to-end in a continuous manner, allowing the compressive force acting on the steel plates to be restrained by the force of the adjacent steel plates (tensile members) pushing back, thereby achieving a "buckling restraint effect."

Figure 2 Overview of Folded Mechanism in Damper Section

This brace is composed entirely of steel and does not require special processing or welding. Therefore, it can be manufactured by steel fabricators (steel manufacturing companies), leading to cost reductions compared to conventional buckling restrained braces with equivalent performance.

Features of This Brace

1 It consists of a damper section that absorbs energy through the plastic deformation of steel and a support member, and can be connected to the main frame using general bolt connections (Figure 3).

Figure 3 Perspective View of Folded Plate Buckling Restrained Brace

Photo 1 Appearance of Brace Test Specimen

2 The damper section is formed by folding nine steel plates of different cross-sections (one core plate, six intermediate plates, and two outer plates) in a continuous manner and joining them alternately with plates provided at both ends of the steel plates (Figure 4).

Figure 4 Detailed Perspective View of Damper Section

Photo 2 Damper Section of Brace Test Specimen

3 By appropriately managing and overlapping the gaps between the steel plates, buckling of the steel plates subjected to compressive force can be restrained by the adjacent steel plates (Figure 5).

Figure 5 Conceptual Diagram of Stress Transfer and Buckling Restraint Effect

4 The load-bearing capacity and rigidity can be freely adjusted by changing the cross-sectional area and length (folding position) of the damper section.

5 All constituent members are made of steel (plates), and it can be manufactured without the need for special processing or welding methods.

6 It has a fail-safe mechanism that prevents sudden loss of load-bearing capacity during deformations exceeding design assumptions.

Future Development

This brace can be applied not only to logistics warehouses but also to commercial facilities and office buildings, making it adaptable to various applications.

Moving forward, we aim to promote the application of this brace to actual projects and its utilization in a wide range of buildings. By further advancing the technology, we will contribute to the widespread adoption of seismic and damping measures in logistics warehouses and to the improvement of business continuity through reduced construction costs.

Related Information

Folded Plate Buckling Restrained Brace (FP-BRB®) (Our Website "Technology and Services" > List of Building Technologies)