Introduction
Prefabricated buildings involve complex connections—not only between various component types but also between different materials, interfaces between the main structure and decorative elements, and new challenges faced by equipment professionals in the prefabrication industry.
This article focuses primarily on connections between concrete components.
Leading European manufacturers of precast concrete structure connectors offer mature products and systems in this field. Let’s explore some of the prominent solutions below.
HALFEN Group
Founded in Düsseldorf, Germany in 1929, HALFEN has evolved over nearly a century to provide a wide range of product lines, including:
Concrete anchoring systems, curtain wall support systems, steel reinforcement and connection systems, precast concrete components, frame assembly systems, and hoisting systems.
As a well-established manufacturer of prefabricated concrete structural connectors, HALFEN offers many innovative products that are valuable for advancing residential and industrial prefabrication.
HALFEN Grooves
One of HALFEN’s core products, the HALFEN groove, refers broadly to all groove-embedded parts.
Product Features
HALFEN groove embedded parts are compact, lightweight, and possess high load-bearing capacity. Their key feature is adjustability, which is crucial for the installation and use of prefabricated assembly components.
Applications and Installation Methods
In Germany, the use of HALFEN groove embedded parts is standardized in design atlases, making it a convenient method for designers. Typical applications include:
▲ Connection between prefabricated walls and slabs or beams
▲ Connection between prefabricated walls
HALFEN groove embedded parts are secured using T-bolts, allowing adjustments in all directions—up, down, left, and right—without the need for on-site welding. Compared to traditional plate embedded parts, this method reduces installation time. The HTA and HZA series are commonly used in curtain wall applications.
▲ Installation and application of HALFEN grooves in curtain walls
The HALFEN groove embedded part consists of a C-shaped channel steel with two or more anchor nails or bolt fasteners fixed to the back (see Figure 1).
▲ Figure 1: Finished HALFEN groove embedded parts
Foam or strip filler materials placed inside the C-shaped channel prevent concrete or debris from entering during pouring. Before concrete placement, the embedded part is positioned as per design, anchor nails are tied to beam reinforcement, and the concrete surface is leveled. Figure 2 shows the groove after concrete pouring.
Once the main structure is complete and curtain wall installation begins, the foam filler is removed from the channel, and a special T-shaped bolt (Figure 3) is inserted. The angle steel is fixed using matching nuts and washers, allowing curtain wall frames to be installed (Figure 4).
▲ Figure 2: Channel steel after concrete pouring
▲ Figure 3: Appearance after removing foam filler
▲ Figure 4: Installation effect
Case Study
The Shanghai World Financial Center, standing at 492 meters, is currently the second tallest building in Shanghai and the seventh tallest worldwide (as of 2013). Opened on August 28, 2008, the project was designed by Kohn Pedersen Fox, an American architecture firm, in collaboration with East China Architectural Design and Research Institute Co., Ltd. HALFEN supplied HTA type channel steel for this iconic project.
The building’s exterior walls, structural elements, and static systems employ modular designs repeating every 13 floors. This approach maximizes the effectiveness of HALFEN HTA channel steel, offering excellent adjustability and significantly reducing construction time and costs, ultimately enabling rapid assembly of highly prefabricated structures.
HALFEN FPA Wall Panel Anchors
Product Features
HALFEN wall panel anchors allow for quick and efficient installation of concrete exterior wall panels onto concrete or steel frame structures. These anchors serve as external attachments for concrete slabs and connect to the main structure through pre-embedded slots or anchor bolts. All pre-installation works can be performed on the ground, enabling easy lifting and installation with minimal labor.
Case Study
This product was used in the La Marseillaise office building in Marseille, France, a 135-meter-high tower with a net floor area of 39,560 square meters. The facade consists of 3,850 independent Ultra High Performance Fiber Reinforced Concrete (UHPFRC) sunshade units and features 16,000 square meters of glass panels. The project extensively utilized the HALFEN SPA system, completing all sunshade installations in under eight months.
Peikko Group
Established in 1965, Peikko is a Finnish company specializing in concrete connectors and reinforcement technologies, as well as thin floor composite beam solutions. Their product range includes over 20 types, such as column base connectors, Delta composite beams, reinforced embedded plates, and more.
Peikko Column Base Connectors
Peikko’s HPKM, PPKM, and PEC column base connectors are fastening products designed to provide rigid moment connections between prefabricated columns or between columns and foundations.
Using these connectors and anchor bolts, all structural forces are transmitted effectively to the load-bearing foundation. Prefabricated columns are fixed to anchor bolts embedded in the base structure, with nuts and washers securing the connection. This system allows precise adjustment of column height and alignment. After installation, the joint between the column base and foundation is grouted promptly, forming a reinforced concrete composite with the connectors.
▲ Column base connection seat and anchor bolt
The number of column base connectors depends on column size, applied loads, concrete strength, and connector type. Typically, four connectors suffice to achieve rigid moment connections.
▲ Installation of column base connection seat during prefabrication
On-site Prefabricated Column Installation:
- Installation level is set using the nut top surface or a steel plate positioned under the column base.
- After bolts are tightened with a torque wrench, the crane can release the column.
- Installation must follow the approved plan.
- Grouting uses non-shrink materials with strength reaching at least 70% of the column’s concrete grade.
▲ Installation of prefabricated columns on site
▲ Application example diagram
Peikko Delta Composite Steel Beam
The Delta composite steel beam is a hollow steel-concrete composite beam fabricated by welding steel plates, featuring circular holes on both sides of the web. After installation, the beam is fully filled with concrete on-site.
Function: The Delta beam acts as a composite beam either combined with hollow floor slabs or thin shell laminated floor slabs, which are then cast in place.
Delta composite steel beams achieve a fire resistance rating of R120 without additional fire protection.
▲ Composite steel beam
Application Method
Combining Delta composite steel beams with prefabricated floor slabs enables optimal structural layouts, achieving frame column grids of 12m x 12m or 8m x 16m. These beams are lightweight, quick to install, and integrate easily with other components, reducing floor-to-floor height by up to 500mm. This allows for efficient use of building space and energy savings. Delta beams are ideal for office buildings, schools, hospitals, administrative centers, and parking structures.
▲ Delta composite steel beams combined with thin shell composite panels and hollow floor slabs
Delta beams can also be used with cast-in-place concrete floor slabs; in these cases, straight beams are preferred over arched beams, and the bottom formwork of the slab aligns flush with the bottom of the composite beam. For longer spans, Delta beams can be installed on the underside of concrete slabs to enable thin floor systems.
Delta beams combined with lightweight prefabricated concrete components and cast-in-place floor slabs
JORDAHL, Germany
Founded in Berlin in 1907, JORDAHL operates in concrete, steel reinforcement, and heavy-duty reinforcement products. JORDAHL® anchoring steel channels have become milestones in structural engineering development. Their portfolio includes approximately 18,000 products suitable for construction, tunnels, civil engineering, sports venues, infrastructure, and framework systems. Most products carry European Technical Assessment (ETA) or general building certifications.
JORDAHL® JVB-V Connectors
Product Features
JORDAHL® JVB-V connectors are ideal for joining prefabricated concrete components such as columns and walls. They combine anchoring channels and screws into a fast, easy-to-install fastening solution that requires no on-site welding or mortar grouting. The system allows flexible alignment of components and compensation for construction tolerances via adjustable blades.
▲ Application of JORDAHL® JVB-V connectors
Learning from International Experience and Adapting to Local Needs
Various types of prefabricated concrete component connectors exist with extensive BIM applications. However, China currently lacks unified standards and design parameters for these connectors, leading to inconsistent design choices and inspection challenges. The government and industry players have begun researching and developing relevant standards.
After thorough experimental research, it is recommended that the industry compiles comprehensive product manuals and software tools based on European precast concrete connector manufacturers’ expertise to aid designers in product selection.
▲ HALFEN Group Product and Application Manuals
HALFEN software assists customers with accurate dimensioning and selecting the correct product combinations.
▲ Peikko Group Product and Application Manuals
▲ Peikko Group Application Software
▲ JORDAHL Product Manual
JORDAHL also provides free design assistance software, containing all essential information for the planning process.
By consolidating existing engineering experiences and referencing international standards, we can develop product and engineering standards for prefabricated component connectors tailored to China’s specific conditions.
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