Connection Joint Design Between UHPC Curtain Wall Panels and Steel Frame Keels: Code Requirements and Optimization Solutions

The connection nodes between UHPC curtain wall panels and steel frame keels are the core load-bearing components of the curtain wall system, and their design directly affects the safety, stability, and durability of the curtain wall. With 28 years of experience in detailed curtain wall engineering design and participation in formulating the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC), Qinglong Group has summarized the node design principles of "strength matching, seismic adaptation, corrosion resistance and durability, and ease of construction", successfully completing complex projects such as the Guangxi New Media Center and Shanghai New World with zero-failure operation of connection nodes.

I. Core Node Types and Design Specifications

Dry-hanging nodes (the most widely applied): divided into short-slot, back-bolt, and through-slot types. Short-slot nodes: a short slot (100-150mm in length, 15-20mm in depth) is cut at the edge of the UHPC panel and connected to the steel frame keel via stainless steel hangers, with a single-node pull-out bearing capacity ≥5kN, suitable for small and medium-sized panels (area ≤6m²). Qinglong selected this node for the Shenzhen Yirui Biotechnology Building for its ease of installation and controllable cost. Back-bolt nodes: special back bolts (8-12mm in diameter) are inserted into the back of the UHPC panel and connected to the keel, with a pull-out bearing capacity ≥8kN, suitable for large panels (area ≥6m²) and high-rise projects. The 12m² UHPC panels at Shanghai New World adopt this node, providing strong connection reliability. Through-slot nodes: continuous slots are cut along the top and bottom edges of the panel and slideably connected to the keel through full-length hangers, allowing slight deformation of the panel, suitable for curved and double-curved panels. The double-curved UHPC panels at the Guangxi New Media Center adopt this node, accommodating the deformation requirements of complex shapes.

II. Key Technical Requirements for Node Design

Strength matching: the node bearing capacity must be ≥1.5 times the sum of the component's self-weight and external loads (wind loads and seismic action). The stainless steel hangers (SUS304/SUS316) and back bolts selected by Qinglong have a tensile strength ≥400MPa, meeting high-strength requirements. Seismic adaptation: elastic gaskets (such as neoprene pads, 3-5mm thick) are installed to absorb seismic energy, with nodes allowing horizontal displacement of ±5mm and vertical displacement of ±2mm. For projects in seismic fortification zones, Qinglong's design ensures that node seismic performance meets the fortification intensity 8 requirement. Corrosion protection: all metal connectors (hangers, back bolts, and bolts) are treated with hot-dip galvanizing plus an anti-corrosion coating (galvanized layer thickness ≥85μm) to prevent electrochemical corrosion. For projects in the high salt-fog environment of Hainan, Qinglong adopted SUS316 stainless steel connectors with a service life ≥50 years. Construction convenience: node design must facilitate on-site installation and adjustment, with fine-tuning devices (adjustment range ±5mm) installed between hangers and keels. Qinglong's quick-install nodes enable a single panel to be installed in ≤30 minutes, improving construction efficiency.

III. Qinglong's Node Optimization Technologies and Innovative Solutions

Finite element analysis optimization: node stress states are simulated using ANSYS software to optimize hanger positions and dimensions and reduce stress concentration. After optimizing the nodes for a super high-rise project, Qinglong reduced the maximum stress by 25%. Modular node design: standardized node modules are designed for different panel types (flat panels and special-shaped panels) to improve versatility and construction efficiency; Qinglong's modular nodes can adapt to more than 80% of UHPC curtain wall panel types. Anti-detachment design: anti-detachment devices (such as clips and limit pins) are installed at the connections between hangers and panels, and between hangers and keels, to prevent panels from falling under extreme conditions. Qinglong's anti-detachment nodes have obtained invention patents and are applied in multiple public building projects. Engineering verification: the connection nodes of the double-curved UHPC panels at the Guangxi New Media Center, tested by a third party, achieved a pull-out bearing capacity of 12kN and a shear bearing capacity of 8kN, with displacement capacity meeting design requirements, and passed 100,000 fatigue tests without damage.

IV. Node Construction and Quality Control

Detailed node design: node dimensions are adjusted according to the actual deviations of the steel frame keels to ensure proper fit. Qinglong uses BIM technology for node detailing, precisely aligning with the keel model with an error ≤2mm. Installation process specifications: connectors must be installed vertically and securely, with torque wrenches controlling bolt tightening torque (≥40N·m); elastic gaskets must be installed flat, without damage or offset. Qinglong implements a "node sample first" system during construction, proceeding to batch installation only after the first panel's node installation passes inspection. Quality inspection: after installation, nodes are spot-checked for pull-out and shear performance (spot-check ratio ≥3%), and the next process may proceed only after passing inspection; node conditions are regularly inspected afterward, with any loosening or corrosion addressed promptly. Qinglong's after-sales maintenance system includes dedicated node inspection services.

The design of connection nodes between UHPC curtain wall panels and steel frame keels is the core guarantee of curtain wall system safety. Qinglong Group always adheres to the principle of "safety and reliability, striving for excellence". With profound technical expertise, innovation capability, and engineering practice, Qinglong provides scientific and sound node design and construction solutions for various projects, ensuring the long-term stable operation of the curtain wall system.