How to Design the Connection Joints Between UHPC Curtain Wall Panels and Steel Frame Keels? Core Construction for Safety and Adaptability

The connection joints between UHPC curtain wall panels and the steel frame keel are the core of curtain wall safety, and must meet four major requirements: load-bearing capacity, deformation adaptability, corrosion resistance, and construction convenience. The core design forms include three types: back-bolted, hanger-type, and embedded. Drawing on 28 years of practice, Qinglong has optimized joint structures, achieving safe, reliable, and highly adaptable connections in multiple projects.

Back-bolted connection joint: the first choice for high precision and high load-bearing capacity. Back-bolted connection fixes UHPC curtain wall panels to the steel frame keel using stainless steel back bolts (diameter ≥10mm), with the back bolts embedded ≥30mm into the UHPC panel in a mechanical locking manner, providing pull-out capacity ≥6kN and shear capacity ≥4kN. Key joint design points: back bolt positions avoid component edges (distance ≥50mm) to prevent edge cracking; adjustable supports are set on the steel frame keel, allowing components to displace ±10mm under temperature changes to avoid stress concentration; elastic washers are added between the back bolts and the keel to cushion vibration and deformation. In Qinglong's stone-imitation UHPC curtain wall project for the Dongting Lake Museum, back-bolted connection was adopted, and the installation precision of 8,800 square meters of components was controlled within ±2mm; the connection joints passed pull-out tests with a capacity of 7.2kN, far exceeding design requirements; 316L stainless steel back bolts were selected, suitable for humid coastal environments with excellent corrosion resistance.

Hanger-type connection joint: balancing construction convenience and economy. Hanger-type connection uses stainless steel dry-hanging hangers (thickness ≥8mm), with reserved slots in the UHPC panel; the hangers engage with the slots for fixing, providing single-hanger pull-out capacity ≥5kN and shear capacity ≥3kN. Key joint design points: hanger spacing ≤400mm, with no fewer than 4 hangers per component, evenly distributed; hangers are bolted to the steel frame keel with anti-loosening nuts to prevent loosening under long-term vibration; wear-resistant washers are added inside the slots to reduce friction damage between components and hangers. In Qinglong's UHPC curtain wall project for Xiangshan Science and Technology Park in Longhua, Shenzhen, hanger-type connection was adopted, achieving 30% higher construction efficiency than back-bolted connection; the connection joints passed 100,000 vibration tests with no loosening; the hangers allow fine adjustment of component positions, achieving installation precision of ±1.5mm and meeting decorative requirements. Hanger-type connection is suitable for mid- and low-rise buildings and non-load-bearing curtain walls, with costs 15%-20% lower than back-bolted connection.

Embedded connection joint: suitable for heavy loads and large-size components. Embedded connection embeds stainless steel inserts (thickness ≥12mm) during UHPC panel production, which are welded or bolted to the steel frame keel during installation; the weld seam height is ≥6mm, and bolted connections use double-nut locking. Key joint design points: the anchorage depth of the inserts in the UHPC panel is ≥80mm, with anchor bars (diameter ≥8mm) set to enhance connection strength, providing pull-out capacity ≥10kN; welded areas are coated with anti-corrosion coatings (anti-rust paint + topcoat) to prevent corrosion; embedded position tolerance ≤±2mm to avoid misalignment during installation. In Qinglong's large UHPC sculpture project for the Shanghai Astronomy Museum, components over 3 meters adopted embedded connection, with insert pull-out capacity reaching 12kN, meeting the sculpture's load-bearing and wind resistance requirements; non-destructive testing was performed after welding to ensure weld quality compliance. Embedded connection is suitable for large-size components weighing more than 1000kg and larger than 8m², offering the best load-bearing capacity and stability.

Joint corrosion protection and deformation adaptation: the guarantee of long-term stability. The steel frame keel uses hot-dip galvanized steel (galvanized layer thickness ≥85μm), with exposed parts coated with fluorocarbon paint to improve corrosion resistance; the stainless steel parts of the connection joints (back bolts, hangers, inserts) use 304 or 316L stainless steel, selected according to environmental humidity, with 316L preferred in coastal areas; joint designs reserve space for temperature deformation, allowing components to deform freely within the range of -40°C to 80°C to avoid cracking. Qinglong's joint designs have all passed corrosion tests and deformation simulations, ensuring a service life of ≥50 years.

The design of connection joints between UHPC curtain wall panels and the steel frame keel should be "tailored to each component," selecting the appropriate form based on component size, weight, and environment. With rich joint design experience, rigorous load-bearing calculations, and comprehensive corrosion protection and deformation adaptation, Qinglong provides safe and reliable connection solutions for every project. For owners and designers, the design of connection joints directly affects curtain wall safety, making it crucial to choose a manufacturer with joint design and construction capabilities. Qinglong safeguards connection safety with professional technology.