How Is UHPC Shaping Integrated with Metal Components? Dissimilar Material Symbiosis and Qinglong Group's Refined Connection Design

The efficient and durable combination of UHPC shaped elements with metal components (such as steel frames, aluminum alloy trim, and stainless steel decorative pieces) is a common construction challenge in modern architecture. Its core lies in solving four major problems: "differences in material performance, deformation compatibility, durability matching, and visual finishing." Through practice, Qinglong Group has developed four categories of mature methods—"embedded connection, post-installed anchoring, clip connection, and adhesive composite bonding"—while strictly adhering to the principles of "calculate before connecting, flexible adaptation, anti-corrosion insulation, and fine construction." In the Wuhan Han Show Theatre project, the red UHPC double-curved panels and the complex internal steel truss support system achieved safe and reliable connection at more than 9,000 connection points through pre-embedded stainless steel sleeves and welded plates, standing the test of many years. For combining dissimilar materials, the essence lies in "harmony in diversity."

Embedded Connection: The Most Reliable Structural Bonding Method

Before UHPC casting, metal parts with threads or openings (such as steel plates, sleeves, and threaded rods) are precisely embedded in place. This requires UHPC to have high bond strength and low shrinkage to ensure the embedded parts do not loosen. We use finite element analysis to determine stress concentration around the embedded parts, and set reinforcement bars or increase local fiber content. This method offers high connection strength with no exposed bolts, but demands extremely high production precision.

Post-Installed Anchoring: A Flexible On-Site Solution

Holes are drilled in hardened UHPC elements, which are then connected to metal components via chemical anchors or high-strength bolts. Key technical points include: 1) drilling precision, to avoid splitting damage to the UHPC; 2) selecting special chemical adhesives suitable for UHPC substrates; 3) conducting on-site pull-out tests to verify anchorage capacity. We generally require an anchorage depth of no less than 8 times the bolt diameter, and use torque wrenches to control the preload.

Flexible Adaptation and Deformation Compatibility Design

UHPC and metals have different coefficients of linear expansion (UHPC approx. 10-12×10⁻⁶/°C, steel approx. 12×10⁻⁶/°C, aluminum approx. 23×10⁻⁶/°C), producing relative displacement under temperature changes. Connection joints must be designed as "flexible" or "slidable," such as using slotted-hole bolt connections, installing elastic gaskets, or employing hinged joints, to release thermal stress and prevent cracking caused by restraint forces.

Anti-Corrosion and Insulation Treatment for Long-Term Durability

When different metals (such as carbon steel bolts and stainless steel hangers) come into contact, there is a risk of electrochemical corrosion. Insulating washers (such as nylon or plastic) must be added between contact surfaces. All exposed metal parts require high-level anti-corrosion treatment (such as hot-dip galvanizing and fluorocarbon coating). In coastal environments with high salt spray, we give priority to connection systems made of the same material (such as all-stainless steel).

Successful combination of dissimilar materials is the culmination of precise calculation, refined detailing, and accurate construction. Qinglong Group's structural engineers and detail designers work closely together to provide safe, aesthetic, and durable customized solutions for every UHPC-metal connection joint.