How to Achieve the Integration of UHPC Shapes with Metal Components?

Combining UHPC shapes with metal components is a common technical junction in modern architecture for achieving material mixing, functional integration, and mechanical complementarity; the key to success lies in the systematic handling of "connection design, embedding workmanship, tolerance control, and anti-corrosion insulation." Qinglong Group has developed a mature UHPC-metal composite connection technology system across various projects, aiming to achieve combined results that are "structurally reliable, finely crafted, and durable and attractive." In projects such as the GRC curtain wall of Poly Peninsula No.1 in Hainan, we successfully met the challenge of strong wind loads in coastal regions through reliable connections between built-in structural steel frames and UHPC panels.

Scientific connection design is the foundation for ensuring a clear load transfer path. UHPC-to-metal connections fall into two main types: the first is the "embedded insert type," in which stainless steel sleeves, anchor bolts, or connection plates are pre-embedded when the UHPC is cast, working through both bonding force and mechanical interlock, and is suitable for transferring larger concentrated loads; the second is the "post-installed anchoring type," in which post-installed anchors are fitted by drilling after the UHPC has hardened, suitable for on-site adjustment or reinforcement. The design requires detailed structural calculations to ensure that the number, specifications, and layout of the connectors can safely transfer wind loads, dead weight, and seismic actions, while also accounting for fatigue and impact effects.

Precise embedding workmanship is the core link in guaranteeing connection strength. The positioning accuracy of embedded components is critical. In factory production, Qinglong uses customized positioning fixtures to precisely fix the embedded components to the molds, ensuring their positional deviation within the UHPC is less than 2mm. During casting, direct impact of vibrators on the embedded components must be avoided to prevent displacement. For composite components of large metal frames and UHPC, "secondary casting" or "layered casting" processes are commonly adopted to ensure the metal frame is fully encapsulated by the UHPC, forming a solid integral unit.

Precise tolerance control and flexible detailing are key to absorbing deformation. UHPC and metal (especially steel) have different coefficients of linear expansion, producing different deformations as temperatures change. Therefore, appropriate expansion allowance must be reserved in connection joint design, or sliding details such as slotted (obround) holes should be adopted. At the same time, a three-dimensionally adjustable bracket system must be set up during installation to absorb structural and installation tolerances, achieving accurate panel positioning and flatness control.

Rigorous anti-corrosion and insulation treatment is essential for long-term durability. In humid environments, contact between UHPC (alkaline) and certain metals (such as ordinary steel) may trigger electrochemical corrosion. Therefore, insulating gaskets (such as nylon or rubber pads) must be provided at contact surfaces. All exposed metal connectors should be made of 316 stainless steel or given heavy-duty anti-corrosion treatment such as hot-dip galvanizing. After assembly, joints must be sealed with high-elasticity weather-resistant sealant to prevent moisture and corrosive media from penetrating. Through these systematic measures, UHPC and metal can achieve a powerful alliance in which each brings out the best in the other.