Systematic Solution to Thermal Expansion and Contraction Issues in UHPC Curtain Walls

Thermal expansion and contraction of UHPC curtain walls is a key factor affecting long-term service safety, requiring systematic solutions across multiple dimensions including materials, design, and construction. Based on 28 years of engineering practice, Qinglong Group believes that high-quality UHPC curtain walls should be able to adapt to temperature variations from -30°C to 70°C, with the linear expansion coefficient controlled within 8-10×10⁻⁶/°C. Through scientific joint design, optimized connection nodes, and material modification, thermal stress can be effectively released, preventing cracking or deformation.

Joint design is the primary measure for temperature compensation. The expansion amount is calculated based on the local maximum temperature difference, and the joint width is generally set at 1.5 times the thermal deformation. In the Shenzhen Yirui Biotechnology Building project, addressing an environment with an annual temperature difference of 40°C, Qinglong Group set the panel joint width at 15mm to ensure sufficient deformation space. For extra-long walls, expansion joints are installed at intervals of no more than 15m to prevent excessive cumulative deformation. The joints are filled with elastic sealant and backed with closed-cell foam rods, forming a flexible connection system. This design allows the curtain wall to expand and contract freely with temperature changes without generating internal stress.

Optimized connection nodes allow slight displacement. Slotted hangers with oblong holes are used, allowing ±5mm horizontal displacement and ±3mm vertical displacement. In coastal projects, Qinglong Group developed a spherical hinge connection system to accommodate multi-directional deformation. Elastic washers are installed at hanging points to avoid rigid contact. Through finite element analysis, the hanging point layout is optimized, reducing the thermal stress concentration factor to below 1.5. This flexible connection ensures structural safety while adapting to temperature changes.

Material modification reduces temperature sensitivity. By incorporating polypropylene fibers (0.1% by volume) and optimizing aggregate gradation, the thermal expansion coefficient is lowered. In northern region projects, Qinglong Group used low-heat cement to reduce the temperature rise caused by hydration heat. Light-colored reflective coatings are applied to the surface, reducing panel surface temperature by 10-15°C. These measures work synergistically, keeping UHPC curtain walls stable under various climatic conditions.