The design of casement window frames requires coordinated optimization across multiple dimensions, including profile strength, structural form, connection technology, hardware system, drainage design, and installation specifications, to systematically improve wind pressure resistance.
Profile selection is fundamental to wind pressure resistance. Thermally broken aluminum alloy profiles are preferred, as their tensile and yield strengths are significantly higher than ordinary aluminum alloys, effectively resisting bending deformation caused by wind pressure. Profile wall thickness must meet specifications: the main profile wall thickness for exterior windows should be ≥1.4mm, and for exterior doors ≥2.0mm, ensuring structural rigidity. Simultaneously, a multi-cavity structural design is employed, using internal partitions to enhance overall rigidity and reduce the risk of deformation under wind pressure. For high-rise buildings, 6063-T5 or 6061-T6 alloy materials can be selected, offering superior mechanical properties to meet wind pressure resistance requirements under extreme weather conditions.
Structural form optimization should focus on the force transmission path. The connection between the casement window frame and the mullion is a critical point for wind pressure resistance. Traditional welding methods easily lead to stress concentration at the corners. A bolted connection can replace welding, improving connection strength. For large casement windows, a reinforced mullion is required, dividing the single window sash into multiple load-bearing units to distribute wind pressure loads. Furthermore, expansion bolts should be used to secure the window frame to the wall, with a bolt spacing ≤600mm and a spacing ≤300mm at corners, ensuring a secure connection between the window frame and the building structure and preventing window frame displacement due to wind pressure.
Improving the connection process is key to enhancing wind pressure resistance. The frame-sash connection should employ a dual process of "pins + adhesive injection." Pins provide mechanical fixation, while adhesive fills the gaps, enhancing the shear strength of the connection joint. Simultaneously, a reinforcing steel lining with a thickness ≥1.5mm should be added inside the window frame, tightly fitting into the profile cavity to form a composite load-bearing structure. For concealed hinge installations, cutting the sealing strip should be avoided to maintain the integrity of the connection, improving stability and wind pressure resistance.
The selection of hardware systems directly affects wind pressure resistance. Key components such as hinges, handles, and transmission mechanisms must meet national standards. A single hinge should have a load-bearing capacity of ≥80kg to ensure stable support of the window sash under strong winds. Hardware materials should be 304 stainless steel, rust-proof and corrosion-resistant, and will not fail over long-term use, preventing displacement of the window frame and sash due to loose hardware. In addition, limit wind braces can be configured, using adjustable damping structures to limit the opening angle of the window sash, preventing violent opening and closing under strong wind pressure and improving safety.
Drainage design is crucial in conjunction with wind pressure resistance. Wind pressure can cause rainwater backflow, requiring a "three-layer sealing" design: the first layer is a EPDM rubber strip seal at the frame-sash overlap to prevent rainwater from entering; the second layer is a seal at the drainage holes in the profile cavity to ensure timely drainage of any rainwater entering the cavity; the third layer is a seal of expanding foam and weather-resistant adhesive between the window frame and the wall to enhance overall waterproofing. Drainage holes should be fitted with dust caps to prevent blockage by debris, ensuring smooth drainage and preventing structural corrosion caused by water accumulation. Installation specifications are crucial for ensuring wind pressure resistance. Before installation, the specifications of doors and windows must be checked against the opening dimensions; deviations should be ≤5mm, and wall flatness deviations ≤3mm. A "dry installation" process is used: first, the window frame is fixed to the pre-embedded parts in the opening, adjusting for horizontal and vertical deviations ≤2mm; then, expanding foam is filled, and finally, weather-resistant sealant is applied. After installation, wind pressure resistance testing is required to simulate wind pressure loads, ensuring that the doors and windows are free from deformation and leakage, and that the sashes open smoothly without jamming.
Through profile reinforcement, structural optimization, improved connections, upgraded hardware, drainage coordination, and adherence to installation specifications, the casement window frame structure design systematically enhances wind pressure resistance, meeting the needs of high-rise buildings and extreme weather conditions.
