In commercial building curtain wall engineering, the dry-hanging method for stone curtain walls requires multi-dimensional technical means to ensure structural safety. Its core lies in constructing a stable and durable curtain wall system through scientific design, rigorous material selection, and meticulous construction techniques. The essence of dry-hanging technology is to create a flexible connection between the stone and the main building structure using metal hangers. This avoids the problems of hollowing and detachment caused by adhesive aging in traditional wet-laying processes. Simultaneously, reasonable mechanical design disperses external loads such as wind pressure and earthquakes, ensuring the safety of the curtain wall during long-term use.
Among the dry-hanging methods for stone curtain walls, the back-bolted dry-hanging method is widely used due to its superior mechanical performance and safety. This method involves precisely machining conical holes on the back of the stone, inserting anchor bolts, and screwing in threaded rods. The bottom of the anchor bolt forms a stress-free convex connection with the hole wall, and then the stone is fixed to the keel using connectors. This connection method evenly distributes the load across the entire stone, avoiding the risk of stone cracking caused by localized stress concentration in traditional slotted dry-hanging methods. Meanwhile, the point-connection design of the back-bolted dry-hanging system allows the stone to expand and contract freely with temperature changes, effectively reducing internal stress caused by thermal expansion and contraction, and preventing structural deformation or cracking due to stress accumulation.
The selection and processing precision of metal hangers are another key factor in ensuring the safety of the dry-hanging structure. High-quality aluminum alloy or stainless steel hangers must possess high tensile strength and corrosion resistance. For example, anodized aluminum alloy hangers can achieve a tensile strength of up to 320 MPa, far exceeding industry standards. The processing precision of the hangers must be controlled within ±0.15 mm to ensure a tight, gapless fit with the stone and keel, avoiding excessive local loads due to installation errors. Furthermore, the hanger design should consider three-dimensional adjustability, achieving flexible connections through elastic pads or bushings, further enhancing the seismic performance of the curtain wall and adapting to the seismic fortification requirements of different regions.
The stability of the keel system directly affects the overall safety of the curtain wall. The specifications of the main keel (such as channel steel) need to be determined comprehensively based on the building height, wind load, and weight of the stone. Generally, 5# to 8# channel steel is used, with spacing matching the stone's grid dimensions. Secondary keels (such as angle steel) must form a rigid grid with the main keel, connected by welding or bolts to ensure structural integrity. The connection between the keel and the building structure must be achieved through embedded parts or post-installed anchors. The tensile and shear strength of the anchors must be verified through pull-out tests to ensure they will not detach from the main structure under extreme weather or earthquake conditions. For super high-rise buildings, wind pressure-resistant hanging systems and thermal deformation compensation devices are also required to cope with the challenges posed by strong winds and temperature variations.
The selection and processing quality of the stone are fundamental to the safety of the curtain wall. Stone used for dry hanging must have sufficient thickness and strength. Generally, granite is no less than 25mm thick. Marble, due to its lower strength, requires back reinforcement or the use of thicker slabs to enhance stability. During stone processing, ultrasonic testing is used to eliminate internal cracks. CNC bridge cutting ensures a thickness error of no more than ±0.3mm. Edge treatment creates protective ridges to prevent damage during transportation. Furthermore, a special protective agent is applied to the back of the stone to form a nano-level hydrophobic film, reducing water absorption to below 0.01% to prevent strength loss due to freeze-thaw cycles or moisture penetration.
The meticulous construction process is the final line of defense for curtain wall safety. Dry-hanging construction must follow the principle of "installing from bottom to top, layer by layer." Before installation, each stone slab must be positioned using laser marking to ensure verticality and flatness. Special structural adhesive must be used to connect the hangers to the stone, and the width and depth of the adhesive joint must meet design requirements to avoid bonding failure due to an insufficiently thin adhesive layer. After installation, a comprehensive inspection is required, including a sway test to verify the hanger's stability. Loose or displaced stones are promptly adjusted and reinforced. Additionally, elastic sealant is injected at curtain wall joints, allowing for ±5mm of thermal displacement without cracking to prevent internal corrosion caused by rainwater leakage.
In commercial building curtain wall engineering, the dry-hanging method of stone curtain walls requires the comprehensive application of back-bolted connections, high-precision hangers, a stable keel system, high-quality stone selection, and rigorous construction techniques to construct a multi-layered safety protection system. This system can not only effectively resist external loads such as wind pressure and earthquakes, but also adapt to environmental factors such as temperature changes and humidity fluctuations, ensuring that the curtain wall maintains structural stability and functional integrity during long-term use, providing a safe and durable facade solution for commercial buildings.
