The construction and development of modern cities have given birth to the development of modern architecture, and commercial buildings have become the main components of urban architecture, especially in relatively developed cities, more attention has been paid to office buildings. Glass curtain walls have become the main materials used in the construction of modern office buildings. Due to the gradual increase in large-scale office buildings at this stage, people's requirements for office buildings have gradually increased, and the application of super-large glass curtain walls has appeared. How to rationally apply super-large glass curtain walls in office buildings has become a key factor in determining the quality and aesthetics of office buildings. In this article, LIJIANG Glass will discuss the design points of super large glass curtain walls of office buildings from multiple angles based on examples.
glass curtain wall building;
super large glass curtain wall;
key points of architectural design
Glass curtain wall is a new type of building material, which is widely used in office buildings and other buildings. Through the application of glass curtain walls, a bright, transparent, and comfortable office environment can be created. At the same time, the overall structure of the glass curtain wall is lighter and its structural performance is superior. Based on this, glass curtain walls are loved by people in the construction industry, especially after the appearance of super-large glass curtain walls, they were quickly applied to high-end office buildings, creating a high-quality look and feel. At this stage, some developing countries still lack sufficient experience in the application of super-large glass curtain walls, and the design points are not grasped precisely enough. It is necessary to continuously deepen the research on the design of super-large glass curtain walls in office buildings to support the design of physical buildings.
1. The usable range and main forms of super-large glass curtain wall
In the envelope system of the office building, the external decorative structure of the glass curtain wall can be seen. Compared with traditional exterior decorative components, the glass curtain wall has obvious advantages of high structural strength, good material durability, and light weight. In recent years, the design concept of "design combined with nature" has emerged in the construction industry, while focusing on creating a modern office environment. Super-large glass curtain walls are more commonly used in modern high-end office buildings. Combined with engineering experience, under normal conditions, the maximum size of any single side in the length and width of the building grid is greater than 2 meters, which can be called a super large glass curtain wall. From the perspective of the area, the curtain wall with an overall area of more than 3m2 can also be called It is a super large glass curtain wall. At this stage, the commonly used super large glass curtain walls include full glass curtain walls, point glass curtain walls, exposed frame glass curtain walls, and hidden frame glass curtain walls, etc.
Figure 1 The commonly used super large glass curtain walls 1
2. The design points of super large glass curtain wall of the office building
2.1 Basic structure design
The glass curtain wall itself has good earthquake resistance and has a certain dynamic load effect. The performance of the above performance needs to rely on the main structure or supporting structure to achieve effective transmission. Based on this, it is necessary to scientifically design the supporting structure of the super-large glass curtain wall, and the design of the column structure requires foundation and important content. Pay attention to the stiffness and strength of the column structure to ensure that the actual design load requirements are met and the overall stability of the structure is improved. And pay attention to the design of the upper and lower connection of the column structure to ensure an orderly and stable connection. Furthermore, to scientifically design embedded parts, including anchor bars or anchor plates, etc., they should be designed as channel-shaped glass curtain walls or flat-shaped glass curtain walls. Some projects need to design post-embedded parts. At this time, metal expansion or anchor plates should be used. The basic form of chemical anchors. The above-mentioned structural design should meet the service life requirements of the super-large glass curtain wall and the overall structure. The aluminum keel material is a commonly used material for the current glass curtain wall support system. The support system of the super-large glass curtain wall structure mainly includes beams connected with the vertical columns of the main body and horizontally connected. The relatively small ones are horizontal connecting beams, and the supporting keel system should be designed in a targeted manner in combination with the actual conditions of the beams and the stress characteristics of the super-large glass curtain wall.
2.2 Glass panel design
When designing super-large glass curtain wall panels, it is necessary to consider the two factors of panel strength and panel stiffness. Super-large glass curtain walls are commonly used as tempered glass. When adjusting its strength, it should rely on panel glass thickness adjustment to achieve strength adjustment. For large-sized glass curtain walls, which have strong deflection, it is difficult to achieve effective control, and the calculation should refer to the specific conditions of the boundary support to achieve accurate calculation. Software such as SAP2000 can be used to improve calculation accuracy and efficiency, and further obtain accurate glass panel stress values and deflection control values to ensure that the designed super large glass curtain wall panels are reasonable and applicable.
2.3 Curtain wall connection design
When designing a super-large glass curtain wall, the designer should always pay attention to the vertical bearing capacity of the contact part between the glass panel and the beam. The specific method is to identify each joint of the aluminum profile and strengthen the aluminum corner operation to improve stability. Set the rubber pad between the glass and the keel to ensure good flexible contact between the two and reduce stress concentration. At the same time, pay attention to the length of the rubber pad installed under the glass. The designer should control it to 100MM. Foam rods can be filled between the panel and the keel to further improve its sealing performance. Specifically, wet sealing can be used.
2.4 Fire protection design
Some building curtain walls do not have window sill walls. When designing fire protection for them, you should first find the outer edge of each floor and set up solid walls here to ensure that the height is higher than 0.8m or set up fireproof glass curtain walls. Secondly, it is necessary to ensure that the fire resistance limit of the curtain wall exceeds 1h and control the same glass unit to prevent it from crossing two fire protection zones. Accordingly, an independent design should be done. When setting up the fire-blocking system, it should be ensured that it has good durability, tightness, and strong deformation resistance. To simultaneously set up the protective surface layer, non-combustible materials and fireproof coatings should be used in it. The fireproof protective surface layer should be set between the glass curtain wall and the floor slab. In addition, it should also be set at the part of the opening of the outer wall. Furthermore, There may be gaps between the structure and other fire isolation components, and the fire protection surface layer should also be set here. For the external gaps of glass curtain walls, floors, and partition walls, filling treatment should be done. The filling material can be mineral wool or rock wool with a thickness greater than 100mm, and the support of mineral wool or rock wool should be done well, and the thickness of the supporting material should be selected. Steel plates larger than 1.5mm. When designing the fire partition, it can be designed as a transparent partition. Fireproof glass materials that meet the fire resistance limit requirements of the curtain wall should be selected, and galvanized steel sheets should be selected to block the horizontal smoke belt between floors.
2.5 Reliability Design
The design of the super-large glass curtain wall of an office building is also related to the connection design between the curtain wall and the ground. At this time, it should be designed from the perspective of improving structural safety and reliability. Accurately calculate the test data, and check the force between the embedded parts and connecting parts to ensure details and comprehensiveness. It is necessary to combine the lightning protection and grounding requirements of the curtain wall structure and the anti-seismic requirements to control the limit deformation value under the anti-seismic situation and do a good job in the firm welding of lightning protection steel bars and embedded parts to ensure the reliability of the overall structure.
3. The case analysis of super large glass curtain wall design in office buildings
Taking an office building in an industrial park as an example, the office building is divided into Building A, Building B, Building C, and Building D. The building curtain wall areas are 15,780 square meters for Building A, 15,766 square meters for Building B, 20,164 square meters for Building C, and 10,000 square meters for Building D. square meters, of which the above-ground construction area and underground construction area are 159,700 square meters and 19,200 square meters respectively. When designing the super-large glass curtain wall, this project made a bold innovation based on the actual situation of the project and engineering experience. It adopted a framed glass curtain wall structure to add oblique decorative lines to the facade. The width of the decorative lines reached 500mm, and aluminum joints (6061- T6) were fixed on the glass curtain wall pole. The super-large glass designed in this project uses warm-edge spacers to ensure the effectiveness of the facade and improve the overall heat transfer performance of the curtain wall. At the same time, the outer curtain wall is coated with a colored glaze, which can block strong light projection to a certain extent, making the whole more comfortable and environmentally friendly.
Figure 2 The super large glass curtain wall design in office buildings 1
Among them, the outer curtain wall is a frame curtain wall structure as a whole, its overall plane is an axisymmetric figure, and its plane projection length is rectangular. Designers pay attention to adjusting its overall shape, specifically through vertical geometric parameters, that is, adjusting the upper reference shape, the lower reference shape, etc. The outer curtain wall is directly attached to the fire separation wall. On the whole, the curtain wall system is vertical and stepped. The inner glass curtain wall is based on the periphery of the standard floor slab, and the specific arrangement is a vertical cylinder. The inner curtain wall is divided into 7 areas, and the glass plates are controlled according to the radius of the cylinder in each area to ensure that it fits with the overall shape of the area structure...
Figure 3 The super large glass curtain wall design in office buildings 2
When designing the support structure of this project, horizontal peripheral ring beams are set on each floor, and double suspender structures are set on the main structure of the equipment floor in each area. Observing the form of the support structure of the inner and outer curtain walls, it can be known that the main structure of the project is connected by a horizontal diameter to the strut. When designing the continuous members supported laterally by giant columns on each floor, the selected support structure is an internal horizontal ring beam with a vertical center distance of 4.45 meters. The ring beam connected with the internal horizontal ring beam should ensure that it can provide External horizontal ring beams provide stable lateral bearing radial support.
Through the application of super large glass curtain walls, the overall quality and appearance of the office building can be improved, and a high-quality office building can be created. In the application of glass curtain walls in office buildings, designers must master the application requirements of high-rise office buildings for super-large glass curtain walls, further understand the structural characteristics of super-large glass curtain walls, and carry out highly integrated structural design and fire protection design of super-large glass curtain walls and reliability design, etc., it is necessary to grasp the key and difficult points of design, use modern technology and software to improve design accuracy and efficiency, and provide a refined, comprehensive and reliable reference for the subsequent construction of super large glass curtain walls.