Since the appearance of human beings, architecture has always been an important part of people's lives, but for a long time, stones, wood and so on have been used. With the development of science and technology, new materials are widely used, and steel is one of them. Building with steel structure as the main body is the mainstream of modern spatial structure development. Compared with reinforced concrete, masonry and wood structure buildings, steel structure buildings are different. Steel structure buildings are usually composed of steel beams, steel columns and steel trusses made of steel, steel pipes and steel plates, and some are also composed of steel hinges and steel ropes (bundles). The connection mode is welding, bolt connection or riveting. It is of great significance and value to discuss the design and performance of modern steel structure buildings.
First, the development history of steel structure buildings
The earliest country that used steel structure to build houses can be traced back to Britain at the end of18th century. One hundred years later, the French engineer Eiffel built the famous iron tower, and people began to try to build single-family houses with steel structures. Since then, steel structure architecture has completely changed the previous architectural modeling mode, and the concept and method of architectural design have also evolved. In the early days, steel structures were only made of cast iron and wrought iron. In 1980s, the appearance of structural steel accelerated the development of steel structure in building engineering, which made the steel structure realize the second leap and innovative development in theory and practice in 1960s. The Bauhaus school in Germany is the birthplace of their theory.
1949 since the liberation of China, steel structures have been applied in long-span heavy industrial workshops, large public buildings and high-rise structures. Especially in recent 20 years, steel structures have been widely used in civil engineering public buildings, such as the roof of Shenyang Taoxian International Airport and the new Beijing Planetarium project. At present, China can not only produce various types of building steel, but also increase the number of new technologies, new processes and new products for steel production, such as the production of color-coated profiled steel plates, color-coated composite plates, color-coated gusset plates, arched workshops and color-coated products, which makes the building structure full of modernity.
Second, the architectural characteristics of modern steel structure
(a) the early stage of high engineering, reduce construction costs, shorten the construction period.
The coordinated and unified standard of steel structure building modulus has realized the large-scale industrial production of buildings, improved the early engineering of buildings, and made building components with different materials, shapes and manufacturing methods universal and interchangeable. At the same time, the preliminary project of steel structure building integrates material processing and installation, which greatly reduces the construction cost; And accelerated the construction speed, so that the construction period can be shortened by more than 40%, thus speeding up the capital turnover of real estate developers and making the building put into use earlier.
(b) The integration of design and function of buildings and structures makes buildings more functional.
In the steel structure building, the structure becomes an important factor in the image composition, and the shape, components and nodes of the structure guide and restrict the image of the building to a great extent. Only by integrating the design and function of architecture and structure can the architecture be more functional, so that the subsequent design links can be carried out and the steel structure building with science and technology and art can be created. There are many bidding schemes for the National Stadium of Beijing 2008 Olympic Games, which all reflect this feature of steel structure. For example, in the opening and closing scheme designed by Tsinghua University Architectural Design Institute, two semi-circular glass top surfaces are set in the center of the stadium roof, and the roof can be opened and closed simultaneously by relative rotation and parallel sliding; Another example is the appearance of the venue scheme of China Architectural Design and Research Institute, which is the structure of the building. The image is perfect and pure, and the function and structure have reached a perfect unity; There is also a folding scheme designed by Japanese Zhu Shihui Architecture Office. The roof is supported by cantilever steel frame structure, which can be opened and closed within 30 minutes to ensure that the competitions and activities throughout the year are not affected by the weather.
(c) The steel structure can meet the requirements of super-high and super-long span.
The steel structure is uniform, close to isotropic isotropic body, with high strength and high elastic modulus. The ratio of density to strength is much smaller than that of masonry, concrete and wood. Under the same stress, the steel structure has a small weight and can be made into a long-span, high-height structure and a flexible structure. Now human beings have the ability to build super-large domes with a span of more than 1000 meters and super-high buildings with a height of more than 1000 meters and a height of up to 4000 meters. Moreover, the cable-membrane structure system formed by the combination of cable and membrane structure can better meet the requirements of building span, making this type of building a landmark building. For example, the roof of Hou Yuan Baseball Stadium in Tokyo is a cable-membrane structure composed of steel cables and air-bearing membranes, covering an area of 28,000 square meters. The Millennium dome in London is a landmark building built by the British government to meet the 2 1 century, and it is also a cable-membrane structure system, with a dome diameter of 320m (refer to the Chinese website of architecture).
(d) Raw materials can be recycled, which is beneficial to environmental protection and sustainable development.
The development of steel structure is of great significance to China, which is very short of resources and energy, because China is the country with the largest brick masonry and concrete buildings in the world. Steel is a kind of high strength and high efficiency material, which has high recycling value, and scrap steel is also valuable, so there is no need to model it. At present, new residential products that attract worldwide attention have been introduced into China, and their characteristics of environmental protection and energy saving are mainly reflected in two aspects:
(1) This type of residence adopts a totally enclosed thermal insulation and moisture-proof system, with little temperature change and low heat loss. There is a comfortable living environment in both winter and summer. When the outdoor temperature is 0℃, the indoor temperature can still be kept above 17℃; When the outdoor temperature reaches 30 degrees Celsius, the indoor temperature is only about 2 1 degree Celsius.
(2) Compared with the brick-concrete structure residence, it can save more than 60% energy, air conditioning equipment can save more than 30% energy in winter and summer, and the utilization rate of structural waste is 1 0,000%. Compared with the brick-concrete structure, under the same floor clear height, the steel structure keeps a smaller wall area, saves the energy needed for air conditioning and reduces the maintenance cost.
Third, the steel structure building design and technical performance
The key to the success of steel structure building design lies in technical conception and performance. In the deepening of scheme design, it needs the close cooperation of structural engineers, equipment engineers and even mechanical engineers. At this time, technical performance is a natural thing, whether it is spatial form, formal volume or structural nodes, it is very important to influence its architectural design and performance. Here, this point is expounded from several aspects.
(1) technical expression of steel structure architectural design
The conception of architectural image is the creation process of conceptual image, which is one of the difficulties in architectural creation and one of the core issues in architectural design. Looking back on the development of the relationship between architecture and science and technology since the industrial revolution, we can clearly find that the response of architecture to technological change is slow, which reflects the deep position of architecture in social culture and the close relationship between architecture and people's lifestyle. In addition, the information revolution, which is in the ascendant in modern times, is widely infiltrating into every field of social activities, making modern scientific thinking integrated into architectural design, and the planning, architecture and landscape design methods of new projects have undergone tremendous changes. The purpose of architectural design has also changed from the simple pursuit of beauty to the pursuit of reasonable solutions to problems, which fundamentally changed people's previous understanding of architecture and design methods, and finally influenced the traditional architectural concepts formed by human beings for thousands of years. For example, high-tech architecture is its main representative, which embodies superb skills with exquisite nodes and fine processing, and designs and "manufactures" buildings with a higher technical level.
(2) The detailed design requirements of steel structure buildings are higher.
The higher the complexity and exquisiteness of steel structure architectural design, the higher the requirements for detail design. Because the detailed design determines whether a place is finally confirmed or not, it determines its quality. In modern steel structure buildings, the details of various metal structural members and nodes connecting metal members are often exposed, which makes the building have a strong sense of science and technology. For example, the Pompidou Art and Culture Center in Paris, built in 1977, has exposed its steel columns, steel beams, trusses and other structural components, which not only embodies the beauty of technology, but also embodies the wisdom and ability of people. Therefore, it is very important for steel structure buildings to maintain high design requirements for detail quality, and special attention should be paid in steel structure buildings.
(3) Architectural planning is also an influential factor in the design and performance of steel structure buildings.
Because the steel structure architectural design has the general attributes of architectural design, the architect does not design at will, and the owner's design task book plays an important role in the architect's plane and design conception. Customers want designers to perform better, and designers and market experts to participate in decision-making more efficiently in the process of determining their final products. At this stage, the construction project emphasizes the overall design, but also emphasizes.
Coordination among professional designers, market experts and developers. The design process includes the continuous exchange and integration of information and knowledge. In addition, the specialization of steel structure building can not only provide rich design knowledge, but also effectively integrate design resources and market experts to take charge of the building, so that the design can be effectively combined with the business intention of the owner, so as to make the project profitable and reduce risks.
Fourth, the problems faced by modern steel structure building design
(A) fire prevention in steel structure building design
Fire is the biggest harm to steel structure buildings. Although steel is a nonflammable material, it is not fire-resistant. When the temperature reaches 400 degrees, the yield strength of steel will be reduced to half of the room temperature strength. When the temperature reaches 600 degrees, steel will basically lose all its strength and stiffness. Therefore, when a building adopts a steel structure without fire prevention measures, it is easy to damage the building in case of fire. For example, the outer wall of the World Trade Center building in the United States is densely packed with steel columns, and the outer bread is made of silver and aluminum plates. In the 9 1 1 incident in the United States, two towers were hit by planes, which softened the steel and eventually led to the collapse of the building. From the fire cases of steel structure buildings, we can find two phenomena, one is that the steel structure with fire protection failed to reach the specified fire-resistant time in the fire, and the other is that the steel structure with fire protection exceeded the expected fire-resistant time without being destroyed. Structural fire protection of buildings is generally easy to solve in reinforced concrete structures, but there are more factors to be considered in steel structure buildings. The following are two common fire prevention measures: one is to adopt a new imported fire prevention board-security board; Second, according to different parts of the steel structure, thick or thin fire retardant coatings are used respectively, and decorative paint is added to the exposed parts.
(2) Corrosion protection of steel structures in architectural design
If steel is exposed to the outdoors for a long time and is eroded by natural forces such as wind and rain, it will inevitably rust and age, its bearing capacity will decline, and the aesthetics of the building will also be affected. Therefore, anti-corrosion is also a common problem to be solved in the design of steel structure buildings. At present, the main method is to adopt new anti-corrosion and structural materials. In the actual architectural design, designers will put forward special requirements for the designed building when they encounter steel structure buildings, such as brushing antirust paint, and fireproof paint belongs to paint. The general practice of fire retardant coating is to brush red lead antirust primer twice and steel structure topcoat twice (the color of topcoat is determined by Party A). In addition, there are certain requirements for the construction of steel structure members of steel structure buildings, such as coating red lead antirust primer on the members before leaving the factory; After the steel structure is installed and adjusted, clean it up, and then brush the first primer and the second topcoat. However, although there are many kinds of anticorrosive coatings, more effective anticorrosive coatings need to be imported from abroad. I think with the enhancement of China's comprehensive national strength, China will produce more excellent new anticorrosive coatings.
(3) Architectural physical problems in steel structure
(1) thermal insulation. The thermal radiation of the external environment mainly affects the thermal environment of the building from two aspects: first, it enters the room through the window and is absorbed by the indoor surface, resulting in heating effect; Second, it is absorbed by the surface of the building envelope, and some heat gradually enters the room through the heat conduction of the building envelope. Because glass can let sunlight shine directly into the room, the room temperature rises rapidly, especially with the continuous emergence of new glass materials, the thermal performance of glass is gradually improved, and the contradiction between architectural lighting and architectural insulation is gradually weakened, and "shielding" and "blocking" are in a balanced state. Therefore, the thermal insulation measures of buildings are mainly focused on the outer envelope, and there are two more effective solutions at present:
1) Develop and optimize the structure of thermal insulation materials and improve the thermal environment performance of buildings. For example, in the inner and outer surfaces of buildings or in the air layer of peripheral structures, most of the infrared rays can be reflected back by using high-efficiency reflective materials, so that the buildings can play the role of thermal insulation; In addition, high-efficiency energy-saving glass, silicon aerogel and new energy-saving wall materials can be used to achieve the purpose of energy saving.
2) Prevent external insulation of thermal insulation materials and intermediate insulation of condensed water. It can prevent the thermal insulation material from getting wet due to the penetration and accumulation of steam. Thermal insulation materials with internal thermal insulation method may get wet in winter, while external thermal insulation can prevent the main load-bearing structure from being affected by the violent fluctuation of outdoor temperature, thus improving its durability. External insulation needs a high protective layer on the external surface, while internal insulation and intermediate insulation are relatively simple to handle because the external surfaces are made of high-strength dense materials.
(2) Sound absorption. In some building halls, especially concert halls, the reflected sound increased by the ceiling reflector reaches the audience's ears almost at the same time, lacking the sense of surround brought by lateral reflection. In the design of such buildings, it is necessary to comprehensively consider the use of materials, including sound absorption, decoration, strength, fire prevention, moisture absorption, processing and so on. At present, the widely used solutions for sound quality design and noise control are sound absorption materials and sound absorption structures.
1) Sound absorption material: The material itself has sound absorption characteristics. Fiber or porous materials, such as glass wool and rock wool, have good sound absorption performance. Due to the viscous resistance of air and the friction between air molecules and the hole wall, acoustic energy is converted into frictional heat energy to absorb sound.
2) Sound absorption structure: the material itself may not have sound absorption characteristics, but the material is made into a certain structure to produce sound absorption. Such as perforated gypsum board ceilings.
(3) Sound insulation. Noise and architecture are inseparable, and the prevention and control of noise pollution has become an important part of architectural acoustics. Theories such as noise planning and noise control are gradually developed. All sounds that people can hear belong to the category of acoustic environment. People can hear conversations, birds singing, music, tinkling of springs, singing and so on. But you can also hear noise, machine roar, vehicle roar and other noises. But mainly rooms with quiet requirements, such as recording studios, studios, hotel rooms, residential bedrooms and other buildings, have very high requirements for sound insulation and vibration isolation and need special acoustic design. For hotels, public buildings and residential buildings, people pay more and more attention to the requirement of silence. And try to be close to the sound source, which will improve the sound insulation effect. The external wall of sound insulation room generally adopts materials or structures with good sound insulation performance, such as brick, concrete, gypsum board wall, etc. The observation part adopts sound insulation window, and the entrance and exit part adopts sound insulation door or sound absorption maze.
Verb (abbreviation of verb) conclusion
From the above discussion, we can draw the following three opinions and conclusions:
(1) The design of steel structure buildings should aim at different specific situations. A good architectural design must integrate image conception and structure conception.
(2) The steel structure building is high in science and technology, and the structure itself is often the manifestation of the building. The expression techniques and techniques of steel structure are not only the necessary means to realize the image conception, but also have a significant impact on the architectural image, which determines that the structural conception is the key to the success of the image conception.
(3) With the progress of science and technology and the change of aesthetic standards, steel structure buildings will constantly expand their expressions and seek development. What we advocate is to put aside the elements of style, proceed from structural rationalism, absorb the essence from many modern and traditional styles and schools, and create a fine steel structure building with organic integration of technology and art.
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