What is steel structure
What is steel structure? In academic language, steel structure is a structure mainly made of steel, and it is one of the main types of building structures. The characteristics of steel are high strength, light weight, good overall rigidity and strong deformation ability, so it is especially suitable for the construction of large-span and super-high and super-heavy buildings. Steel structures are steel beams, steel columns, steel trusses and other components made of profiled steel and steel plates; each component or component is connected by welds, bolts or rivets.
The characteristics of steel structure
1. Steel has good toughness, good plasticity, uniform material, high structural reliability, suitable for bearing impact and dynamic load, and has good seismic performance. The internal structure of the steel is uniform, which is close to an isotropic homogeneous body. The actual working performance of the steel structure is more in line with the calculation theory. Therefore, the reliability of the steel structure is high.
2. The material has high strength, light weight, high steel strength and high elastic modulus. Compared with concrete and wood, the ratio of its density to yield strength is relatively low, so under the same stress conditions, the steel structure has a small cross-section and light weight, which is convenient for transportation and installation, and is suitable for large spans, high heights, and heavy loads Structure.
3. The steel structure has good sealing performance. Because the welded structure can be completely sealed, it can be made into high-pressure containers, large oil pools, pressure pipes, etc. with good air-tightness and water-tightness.
4. The steel structure is not heat-resistant and fire-resistant. When the temperature is below 150 °C, the properties of the steel change very little. Therefore, the steel structure is suitable for the hot workshop, but when the surface of the structure is exposed to the heat radiation of about 150 °C, the heat insulation board should be used to protect it. When the temperature is between 300°C and 400°C, the strength and elastic modulus of the steel decrease significantly. When the temperature is around 600°C, the strength of the steel tends to zero. In buildings with special fire protection requirements, the steel structure must be protected by refractory materials to improve the fire resistance rating.
5. The steel structure has poor corrosion resistance, especially in the environment of wet and corrosive media, it is easy to rust. Generally, the steel structure needs to be derusted, galvanized or painted, and it needs to be maintained regularly. For the offshore platform structure in seawater, special measures such as "zinc block anode protection" should be adopted to prevent corrosion.
6. The degree of mechanization of steel structure manufacturing and installation is high, and the steel structure components are easy to be manufactured in factories and assembled on site. The factory mechanized manufacturing of steel structural components has high finished product precision, high production efficiency, fast assembly speed on site, and short construction period. Steel structure is the most industrialized structure.
The development history of steel structure
In the early days of our country, there were outstanding achievements in iron structures, but due to the constraints of the feudal system and the underdevelopment of science, our country has stayed at the level of iron buildings for a long time for more than 2,000 years. It was not until the end of the 19th century that my country began to adopt modern steel structures. After the founding of New China, the application of steel structures has been greatly developed, far exceeding the past in terms of quantity and quality. After 2000, my country's national economy has grown significantly, its national strength has increased significantly, and its steel output has become a world power. Around 2008, under the impetus of the Olympic Games, there was a boom in steel structure buildings, and the strong market demand promoted the rapid development of steel structure buildings. A large number of steel structure venues, airports, stations and high-rise buildings were built. The building has a world-class level in production and installation technology, such as the Olympic National Stadium and other buildings. He has reached a high level in technical aspects such as design, manufacture and installation, and has mastered the design and construction techniques of various complex buildings.
The main characteristics of steel structure
wind resistance
The steel structure building is light in weight, high in strength, good in overall rigidity and strong in deformation ability. The self-weight of the building is only one-fifth of that of the brick-concrete structure, and it can resist a hurricane of 70 meters per second, so that life and property can be effectively protected.
Shock resistance
The roofs of low-rise villas are mostly sloping roofs, so the roof structure basically adopts a triangular roof truss system made of cold-formed steel components. Slab-rib structural system", this structural system has stronger seismic and horizontal load resistance, and is suitable for areas with a seismic intensity of more than 8 degrees.
sound insulation
The sound insulation effect is an important indicator for evaluating a residence. The windows installed in the light steel system are all made of insulating glass, which has a good sound insulation effect, with a sound insulation of more than 40 decibels. 60 decibels.
Thermal insulation
The thermal insulation material used is mainly glass fiber cotton, which has a good thermal insulation effect. The use of thermal insulation boards for external walls can effectively avoid the "cold bridge" phenomenon of the walls and achieve better thermal insulation effects. The thermal resistance of R15 insulation cotton with a thickness of about 100mm can be equivalent to a brick wall with a thickness of 1m.
health
Dry construction is used to reduce environmental pollution caused by waste. 100% of the steel structure materials of the house can be recycled, and most of the other supporting materials can also be recycled, which is in line with the current environmental awareness; all materials are green building materials, which meet the requirements of the ecological environment and are beneficial to health. .
Durability
The light steel structure residential structure is all composed of cold-formed thin-walled steel member system, and the steel frame is made of super anti-corrosion high-strength cold-rolled galvanized sheet, which effectively avoids the influence of corrosion of steel plates during construction and use, and increases the service life of light steel members. The structural life can be up to 100 years.
comfort
The light steel wall adopts a high-efficiency energy-saving system, which has a breathing function and can adjust the dry humidity of the indoor air; the roof has a ventilation function, which can form a flowing air space above the house to ensure the ventilation and heat dissipation needs of the roof.
The advantages and disadvantages of steel structure
Advantage
1. Compared with traditional buildings, steel structure houses can better meet the requirements of flexible separation of large bays in buildings. By reducing the cross-sectional area of columns and using lightweight wall panels, the area utilization rate can be improved, and the indoor effective use area can be increased by about 6 %.
2. The energy-saving effect is good. The wall adopts light-weight energy-saving standardized C-shaped steel, square steel and sandwich panel, which has good thermal insulation performance and good shock resistance. 50% energy saving,
3. The use of steel structure system in residential buildings can give full play to the good ductility, strong plastic deformation ability of steel structure, excellent seismic and wind resistance performance, which greatly improves the safety and reliability of residential buildings. Especially in the event of earthquakes and typhoons, the steel structure can avoid the collapse of buildings.
4. The total weight of the building is light, and the steel structure residential system is light in weight, which is about half of the concrete structure, which can greatly reduce the basic cost.
5. The construction speed is fast, and the construction period is at least one third shorter than that of the traditional residential system. It only takes 20 days and five workers to complete a 1,000-square-meter building.
6. Good environmental protection effect. The amount of sand, stone and ash used in the construction of steel structure houses is greatly reduced. The materials used are mainly green, 100% recycled or degraded materials. When the building is demolished, most of the materials can be reused or degraded without causing waste. .
7. To be flexible and substantial. Large bay design, indoor space can be divided into multiple schemes, which can meet the different needs of users.
8. It meets the requirements of housing industrialization and sustainable development. The steel structure is suitable for mass production in factories, with a high degree of industrialization, and can integrate advanced products such as energy saving, waterproofing, heat insulation, doors and windows into one, complete application, integrate design, production and construction, and improve the level of the construction industry.
Disadvantage
1. Complexity
The complexity of construction quality problems of steel structure engineering projects is mainly manifested in that there are many factors that cause quality problems, and the causes of quality problems are also complex. Even for quality problems of the same nature, the reasons are sometimes different. And processing adds complexity. For example, welding cracks can occur in the weld metal or in the thermal influence of the base metal, either on the surface of the weld or inside the weld; the direction of the crack can be parallel to the weld bead or perpendicular to the weld For the weld bead, the crack may be either a cold crack or a hot crack; the causes also include improper selection of welding materials and improper welding preheating or post-heating.
2. Variability
The quality problems of steel structure engineering construction will continue to develop and change with external changes and the extension of time, and quality defects will gradually be reflected. For example, due to the change of stress in the weld of steel components, cracks occur in the original weld without cracks: delayed cracks can be generated due to the action of hydrogen in the weld after welding. Another example is that if the component is overloaded for a long time, the steel component will have bending deformation of the lower arch, causing hidden dangers.
3. Severity
The seriousness of the construction quality problems of steel structure engineering projects is as follows: generally, it affects the smooth progress of the construction, causes delays in the construction period, increases the cost, and in serious cases, the buildings collapse, cause personal injury, property damage, and cause adverse social impacts.
4. Frequent
Since modern buildings in our country are mainly made of concrete structures, the management personnel and technical personnel engaged in construction are relatively unfamiliar with the production and construction technology of steel structures, and the specific construction personnel, mainly migrant workers, do not understand the scientific construction of steel structure projects. method, resulting in frequent accidents during the construction process.
Sixth, the development prospect of steel structure
China's steel structure industry has developed rapidly in the past 10 years, and has become the world's largest steel structure country with the largest amount of steel structure, the strongest manufacturing and construction capacity, the largest industrial scale, and the largest enterprise scale.
Steel structure enterprises: attention should be paid to the development of the "Twelfth Five-Year Plan"
The successful construction of major steel structure projects in various places shows that the comprehensive technical level of steel structures in my country has reached the international advanced level. However, there is still a big gap between my country's steel structure industry and developed countries in terms of informatization, automation, standardization, scientific research and innovation. 2011 is the first year of the national "Twelfth Five-Year Plan". Relevant national ministries, industry associations, enterprise groups, and steel structure enterprises are all conducting research and analysis on the market and future development trends. The National Development and Reform Commission, the Ministry of Industry and Information Technology, and the Ministry of Science and Technology are also studying the determination and planning goals of relevant strategic new industries. For industries with international advanced level, strong independent innovation ability, strong international competitiveness and can occupy more markets, they will be included in the planning and given. Support and support policies. Opportunities are also challenges. Whether my country's steel structure industry can reach a higher level and scale, the development during the "Twelfth Five-Year Plan" period is very important.
After investigation and research, and after listening to the opinions and suggestions of relevant experts, the China Steel Structure Association drafted the "Draft of Strategic Thinking and Suggestions on the Steel Structure Industry in the National "Twelfth Five-Year Plan". After soliciting the opinions of relevant personnel, the association will Organize relevant experts to implement and improve them in order to promote greater development of the steel structure industry during the "Twelfth Five-Year Plan" period.
Due to its economic and technological advantages, low-carbon emission reduction, circular economy, and industrialization and industrialization development, the steel structure industry can better adapt to and meet the current needs of my country's national economic construction, and will also become a market with a broad market and many enterprises. ,
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