钢结构（建筑结构类型）

Steel structure

Steel is characterized by high strength, light weight, good overall stiffness, and strong resistance to deformation, so it is used in construction long-span It is especially suitable for tall and heavy buildings; Material homogeneity sum isotropy Good, genus An ideal elastomer , most in line with the general Engineering mechanics The basic assumption of; The material has good plasticity and toughness, can have large deformation, and can bear dynamic load well; Short construction period; Its degree of industrialization is high and can be carried out Degree of mechanization high Specialized production .

Steel structure should study high-strength steel, greatly improve its Yield point Strength; In addition to rolling new varieties of section steel, for example H-section steel (Also known as wide flange Section steel) and T-shaped steel as well Molded steel plate accommodate Long-span structure and Supertall building The need.

There are also thermal Bridges Light steel structure System, the building itself is not energy saving, this technology uses clever special connector Solved the building Thermal bridge A question; small Truss structure Cable and Water supply and drainage The pipe runs through the wall, the construction and decoration are convenient.

1, high material strength, light weight

High strength steel, Modulus of elasticity They're high, too. with concrete Compared to wood, its density is compared to Yield strength The ratio is relatively low, so under the same stress conditions, the component of the steel structure is small, light weight, easy to transport and install, and suitable for the structure with large span, high height and heavy load.

2, steel toughness, good plasticity, uniform material, Structural reliability high

It is suitable for bearing impact and dynamic loads and has good seismic performance. Steel interior Organizational structure Homogeneous, almost isotropic plastid . The actual working performance of the steel structure is in accord with that of the steel structure Theory of computation . Therefore, the steel structure has high reliability.

3, steel structure manufacturing and installation of high degree of mechanization

Steel structure components are easy to be manufactured in the factory and assembled on the site. The factory mechanized manufacturing of steel structure components has high precision, high production efficiency, fast site assembly speed and short construction period. Steel structure is the most industrialized structure.

4, the steel structure sealing performance is good

On account of Welded construction It can be completely sealed. It can be done Air tightness , Water tightness All good High pressure vessel , large oil pool, Pressure pipe Let's wait.

5, steel structure heat resistance is not fire resistant

When the temperature is below 150℃, the steel properties change little. Therefore, the steel structure is suitable for hot workshops, but when the surface of the structure is subjected to thermal radiation of about 150 ° C, it is necessary to use heat insulation panels to protect it. The temperature is 300℃ -400℃. The strength and elastic modulus of steel are significantly reduced, and the strength of steel tends to zero when the temperature is about 600℃. In buildings with special fire protection needs, steel structures must be protected by refractory materials to improve Fire rating .

6. Steel structure Corrosion resistance poor

Especially in the environment of wet and corrosive media, easy corrosion . General steel structure to remove rust, galvanized or paint, and to Scheduled maintenance . For the ocean in the water Platform structure , need to use "zinc block Anode protection And other special measures to prevent corrosion.

7, low carbon, energy saving, Green and environmental protection , but reuse

Steel construction Demolition hardly ever happens Construction waste Steel can be recycled.

Steel structure (13 photos)

Although China had early achievements in iron structure, it remained at the level of iron buildings for a long time. Until the end of the 19th century, China began to use modern steel structure. The founding of New China After that, the application of steel structure has been greatly developed, both in quantity and quality are far beyond the past. The floor of the light steel structure consists of cold-formed thin-walled steel frames or Composite beam , floor OSB structure board, support, connecting parts, etc. The materials used are Oriented particle board , Cement fiber board , and plywood . These lightweight floors can withstand loads of 316 to 365 kilograms per square meter.

The number of steel structure buildings marks the economic strength and economic development of a country or a region. After entering 2000, our country National economy Significant growth, the national strength has been significantly enhanced, steel production has become a world power, in the construction put forward to "actively and reasonably use steel", from now on got rid of the "restriction of steel" constraints, steel structure building in the economically developed areas gradually increased. Especially around 2008, when Olympic Games Driven by the emergence of steel construction boom, strong Market demand Promote the rapid development of steel structure buildings, built a large number of steel structure venues, airports, stations and High-rise building Among them, some steel structure buildings have a world-class level in the production and installation technology, such as the Olympic Games National stadium Wait for the building.

After the Olympic Games, steel structure buildings have been popularized and improved Sustainable development Steel structure is widely used in construction, railways, Bridges and housing, there are tens of thousands of steel structure enterprises of various sizes, and the world's advanced steel structure processing equipment is basically complete, such as multi-dimensional Drilling machine Steel pipe multidimensional Intersecting line cutting machine , Corrugated plate Automatic welding machine, etc. And the processing and production level of hundreds of steel structure enterprises has the world's advanced level, such as steel structure production and first-class enterprises. Steel production amounts to more than 600 million tons per year, Steel variety It can fully meet the architectural needs. Steel structure design code, steel structure material standard, steel structure engineering Construction quality acceptance code And a variety of professional norms and enterprise construction methods are basically complete. ^[1]

The downstream steel structure industry has a greater traction and driving effect on the development of the steel structure industry, and their changes in demand directly determine the future development of the industry.

1. The upstream industry of steel structure is the raw material supply industry such as steel

Iron and steel industry Is steel structure Industrial development The material basis of the steel industry Technological progress It creates favorable conditions for the application of steel structure. Some of the biggest companies in the domestic steel industry have already started Building structure Research and development of steel varieties and technologies have been developed High-strength steel And fire resistance, weather resistance, sea water resistance, resistance Lamellar tear Low temperature resistant steel, and H-shaped steel, high performance Color coated steel plate , Cold formed steel It has laid a good application foundation for the development of steel structure industry.

2. The impact of upstream and downstream on the industry

The upstream of steel structure is mainly the steel industry and steel products Price fluctuation Directly affecting the industry Purchase cost . On the whole, the upstream industry basically belongs to competitiveness Industry, the production of various types of steel plate, steel pipe, section steel and other steels for steel structure, including H section steel and Medium plate It is the most commonly used product in steel structure construction. Industry Insight research data 2011 Crude steel output Up to 696 million tons, the output is relatively saturated, and the raw materials required for the production of steel structures can obtain a stable supply.

The downstream industry has a greater traction and driving effect on the development of the steel structure industry, and their changes in demand directly determine the future development of the industry. Steel structure with its high strength, light weight, good seismic performance, high degree of industrialization, short construction period, strong plasticity, Energy saving and environmental protection Such comprehensive advantages as Industrial building Municipal infrastructure construction, culture, education and sports construction, electric power, Bridges, offshore oil engineering, aerospace And other industries have been widely used, Market space Gradually expand. In addition, once the residential steel structure market has made a breakthrough and gradually replaced the traditional building form into the residential construction field, the steel structure industry will lead to explosive growth.

Roofing system

Light steel structure residential roofing system

Be due to Roof truss , structure OSB panel, Waterproof course , light duty Roof tile (Metal or Asphalt shingle ) and related connecting parts. Matt Building light steel structure roof, appearance can be a variety of combinations. There are many kinds of materials. Under the premise of ensuring the waterproof technology, there are many options for the appearance.

Wall structure

The wall of light steel structure housing is mainly composed of wall frame column, wall top beam, wall bottom beam, wall support, wallboard And connecting parts. Building light steel structure housing generally will be inside Cross wall structural Bearing wall The wall column is a C-shaped light steel member, and the wall thickness is determined according to the load, usually 0.84 ~ 2 mm, the wall Column spacing Generally 400 ~ 600 mm, building light steel structure residential wall structure arrangement, can effectively withstand and reliable transmission Vertical load , and convenient layout.

Keep warm Energy-saving technology Light steel structure to ensure reach Insulation effect Used on the exterior walls and roofs of buildings Thermal insulation material Can be used for a long time and can keep heat and insulation. The building of light steel structure housing is generally filled in addition to the wall pillars Fiberglass mesh cloth Outside, put another layer on the outside of the wall Thermal insulation material Effectively partition the thermal bridge from the wall pillar to the outer wall panel; Joists fill inside between floors Glass fibre To reduce heat transfer through the floor; own Interior wall The wall columns are filled with glass fiber to reduce the heat transfer between the household walls.

Fire prevention technology One of the most critical problems of light steel structure is the application of fire prevention technology, and the fire resistance grade of light steel structure residential buildings is four grades. Building light steel structure housing on both sides of the wall with floor the variola adhibition Fireproof drywall , for common firewalls and Separating wall 25.4 mm thick (1 inch) plasterboard Protection to meet the fire protection requirements of 1 hour, in addition, the glass fiber filled between the wall column and the floor joist also plays a positive protective role for fire protection and heat transfer.

Sound insulation technique Light steel structure in the interior and exterior walls and floor joist inter-filling Glass wool , effectively blocking passage airborne For the impact sound propagated through solids, the following structural treatment is made: for the household wall, two wall pillars are used to form two walls with a middle gap; And for the small keel used to fix the gypsum board for the ceiling, use a small fluting Elastic construction to effectively reduce solids between floors Acoustic propagation .

Connection method

Welded joint

Bolted connection

Rivet joint

Heavy steel structure

1. Lifting weight: ≥25 tons.

2. Steel per square meter: ≥50KG/㎡.

Light steel structure

Light steel structures made of round steel and Angle steel less than L45×4 and L56×36×4. National norms and technical documents do not say heavy steel.

Code for Design of Steel Structures GB J17-88 has been abolished since December 1, 2003, and the current practice is "Steel structure design Code" GB50017-2017

Equipment steel structure

Equipment steel structure Refers to the steel structure part of large equipment, according to the experience of technical personnel, the following structures should be classified into the equipment steel structure category: Bridge erecting machine The steel structure of the tower, the lifting girder of the crane, the body of the crane, the support of the large equipment, etc., belong to the high requirements for precision, material and connection Precision steel structure One of them. For complete sets of equipment, it is the most important force part and plays a structural role in function.

The processing and production of the steel structure of the equipment is similar to that of the precision steel structure, between the ordinary structural parts (the processing requirements are not high) and Precision machining (requires more fine processing) between, using welding or Bolted joint Connection mode.

At the same time, the main types of steel structure are: used for factory buildings Shelving structure , for multi-high-rise buildings Frame structure Frame 1 Shear wall structure Frame and cylinder structure, used for large space flat plate Grid structure And curved top mesh charging structure and so on. Architectural function Different, the use of structural forms are also different. Steel structure design to be executed by the state Technical specification To achieve advanced technology, economic and reasonable, safe and practical, to ensure quality. Therefore, pay attention to the following requirements when designing and making structures:

1. First of all, according to the functional requirements of the building, the corresponding reasonable Structural system . To achieve advanced technology, novel structure, to achieve the unity of architecture and structure.

2. The steel structure (except the container) is mainly composed of rods, so the rod size is as modular and standardized as possible, which is easy to mechanized manufacturing, transportation, installation and improvement productivity .

3. The adoption has a high Economic indicator the High efficiency steel .

4. The nodes of the steel structure are crucial, and appropriate connection methods should be adopted to make the node design and design Structural calculation Simplified model Be consistent with. Most of the structural damage in the past occurred at the nodes, so the nodes should be carefully designed and constructed. Adopt advanced and reliable connection methods.

Steel structure will be subjected to various forms of action during use ( load , Basics Inhomogeneous settlement Temperature, etc.), so the steel should be required to have good Mechanical property (strength, plasticity, toughness) and workability (hot and cold working and weldability ) to ensure the safety and reliability of the structure. There are many kinds of steel, and only a few kinds meet the requirements of steel structure, such as Carbon steel In Q235, Low alloy steel l6Mn, used for High strength bolt 20 manganese Vanadium steel ( 20MnV ), etc. ^[2]

Performance index

1. intensity

Strength index of steel by Elastic limit Sigma e, Yield limit σy, and tensile limit σu, the design is based on the yield strength of steel, high yield strength can reduce the weight of the structure, save steel, reduce the cost. Tensile strength Sigma u is what steel can withstand before it is damaged Maximum stress At this time the structure of the cause Plastic deformation Lose by a mile Service performance However, the structure deformation is large and does not collapse, which meets the requirements of structural resistance to rare earthquakes. The magnitude of the 'σu/σy value can be regarded as the parameter of the steel strength reserve.

2. Plasticity

The plasticity of steel generally refers to the property of significant plastic deformation without fracture after the stress exceeds the yield point. The main index to measure the plastic deformation ability of steel is elongation Delta sum Shrinkage of section ψ.

3. Cold bending property

The cold bending performance of steel is measured when the steel is bent at normal temperature and produces plastic deformation crack The ability to resist. The cold bending performance of steel is tested by cold bending test to test the steel to withstand the specified bending degree Bending deformation Performance.

4. Impact toughness

The impact toughness of steel refers to the ability of steel to absorb mechanical kinetic energy during the fracture process under impact load, which is a measure of steel resistance to impact load. Stress concentration And lead to Brittle fracture One of the mechanical properties. General pass Standard specimen the Impact test To obtain the impact toughness index of steel.

5, welding performance

The weldability of steel is defined in a - Welding process Under conditions, good performance is obtained Welded joint . The welding performance can be divided into two kinds: welding performance in the welding process and welding performance in the use of the welding performance. The welding performance in the welding process means that the welding seam and the metal near the welding seam are not produced during the welding process Hot crack Or cooling does not produce cooling shrinkage cracks sensibility . Good welding performance means that under certain welding process conditions, Weld metal And nearby Base metal No cracks were found. The weldability in service performance refers to the impact toughness and heat affected zone at the weld ductility Properties required for weld and heat-affected zone steels Mechanical property Not lower than the mechanical properties of the base material. Our country adopts welding process Performance test Methods The test method of weldability based on serviceability was also adopted.

6. durability

There are many factors that affect the durability of steel. The first is the poor corrosion resistance of steel, which must be taken Protective measure To prevent corrosion and rust of steel. Protective measures are: regular maintenance of steel paint, use Galvanized steel There are acids, bases, salts and other strong Corrosive medium Under these conditions, special protective measures are adopted, such as "anode protection" measures for the offshore platform structure jacket Corrosion in jacket Upper fixation Up. Zinc ingot , seawater electrolyte The zinc ingot is automatically corroded to protect the steel jacket. Secondly, due to the steel under high temperature and long-term load, its failure strength is reduced more than the short-term strength, so the steel under long-term high temperature action should be measured Permanent strength . Steel will automatically harden and become brittle over time, that is, "aging" phenomenon. The impact toughness of steel under low temperature load should be tested. ^[3]

Equipment steel structures usually put forward special requirements or higher requirements in the following aspects:

Structural parts: material, Surface roughness , tolerance, Surface treatment , straightness (or radian)

Connection: hole deviation, bolt grade; Welding methods, welding standards, welding materials; Airtight, required to proceed Nondestructive testing , Liquid penetration testing Etc.

Overall structure : perpendicularity , levelness, etc

Packaging: Packaging materials, Packing method

Storage: Ambient temperature , Ambient humidity

Transportation: loading and unloading, in-car placement, container placement, etc.

It refers to the structural form of steel plate and hot-tied, cold-formed or welded profiles connected by connecting parts that can withstand and transfer loads. The steel structure system has light weight, factory manufacturing, fast installation, short construction period, good seismic performance, Investment recovery Fast, less environmental pollution and other comprehensive advantages, and Reinforced concrete structure Compared with, it has more development in three aspects of "high, large and light" Unique advantage , on a global scale, especially Developed country Steel structure has been used reasonably and widely in the field of construction engineering. The steel structure industry is usually divided into light steel structure, High-rise steel structure , residential steel structure, Space steel structure and Bridge steel Structure five subclasses.

Steel structure is widely used in various engineering construction, such as steel bridge, steel plant, Steel gate , a variety of large pipeline containers, high-rise buildings and tower rail institutions.

When the steel structure is also damaged, we must immediately find and solve the problem, the main factors of steel structure damage are:

(1) Changes by load, Extended service Norms and procedures change resulting in structure Bearing capacity Insufficient;

(2) the component due to various accidents caused by deformation, distortion, disability, depression, etc., resulting in the weakening of the component section, rod warping, connection cracking, etc.;

(3) Deformation, cracking and cracking of components or connections under the action of temperature difference warping ;

(4) Due to chemistry matter The erosion results in corrosion as well Electrochemical corrosion The cross-section of steel structure members is weakened;

(5) Others include mistakes in design, production and construction, and illegal use and operation during the service period.

Reinforcement of steel structure Technical measure There are three main types:

(1) Section reinforcement method: In the local or along the full length of the member with steel reinforcement, connected into the whole so that the common force;

(2) Change the calculation diagram: add additional supports, adjust the load distribution, reduce the level of internal forces, right Statically indeterminate structure The support is forced to displace to reduce the stress peak;

(3) Prestressed cable method: The use of high-strength cable reinforcement structure Weak link Or improve the overall bearing capacity, stiffness and Degree of stability .

Shanghai World Expo steel structure project

First, the preparation of steel structure installation and welding

Test steels include Q345GJC-Z15 (wall thickness 70mm), Q345GJC-Z15 (wall thickness 40mm), Q345C (flange thickness 28mm), Welding position For column - column transverse welding, column - beam Flush welding (include Truss beam Flat welding of upper and lower flange), T-angle Vertical welding . groove Form and size according to design requirements. After welding appearance and Ultrasonic examination The mechanical and physical tests were carried out after the samples were qualified.

The tensile strength of the joint reaches the tensile strength of the base material Standard value The joint is bent 180° without crack. adoptive Welding material and Welding equipment Technical condition Shall conform to National standard Excellent performance. Skimming slag , gouging Welding rod drying and heat preservation devices should be complete and effective.

Two. Manual arc welding And CO2 Gas shielded welding Welding materials and equipment

(1) The electrode should be at high temperature Drying oven Medium drying, welding rod drying times shall not exceed two times.

(2) The packaging of the welding wire should be intact. If it is damaged and leads to contamination of the welding wire or bending or disorder, it should be partially abandoned.

(3) CO 2 Gas purity should not be less than 99.9% (volume ratio), Water content It should be lower than 0.05% (weight ratio), and should be stopped when the pressure in the bottle is lower than 1MPa.

(4) The voltage of the welding machine should be normal, the ground wire should be firmly pressed, the contact is reliable, the cable and the cable Welding clamp There is no damage, the wire feeder should be able to feed the wire evenly, and the gas pipe should be free of air leakage or blockage.

3. Installation and welding procedures and general regulations

The general order of welding is: pre-welding inspection → preheating and rust removal → Install and weld Pad sum Strike plate → Welding → Inspection

1. Preweld inspection Groove Angle , Blunt edge , gap and stagger The amount of rust, oil stains in and on both sides of the groove, Iron oxide Etc. should be cleared clean.

2. Warm up. pre-welding Gas welding Or a special baking gun uniformly heats the base material within 100mm on both sides of the groove, and measures the temperature with a surface thermometer to prevent the temperature from not meeting the requirements or local oxidation of the surface. Preheating temperature .

3. Recheck the preheating temperature, if the temperature is not enough should be reheated to meet the requirements.

4. The surface cleanliness requirements of the welding pad and the arc plate are the same as that of the groove surface, the pad and the base material should be tight, and the arc plate and the base material should be welded firmly.

5. Welding: The first layer bead The joint between the base material and the backing plate in the groove should be sealed, and then welded layer by layer until the groove is filled, and each weld must be removed after welding Welding slag And spatter, appear Weld defect Should be promptly worn off and repaired.

6. An interface must Continuous welding In the end, if the welding is stopped halfway, the thermal insulation and cooling treatment should be carried out, and the heating should be re-heated according to the regulations before welding.

Seven. In case of rain, snow should stop welding, components Welding joint There should be wind and canopy around and above, and welding should be stopped when the wind speed is greater than 5m/s. When the ambient temperature is below zero, preheating and heating should be taken according to regulations After heating Measure construction.

8. Carbon structural steel The weld should be cooled to ambient temperature, Low alloy structural steel Weld inspection should be carried out 24h after completion.

9. Welders and inspectors should fill in the work carefully Record sheet .

Iv. Welding sequence of canonical joints Process parameter

(1) Two welders on the earless side of the upper and lower columns Bilateral symmetry Weld to Plate thickness When 1/3 of the place, cut off the ear plate.

(2) Then, on the side of the cut ear plate, two welders weld symmetrically on both sides to 1/3 of the thickness of the plate.

(3) Two welders shall undertake the welding of the adjacent two sides respectively.

(4) The joints of the solder joints between each two layers should be staggered and welded by two welders Bead joint Also pay attention to each layer staggered, welding process should pay attention to detection Interlayer temperature .

(5) Welding process parameters:

CO2 gas welding: wire diameter Φ1.2mm, current 280 ~ 320A, welding speed 350 ~ 450mm/min

Wire extension length: about 20mm, Gas flow 25 ~ 80L/min,

The voltage is 29 ~ 34V, and the interlayer temperature is 120 ~ 150℃

Five, column - beam, beam - beam node

(1) Weld the lower flange of the beam first, Web of beam The flange bead on both sides should be welded symmetrically.

(2) Wait until the lower flange is welded, and then weld the upper flange.

(3) If the flange plate thickness is greater than 30mm, the upper and lower flange should be welded alternately.

(4) Welding process parameters:

CO2 gas welding: wire diameter φ1.2mm, current 280 ~ 360A, welding speed 300 ~ 500mm/min

The extension length of the welding wire is about 20 mm, and the gas flow rate is 20 ~ 80L/mm

The voltage is 30 ~ 38V, and the interlayer temperature is 120 ~ 150℃

1. Carbon structural steel : Q195 , Q215 , Q235 , Q255 , Q275 Etc.

2. Low alloy high strength structural steel

3. High quality carbon structural steel and Alloy structural steel

4. Special purpose steel

High-rise steel structure

It is true that there is no unified standard for determining the structure of heavy steel and light steel structure, and many experienced designers or project managers often cannot fully explain it, but we can comprehensively consider and judge with some data:

1. Lifting weight of plant crane: Greater than or equal to 25 tons, can be considered as heavy steel structure.

2, the amount of steel per square meter: greater than or equal to 50KG/㎡, can be considered to be heavy steel structure.

3, the main component steel plate thickness: greater than or equal to 10MM, light steel structure with less.

Plus, there are some Reference value : such as cost per square meter, maximum component weight, maximum span, structural form, high eaves, the above can provide empirical data in judging whether the plant is heavy steel or light steel, of course, many buildings are light and heavy steel. But there are some we can be more certain that heavy steel: such as: petrochemical plant facilities, power plant, large-span Sports venue Exhibition center, high-rise or super high-rise steel structure.

Actually state norms and Technical document There is no heavy steel said, in order to distinguish the light house steel structure, perhaps the general steel structure is more appropriate. Because the range of ordinary steel structures is very wide, it can include a variety of steel structures, regardless of the size of the load, even including Light steel structure Many of the contents of the light house steel structure Technical specification Only for its "light" characteristics and some more specific content is specified, and the scope is only limited to single layer Portal frame .

Light steel is also a relatively vague term, which can generally be understood in two ways. One is Chapter 11 of the current "Steel Structure Design Code" (GBJ 17-88). Round steel "Light steel structure with small Angle steel" refers to the light steel structure made of round steel and Angle steel less than L45*4 and L56*36*4

It can be seen that the difference between light steel and heavy steel is not in the weight of the structure itself, but in the weight of the enclosing material Structural design The concept is still consistent.

Prefabrication of steel components

According to the installation sequence and Process requirement in Steel platform The prefabrication and assembly of steel components should ensure the quality of welding production.

Splicing of section steel Flange plate Splice joint sum sternum The spacing of the splicing seam should be greater than 200㎜. Flange plate splicing length should not be less than 2 times the plate width; The width of the web splicing should not be less than 300㎜, the length should not be less than 600㎜.

For easy welding, guaranteed Welding quality As far as possible, the reinforcement plate on the column and beam, Connecting plate , backing plate, Outrigger beam (Beam) etc. pressed on the ground steel platform Working drawing Size for group pair welding.

The steel members prefabricated on the steel platform shall be divided according to the construction drawings and Specification requirement In addition to production and assembly, on-site installation should also be considered manufacturability And mounting size changes.

Steel structure (8 photos)

Steel structure development: three major areas should be paid attention to

According to the development of the industry, Offshore oil Engineering equipment The development of three areas, such as steel structure housing and steel structure Bridges, should attract the attention of the relevant competent departments of the state, if it is valued and encouraged by policies, it can fully achieve the goal of doubling the industry.

Offshore oil production is expected to reach 100 million tons by 2015, Ocean engineering The goal of equipment enterprises is to provide a large amount of equipment for the deep-sea mining of 1500 meters to 3000 meters, and the industrial level and scale must be improved; Steel structure housing conforms Green and environmental protection , Energy conservation and emission reduction Sum cycle Economic policy Its industrialized and standardized steel structure residential products have broad and unlimited Market space ; There are 590,000 highway Bridges in the country Sinosteel Structural Bridges are less than 1%, the railway system is developing rapidly, and new lines are being built Replace roads with Bridges 80% of them are Prestressed reinforced concrete Bridge. The steel structure bridge in Japan accounted for 41%, the United States accounted for 33%, which shows that China's steel structure bridge Market demand and Industrial development with Developed country There's still a big gap.

China steel structure The industry has developed rapidly in the past 10 years, and has become the world's largest steel structure consumption, the strongest manufacturing and construction capacity, Industrial scale First, Enterprise scale The first steel structure country.

Steel structure enterprises: must pay attention to the "Twelfth Five-Year" development

Local importance Steel structure engineering The successful construction, explains our country's steel structure Comprehensive technology The level has reached the international advanced level. But China's steel structure industry in information, automation, standardization, Scientific research innovation Compared with developed countries, there is still a big gap.

2011 is the country The 12th Five-Year Plan In the initial year, the relevant ministries and commissions of the State, Trade association And enterprise groups, steel structure companies are conducting research, analyzing the market and the future Development trend . 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 objectives of strategic new industries, and will include in the planning and give support and support policies to industries with international advanced level, strong independent innovation ability, strong international competitiveness and can occupy more markets. Opportunities are also challenges, whether China's steel structure industry can step up, on the scale, the development of the "Twelfth Five-Year" period is crucial.

China Steel Structure Association Go by Investigation and research After listening to the opinions and suggestions of relevant experts, the draft of the strategic thinking and suggestions on the steel structure industry in the national "Twelfth Five-Year Plan" was drafted, and after soliciting the opinions of relevant personnel, the Association will organize relevant experts to implement and improve, in order to promote greater development of the steel structure industry during the "Twelfth Five-Year Plan" period.

Steel structure industry due to its economic and technological superiority, Low-carbon emission reduction , Circular economy As well as industrialization, industrialization development, can better adapt and meet the current China National economy Construction needs, will also become a broad market, many enterprises, continuous innovation, full of vitality Emerging industry One of them.

Steel structure

The analysis believes that during the "Twelfth Five-Year Plan" period, the steel structure industry with policy support is expected to play a big role in the field of Marine engineering, housing and Bridges, and achieve a doubling of output.

The roof of the low-rise villa is mostly Pitched roof Therefore, the roof structure is basically adopted by Cold formed steel The triangular roof truss system made of members, light steel members in the sealing structure board and plasterboard After that, a very strong "slab rib" is formed Structural system "This structural system has stronger seismic resistance and resistance Horizontal load The ability to apply Seismic intensity It is more than 8 degrees.

type Steel construction Light weight, high strength, good overall rigidity, strong deformation ability. The building weight is only Brick-concrete structure One fifth of it can withstand a hurricane of 70 meters per second, so that life and property can be effectively protected.

Light steel structure The structure of the house is all cold formed with thin walls Steel member The system is composed of super anti-corrosion and high strength cold rolled steel bones Galvanized plate Manufacturing, effectively avoid the influence of steel plate corrosion in the construction and use process, increase the service life of light steel components. The structure can last up to 100 years.

adoptive Thermal insulation material Mainly made of glass fiber cotton, it has good thermal insulation effect. facades Insulation board Effectively avoid the "cold bridge" phenomenon of the wall and achieve better results Insulation effect . About 100mm thick R15 Thermal insulation cotton The thermal resistance value can be equivalent to 1m thick brick wall.

The sound insulation effect is an important index to evaluate the housing, and the Windows installed in the light steel system are all used Insulating glass Sound insulation effect is good, sound insulation up to 40 decibels or more; by Light steel keel , Thermal insulation material Walls made of plasterboard have a sound insulation effect of up to 60 decibels.

Dry operation construction, reduce the pollution caused by waste to the environment, housing steel structure materials can be 100% recycled, other Supporting material Can also be mostly recycled, in line with the current Environmental awareness ; All materials are Green building materials , meet Ecological environment Requirements, good for health.

Light steel wall adopts high efficiency and energy saving system, with Respiratory function Can adjust the indoor air dry humidity; The roof has a ventilation function, which can form a flowing air room above the interior of the house to ensure the ventilation and heat dissipation requirements inside the roof.

All dry work construction, not affected by environmental seasons. A building of about 300 square meters, only five workers can complete the whole process from foundation to decoration in 30 working days.

The material can be 100% recycled, truly green and pollution-free.

All adopt high efficiency and energy saving wall, good thermal insulation, heat insulation, sound insulation effect, can reach 50% energy saving standards.

Steel construction and housing

Compared with other construction, steel structure has advantages in use, design, construction and comprehensive economy, low cost, and can be moved at any time.

First, steel structure residential buildings can better meet the building than traditional buildings Large bay Flexible separation is required and can be achieved by reducing columns Area of section And use Lightweight siding , improve the area Utilization rate Effective indoors Usable area An increase of about 6%.

Second, the energy saving effect is good, the wall uses light energy saving standardization C-section steel , Square steel , Sandwich board Good thermal insulation performance, good seismic resistance. 50% energy saving,

Third, the steel structure system is used Residential building Can fully play the steel structure ductility Ok, Plastic deformation Strong ability, with excellent seismic and wind resistance performance, greatly improve the safety and reliability of the house. Especially during earthquakes, Typhoon disaster In this case, the steel structure can avoid the collapse of the building.

Fourth, the total weight of the building is light, and the steel structure residential system is light in weight, about half of the concrete structure, which can greatly reduce the basic cost.

Five, the construction speed is fast, the construction period is at least one-third shorter than the traditional residential system, a 1000 square meters only 20 days, five workers can complete.

6. Good environmental protection effect. Steel structure residential construction greatly reduces the amount of sand, stone, ash, the materials used are mainly green, 100% recycled or degraded materials, in the demolition of the building, most of the materials can be reused or degraded, will not cause garbage.

7. Flexibility and richness. Large room design, indoor space can be divided by multiple schemes, can meet the different needs of users.

Viii. Compliance Housing industrialization And sustainable development requirements. Steel structure suitable for factory Mass production High degree of industrialization, and can save energy, waterproof, heat insulation, doors and Windows and other advanced products in one, complete sets of applications, the design, production, construction integration, improve the level of construction industry.

Steel structure with ordinary Reinforced concrete structure Compared with its uniformity, high strength, fast construction speed, good earthquake resistance and recovery High superiority, strength and strength of steel over masonry and concrete Modulus of elasticity Many times higher, so under the same load, Steel member The weight of light. From the point of view of destruction, the steel structure has a large deformation omen in advance, which belongs to Ductile failure Structures that can detect hazards in advance and thus avoid them.

Steel building With the overall light, saving foundation, less material, low cost, short construction period, large span, safe and reliable, beautiful shape, Structural stability Such advantages. Steel structure plant is widely used long-span Industrial building , warehouse, cold storage, High-rise building Office building, multi-storey parking lot and residential construction industry.

Steel structure engineering Medium quality problem

(1) Complexity

Steel structure Engineering project The complexity of construction quality problems is mainly manifested in the variety of factors that cause quality problems, and the reasons for quality problems are complex, even if it is a quality problem of the same quality, the reasons are sometimes different, so that the analysis, judgment and treatment of quality problems increase the complexity. Such as Weld crack It can happen either in Weld metal In, can also occur in Base metal In the heat effect, it can be either on the weld surface or inside the weld. The fracture strike can be parallel to bead It can also be perpendicular to the weld pass, and the crack may be a cold crack or a hot crack; There are also reasons for this Welding material Improper selection and welding preheating or After heating The improper distinction.

(2) seriousness

The seriousness of the construction quality problems of steel structure engineering projects is manifested in: general, affecting the smooth construction, resulting in Construction delay Increased costs, serious, caused by building collapse Personal injury or death Property is damaged, causing adverse social impact.

(3) Variability

Steel structure Engineering construction quality The problem will continue to develop and change with the changes in the outside world and the extension of time, Quality defect Gradually manifest. For example, the weld of a steel member, due to the change of stress, cracks occur in the weld that originally had no cracks: delayed cracks can occur due to the activity of hydrogen in the weld after welding. If the member is subjected to overload for a long time, the steel member should produce a downward arch Bending deformation , create hidden dangers.

(4) Frequent frequency

Since modern buildings in our country are mainly 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 by migrant workers do not understand the science of steel structure engineering Construction method , result in Construction process Accidents happen all the time.

Steel structure corrodes easily

Steel structure must pay attention to protection, especially thin-walled components, therefore, in the strong corrosive media in the building should not use steel structure. The steel structure should be thoroughly removed from rust, paint quality and coating thickness before painting Equal response Coincidence correlation Specification requirement . In the design, the structure should be avoided from moisture and rain leakage, and the dead Angle of inspection and maintenance should be avoided as far as possible in the structure. Newly constructed steel structures usually have to be repainted at regular intervals, Maintenance cost High. At home and abroad are developing a variety of high-performance coatings and not easy to rust Weathering resistant steel The problem of poor corrosion resistance of steel structure is expected to be solved.

Steel structure is heat resistant but not fire resistant

When the temperature exceeds 250 ° C, the material changes greatly, and not only the strength gradually decreases, but also occurs Blue shortness and creep Phenomenon. When the temperature reaches 600℃, the steel enters the plastic state and cannot continue to bear, and the strength of the steel is almost zero.

Fracture of steel structure

Steel structure at low temperature and under certain conditions, May happen Brittle fracture , and Thick plate the Lamellar tear Should attract the designer's special attention.

Steel is more expensive

The cost of the structure will increase slightly after the use of steel structure, which often affects the choice of the owner. In fact superstructure Cost accounts for Total project investment The percentage is very small, the increase is about 10%. In the case of tall buildings, the increase was less than 2%. Obviously, the single factor of structural cost should not be used as the basis for deciding which materials to use. If various factors are considered comprehensively, especially the advantages of the construction period, the steel structure will be increasingly valued.

(1) Friction coefficient Where F is the force that causes the initial slip of the specimen measured by the anti-slip test, and nf is Friction surface Number, which corresponds to F High strength bolt Sum of measured values of tightening pretension.

(2) Torque coefficient : Where d is a high-strength bolt Nominal diameter (mm), M is applied Torque value (N·M), where P is Bolt pretightening force . 10.9 High strength Hexagon bolt The connection must guarantee torque factor K Mean value It ranges from 0.110 to 0.150. its Standard deviation Should be Less than or equal to 0.010.

(3) Initial torque: In order to reduce the influence of steel plate deformation during bolt fastening, secondary tightening can be used to reduce the mutual influence between successively tightened bolts. The first twist of the high-strength bolt is the initial twist to make it Axial force It should reach 60% to 80% of the standard axial force.

(4) final torque: the torque used for the final tightening of the high-strength bolt is the final torque. Consider all kinds of prestress The final torque is generally 5% ~ 10% larger than the torque value calculated theoretically according to the design pre-tensile force.

Cleaning of steel structure - Steel structure shot blasting machine

I. Process

Adjustable speed transfer by electrical control during cleaning Roller bed will Steel structural parts Or steel feed in Cleaning machine Intraventric ejection area, all sides of the body are hit by powerful and dense projectiles from different coordinate directions and friction, so that it is above Scale oxide The rust layer and its dirt fall off quickly, and the steel surface obtains a certain amount roughness The smooth surface of the cleaning outside on both sides of the import and export roller table loading and unloading work. The pellets and rust dust falling on the steel are blown by the purging device, and the mixture of pellets and dust falling down is transported to the funnel of the chamber through the recovery spiral Screw conveyor Gather in hoister Lower part, and then raised to the top of the machine separator In the separator, the separated pure projectile falls into the separator hopper for shot blasting cycle. Shot blasting The dust is produced and sent to it by the exhaust pipe Dust removal system , after purification treatment Net gas Released into the atmosphere, graininess Dust is captured and collected.

Ii. Main composition

DISA steel structure shot blasting machine

1. Clean the room

The cleaning room is of large volume chamber type Box shape The internal wall of the chamber is lined with ZGMn13 wear-resistant protective plate, and the cleaning operation is carried out in the sealed chamber.

2. Conveying roller table

It is divided into indoor conveyor table and loading and unloading section conveyor table.

Indoor roller table coat high chromium wear resistant sheath and limit ring, high chromium wear resistant sheath used to protect the roller table, withstand the impact of the projectile, limit ring can make the workpiece according to the predetermined position to prevent deviation, resulting in accidents.

3. Elevator

Mainly driven by the upper and lower parts, barrel Composed of belt, hopper, etc.

The lower pulley of the same diameter on the lifting machine is welded by the reinforcement plate, the wheel plate and the wheel hub Polygon structure To enhance friction, avoid slipping phenomenon, prolong the service life of the belt.

hoister casing Bend to form and open the cover plate on the housing of the hoist to repair and replace the hopper and lap belt. Open the hoist Lower casing The upper cover plate removes the obstruction of the bottom projectile.

Adjusting hoist epithecium Bolts on both sides drive the pull plate up and down to maintain the tightness of the lifting belt.

The upper and lower belt wheel adopts square seat Outer spherical ball bearing When subjected to vibration impact can be automatically adjusted, good sealing.

4. Separator

spiral conveyer Mainly by Gear motor The spiral axis and the spiral shell are composed.

Using the outer spherical ball bearing with square seat, the bearing can adjust automatically when the vibration impact, good sealing.

6. Pill delivery pipeline

The shot delivery pipeline has a double shot control function, and a gate plate is arranged above each gate pipe to cut off the shot from the separator respectively, which is convenient for maintenance of their own Shot blasting machine ; The opening size of the gate can adjust the flow rate of the projectile, and can also be arbitrarily combined according to the specifications of the cleaning workpiece to open and close the number of gates Save energy Reduce wear on the machine and ensure that production needs are met.

7. Shot blasting machine

The single disc shot blasting device is adopted, which has become the highest level shot blasting device in China. It is mainly composed of rotating mechanism, impeller, cover shell, directional sleeve, shot parting wheel, protection plate, etc. The impeller is made of Cr40 material by forging, and the blades, directional sleeve, shot parting wheel and protection plate are all made of high chromium.

8. Purging device

The device adopts High pressure fan And multiple sets of elastic mouthpieces with different angles are provided in the auxiliary chamber to purge the pellets remaining on the surface of the workpiece.

9. Seal inlet and outlet

Workpiece import and export Sealing device , all adopted Rubber spring Made of steel plate, in order to prevent the projectile splashing out of the cleaning room during shot blasting, the workpiece inlet and outlet are equipped with multiple reinforced seals, which are characterized by strong elasticity, long life and good sealing effect.

10. Dust removal system

cloth Bag type dust collector

Mainly by Bag type dust collector And fan, dust pipe together to form dust removal system. Dust removal efficiency Up to 99.5%.

11. Electrical control

Electrical control system adopt Conventional control To achieve the control of the whole machine, the use of domestic and foreign production of high quality Electrical component , has the advantages of high reliability and easy maintenance, the main circuit by Miniature circuit breaker and Thermal relay To achieve short circuit, phase loss, Overload protection . And there are many places Scram switch , convenient Emergency shutdown To prevent further accidents.

Each access door of the cleaning room and the cleaning room is provided Security protection When either access door is opened, the shot blasting device cannot be activated.

Iii. Summary

Through shot blasting machine Mainly used for metal structure, Machine tool bed , steel (cast iron) products, grid, Construction machinery With the bridge manufacturing industry, with the increase of the state's punishment for environmental pollution, pickling cleaning has been gradually eliminated by the market, and the shot blasting opportunity has been more and more used.

The structure made mainly of steel is the main one Type of building structure One of them. Steel is characterized by high strength, light weight and high stiffness, so it is especially suitable for the construction of large-span and ultra-high and super-heavy buildings;

The homogeneity and isotropy of the material are good, and it is an ideal elastomer, which is most in line with the general Engineering mechanics The basic assumption of; The material has good plasticity and toughness, can have large deformation, and can bear dynamic load well; Short construction period; Its degree of industrialization is high and can be carried out Degree of mechanization high Specialized production ; High processing precision, high efficiency, good tightness, so it can be used in the construction of gas tanks, oil tanks and transformers.

The disadvantage is that Fire resistance And poor corrosion resistance. Mainly used for heavy workshop bearing skeleton, plant structure under dynamic load, Plate and shell construction , soaring Television tower And mast structures, Bridges and warehouses Long-span structure , high level and Supertall building Let's wait.

In the future, high-strength steel should be studied and greatly improved Yield point Strength; In addition to rolling new varieties Section steel For example, H-shaped steel (also known as wide flange steel) and T-shaped steel and molded steel plates to meet the needs of large-span structures and super high-rise buildings.

The steel structure is divided into light steel and heavy steel. There is no uniform standard for determination, and many experienced designers or project managers often cannot fully explain it, so it can be comprehensively considered and judged with some data.

1. The steel structure has light weight

2. The reliability of steel structure is higher

3. Vibration resistance of steel, Impact resistance good

4. Steel structure manufacturing has a higher degree of industrialization

5. The steel structure can be assembled accurately and quickly

6. The steel structure has large interior space

7. Easy to make Seal construction

8. Steel structure corrodes easily

9. The steel structure has poor fire resistance

10. The steel structure can be recycled

11. The construction period of steel structure is short

① Before installation, Construction unit component-responsive Product certificate , Design document Check with the pre-assembly record and recheck the dimensions of the recording member. The deformation and defect of steel structure exceed Allowable deviation When, should be processed.

Before installation, a detailed measurement and correction process should be prepared. Thick steel plate The welding should be simulated before welding installation Product structure the Process test Prepare the corresponding construction technology. A certain camber degree should be preset for the assembled roof truss.

② After the steel structure is hoisted into place, the components should be dealt with Positioning axis Design requirements such as elevation Control point Make measurements, mark them, and hoist them Butt joint Quality is checked before welding. installed Temporary support And steel swells to make the steel roof truss Construction process China is safe and stable.

3. Steel installation The construction unit shall submit the elevation dimensions, welding, painting, etc. of each component after hoisting to the supervisor for acceptance.

China steel structure The industry showed a sustained and rapid growth momentum, steel structure production increased from 8.5 million tons in 2002 to 22.94 million tons in 2009, Compound annual growth rate Up to 15.24%. According to relevant data estimates, in 2010, steel structure production reached 26 million tons. In 2011, steel structure production was about 29 million tons. China's steel structure industry is in a period of rapid development.

China steel structure industry overall Concentration degree It's low. Annual output The number of steel structure enterprises below 10,000 tons, 1-50,000 tons, 5-300,000 tons, and more than 300,000 tons is 4000-5000, 100, 20, and 6-8, respectively; There are 51 enterprises with special manufacturing qualification of steel structure, with Light steel structure Engineering design There are 82 enterprises with special Grade A qualifications, and at the same time, they have the above qualifications and Specialized contracting First-class qualification There are fewer businesses. With the continuous development of the industry, mergers and acquisitions in the industry will become the norm.

1, the steel structure system has light weight, easy installation, short construction period, good seismic performance, Investment recovery Fast, less environmental pollution and other comprehensive advantages, good plasticity and toughness good impact resistance.

2, the types of steel are: according to the thickness of different thin plate ( Sheet steel Thickness < 4mm), medium plate (medium thickness 4-20mm) and thick plate (thickness 20-60mm) greater than 60 are four kinds of extra thick. Steel strips are included in the steel plate category.

3. Plain bolt What is the difference with high strength bolts?

Ordinary bolts are generally used Ordinary carbon structural steel Manufactured, without heat treatment, high strength bolts are generally used High quality carbon structural steel or Alloy structural steel Manufacturing requires tempering heat treatment to improve synthesis Mechanical property . High strength is divided into 8.8, 10.9, 12.9.

From strength grade: High strength bolts commonly used 8.8S and 10.9S two strength grades. Ordinary bolts are generally 4.4, 4.8, 5.6, 8.8.

From the stress characteristics of high-strength bolts apply pre-tension and lean Friction force Transfer external force, ordinary bolts rely on bolt rod resistance Shearing force And hole wall pressure to transfer shear force.

4. Press Force characteristic Divided into: friction type and pressure type

Friction type high-strength bolt is based on the friction between the connected parts to transfer external force, when the shear force is equal to the friction force, extremely friction type High strength bolted connection The design of Ultimate load . At this time, the rod of Lianzhong will not slip relative, the bolt rod will not be cut, and the bolt hole wall will not bear pressure.

Bearing type high-strength bolts are similar to ordinary bolts, the shear force can exceed the friction force, at this time there will be relative slip between the connected members, the bolt rod and the hole wall contact, the connection depends on the friction force and the shear and pressure of the bolt rod to transmit force.

The deformation of compressive high-strength bolts is large, and it is not suitable for the connection of structures directly under dynamic load.

5. Several kinds of electrode

There are roughly a dozen kinds: Carbon steel electrode , Low alloy steel electrode , Molybdenum and chrome-molybdenum heat resistant steel electrode , Low temperature steel electrode , Stainless steel electrode , Surfacing electrode , Cast iron electrode , Nickel and nickel alloy electrode Copper and copper alloy electrode, aluminum and aluminum alloy electrode and Special purpose electrode .

6. Weld defects:

(1) Lack of penetration : The middle of the parent metal joint (X groove ) or root (V, U groove) Blunt edge Parts left behind that are not fully fused together Lack of fusion . Failure to weld has been reduced Welded joint the Mechanical strength Unwelded notches and ends will form Stress concentration point , in the welding parts Bear load It is easy to cause cracking.

(2) Unfused: solid metal with Filled metal Between (between the bead and the base metal), or between the filler metal ( Multipass welding When between the weld bead or Weld layer Partial incomplete melting of the bond, or in Spot welding ( Resistance welding When the base material is not completely fused together with the base material, it is sometimes often accompanied Slag inclusion Exists.

(3) Pores: During the process of melting and welding, the gas in the weld metal or the gas invaded by the outside world does not overflow before the cooling and solidification of the molten pool metal and remains inside or on the surface of the weld metal hole Or pores, depending on their morphology can be divided into single pores, chain pores, dense pores (including cellular Stomata) etc., especially in Arc welding In due to metallurgy The process time is very short, the molten pool metal quickly solidifies, and the gas produced in the metallurgical process, Liquid metal Absorbed gas, or electrode flux Moisture and decomposition at high temperatures produce gas, even if the humidity in the welding environment is too large, it will decompose gas at high temperatures, etc., and these gases will form porosity defects when they are too late to precipitate. Although the porosity is more stressed than other defects Central tendency It is not that large, but it destroys the density of the weld metal and reduces the effective cross-sectional area of the weld metal, resulting in a reduction in the strength of the weld.

7. Nondestructive testing It is done without damaging the workpiece or raw materials Working condition A means of testing the surface and internal quality of the parts being inspected.

Common non-destructive testing methods:

Ultrasonic inspection : Can be penetrated by ultrasound Metallic material A method of checking the defects of parts by reflecting at the edge of the interface, when the ultrasonic beam passes from the probe to the inside of the metal from the surface of the part, and encounters the defects and the bottom of the part respectively Reflected wave Then, pulse waveforms are formed on the fluorescent screen, and the position and size of defects are judged according to these pulse waveforms.

Radiographic inspection ( X-ray , Gamma rays ) : Discover objects by penetrating them with rays Internal defect Method of flaw detection.

Magnetic particle detection : Is used to detect iron Magnetic material Surface and proximity Surface defect A method of detection. When the workpiece is magnetized, if there is a defect on the surface of the workpiece, due to the defect Magnetic resistance Increase and create magnetic leakage, forming a local magnetic field, Magnetic particle The shape and position of the defect are displayed here to determine the existence of the defect.

8, parts processing procedures: preparation, correction, lofting, cutting, bending, hole making, assembly, welding, testing, rust removal, painting.

9, metal surface rust removal methods are: manual treatment, Mechanical treatment , Chemical treatment and Flame treatment Four kinds.

(1) Manual processing

Manual processing mainly with shovel knife, Wire brush Emery cloth, broken steel Saw blade Such tools, by hand tapping, shoveling, scraping, brushing, sand methods to achieve rust removal, this is the traditional rust removal method of painters, but also the most simple method, without any environmental and construction conditions, but due to poor efficiency and effect, can only apply to a small range of rust removal treatment.

(2) Mechanical derusting method

Mechanical rust removal is mainly the use of some electric, Pneumatic tool To get rid of the rust. In common use Power tool Such as electric brush, electric grinding wheel; Pneumatic tools such as pneumatic brushes. Electric brush and pneumatic brush is the use of special circular steel wire brush rotation, by impact and friction to clean rust or oxide, especially on the surface rust, the effect is better, but it is difficult to remove deeper rust spots. The electric grinding wheel is actually portable grinder Can be moved at will in the hand, using the high-speed rotation of the grinding wheel to remove rust, the effect is better, especially for deeper rust spots, its work efficiency is high, the construction quality is also better, easy to use, is a more ideal rust removal tool. But in the operation must be careful not to punch through the metal skin.

(3) Sandblasting, Shot peening method

Sand blasting, shot blasting treatment with the previous section to remove the old Coating film How to use it. (4) Flame treatment method Flame treatment method is used Gas welding gun A small number of deep rust spots that are difficult to remove by hand are burned red, and the high temperature makes the rust oxide Change the chemical composition to achieve the purpose of rust removal. Using this method, care must be taken not to let the metal surface burn through, and to prevent a large area of the surface from being deformed by heat.

(5) Chemical treatment

The chemical treatment method is actually pickling and rust removal method, using acid solution and Metal oxide (Rust) occurs Chemical reaction , generated salts While detached from the metal surface. Common acidic solutions are: vitriol , Hydrochloric acid , Nitric acid , Phosphoric acid . The acid solution is applied to the metal rust part of the operation so that it is slowly removed by chemical reaction with the rust. After removal of rust, rinse with clean water and use together Weak base Solution process Neutralization reaction Rinse with clean water and then wipe and dry to prevent rust quickly.

The surface of the acid-washed metal needs to be roughened or phosphating It is mainly to increase the metal surface and primer Adhesive force . In dilution Concentrated sulfuric acid When, the sulfuric acid should be slowly poured into the water of the container, and constantly stirring, do not operate on the contrary, so as not to spill the sulfuric acid.

10, common lifting equipment: Gantry crane Tower crane Crawler crane Truck crane Wheeled crane Mast crane Jack hoist Bridge crane .

The Eiffel Tower in Paris

World famous steel structure building (7 photos)

Eiffel Tower It was built in 1889 in France Paris The hollow structure of the Eiffel Tower on the Champ de Mars is 300 meters high, the antenna is 24 meters high, and the total height is 324 meters.

The tower is a steel skeleton skeleton structure, with an elevation of 57 meters, 115 meters and 274 meters above the sea level of three layers of the platform to visit, the fourth layer of the platform is 300 meters above the sea level, set Meteorological station . There's an antenna on the top, for Paris Television center . There are elevators and stairs from the ground to the top of the tower, 710 steps.

It is understood that the tower uses more than 1,500 giant prefabricated beams, 1.5 million rivet 12,000 steel castings, All up weight 7,000 tons, it took 250 workers 17 months to build.

Petronas Twin Towers

Kuala Lumpur The Twin Towers, 88 storeys high, are located in the city center of Kuala Lumpur Title title The first super building. Towering, imposing, imposing, yes Malaysia The pride of... It broke the United States at a height of 451.9 meters Chicago The Hills Building held the record for 22 years, becoming the largest building in the world today.

The project began on December 27, 1993, was officially capped on February 13, 1996, and was completed in 1997. It's Malaysia National oil company With 2 billion Malaysian ringgit It was built. The world famous architect - Caesar Pei lucky The designer of this building.

New York Empire State Building

Empire State Building It is a building Super high-rise The modern office building, it and Statue of Liberty Together they are known as the symbols of New York. The Empire State Building, 381 meters high, has stood since 1931 World's tallest building He was on the throne for 40 years until 1971 World Trade Center Over.

In the 1930s, architects managed to add a 200-foot round tower, giving the Empire State Building a height of 1,250 feet. This building skyscraper It only took 410 days to build, which counts Architectural history The miracle on. For a long time, the Empire State Building was the tallest building in the world.

Millennium Dome, London

Millennium dome , located in London East of the Thames Greenwich The peninsula was built by the British government for the 21st century Landmark building . The bend diameter is 320m, the circumference is greater than 1000m, and there are 12 masts that penetrate the roof up to 100m. roof It is spherical in shape Tension film structure . The membrane surface is supported on 72 radial steel cables with a cross-section of 2×φ32, which are cable-stayed at a distance of 25m sling with lanyard Supported by the mast, the sling and the lashing are raised to the mast at the same time Stabilizing effect .

It is understood that the Millennium Dome covers a total area of 73 hectares, Total construction cost Up to $1.25 billion in size Comprehensive exhibition Buildings, including a series of exhibition and performance venues, as well as shopping malls, restaurants, bars and so on.

San Francisco Golden Gate Bridge

Golden Gate Bridge It runs north and south, connecting the city of San Francisco with Marin County. The bridge, which took over four years to build, is one of the most beautiful structures in the world. It is no longer the longest in the world Suspension bridge But it is the most famous. The great bridge of the Golden Gate Bridge Tower height 227 meters, each cable weighs 6,412 metric tons and is made of 27,000 strands of steel wire. Construction began in January 1933 and was first completed and opened to traffic in May 1937. Steel tower Standing on the north and south sides of the bridge, it is 342 meters high, of which the part above the water is 227 meters, equivalent to a 70-story building. The top of the tower is made of two pieces with a diameter of 92.7 centimeters and a weight of 24,500 tons Steel cable It's connected. The cables are down in the middle, almost close Bridge body The steel cable and the bridge body are connected with a thin steel rope. Data show that the span of the bridge between the steel towers is 1280 meters, which is one of the rare single-hole long span suspension Bridges built in the world.

The Gateway Arch

Missouri St. Louis The Gateway Arch is the tallest single-standing monument in the United States. This shiny circular shape made of steel rises from the ground, nearly 200 meters high, the span is nearly 200 meters, and the height is exactly the same. According to records, Finland American, famous Architectural designer Ilo? Salinen in the late 1940s a national Design competition The Gateway Arch was designed in China. However, construction did not begin until February 1963 and was completed in October 1965. Later, another was added to the arch Transportation system To allow people to climb to a viewing platform at the top of the arch. Located on the Mississippi River, Gateway Arch is known as the gateway to the West.

Sydney Opera House

Sydney Opera house The entire building covers an area of 1.84 hectares, is 183 meters long, 118 meters wide and 67 meters high, which is equivalent to the height of a 20-story building. It has the appearance of three sets of huge shells, standing on the base of a cast-in-place reinforced concrete structure that is 186 meters long from north to south and 97 meters wide from east to west. The Opera House is divided into three parts: Opera hall, odeum And Beniland's restaurant. The opera hall, the concert hall and the lounge stand side by side and are built on a huge granite base, each consisting of four lofty shell roofs.

It is said that the most special thing about the concert hall of the opera House is that it is located directly in front of the concert hall Australia Artist Ronald Sharp Design and construction the bassoon organ . This big organ is made up of 10,500 air pipes and claims to be the largest mechanical wood in the world Connecting rod In addition, the building materials of the entire concert hall are made of Australian wood, faithfully presenting Australia's own style.

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