Since the 1990s, China Jiangmen steel structure construction carried out very rapidly, particularly the completion of some representatives of the city's iconic high-rise construction, steel structure in China to carry out opened a new page. Shanghai as an international third-highest 88-storey, 420m high Jinmao Tower has been completed, has been put into operation. Allegedly the first height Shanghai Pudong International Financial Centre universally high 460m, a total of 95 layers, the construction area of ​​310,000 m2, is being hastened construction. Dalian Presidential Mansion foreign investment, is quickly in preparation, a total of 95 layers, its height will be built after allegedly among the international forefront.

Jiangmen steel structure to carry out even more is in full swing, especially in the construction of industrial plants is more rapid. We can get a glimpse of the steel structure fabrication and construction of substantial growth in the number of companies, such as steel structure fabrication and construction unit of Shanghai has been carried out have been dozens to more than 400 now, only Shanghai Baosteel region there are nearly home construction steel factory. Excellent situation, how to capitalize on the trend, grasp the quality of planning and construction, is a very current problem Huoji.

Light steel structure and scope

The so-called light steel structure usually refers to the steel structure constituted by the following: cold-formed steel structure; lightweight hot-rolled steel construction; welding or high-frequency welded light steel structure; light steel structure; siding thin composite beam welding and soldering combination of structural column constituted.

1. Scope

According to China's current situation, this configuration because of its wide costs, a significant advantage, has been used in many industrial plants single, multi-storey industrial plants, office buildings and high-rise construction in the non-load bearing member and the like. For single industrial plant, the generally H-shaped steel-based, as the choice of welding beams convergence, the C-shaped or Z-shaped light steel purlins for roof and floor systems or systems with colorful profiled steel plate for the surface layer of the above can be poured concrete, the pressure plate can be used as reinforcement to be matched with steel if necessary. Retaining walls can also be used single or sandwich pressure plate, sandwich plate can be filled with a variety of internal insulation.

2. The main advantage

(1) construction cycle is short: greatest strength lightweight steel structure is that all components are on-site splicing apparatus can be manufactured by the factory, usually on a smaller scale industrial plant just 45 days to two months, and if the choice will have to reinforced concrete construction 8 to 12 months.

(2) the overall economic efficiency is good: because a short work cycle, can be put to use in advance to obtain benefits funded in advance; and because the choice colorful colorful pressure plate, beautiful gorgeous, improved dynamic sense the surrounding environment; because of the construction material itself light weight, under normal conditions do not need to pile, you can save investment; chosen because polystyrene foam sandwich panels or hexene plus cotton insulation board after other measures to make thermal insulation and separated chapter and other good results. Colorful galvanized steel sheet is a substrate and with a silicone as surface processing in addition to two by two and baked, durability is also good, according to the current cost of China's market price, light steel structure is now lower than the reinforced concrete structure, when the plants span the greater its advantage is more significant, this is a big advantage which it contests.

(3) seismic performance is good: as part of a flexible steel structure construction, light weight, which can effectively reduce the degree of seismic response and disasters, it is highly beneficial to the earthquake. China is a multi-national seismic zone, the construction in the earthquake zone should be a lot to promote the use of steel construction, can greatly reduce the earthquake and casualties. Now, officially launched in Tianjin light steel structure housing.

(4) suitable for demolition Relocation: Once made, the owners of the site are not satisfied or the occurrence of unexpected changes in the external environment, the entire construction in a very short period of demolition, a very small loss, all of which are built of reinforced concrete can not have.

It is because of the many advantages of light steel structure, and follow in the fire, corrosion emerging these new products have been well handled light steel structure defects poor corrosion resistance makes it received widespread in industrial plants as well as civilian facilities usage of.

Data selection and planned matters needing attention

Light steel structure as a derivative structure ordinary steel structure, the fundamental theory of computation and the latter fundamentally the same. Details can be found in Shanghai, health standards DBJ08-68-97 "light steel structure plan procedures" and the China Engineering Construction Standardization Association standard CECS102: 98 "portal frame light house steel construction skills of order", where only a few highlights:

1. On the timber should be preferred "H" shape steel, it is subject to reasonable force to facilitate the splicing process is simple. Q235 is appropriate for the load-bearing structure of steel and low alloy steel 16Mn, 15MnV 15MnV or steel, but be careful that the carbon content of Q235-A steel omission delivery conditions, weldability ensure that no, it should not be selected as a welded structure. For thickness greater than 25mm flange beams and columns, field welding beam-column joints should not be used Q235-B.F, should try to use Q235-B or Q235-B.b, especially for the primary structure should be chosen Q235-C or Q235-D.

2. The thickness of the planned target of 17 ~ 40mm Q235 steel than the current GBJ17-88 "standard steel construction plan" in the rules of value progress 5MPa (Shanghai standard), weld strength also been adjusted accordingly.
3. Thinking skills progress elements, the wall thickness of the primary transfer a small force component, that the wall thickness of the existing GBJ18-97 "cold-formed steel construction skill standards" in the primary force component is not adjusted to not less than 2mm small 1.5mm, frame beam member is not less than 3mm.

4. Under the effect of wind load, the lateral portal frame press GBJ18-87 "cold-formed steel construction skill standards" rule capitals height of 1/150. In these two statutes are made to refine the rules and make the appropriate adjustments, but details are not the same as the value. Planners should be used to be in the attention.

5. When planning steel frame, roof trusses and purlins, etc., should consider unlucky influence by the wind suction effect caused by the member forces change. Now lasting load coefficient is taken as 1.0 points. The first rule is to ponder when planned steel frame, roof trusses, roof purlins under mild condition data; if the wind suction effect, member forces will become number will appear plunger rod into the situation. No lasting change when internal forces from the load shedding effect will be lasting load factors taken as 1.2, will result in reducing the degree of solid construction, resulting in unsafe elements.

Skin effect

Pressure plate because of its light weight, high strength, beautiful appearance, convenient means other advantages and widespread use, not only foreign hand industrial plants, civil construction and many also use it to do the roof and wall panels and other building envelope construction.

Skin effect refers to the so-called pressure plate shear capacity in their plane, it may be referred to the force skinning effect. As the pressure plate and member conduct reliable convergence, this effect can make the skin envelope structure together into a primary part of the structure involved in the entire structural system work for the compression associated therewith, flexural member provides continuous pressure lateral support, thereby enhancing the stiffness of the bearing capacity and secure this member. American Standard plans to support the introduction of a blindfolded plan approach. China "cold-formed steel skin force structure plan standard" is still in preparation.

Now Chinese steel construction occupation are still many problems, mainly comprising:

1. The steel construction industry is in line with energy-saving environmental protection, occupational awareness of sustainability has yet to be carried out in progress. In recent years Japan, Canada, the UK government and research institutions published a number of articles devoted to carry out a house built of steel strengths and approaches to draw on.

2. The plan is not accustomed to the concept of market needs. Such as super-tall now and have special requirements for the construction of most of the planned bid by a foreign construction division, they do have in common on the plan, the environment, construction and function. But convergence node is too complicated, excessive consumption of steel and equipment to manufacture and bring more challenges, but also increases the cost of the project.

3. some areas steel construction company blind horse, herd, resulting in overcapacity and waste a lot of resources.

4. The operation of the market is not standard, plus bidders competing prices down steel prices, resulting in a loss of process and apparatus.

5. The lack of steel construction research and development funding, standards and standard revision cycle is too long; standards and use of standards, procedures missing items, lag; steel standards and projects, the construction of convergence is not on the standard protocol.

6. The steel construction plant equipment and construction equipment company, computer management, labor productivity needs to be further progress.

7. The steel construction expertise personnel, lack of skilled workers, especially in small and medium companies more shortages, the company management skills and quality of work are not accustomed production.

8. professional associations function and effect is far from in place. Particularly in terms of standards and guide the market order and service in the company, to develop steel structure market, training and preparation of revised standards Standards and other professionals, should be improved.