Sichuan Xirong tells you why there are few high-rise steel structure houses?

Steel structure housing represents a new model of residential development in the future. Its main advantages are: greatly saving construction time, not affected by the season; Increase the area of residential space; Reduce construction waste and environmental pollution, and reuse building materials; Stimulate the development of other new building materials industries; Good seismic performance; Easy to transform, flexible and convenient in use; Give comfort and more. According to the person in charge of the construction of this high-rise steel structure residential building, the total construction area of this residential building is 9,800 square meters, which will be topped out within 3 months and delivered within 7 months.

First of all, your question is also crossed over the yes or no, directly ask why. I am engaged in concrete, but I still think that steel structure is the future development direction in the absence of new materials. The reason is not high and strong cost, or something, the cost you gave that article, you look at who the author is. Steel production enterprises, don't blindly advocate how about the steel structure, you first produce some good steel out. What age is it, and what strength of steel are we still using? How many years has the ordinary steel bar grade500 used abroad, we are still pushing HRB400. The biggest advantage of steel structure, I think, is that after it is abandoned, it will be easier to handle. Let's imagine how the Hong Kong-Zhuhai-Macao Bridge, the Three Gorges Project, 200 years from now, will be handled by our children and grandchildren. When it comes to the shortcomings of the steel structure, I will say a few points, which may not be accurate, and throw bricks and jade.

1. Structural rigidity and quality problemsA major advantage of steel structure is high strength and light weight, which is an advantage in conventional buildings. But on some structures, this can become a disadvantage. The density of steel is greater than that of concrete, but why steel is lightweight, because the strength of steel is high, under the same load, steel needs less and overall the quality will be lighter than concrete. This is a big advantage of steel structure. At the same time, due to the small amount of steel structure, it will lead to the problem of insufficient rigidity. At the same time, in the power problem, small mass is not necessarily a good thing. High-rise super high-rise wind and earthquake resistance is a big problem, and the wind and earthquake resistance mentioned here is not a matter of strength, but a problem of stiffness. That is to say, in the case of strong winds and earthquakes, I am not afraid that the building will fall, but that the shaking is too large, to be precise, I am afraid that the acceleration of shaking is too large. Imagine a building that is shaking all the time, do you dare to live there? A building that is not functioning properly is undoubtedly a time bomb. At this time, the strength advantage is difficult to exert, although the stiffness problem can be dealt with by structural means, but the weight is too light, which may be a fatal problem. In long-span bridges, especially suspension bridges, because the weight of the steel structure is too light, we even have to add counterweights to the steel box to improve its dynamic characteristics. The corresponding house structure should use steel structure and concrete core tube to solve the stiffness problem. The Empire State Building, the twin towers, and the Sears Tower are indeed steel supertallers, but they are all going for world records, and the key problems they solve are steel high-rise wind resistance, and they are too expensive, if used for housing. In addition, the power problem should be noted that the power problem is very complex, low stiffness may not be appropriate, high stiffness may not be good, only the right range is reasonable.

2. Anti-corrosion problemSteel structure anti-corrosion is a big problem, especially in coastal areas.

prevention problem Steel structure usually loses bearing capacity at 450~650 °C temperature, great deformation occurs, resulting in steel columns and steel beams bending, and as a result, it can not continue to be used due to excessive deformation, and the fire resistance limit of the general unprotected steel structure is about 15 minutes. The length of this time is also related to the speed at which the component absorbs heat. In terms of construction, steel structures may be difficult to construct. ——— dividing line TheoChou mentioned several problems, I think it is not necessarily the shortcomings of the steel structure, you can discuss ———— 1, transportation problems My view is the opposite, transportation problems are a major advantage of steel structures. Is concrete shipping really cheap? That's low-strength concrete. Above C60 concrete, the requirements for aggregates are high. For example, there is no qualified aggregate in Guizhou Province to configure concrete above C60. We now have an arch bridge project in Guizhou, and all the aggregates of C60 concrete are shipped in from Hubei. You look at this shipping cost. Therefore, long-distance transportation is not a unique situation of steel structure. The steel structure is prefabricated in the factory and assembled on site, which can save a lot of on-site costs and control the quality of the project. The same truck, carrying a ton of steel and a ton of sand, of course, the cost of transporting steel (unit price cost) is lower. At the same time, the transportation cost of getting concrete to a high-rise above 100 meters is probably higher than that of steel structure. By the way, the cost of steel structure is not only the cost of steel, but also the cost of processing, the two are about 1:1 relationship, that is, 5,000 tons of steel, processed into components, the total cost will become 10,000 yuan a ton. No matter how expensive the transportation cost is, and 10,000 yuan per ton, it is also a small number. 1 square concrete, the cost is less than 500 yuan, converted into 200 yuan per ton. The difference between the two is 50 times, of course, considering the strength gap, this cost gap will be narrowed a little. 2. Large span may not be said to be the unique advantage of steel structure. Why should the steel structure be made into a truss, the truss as a whole is a hollowed-out beam. A single steel structure member cannot make such a large beam height, so trusses are used to assemble. However, due to the problem of pressure bar stability, the span made of steel truss is very limited. Can the span of the truss be 100m?200m? At the same time, the out-of-plane stability of the truss is also a big problem.

The problem of water leakage and sound insulation is not a difficult problem, that is because the factory has not paid attention to this aspect or has not done a good job. In the case of leakage, cast-in-place a thin concrete floor will solve the problem.