The Market Potential For Light Steel Frame Building And The Design Theories

Since the reformation and opening, the residential construction of China has been developing very rapidly. Great demands for residences has been stimulated with the increase of population, the acceleration of urbanization, the promotion of the standard of living and the development of national economy. But the traditional brick-stone residential structure system now could not fulfill the requirements of the market and the costumers and the theme of "Sustainable Development", because of its high investment, high expense, heavy pollution, low productivity, poor function and low quality. The Light Steel Framing Building adopts the cold-formed steel as the bearing framework and light material as the enclosing structure. As its strength-weight ratio is comparably high and it could be formed according to the design, the cold-formed steel has obvious integrate economic benefits. Because of the basic features of steel itself, the system could better serve the need of industrialized production and the demand of "Sustainable Development". Especially after forbidding using solid clay brick, the development potential of the Light Steel Framing Building is promising.Since the plate is relatively wider and the width-thickness ratio of plate is always larger, the section of cold-formed steel is easy to buckle. Allowed the local buckling of elements and made use of the post-buckling strength, the effective width method is often used to calculate the load-carrying capacity. This article analyzes the difference of theories calculating the effective width between Chinese Code and North American Codes .The author finds the results based on the Technical Code for Design of Cold-Formed Thin-Wall Steel Structure is lower than that of North American Codes, especially for flat plate with relatively larger width-thickness ratio whose thickness is thinner than 2mm, the difference is more obvious. The Chinese codes stipulate both the width-thickness ratio and the minimum thickness of the elements. That is stricter than the stipulations of North American codes. The production ability of thin steel sheet in China is promoted. However, limited by the ability of production and anti-corrosion, the limitation of the minimum thickness could not fulfill the requirements of the development. The author compared the difference of steel-using amount between Chinese codes and North American codes, and made the full-scale test. Based on the theoretical analysis and the experimental research, the author puts forward the suggestion abolishing the limits on the thickness and only limiting thewidth-thickness ratio of the element. This suggestion could be consulted by the drafting of the "Chongqing's Technical Specification for Light Steel Structural Residence".