If we only look at the cost of materials, the cost of steel structures is much higher than that of concrete structures. So why should steel structures be used as the main structure of high-rise buildings? The main reasons are as follows:
- Although steel structures are generally more expensive than concrete structures, compared with traditional concrete structures, steel-structured multi-story buildings have incomparable advantages over traditional structures in terms of construction and comprehensive benefits: such as light weight, low foundation cost, good seismic performance, easy repair after disasters, recyclable and renewable materials, energy saving, land saving, and water saving. On the one hand, these advantages enable developers to reduce investment risks and speed up capital turnover, which is very beneficial to developers’ sales and capital recovery. On the other hand, for builders, the construction period is short, the construction is not affected by climate and seasons, and processing and on-site installation can be carried out simultaneously;
- Environmental protection. Steel structure materials can be almost 100% recycled, greatly reducing the generation of construction waste;
- Due to the light weight and high strength of steel structures, the height of structural beams and the cross-section of columns are smaller than those of concrete under the same span. If the planning height is limited, there will be more usable area. For example, if a 30-story building is replaced with a concrete structure, the actual usable area will be two floors less.
- The toughness of steel structure is better than that of concrete structure, and its earthquake resistance is good, which is incomparable to concrete structure. The maximum applicable height specified in GB50011-2010 “Code for Seismic Design of Buildings” is 80M for concrete structure and 300M for steel structure in the area with a fortification degree of 6;
- The self-weight of steel structure is much lighter than that of concrete structure. The self-weight of concrete in super-high-rise structure is about 1200kg/㎡ building area, while the self-weight of steel is about 500kg/㎡ building area. Therefore, with the same foundation, the steel structure may be built higher;
- The strength (tensile and compressive) of steel is much greater than that of concrete. The steel (standard value) is above 345Mpa (tensile) and above 200Mpa (compressive), while the concrete (standard value) is less than 10Mpa (tensile) and 100Mpa (compressive), so there is no need for bulky component sections.
