The problems and difficulties in the promotion of steel-structured houses in China are mainly as follows:
(1) The degree of industrialization of supporting parts is low. Steel structure housing is a complex technology and component, material integration, is the discovery direction and inevitable product of the housing industry gradually modernization. Therefore, steel structure housing must first be industrialized. However, currently the steel structure residential related, mature parts, accessories, or lack of, or low degree of industrialization, or lack of technical standards or inconsistent with the standards of steel structure residential, especially wall, floor, balcony, stairs, etc., wet operation More, leading to the current steel structure residential is basically in the embarrassing situation of "wearing a T-shirt and tie".
(2) The lack of modularization seriously restricts the industrialization of steel-structured houses. At present, there are only modular standards for stairs, doors and windows, kitchens and bathrooms, and most parts and parts such as roofs, partitions, and elevators lack uniform modular standards.
(3) Optimization of steel structure design, such as optimization of building plane and column net, cold-bent rectangular tube instead of welded box type column, variable section column application, buckling restraint support application, etc., to reduce project cost and improve the economics of steel structure residence.
3.1 For the current various structural systems, the scope of application has not been clearly defined, and there is a lack of design reference. Therefore, the current structural selection can only be based on the structural performance of the structure, to reduce the amount of steel used as the goal, to meet the architectural design constraints and to obtain qualitative conclusions. In the structural design, the engineering cost can be effectively reduced by optimizing the design. This process is cumbersome and complicated, and requires the structure and the building to cooperate. At present, this work still has a long way to go.
3.2 The study of new beam-column joints can further reduce production and transportation costs. In the National Building Standard Design Atlas "Steel Structure House (2)" (05J910-2), only seven common beam-column joints, new type of baffle-through joints, sleeve-type reinforced joints, and outer ribs are given. Ring plate nodes and the like are not listed. In addition, from the aspect of the force transmission characteristics of the nodes, the selection of the node form (rigid, semi-rigid, articulated) should be combined with the actual calculation and comparison, and the optimal node form should be selected to further reduce the amount of steel used, but the current specifications (such as GB50017- 2003) There are many lags, lacking the criteria for judging rigid, semi-rigid, and articulated nodes and the calculation basis for semi-rigid nodes.
(4) The lack of design specifications has led to problems such as the promotion of some new high-quality steel products or the emergence of superior materials. For example, the current "Code for Design of Steel Structures" (GB50017-2003) and "Technical Regulations for Steel Structures for High-rise Civil Buildings" (JGJ99-98) have not listed Gaojian Steel and weathering steel as recommended materials, and have not given corresponding explanations. This type of steel cannot be used in the design or the strength of the high-quality Q345GJ steel is taken as the value of ordinary Q345 steel.
(5) Anti-corrosion problem. The current "Steel Structure Design Code" (GB50017-2003), "Industrial Building Corrosion Protection Design Code" (GB50046-2008), "Steel Structure Construction Quality Acceptance Specification" (GB50205-2001), etc. have not been applied to the performance of steel structure anti-corrosion coatings. The design life is clearly defined. Even the newly published "Code for Design of Steel Structures" (CECS261-2009) simply makes general provisions on the number and thickness of anti-corrosion coatings, and its anti-corrosion effect and maintenance and repair cycle lack clear standards. Claim. In addition, since the steel components of steel structure houses are mostly concealed in the wall, the anti-corrosion coating maintenance is very difficult, the maintenance is difficult, and the cost is high. The regular inspection and maintenance requirements usually mentioned in the design description are both vague and difficult to achieve. .
(6) Application problems of high strength steel. The third paragraph of 3.9.2 of the Seismic Design Code (GB50011-2010) specifies the material properties of steel for steel structure: “The yield ratio of steel should not exceed 0.85; the steel should have obvious yielding steps and The rate of growth should not be less than 20%; steel should have good weldability and acceptable impact toughness." Limited to these requirements, the strength of steel for steel structures in China is only about Q460, and the development of high-performance steel with higher strength and meeting the requirements of the specification. It is imminent. In addition, the steel rolled by TMCP technology also puts high demands on the welding technology.
(7) The detailed processing process needs to be improved. Due to the large ductility of the steel structure itself, the existing retaining structures commonly used in the industry, such as strips, whole plates, blocks, etc., some of the joint forms are not well adapted to the deformation of the structure itself, and there are cracks and leaks in the joints. And other issues. In addition, steel structure houses need to be further strengthened in sound insulation treatment.
(8) The quality of the construction team needs to be improved. The development of steel structure residential buildings is standardized design, factory production, and on-site assembly construction. It is entirely a development model of industrialization, which requires a highly qualified and professional construction team. Most of the current steel structure engineering construction still uses the traditional extensive management mode, and the professional skills of the personnel are not uniform, which is difficult to meet the industrial production needs, especially in the "three-board" installation, structural installation, equipment and pipeline installation, the overall kitchen and bathroom modules. The problems of installation and other aspects are particularly prominent. The construction speed advantage is not exerted. What is more serious is the impact on the construction quality and the promotion of steel structure housing. Therefore, we must start from the two aspects of ideological understanding and operational skills to cultivate a group of specialization. Industrial workers and a professional construction team.
(9) Lack of national policy support measures. Since 1996, the state has successively issued a series of steel structures such as the "Building Technology Policy for 1996-2010", "Notice on Further Promoting the Application and Application of 10 New Technologies in the Construction Industry" and "Technical Guidelines for Green Buildings". Technical standards, norms and policies have guided and promoted the development of steel-structured houses to a certain extent, but lacked specific support policies that can directly stimulate developers, such as the Ministry of Construction’s science and technology demonstration projects and green demonstration projects. There are no technology subsidies. In the initial stage of the development of steel structure housing, the degree of industrialization and standardization is not high, and the actual cost of R&D and promotion is high. It is recommended that the competent national authorities give specific policy incentives that can form economic benefits to enhance the promotion of developers. The enthusiasm and market competitiveness of the application of steel structure housing.