1 Multi-storey steel structure residential structure system
The steel structure system of multi-storey and high-rise residential buildings is very different from the traditional brick-concrete structure system and concrete structure system. It is mainly composed of load-bearing steel structure system, floor structure system and enclosure structure system.
1. 1 load-bearing steel structure system
1. 1. 1 system classification
(1) steel frame structure system. Its characteristics are clear stress, flexible plane layout, large indoor space for the building, uniform stiffness of all parts of the structure, large ductility and long natural vibration period, so it is insensitive to earthquake action, good seismic performance, simple structure, easy standardization and finalization of components and fast construction speed. Frame structure is a typical flexible structural system, and its lateral stiffness is poor, which is easy to cause the destruction of non-structural members.
(2) Steel frame-supporting structure system. In order to improve the lateral stiffness of steel frames, effectively resist horizontal loads, and reduce inter-story displacement, a vertical support system consisting of angle steel or channel steel is usually set in the wall plane. When the house is high, it is more economical than the pure frame. The position of the bracket should be appropriate. In order to coordinate with the architectural design, it is generally arranged between the windowsill and the top of the lower window, which is both hidden and can meet the needs of the support system. Considering the layout of doors and windows, W-type, X-type, K-type, herringbone and portal type can be adopted. The bracket is hinged with the frame and designed according to the pull rod or compression rod. The number, form and stiffness of braces can be adjusted according to the height and horizontal force of the building. In order to effectively improve the lateral stiffness of the steel frame, the braces should be arranged circumferentially along the same plane of the building to form a closed reinforcement hoop. Eccentric bracings have good ductility and energy dissipation performance under earthquake action, and can be used in strong earthquake areas.
(3) Staggered truss structure system. It consists of columns outside the house and trusses with a span equal to the width of the house. The height of truss is equal to the height of floors, and the upper and lower floors are staggered on adjacent columns. One end of the floor is placed on the upper chord of the truss, and the other end is placed on the lower chord of the adjacent truss. Because the two bays are arranged with a truss and there are no columns in the middle, it is very suitable for residential and hotel buildings that need flexible arrangement of each unit. At the same time, due to the arrangement of truss interlayer, the local bending moment caused by truss chords is reduced, so that the bending moment of columns in the plane of the frame is very small, mainly axial force, which is beneficial to reducing the cross-section size of columns, and the lateral stiffness of the frame is large and the lateral displacement is small.
1. 1.2 Scope of application
(1) Low-rise residence with 3 floors and below:
(1) light steel frame structure system;
② Cold-formed thin-walled steel column (light steel keel, C-shaped or Z-shaped purlin) structural system.
(2) 4 ~ 6 floors multi-storey residential:
(1) steel frame structure system;
(2) Steel frame-supporting structure system;
③ Steel frame-concrete shear wall structure system.
(3) High-rise residential building with 7 ~12 floors:
(1) steel frame-supporting structure system;
② Steel frame-concrete core tube structure system.
(4) 13 ~ 30-storey high-rise residence:
(1) steel frame-supporting structure system;
(2) Steel frame-shear truss structure system;
③ Steel frame-concrete core tube structure system;
④ Steel frame-precast concrete shear wall structure system with vertical joints;
⑤ Steel frame-shear steel plate shear wall structure system.
1. 1.3 design principles
The structural design of load-bearing steel structure system should follow the general design principles of strong columns and weak beams and strong joints and weak members. In the concrete design, if it is difficult to meet the design formula of strong column and weak beam, it can also meet the requirements of axial compression ratio. Generally, the main beam of a frame can be made of hot rolled or high-frequency welded H-beam, and the secondary beam can be made in many ways. General frame column materials can be hot-rolled or welded I-beams, H-beams, square (box) steel pipes, round steel pipes or cold-formed thin-walled steel pipes, light hot-rolled steel pipes, etc. In order to save steel and reduce the cost, the frame column can also be made of concrete filled steel tube formed by pouring high-strength plain concrete into the empty steel tube. Because concrete-filled steel tubular columns combine the advantages of steel columns and concrete columns, they have good mechanical properties, seismic performance and fire resistance. The axial bearing capacity of single column is greatly improved, and the section size of steel column is greatly reduced. Compared with H-shaped steel columns, the steel consumption can be saved by about 50% and the cost can be reduced by about 45%.
1. 1.4 connection form
Frame beams and columns are suitable for rigid connection in the direction of strong axis; In the direction of weak axis, the design scheme of steel tube column should be adopted in combination with the support arrangement. The structural forms of beam-column joints in steel frames are as follows: ① bolt connection; (2) welding connection; (3) Mixed connection of bolts and welding. The connection stiffness of welded joints is higher than that of mixed joints, and the connection stiffness of bolted joints is lower, but the installation and construction speed of bolted joints is the fastest, and the construction quality is easy to ensure when splicing and installing on site. Generally, the main beam and the secondary beam are hinged, which is mainly connected by welding and high-strength bolts, or a mixed connection mode of bolts and welding can be adopted: the beam web is connected by high-strength bolts, and the flange is welded, and the flange can be installed and positioned by bolts first, and then welded.
1.2 layer structure system
The floor structure consists of steel beams and floors. In addition to distributing the vertical load directly to the walls and columns, the main function of the floor is to participate in and ensure the spatial synergy with the lateral structures. Therefore, it is necessary to ensure that the floor slab has sufficient strength, stiffness and overall stability, and at the same time take technical and structural measures as much as possible to reduce the weight of the floor slab and improve the construction speed. As the floor structure of civil residence, the floor should also have good thermal insulation, sound insulation, heat insulation, waterproof and fireproof performance. In order to ensure the overall stability of steel beams, compact structural measures should be taken for the primary and secondary beams of the floor. At present, the main floor forms are as follows:
(1) profiled steel plate-cast-in-place concrete composite floor slab. The influence of anisotropy of composite floor slab on frame beam should be considered in the overall analysis.
(1) According to the floor setting, determine whether it is a continuous slab or a simply supported slab, and whether the force transmission path is unidirectional or bidirectional;
(2) Stiffness difference caused by the combination of composite steel beams with strong or weak edges;
(2) Precast prestressed concrete composite floor slab. That is, the steel beam is connected with the precast prestressed concrete slab, and the concrete slab is poured to form the composite floor slab. Because this kind of floor not only has the integrity of cast-in-place composite floor, but also saves the support of profiled steel plate and formwork, it is convenient to construct and can reduce the cost of floor, so it should be the first choice.
1.3 envelope system
The cost of internal and external walls accounts for about 30% of the total cost of steel structure residence, which has a great influence on the cost of steel structure residence. At the same time, in order to reduce the dead weight of the structure, meet the requirements of building energy saving and give full play to the advantages of steel structure residence, its enclosure wall should meet the requirements of light dead weight, high strength, good thermal insulation, reliable installation, durability and economy, so light materials should be used. Such as autoclaved lightweight aerated concrete wallboard (ALC board), SRC composite thermal insulation wallboard, steel wire mesh composite thermal insulation wallboard, plant fiber reinforced hollow wallboard, glass fiber reinforced cement wallboard and other factory prefabricated standardized lightweight wallboard and glass curtain wall can be used for external walls. The interior wall can be made of light steel keel gypsum board, aerated concrete lightweight wallboard, ALC lightweight block, lightweight modified gypsum board, sandwich composite board, straw board, etc. ALC slab has the advantages of light weight, good seismic performance, convenient installation, fast construction speed, good thermal insulation, waterproof and fireproof performance, and is very suitable for supporting steel structure. Using ALC board with thickness greater than 250 mm as external wall can meet the requirement of energy saving by 50%, and it is an ideal energy-saving wall material. Steel wire mesh composite insulation board or sandwich composite board has the characteristics of light weight, thin wall, high construction efficiency and good seismic and sound insulation performance, and can be used for external walls of various structures or non-load-bearing walls of frame structures respectively. Straw board not only has the characteristics of light weight, thin wall and high construction efficiency, but also has the characteristics of earthquake resistance, air permeability and good human affinity, and is suitable for non-load-bearing interior partition walls of multi-storey buildings. As far as possible, the roof system adopts purlin system, the roof material can be the same as the floor, and the waterproof roof can also adopt colored profiled steel plates. This roofing system not only has good waterproof and anti-corrosion effect, but also plays the role of roof heat insulation, enriching the external shape of the building.
For example, a profiled steel sheet roofing system with a clean color coating has the following characteristics:
(1) The roof has no nails, excellent waterproof performance, and can be made into large and small heads, which can adapt to the complex changes of the roof and can freely expand and contract;
(2) The plate reinforcement is low, and it is fixed by pressure welding;
(3) the moment of inertia is small, and it is easy to make three-dimensional curved panels with yield strength of 300MPa; ;
(4) moderate cost;
⑤ Applicable plates: steel plate, aluminum plate, copper plate, titanium zinc plate, etc. Among them, steel plate is the most economical. The color-coated board itself has good water resistance and will not leak. The main reason for water leakage is that the joint between profiled steel plate and sandwich panel is not handled well.
2 Characteristics and comprehensive benefits of steel structure residence
(1) structure is light and high strength, with good seismic performance and low engineering cost. The tensile and shear strength of steel is relatively high. Steel structure residence can give full play to the characteristics of light weight, high strength, good ductility, strong plastic deformation ability and good seismic performance of steel. It not only bears less gravity and earthquake, but also reduces the section size of beams and columns, saves steel, and reduces the construction cost and transportation and installation cost.
(2) Beautiful appearance, flexible spatial layout and enhanced architectural functions. Due to the characteristics of light weight and high strength of steel, it is convenient to form a building space with large column spacing and large bay, flexibly divide and arrange indoor partitions, and better meet the functional requirements of modern residential buildings. Compared with brick-concrete structure or concrete structure, its effective use area can be increased by 10 ~ 15%. Architectural modeling can be colorful or simple.
(3) It is easy to transform and the pipeline layout is convenient. The internal division, joint height and reinforcement of steel structure are more flexible. The web of the steel beam is allowed to pass through the pipeline with a certain diameter, and the holes in the structural space make the pipeline arrangement, replacement and maintenance convenient.
(4) Meet the requirements of energy conservation and environmental protection. The materials used in steel structure residential buildings are mainly environmentally friendly, green, recyclable or degradable materials. When the building needs to be demolished, all the steel can be recycled, which greatly reduces the construction waste.
To sum up, the steel structure system of residential buildings not only has the advantages of light weight, high strength and good seismic performance, but also has the technical and economic comprehensive advantages of convenient component installation, shortened construction period, accelerated capital turnover, improved investment benefit, flexible and reasonable building layout, increased effective use area, improved building use function, easy quality assurance, and high degree of commercialization.
3 domestic typical engineering applications
(1) China Research Institute cooperated with Tianjin Construction Engineering Group to form a complete set of steel-concrete composite building system steel structure residential technology from research and development, technical design, product production and engineering construction, and built a 300,000 ㎡ steel structure residential building in Tianjin. The steel structure residential system is composed of load-bearing frame-support system, energy-saving composite external wall panel and extruded internal wall panel, and has many patents. The engineering cost of this system can be comparable to that of reinforced concrete structure, with high degree of industrialization, fast construction speed and advanced comprehensive technical and economic level.
(2) Shanghai Luhai City is composed of six 25-story high-rise steel residential buildings with a construction area of 70,000m2. Steel frame-concrete core tube (shear wall) structure system and profiled steel plate composite floor are adopted. The frame columns are made of concrete-filled circular steel tubes, and all the frame beams are made of high-frequency welded light H-beams. 200mm thick blocks are used for external walls and household walls, and 150mm thick blocks are used for internal partition walls. The fire resistance rating of the component is Grade I, and the design adopts thick fire retardant coating.
(3) In February, 2002, Maanshan Iron and Steel Co., Ltd. built a 1 18-story steel frame reinforced concrete shear wall residential building in Guangming New Village of Maanshan Iron and Steel Co., Ltd., with a construction area of 9800m2. The frame beams and columns are all made of hot-rolled H-beams produced by Masteel, and each floor has 37 frame columns and 74 frame beams. The columns and beams are connected by bolts, and the steel consumption is 400 tons.
4 conclusion
Steel structure residence is an environment-friendly green residential building system, and its rapid development at home and abroad conforms to the development trend of residential industrialization. The steel structure system has obvious comprehensive technical, economic and social benefits, such as light weight, high strength, good seismic performance, low foundation cost, short construction period, easy quality assurance, high degree of commercialization, beautiful appearance, wide applicability, flexible and reasonable building layout, increased effective use area, improved building use function, energy saving and environmental protection. It is conducive to promoting the development of energy-saving and environmentally-friendly building materials and stimulating domestic demand in the metallurgical industry. Therefore, the steel structure residence will have a broader development prospect.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd