Structural Program The most commonly used structural system in lightweight steel multi-story houses is the frame structure, and the suspension system is sometimes used according to the needs of the building program. The beams and columns are mostly rolled or welded sections, and sometimes the columns can be box sections. Due to the limitations of the varieties and supply of steel sections in China, welded members are mainly used at present. Frame structure plane cloth need to be flexible, each part of the stiffness is relatively uniform, simple structure, easy to construct. Its self-oscillation period is longer, its self-weight is lighter, and it is not sensitive to seismic effects. However, its lateral stiffness is small and lateral displacement is difficult to control. For some multi-storey houses with elevators, in order to enhance the lateral

stiffness, combined with the arrangement of the elevator shaft, a frame-shear-resistant frame system or a frame-shear wall (usually steel plate shear wall) structural system can be adopted. Floor cover system The floor slab of steel structure of multi-storey house must have sufficient bearing capacity, rigidity and integrity. Currently more commonly used in steel beams laying pressure steel plate, and then poured 100 ~ 150m of reinforced concrete plate, that is, pressure steel plate combination floor, pressure steel plate and steel beams connected with bolts. Also available pre-stressed thin plate plus concrete cast-in layer or general reinforced concrete floor, at this time should ensure that the reliable connection between the floor and steel beams. If the combined effect of steel beam and cherry plate is considered during design, the bearing capacity and overall stability of the beam can be significantly improved, and the beam height can be effectively reduced. The connection between the main beam and the secondary beam is generally simply supported isometric connection, sometimes also made into unequal connection, such as the use of compression steel plate combination floor, in order to facilitate the laying of compression steel plate, the main and secondary beams on the top surface of the difference between the thickness of the compression steel plate, but also can increase the net height of the building

building. Enclosure structure In order to reduce the self-weight of the steel structure of multi-storey houses, the enclosure structure is mostly made of lightweight materials. Lightweight filling materials, such as hollow block, aerated concrete, etc., are mostly used for the external wall, and sometimes composite wall composed of pressurized steel plate and lightweight heat preservation layer can be used, and lightweight and beautiful glass tomb wall structure is also used for the external wall of many houses. The internal partition wall can use hollow block, aerated concrete and other lightweight filler wall or light steel keel gypsum board, and at present there are also aluminum alloy frame glass partition.

For light steel structure houses, the traditional linoleum plus asphalt roof waterproof layer is very uneconomical, now most of the coil waterproofing. The roof also abandons the traditional cement mortar leveling layer and coke slag heat preservation layer, and adopts lightweight heat preservation materials, such as JQ board, polyethylene concrete board, etc., which can be made into variable thickness according to the requirements and cancel the roof leveling layer. Foundation form The foundation of multi-storey light steel house is commonly used as independent foundation under column, strip foundation, cross-shaped foundation, and sometimes raft foundation can also be used. When independent foundation under column is adopted, attention should be paid to the influence of relative uneven settlement of each foundation on the superstructure. Foundation beams are commonly used in cast-in-place or prefabricated reinforced concrete structure, and sometimes steel foundation beams can be used according to the requirements, but usually the column footings and steel beams buried below the ground are outsourced with concrete to solve the problem of anticorrosion. Nodal structure The steel structure columns of multi-storey houses mostly adopt welded work-shaped or box-shaped cross-section. Due to the thin web of the work-shaped section, the weak axis direction and beam connection is mostly articulated, while the strong axis direction is in the form of rigid connection. Sometimes semi-rigid connection can also be used, but its stress characteristics are more complex, often through the test to obtain more accurate design data. At the same time, the components of the steel structure of multi-story houses are relatively thin, and should

avoid site on-site weld connections as much as possible. In order to strengthen the overall stiffness of the structure, the secondary beams can be made in the form of continuous beams. Fireproofing and anti-corrosion measures The fireproofing of steel structure in China mainly adopts the methods of fireproof coating, foaming fireproof paint and outsourcing fireproof layer. For the exposed steel structure components, such as stairs, etc., mostly use coatings and paints, using 10~40mm thick coatings, the fire-resistant limit can be up to 1.5~3h, while the fire-resistant time of the foaming paint is generally 0.5h. For hidden components, perlite and vermiculite fireproofing spray or fireproofing board is a cost-effective method, and the spraying of 30~40m dry can realize the fire-resistant limit of 1.5, and also has a certain corrosion-resistant ability. Exposed steel components are generally corrosion-resistant coatings or paint anti-corrosion, consisting of primer and top coat. The validity of the former anti-barrier coating is 10~20 years, so it should be re-painted periodically. Galvanized compression steel plate itself has a certain anticorrosion ability, when used for the building cover can be used with the help of fireproof coating to solve the problem of anticorrosion, but used for roofing and exterior wall surface should also be coated with organic coatings to increase its durability.