Key points of structural design of high-rise office building?

At present, with the development of urbanization, higher requirements are put forward for the shape and function of buildings. Some buildings, such as high-rise hotels and office buildings, need to design high-rise enjoyment space or local high-rise green space, but traditional architectural structure design methods can not meet their functional requirements. Therefore, structural engineers need to make concrete analysis and handle it properly on this basis to ensure the safety and reliability of the building. The following are the main contents of the structural design points of high-rise office buildings brought by Zhong Da Consulting Company for reference.

One. Research background

Under the current economic background, China has made great progress and development in science and technology, which has greatly promoted the process of urbanization in China, especially with the improvement of people's living standards, which has further promoted the rapid development of the construction industry in China. In addition, due to the rising demand of modern people for the quality of life, not only the requirements for architectural space are improved, but also the requirements for the safety and reliability of buildings are getting higher and higher. However, the traditional architectural structure design method can not meet its functional requirements. Therefore, it needs to be redesigned to ensure its scientific, rational, normative and economical design. Because the traditional structure can not meet its requirements and the structural design is complex, it is necessary to fully consider the reasonable design from all aspects of the structural function of the building to improve the safety and reliability of the building.

Second, the general high-rise office building structure design points

1 main structure

For the design of the main structure, the structural type, scope of application and basic dimensions are mainly considered. The following are specific analysis and explanation: 1. Frame structure. Generally speaking, frame structure is mainly used for office buildings and high-rise buildings below 50m (10~ 12 floors). Therefore, when designing the frame structure, we should pay attention to the following points: First, we should ensure the directness and symmetry of the frame structure. At the same time, in order to facilitate the effective layout and economy of the basement, the column grid size of 7.4m~ 12m should be selected, which is also the most commonly used column grid size in high-rise buildings. At the same time, in order to ensure the setting and layout of the upper business district and ensure its good landscape vision and counter layout, the small column network should be controlled at 5 m. Secondly, from the structural point of view, the size of the column network can be appropriately enlarged, but the structure does not need to be directly transferred or converted up and down. In order to be more conducive to the seismic anchorage of frame beam reinforcement, the section of frame column can be appropriately increased. At the same time, in order to achieve better economic effect, speed up construction and ensure the rationality of frame structure stiffness, the number of frame columns can be reduced appropriately. Thirdly, for the frame structure itself, in order to ensure its overall stability and lateral force resistance, it is closely related to its own structure. Therefore, in the early stage of setting, the column section should be reasonably determined, and the section size should not be too small. Under vertical load, the specific values of controlling the axial compression ratio (usually the ratio of section compressive stress to concrete compressive strength) are: corner column 0.65-0.75, side column 0.7-0.8 and middle column 0.75-0.

Secondly, the simplified thin-column frame structure, which is a promising frame structure system developed in recent years, is mainly composed of peripheral thin-column frames and central core tubes, which was also developed in recent years. Most foreign countries adopt steel structure, the core tube and steel beam of steel frame are combined with concrete, the peripheral steel column is hinged with steel beam, and the peripheral thin column outer frame tube works together with the core tube. If the rigidity is insufficient, the refuge floor and equipment floor can be equipped with legs, which work together with the refuge floor and equipment floor. It has an obvious advantage, that is, it can reduce the construction cost, reduce the labor force and speed up the construction progress. However, there is also an obvious advantage, that is, the anti-lateral function of floor beam hinge can not be played effectively in time, thus ignoring the rationality of the whole building and only ensuring the rationality of a certain component and part, which will not only affect the use standard of the building. Moreover, the height is too high, which will reduce the utilization coefficient of the aircraft and eventually lead to an increase in the overall cost. Therefore, in practical application, it is necessary to comprehensively consider, adhere to reasonable design ideas and choose reasonable design methods, so as to give full play to the role of each component and ensure its synergy, which can not only ensure the lateral force resistance of the whole space, but also design an excellent work, as shown in figure 1 The third type is shear wall structure. In building engineering, shear wall structure is mainly suitable for high-rise residential buildings, especially for the separation and arrangement of furniture, which has good functions of sound insulation, theft prevention, fire prevention and home separation. According to a large number of engineering practice research, it is found that the application of shear wall in large bay wall can bear horizontal load and vertical load at the same time, and the spacing is about 6m ~ 8m ~ 8m, which can be said to be a feasible and practical structural arrangement. For high-rise apartment buildings, their own weight is only about half of their own, and there are many walls with small bays, which are heavy, difficult to construct, inflexible in plane, harmful and useless, with large structural stiffness and increased steel consumption. It has been eliminated by history.

2 floor covering structure

The design and analysis of floor structure also starts from three aspects, namely, type, basic scale and scope of application, as shown below:

(1) Main girder layout and floor slab. In order to ensure its own stability and levelness, the floor of high-rise building needs to maintain its due stiffness in the horizontal plane, especially for cast-in-place reinforced concrete structures. At the same time, it can improve the sound insulation and shock-proof effect of the floor, and more importantly, it is convenient for wiring and burying pipes of electrical equipment. In general, the thickness of the slab should be kept at 8cm~ 10cm, and the distance of beam grid layout should be 3cm~4cm if it is based on the economic angle of work. Especially for high-rise buildings, the sections and components (columns, walls and simplified walls) are relatively large. Under the influence of horizontal temperature difference, the beam and slab will produce relatively large shrinkage stress and the slab thickness will be higher. Therefore, the steel bars distributed through the floor can be properly configured as required to prevent the floor decoration from being damaged, improve the overall floor stiffness and control the occurrence of cracks. For the layout of the beam lattice, it is required to make the force transfer as direct as possible when designing the floor structure. In order to improve the quality of indoor space, it is necessary to ensure the alignment and organic unity between the beam grid layout and the internal partition wall of the building. When there are some difficulties, prestressed long-span thick plates can be used to adapt to the expansion and contraction of beams. At this time, the prestress value of the plate thickness is L/40-L/50, where L is the short span of the plate. Besides,

(2) the use of beams. With the development of modern social production and the improvement of architectural technology, people's requirements for architectural space are constantly improving, mainly in the improvement of spatial flexibility and landscape vision. Therefore, in this case, the span of the floor beam should be appropriately increased, but it is not allowed because of the height of the building, so this becomes a key problem. In practical application, the following aspects can be considered: first, in order to ensure the rationality of building height, it is necessary to ensure the rationality of reinforcement and the corresponding increase of beam height and vertical structure, which will lead to the increase of cost. Therefore, flat beam or wide flat beam can be used to ensure its strong vitality, which can not only reduce the structural cost, but also ensure good stability; Secondly, from the seismic point of view, because there is a big difference between high-rise buildings and multi-storey buildings, it is necessary to consider the lateral stiffness of the whole structure, including braces, shear braces, tubes, rigid arms and so on. And increase the stiffness appropriately to ensure the overall stiffness, stability and lateral force resistance of the structure. In addition, when determining the seismic grade, when the basement roof is used as the embedded end of the superstructure, the floor here will affect the underground layer when it yields under the earthquake, so the seismic grade of the underground layer should be the same as that of the superstructure; When determining the seismic grade of the podium connected with the main building, it should not be lower than the seismic grade of the main building except for its own consideration; If the overturning moment of the frame part is greater than 50% of the total overturning moment of the structure, it can no longer be regarded as a secondary lateral force resisting member.

In a word, modern life requires that the design of high-rise office buildings should be more reasonable, scientific and comfortable, and have more flexible and free space. Through the design of shear wall, the lateral strength can be improved to meet the different requirements of buildings, the seismic load and wind load can be reduced, and the seismic capacity of the structure can be improved. In the process of regional design, the use function and structural rationality of buildings should be fully considered, and shear walls, columns and frame beams should be rationally arranged to effectively meet horizontal and vertical loads.

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