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          85 easily stepped pits in structural design parameters

          85 easily stepped pits in structural design parameters

          Classification:
          Industry information
          Author:
          Source:
          2019/12/04
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          [Abstract]:
          Source: Network

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          I. structural calculation (10 pits)
           
          1. The difference of stiffness between two directions of the structure should not be too large
           
          ① it is necessary to control the ratio of the first vibration period in two main shaft directions. Generally, it can be controlled according to the period ratio of no less than 0.8.
           
          ② the displacement ratio exceeds the limit and no two-way earthquake is calculated. Irregular, especially irregular, serious irregular: if the displacement ratio is greater than 1.2, the torsion is irregular, and two-way earthquake shall be calculated.
           
          ③ the displacement ratio shall not exceed 1.5 when considering torsion coupling and two-way seismic calculation. If it exceeds 1.5, the structural arrangement shall be readjusted.
           
          2. The torsional displacement ratio is calculated under the assumption of rigid floor, and the actual rigidity shall be considered in the reinforcement calculation.
           
          3. When width ratio control is used for structural calculation, each coefficient shall be taken reasonably.
           
          ① the periodic reduction coefficient shall be determined comprehensively according to different structural systems, types of infilled walls (considering possible changes) and the number of infilled walls, and shall not be reduced or not reduced for the convenience of reinforcement regardless of the actual situation. Article 3.3.17 of the high regulation: when the infilled wall is brick wall, the frame structure can be taken as 0.6-0.7, the frame shear wall structure as 0.7-0.8, and the shear wall structure as 0.9-1.0 (attention should be paid to the short leg shear wall structure)
           
          ② the rigidity reduction coefficient of shear wall coupling beam shall ensure that the coupling beam will not crack under normal use conditions. If necessary, secondary calculation shall be carried out to avoid cracking of coupling beam under normal use.
           
          4. When some components are not suitable for computer calculation, the software reduces the torque of all components according to the input torque reduction coefficient. This will make the bending beam or bending beam with torque reduced, and the structure has potential safety hazards. The torque of these components shall not be reduced. The coupling beam (folding beam) of the corner window shall fully consider that the structural software can not be fully reduced in accordance with the requirements of clause 4.1.2 of the load code. For components with large reduction of software, manual calculation and review shall be carried out.
           
          ① when calculating the wall, column and foundation of the structure with the main podium connected as a whole, there is an error in the calculation of the number of floors in the reduction for the podium part. Special attention should be paid to this situation.
           
          ② in case of staggered floor structure or missing floor in the middle, if the calculated floor number is quite different from the actual one, it shall be calculated separately. ③ load reduction of special room.
           
          5. It should be noted that when the storey height changes greatly (such as equipment layer), the rigidity ratio and shear bearing capacity ratio of the weak layer of the structure meet the specification requirements.
           
          6. When the shear bearing capacity of the floor is lower than 80% of the upper layer, the weak layer shall be designated and the ratio of shear bearing capacity shall not be less than 65%. Floors cannot be both weak and weak.
           
          7. It shall be ensured that the calculated vibration mode number makes the mass participation coefficient not less than 90%. Steel structure roof and open structure. The number of calculated vibration modes of high-rise structure shall not be less than 9; when considering torsional coupling, it shall not be less than 15; the number of multi tower structure shall not be less than 9 times of the number of towers.
           
          8. The deflection and crack checking calculation shall be carried out for the long-span simply supported secondary beam, especially for the beam with large span height ratio. The span height ratio should not be too large. In the calculation of long-span floor slab, the bearing constraint shall be considered comprehensively, and the thickness, elevation and reinforcement amount of adjacent slab shall be coordinated. The beam used as the support shall be more than twice the plate thickness.
           
          9. For the concrete frame tube structure, it should be noted that the 0.2Q0 internal force adjustment coefficient of the outer frame should not be 2 times of the maximum value, and should be used according to the actual ratio. Ensure that the shear force borne by the outer frame is not less than 20% of the bottom shear force and the larger value of 1.5 times of the maximum shear force of the calculated floor (note that this is not the smaller value of the two).
           
          10. For the two-story structure of the bottom frame, the rigidity of the next two stories should be close. The stiffness ratio of the third floor and the second floor, 6 and 7, should not be greater than 2.0, 8 degrees 1.5. But they should not be less than 1.0. Shear walls should be arranged in both directions, the best result is close, too big or too small is not good. When the stiffness is close, the failure will not focus on one floor. The main purpose is to reduce the weak degree of the bottom, and prevent the bottom structure from excessive lateral displacement and serious damage, or even collapse. However, if there are too many concrete walls in the bottom layer, the stiffness may be greater than that of the upper brick concrete structure. In this way, the weak layer may be transferred to the transition layer under the earthquake. The transition layer is a masonry structure, its ductility is not as good as the reinforced concrete structure at the bottom, which is prone to brittle failure. Therefore, the lateral stiffness ratio of the transition layer and the bottom layer of the frame shear wall building should be controlled in a reasonable range. Pay attention to check the calculated length coefficient of the column layer by layer, especially in the case of only cantilever beam in the other direction. The program often considers the cantilever beam as a common frame beam, resulting in errors.

           

          II. Load problem (7 pits)
           
          1. The load shall be carefully converted for the squatting position of toilet, bathtub and kitchen of toilet; the load shall be taken for the library and database according to the actual layout.
           
          2. For stores with supermarket nature such as shopping malls, the live load should be taken according to the specific situation, not all of which should be 3.5. If necessary, it should be negotiated with Party A.
           
          3. The load shall be taken according to the construction practice and shall not be increased indefinitely. (load increase is not completely safe)
           
          4. The energy-saving requirements of the building shall be considered for the external wall of the structure, and the increased load shall be fully considered.
           
          5. The load of fire truck in item 8 of table 4.1.1 of the load regulation 3 ‐ refers to the load that the fire truck directly runs on the top plate, and its wheel compression is combined. If there is floating soil or other fillings below, it shall be converted according to the covering thickness, and 20KN / m2 shall not be taken directly. When considering the thickness of cover soil to reduce the load of fire truck, the load reduction should not be too small. It is introduced that after reduction, it should not be less than 10kN / m2. Different values shall be taken for the load of fire truck when calculating beam column and slab. Frequency combination can be considered. For plates, the larger value shall be taken. It can be reduced for beams and columns. Most of the reinforcement of beam, slab and column is controlled by variable load, and part of the case with thick soil cover may be controlled by permanent load.
           
          6. Pay attention to whether there is dry hanging stone on the outer wall when taking the load value of the infilled wall. When there is dry hanging stone, there is also the weight of stone and keel, generally not less than 1.0kn per square meter, in addition to the weight of the infilled wall itself.
           
          7. When the dead load is large, it should be noted that the load effect may be controlled by the dead load, and the partial factor of 1.35 should be considered. This often occurs when the roof and basement roof are covered with soil.

           

          III. Foundation (28 pits)
           
          1. If the foundation of independent column or strip foundation is too large and the side is five or six meters long, the foundation form should be changed. The foundation slope is too steep, which should not be greater than 1:3 (ratio of vertical to horizontal). Attention should be paid to the short side of rectangular foundation. The total thickness of the foundation with large side length should be increased appropriately to ensure the rigidity of the foundation itself and reduce the bending deformation of the foundation.
           
          2. The pull beam of independent foundation or independent bearing platform shall be connected to the foundation pull beam on the column to strengthen the foundation rigidity and balance the bending moment at the bottom of the column. When the independent foundation or bearing platform is large, it may not be necessary to use the foundation pulling beam. However, when the column foundation or bearing platform is small, especially for single pile or two pile bearing platforms, it is necessary to use pulling beam. At this time, the tension beam is in tension at the bottom of the column. The longitudinal reinforcement of the tie beam shall be extended into the column.
           
          3. When the bearing capacity of the foundation is very large, it is suggested that the foundation should increase the shear bearing capacity calculation note 4 of article 8.1.1 of the foundation specification: "for the concrete foundation with the average compressive stress at the bottom of the foundation more than 300kPa, the shear resistance calculation should be carried out." article 8.2.7 of the extended foundation states: "the shear reduced width of the inclined section of the stepped independent column foundation and the tapered independent column foundation can be in accordance with the appendix of this specification S OK ". For the independent column foundation, especially the non square independent column foundation, the shear bearing capacity should be checked. The influence coefficient of section height should be considered in shear checking calculation.
           
          4. Pay attention to the checking calculation of the bearing capacity of the foundation under the combination of earthquake action. Under the combined action of earthquake, the vertical load increases, but the bearing capacity of foundation is not all improved enough to meet the requirements. The adjustment coefficient of bearing capacity is only 1.0 and 1.1 for the part of soil with ground resistance less than 150kPa. According to the non seismic consideration, the requirements can not be met under the earthquake combination.
           
          5. The base elevation of the high-rise main building shall be higher than that of the podium (garage) as far as possible. If necessary, the structural overhead layer shall be set. If it can not be avoided, ensure that the base elevation of the main building is not higher than the ground elevation of the basement of the podium, and that the horizontal spacing of the base of the main podium is greater than 2-5 times of the base elevation difference (according to the soil).
           
          6. When the underground garage is set between the main buildings in a residential area, the basement elevation of the underground garage may be lower than the basement elevation of the main building
           
          7. High rise building foundation buried depth.
           
          8. Foundation bearing capacity correction and anti overturning.
           
          9. The correction of foundation bearing capacity shall consider that the conversion of the converted load to the live load shall not be considered. If the main building is not the same around, comprehensive consideration or weighted conversion can be made. But there should be some prosperity.
           
          10. Anti overturning should consider the most unfavorable condition, the buried depth of the foundation should be 1 / 15, 1 / 18. This requirement can only be waived if the foundation is rock. But overturning and sliding should be considered. Pay attention to the height difference between the two sides.
           
          11. Article 12.1.7-2 of the high-rise Code stipulates that "when the building adopts rock foundation or takes effective measures, under the premise of meeting the bearing capacity, stability and article 12.1.6, the buried depth of the foundation may not be limited by 1 / 15". At this time, attention should be paid to checking the overturning and sliding of buildings under large earthquake, so as to ensure the design principle of "no collapse under large earthquake".
           
          12. The base elevation of high-rise building may be higher than the adjacent foundation or river course, and sufficient safety distance shall be ensured. It should not be less than 3 times of height difference. In the structural design, the embedded depth of the foundation shall be determined in strict accordance with the requirements of the code, and the adverse effect of the surrounding construction pipe trench (such as garage entrance, underground Square) on the embedded depth shall be fully considered.
           
          13. The lower part of the detail of the post cast strip of the bottom slab shall be lower than the bottom of the bottom slab for a certain distance to ensure the effective height of the concrete of the bottom slab. And reinforcement shall be provided.
           
          14. When adopting raft foundation, whether the foundation is overhanging or not can refer to the requirements of article 3.8.5 of technical rules for architectural design (Beijing Institute) and Article 17 of article 3.8.5 of structural part of technical measures for design of national civil construction engineering. When the raft foundation is calculated according to the linear distribution of base reaction, the moment in the middle of side span and the moment of the first inner support shall be multiplied by a factor of 1.2 (article 8.4.11 of the foundation code).
           
          15. The depth d used for foundation bearing capacity correction shall be the reduced depth. That is, d = P / R, where p is the average pressure of the basement bottom of the podium (not the basement pressure of the corresponding foundation), and R is the weight of soil above the basement.
           
          16. When the pile foundation is adopted, when the relationship between the pile end elevation and the depth of the exploratory hole, attention shall be paid to whether the drilling depth meets the requirements of the survey specification, and supplementary survey shall be conducted if necessary.
          III. Foundation (28 pits)
           
          1. If the foundation of independent column or strip foundation is too large and the side is five or six meters long, the foundation form should be changed. The foundation slope is too steep, which should not be greater than 1:3 (ratio of vertical to horizontal). Attention should be paid to the short side of rectangular foundation. The total thickness of the foundation with large side length should be increased appropriately to ensure the rigidity of the foundation itself and reduce the bending deformation of the foundation.
           
          2. The pull beam of independent foundation or independent bearing platform shall be connected to the foundation pull beam on the column to strengthen the foundation rigidity and balance the bending moment at the bottom of the column. When the independent foundation or bearing platform is large, it may not be necessary to use the foundation pulling beam. However, when the column foundation or bearing platform is small, especially for single pile or two pile bearing platforms, it is necessary to use pulling beam. At this time, the tension beam is in tension at the bottom of the column. The longitudinal reinforcement of the tie beam shall be extended into the column.
           
          3. When the bearing capacity of the foundation is very large, it is suggested that the foundation should increase the shear bearing capacity calculation note 4 of article 8.1.1 of the foundation specification: "for the concrete foundation with the average compressive stress at the bottom of the foundation more than 300kPa, the shear resistance calculation should be carried out." article 8.2.7 of the extended foundation states: "the shear reduced width of the inclined section of the stepped independent column foundation and the tapered independent column foundation can be in accordance with the appendix of this specification S OK ". For the independent column foundation, especially the non square independent column foundation, the shear bearing capacity should be checked. The influence coefficient of section height should be considered in shear checking calculation.
           
          4. Pay attention to the checking calculation of the bearing capacity of the foundation under the combination of earthquake action. Under the combined action of earthquake, the vertical load increases, but the bearing capacity of foundation is not all improved enough to meet the requirements. The adjustment coefficient of bearing capacity is only 1.0 and 1.1 for the part of soil with ground resistance less than 150kPa. According to the non seismic consideration, the requirements can not be met under the earthquake combination.
           
          5. The base elevation of the high-rise main building shall be higher than that of the podium (garage) as far as possible. If necessary, the structural overhead layer shall be set. If it can not be avoided, ensure that the base elevation of the main building is not higher than the ground elevation of the basement of the podium, and that the horizontal spacing of the base of the main podium is greater than 2-5 times of the base elevation difference (according to the soil).
           
          6. When the underground garage is set between the main buildings in a residential area, the basement elevation of the underground garage may be lower than the basement elevation of the main building
           
          7. High rise building foundation buried depth.
           
          8. Foundation bearing capacity correction and anti overturning.
           
          9. The correction of foundation bearing capacity shall consider that the conversion of the converted load to the live load shall not be considered. If the main building is not the same around, comprehensive consideration or weighted conversion can be made. But there should be some prosperity.
           
          10. Anti overturning should consider the most unfavorable condition, the buried depth of the foundation should be 1 / 15, 1 / 18. This requirement can only be waived if the foundation is rock. But overturning and sliding should be considered. Pay attention to the height difference between the two sides.
           
          11. Article 12.1.7-2 of the high-rise Code stipulates that "when the building adopts rock foundation or takes effective measures, under the premise of meeting the bearing capacity, stability and article 12.1.6, the buried depth of the foundation may not be limited by 1 / 15". At this time, attention should be paid to checking the overturning and sliding of buildings under large earthquake, so as to ensure the design principle of "no collapse under large earthquake".
           
          12. The base elevation of high-rise building may be higher than the adjacent foundation or river course, and sufficient safety distance shall be ensured. It should not be less than 3 times of height difference. In the structural design, the embedded depth of the foundation shall be determined in strict accordance with the requirements of the code, and the adverse effect of the surrounding construction pipe trench (such as garage entrance, underground Square) on the embedded depth shall be fully considered.
           
          13. The lower part of the detail of the post cast strip of the bottom slab shall be lower than the bottom of the bottom slab for a certain distance to ensure the effective height of the concrete of the bottom slab. And reinforcement shall be provided.
           
          14. When adopting raft foundation, whether the foundation is overhanging or not can refer to the requirements of article 3.8.5 of technical rules for architectural design (Beijing Institute) and Article 17 of article 3.8.5 of structural part of technical measures for design of national civil construction engineering. When the raft foundation is calculated according to the linear distribution of base reaction, the moment in the middle of side span and the moment of the first inner support shall be multiplied by a factor of 1.2 (article 8.4.11 of the foundation code).
           
          15. The depth d used for foundation bearing capacity correction shall be the reduced depth. That is, d = P / R, where p is the average pressure of the basement bottom of the podium (not the basement pressure of the corresponding foundation), and R is the weight of soil above the basement.
           

          16. When the pile foundation is adopted, when the relationship between the pile end elevation and the depth of the exploratory hole, attention shall be paid to whether the drilling depth meets the requirements of the survey specification, and supplementary survey shall be conducted if necessary.

          IV. problems in basement design (6 pits)
           
          1. The calculation sketch of basement exterior wall generally takes the top of the wall as the hinged wall bottom, which is the fixed end only when the basement floor thickness is greater than the wall thickness. When it is an independent foundation or bearing platform, the thickness of the waterproof bottom plate is usually less than or equal to the thickness of the wall. At this time, it should be an elastic support and cannot form a fixed end. The exterior wall of basement belongs to deep beam, so it does not need to add girders at the top and bottom of the wall, but only needs to be designed according to the deep beam.
           
          2. The coefficient of static earth pressure 7 should be used in the calculation of the outer wall of the basement. The earth pressure at the depth h is generally 0.5. Note that when there is groundwater, the water and soil should be calculated separately (the pressure of water on the wall is not multiplied by the earth pressure coefficient). Generally, the column should not be considered as the support in the calculation of exterior wall of basement, and the calculation should be based on the one-way slab of vertical force transmission. If the calculation is based on the two-way slab figure, the column should have certain lateral bending stiffness and strength, and the lateral earth pressure should be considered in the calculation of column reinforcement. The concrete wall should be added to the large underground garage connected with the main building. The main building is connected with the basement, and the horizontal seismic force is transmitted to the surrounding soil by the basement, so the basement is required to have certain rigidity. For the large-area basement, its stiffness can not meet the requirements, it is appropriate to set a certain number of concrete walls in two directions according to the distance between the main building and the basement.
           
          3. The thickness of basement floor shall not be less than 250mm.
           
          4. The calculation diagram of the concrete external wall at the stairwell of the basement shall be considered according to the actual situation.
           
          5. The strength grade of exterior wall and column of basement generally, the exterior wall of basement is only used as retaining wall, and its concrete strength grade is not high. The column or shear wall cast together with the external wall has higher strength grade, so it is difficult to construct. The general requirements of the construction unit are in accordance with the high-grade construction. This may cause serious cracking of concrete on the outer wall. The strength grade of exterior wall column or shear wall in basement can be reduced (SATWE can achieve this). At this time, part of the wall can be considered as flange to form T-shaped column for calculation. The ratio of reinforcement to axial compression will not change much.
           
          6. The thickness of concrete protective layer of basement structural members shall not be taken as per table 9.2.1 of concrete specification according to the environmental category. For the basement exterior wall and the bottom slab roof, the thickness of the protective layer inside and outside should be considered. It is easy to ignore the case of the basement roof with only one basement. In the calculation of components, the effective height of components should be different according to the thickness of protective layer. In the calculation of anti floating, a certain degree of safety should be considered. The live load is taken as zero, the dead load volume weight is taken as small value and the part that may not be available is removed.

           

          V. superstructure (30 pits)
           
          1. The rigidity of the secondary cross beam is obviously different. Because of the different bearing conditions, cross-section and span, the positive rigidity of the secondary cross beam is different, which forms the relationship between the primary and secondary beams in fact, but the weight is different. If the difference between the two stiffness is large, the secondary beam with small stiffness may have negative bending moment at the secondary beam with large stiffness. If the upper full-length reinforcement is not provided, the upper reinforcement joint is just located at the support, which is easy to crack. If necessary, the section size can be adjusted to make the main and secondary beams directly.
           
          2. When the structure is set with anti-seismic joints, in accordance with the latest anti-seismic concept, in addition to the width of the joints specified in the specifications, it shall also meet the requirements of non-collision under moderate earthquake. That is to say, the displacement at this point is calculated twice according to the moderate earthquake (basically 1.5 degrees higher).
           
          3. The layout of reinforced concrete structure system shall meet the following requirements
           
          ① it is forbidden to adopt the out of gauge structure system with irregular plane and vertical at the same time.
           
          ② at least one transverse frame shall be pulled through within 15m, and at least two longitudinal frames shall be pulled through.
           
          ③ it is forbidden to use cantilever structure in elevator shaft and stairwell.
           
          ④ when corner windows or bay windows are set in high-rise buildings, vertical stress components must be set at the corner of the external corner of the building.
           
          ⑤ pure frame structure system is not suitable for large-span and open public buildings such as theater, gymnasium and auditorium.
           
          4. The seismic overturning moment of the shear wall of frame shear wall structure shall be greater than 50%. If it does not reach 50%, the seismic grade of the frame part shall be adopted according to the frame structure, and the limit value of column axial compression ratio shall be adopted according to the frame structure. In order to meet the requirement of 50%, some designers only add some shear walls at the bottom. This practice does not meet the requirements of the code, and the shear walls should be connected up and down.
           
          5. When the lower part of the girder out of the plane of the shear wall is not vertical enough to set the girder (the span is more than 5m) in the shear wall, whether it is the main beam or the secondary beam, the flange and buttress column should be set at the corresponding part of the shear wall under the girder, and the darkest column should also be set (the darkcolumn can take the beam width plus twice the wall thickness). In many projects, beams are set because of walls, and wing walls can be set completely.
           
          6. When the back of the elevator shaft is facing the back of the frame shear wall structure or shear wall structure, special attention should be paid to the stability of the shear wall between the elevators, and its thickness should not be too small. Both sides of the wall within the scope of stair treads are equivalent to openings, without floor slab as lateral support. The thickness value is not clearly defined, and the stress is not good. If necessary, the shear wall perpendicular to the wall shall be arranged in the elevator shaft.
           
          ① the understanding that the length of shear wall should not be greater than 8m (uniform stiffness, bending failure) to avoid each break, such as uniform stiffness can also be;
           
          ② short leg shear wall (L / h = 5 ~ 8), try to avoid that most of them just exceed 8.0, which is the gap of drilling specification ③ shear wall thickness: H / h limit. There are some problems in the stability checking calculation, which should meet the requirements as much as possible.
           
          7. No matter where the embedded part elevation is in the structural calculation, the height of the reinforcement area at the bottom of the shear wall shall be calculated from the outdoor terrace upward. The total height of the building shall also be calculated from the outdoor terrace to the main roof.
           
          8. When the outdoor floor around the building is different, it should be calculated from the highest floor upward (when the outdoor floor is one floor different from the front and back), the height of the strengthening part should be calculated from the embedded part to the next floor, and the total height of the shear wall H should be taken to the highest point of the shear wall, not just to the large roof.
           
          9. When calculating the length Lc of restrained edge members of the first and second shear walls, the length HW of the wall limb is not correct. It shall be determined according to the location and function of edge components. The arrangement of vertical reinforcement in the edge member has a great effect on improving the bearing capacity and ductility of the wall. The stirrup in the concealed column can restrain the concrete, improve the ultimate strain of the concrete, and make the shear wall have a strong frame, so as to prevent the shear crack from penetrating the whole wall quickly. If the size of the wall opening is small, so that the force of the wall remains a whole wall limb, the shear wall with the opening should be treated as a whole wall limb. When the constraint component is in the middle, it basically belongs to the neutral axis position, which can not play a great role. It is not right to take HW1 for wing column A and HW2 for wing column C in X direction. The wall limb length of wing column A and C shall be HW.
           
          10. For the frame beam with large-span secondary beam on one side, the waist reinforcement should be increased properly.
           
          11. The reinforcement and stirrup can be used to reduce the stirrup ratio by half for the parts within LC and outside the shadow area of the shear wall restraining edge member. The tie bar shall not be more than 1 / 3 of the number of legs, the vertical spacing shall be the same as the shadow part, and the horizontal spacing shall not be more than 300. You can change the diameter here, but you cannot increase the vertical spacing.
           
          12. When the top plate of the basement is used as the embedded part, the reinforcement on each side of the basement column shall not be less than 1.1 times of the bottom column. It is not allowed to enlarge the bottom column reinforcement at will.
          13. When the shear force of the frame beam is mainly contributed by the concentrated force, the shear strength outside the stirrup densification area shall be paid attention to.
           
          14. For shear wall coupling beams with span height ratio less than 5, stirrups shall be added throughout the whole span. When the shear force is more than 5, the shear force is mainly provided by the bending moment of the wall limb caused by the earthquake, and the shear force itself has little change. When the span height ratio is large, the bending moment is not large.
           
          15. At present, the research on the reinforcement ratio of flexural reinforcement of shear wall coupling beam is not enough. When the span to height ratio is less than 0.5, the coupling beam is a part of the wall, and it should be reinforced according to the requirements of the wall; when the span to height ratio is greater than 0.5, from the perspective of "strong shear weak bending", the coupling beam for seismic design is recommended to be adopted as per the table below. The reinforcement ratio of longitudinal reinforcement structure of coupling beam in seismic design.
           
          16. For the length of the mechanical anchoring horizontal section, the wide beam can be set, but the width beam shall not be too large out of the wall, and the armpit shall be added if necessary.
           
          17. For the transfer of girder and supporting column, attention shall be paid to the frame column rising from the beam. There are two bending moments at the bottom of the column. A beam perpendicular to the other direction of the girder shall be set at the bottom of the column to balance the bending moment at the bottom of the column in that direction. For the transfer girder of supporting column transformation, attention should be paid to checking the local bearing capacity of the column bottom. At this time, it is not suitable to consider the increase of the bottom area of the local compression calculation. The coefficient of increase of the local compression strength is taken as 1.0. If necessary, reinforcement mesh should be set.
           
          18. The reinforcement of the frame supporting layer of the frame supporting structure shall be calculated according to the elastic floor. The concrete strength of the transfer member of the transfer layer structure shall reach 100% when the formwork is removed. In order to avoid the deformation of the upper structure following the transfer member in advance.
           
          19. The influence of prestressed concrete with bond on the main components (especially the out of plane bending moment on the shear wall), and the influence of the related components on the establishment of prestress.
           
          20. For the frame structure with seismic grade I and II, the ratio of the measured value of the tensile strength to the measured value of the yield strength shall not be less than 1.25, the ratio of the measured value of the yield strength to the standard value of the strength shall not be greater than 1.3, and the measured value of the total elongation of the steel bar under the maximum tension shall not be less than 9%.
           
          21. Are the frame columns at the corners of reinforced concrete frame structures all corner columns? Corner column refers to the frame column which is located at the corner of the building and connected with only one frame beam in two orthogonal directions of the column. Therefore, the frame columns located at the convex corner of the building plane are generally corner columns, while the frame columns located at the concave corner of the building plane are not treated as corner columns if there is a frame beam connected with each side of the column.
           
          22. Divide the seismic protection category according to the unit "the importance of each unit of the building is significantly different, and the seismic protection category can be divided according to the local unit section". Set up the seismic joint to divide the structure into several units, each unit has a separate evacuation entrance and exit, each unit undertakes the seismic function independently, there is no interaction between each other, and the flow of people is easy to evacuate.
          23. When the lower podium of a high-rise building with large chassis belongs to class B building of a large retail mall, the second floor of it and the adjacent upper high-rise building can be generally defined as the strengthening part, and the seismic design can be carried out according to class B, and the other floors can be carried out according to class C. However, when the superstructure is class B, the substructure is class B no matter what type it is.
           
          24. The bottom frame structure shall ensure that most masonry anti-seismic walls are supported by the lower frame main beam or reinforced concrete anti-seismic wall. At most two masonry anti-seismic walls of each unit can be supported by the secondary beam instead of the frame main beam or reinforced concrete anti-seismic wall (secondary conversion). The longitudinal anti-seismic wall at the bottom of the bottom frame structure is distributed, uniform and symmetrical.
           
          25. When the ratio of the maximum elastic horizontal displacement (or inter story displacement) of the floor to the average elastic horizontal displacement (or inter story displacement) of both ends of the floor is greater than 1.2, it is judged as torsional irregularity; when the ratio is close to 1.5, it is judged as special irregularity; when the ratio is greater than 1.5, it is generally judged as serious irregularity Rules. At this time, the calculated elastic horizontal displacement (or interlaminar displacement) is an algebraic value. When the displacement value is less than 50% of the limit value of the code, the ratio of judging serious torsional irregularities can be relaxed properly. The calculation of the maximum value and the average value is based on the vertical components at both ends of the same axis in the floor, regardless of the end of the cantilever in the floor.
           
          26. When the high-rise building structure is equipped with large chassis podium, when calculating the floor stiffness ratio of podium and its upper tower, the vertical components within the effective influence range can be taken as so-called. The effective influence range can be calculated by making a 45 o outward oblique line at the junction of tower and group buildings, and the vertical components (walls and columns) within the oblique line range can be taken as part of the calculation. The basement part can also be treated according to this method, but not all the vertical components, especially the outer wall of the basement. The seismic grade of podium shall not be lower than that of main building. When the podium and the main building are completely separated in structure, the seismic grade of the main building and the podium shall be determined according to their respective structural system and building height. When the main building and the podium are connected as a whole, the podium shall not be lower than the seismic grade of the main building except for determining the seismic grade according to its own structural system and height. When the podium is a pure frame and the main building is an anti-seismic wall structure and connected as a whole, the anti-seismic grade of the main building shall be determined according to the anti-seismic wall structure. The anti-seismic grade of the podium frame shall not be lower than the anti-seismic grade of the frame part of the whole structure determined according to the frame anti-seismic wall structure system and the height of the main building. When the main building is part of the frame supported seismic wall structure system, the seismic grade of the frame supported layer frame should be determined according to part of the frame supported seismic wall structure, and the seismic grade of the podium building can be determined according to the frame seismic wall system. At this time, when the seismic grade of the non frame supported frame which is directly connected with the frame supported floor frame of the main building is lower than the seismic grade of the frame supported floor frame of the main building, the seismic structural measures should be properly strengthened.
           
          27. In the frame shear wall structure, the seismic grade of the frame part shall be determined according to the formula of the frame structure ----- the structural system of each project shall be determined comprehensively according to the intensity, height width ratio, length width ratio, use function, plane shape and many other factors of its area. Generally, the economy is poor when approaching the maximum use height. For example, the frame structure with more than 10 floors in the seventh degree area may not be as good as the frame shear wall; for class B buildings, the maximum use height can be taken according to the original fortification intensity, but if the anti-seismic measures are increased by one degree, the problem of exceeding the anti-seismic level will occur. It is difficult to control the torsion of the structure with large aspect ratio. If necessary, it is necessary to consider setting joints or changing the structural system. Frame shear wall should be used for high-rise structures with small width under large horizontal load. Generally, the economy of short leg shear wall structure is not as good as that of ordinary shear wall structure (longitudinal reinforcement ratio, minimum thickness); as far as possible, complex structure system should not be used. The most direct structure is the most economical structure system.
           
          28. The transfer structure (frame support, bottom frame) has the problem of sudden change of stiffness, which is seriously damaged. Try to avoid it. An excellent structural designer should design the structure with relatively simple force transmission under the condition of satisfying or satisfying the building function as far as possible.
           
          29. Setting and non setting of seismic joint, width problem.
           
          30. Economic problems of structural design. Factors related to structural economy adjustment of structural system (frame, frame shear, short leg, shear wall), load, coefficient, amplification and calculation coefficient related to reinforcement amount: periodic reduction coefficient, seismic force amplification coefficient, bending moment amplification coefficient cast-in-place hollow floor (pay attention to pipe laying direction, leave enough transverse ribs, two-way stress difference, calculation sketch of slab, surrounding area Shear checking calculation of the rigidity of the supporting member and the direction of the cross pipe).

           

          Vi. civil air defense design (4 pits)
           
          1. The collapse load of civil air defense shall be taken into account when the civil air defense code requires that level 6 Civil Air Defense pass through the outdoor. Stair treads are everywhere.
           
          2. The civil air defense basement indicates that the civil air defense equivalent load of each component should distinguish the nature of the civil air defense basement, whether it is a conventional weapon or a nuclear weapon. Pay attention to the design of civil air defense basement. If it is a class a civil air defense basement (both anti nuclear weapons and conventional weapons), the protection level of nuclear weapons and conventional weapons must be specified. They are not necessarily the same. For example, the basement of nuclear level 6 civil air defense may not be level 6 or level 5. The equivalent load of conventional weapon protection is greater than that of nuclear weapon protection.
           
          3. When the door frame wall of civil air defense basement is large, it is difficult to only rely on the wall reinforcement, so beams or columns should be added. Article 4.6.13 of the civil air defense Code stipulates that when the side length of the door opening is less than 2 times of the wall overhang length, beams or columns should be set at the side of the door opening to support the door frame wall of the flat door.
           
          4. If the six level peace and war combined with civil air defense temporary plugging does not meet the requirements of the new specification, the post can be used only when the span is more than 12 meters, but the post in each room shall not be more than 4.
          . 日韩a片