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1. Displacement ratio (interlayer displacement ratio):

1. 1 noun definition:

(1) Displacement ratio: that is, the ratio of the maximum horizontal displacement to the average horizontal displacement of the vertical members of the floor.

(2) Inter-story displacement ratio: that is, the ratio of the maximum inter-story displacement angle to the average inter-story displacement angle of the vertical members of the floor.

These include:

Maximum horizontal displacement: the maximum horizontal displacement of joints at the top of walls and columns.

Average horizontal displacement: the sum of the maximum horizontal displacement and the minimum horizontal displacement of the wall top and column top nodes is divided by 2.

Inter-story displacement angle: the ratio of inter-story displacement of walls and columns to story height.

Maximum inter-story displacement angle: the maximum inter-story displacement angle between walls and columns.

Average story drift angle: the sum of the maximum and minimum story drift angles of walls and columns divided by 2.

1.3 control purpose:

High-rise buildings have many floors and large heights. In order to ensure the necessary stiffness of high-rise buildings, the maximum displacement and interlayer displacement should be controlled. The main purposes are as follows:

1 ensure that the main structure is basically in an elastic stress state, avoid cracks in concrete wall columns, and control the number and width of cracks in floor beams and slabs.

2 Ensure that the non-structural components such as filler wall, partition wall and curtain wall are intact to avoid obvious damage.

3. Control the plane regularity of the structure to avoid torsion and adversely affect the structure.

1.2 control of clauses in relevant specifications:

[Anti-code] Article 3.4.2 stipulates that the plane layout of the building and its lateral force resisting structure should be regular, symmetrical and have good integrity. When there is structural plane torsion irregularity, the maximum elastic horizontal displacement (or interlayer displacement) of the floor should not be greater than 1.2 times of the average elastic horizontal displacement (or interlayer displacement) at both ends of the floor.

Article 4.3.5 of 【 High Code 】 stipulates that the maximum horizontal displacement and interlayer displacement of floors and vertical members of high-rise buildings with Class A and Class B height should not be greater than 0.2 times of the average value of 65438+ floors; Moreover, A-level high-rise buildings should not be more than 1.5 times the average floor, and B-level high-rise buildings, mixed-structure high-rise buildings and complex high-rise buildings should not be more than 1.4 times the average floor.

According to Article 4.6.3 of [High Code], for a high-rise building with a height not exceeding 150m, the ratio of the maximum inter-story displacement to the inter-story displacement angle (i.e. the maximum inter-story displacement angle) δ U/h shall meet the following requirements:

δu/h limit of structural suspension system

Framework 1/550

Frame-shear wall, frame-core tube 1/800

Tube in tube, shear wall11000

Frame support layer11000

1.4 Key points for judging and adjusting the results of computer calculation;

SATWE program in PKPM software calculates and outputs the maximum horizontal displacement, maximum inter-story displacement angle, average horizontal displacement, average inter-story displacement angle and the corresponding ratio of each floor. See displacement output file WDISP. The details came out. But for the interpretation of the calculation results, we should pay attention to the following points:

(1) If the displacement ratio (inter-story displacement ratio) exceeds 1.2, it is necessary to consider the bidirectional earthquake action in the setting of total information parameters;

(2) Accidental eccentricity should be considered when checking displacement ratio, but it is not necessary to consider accidental eccentricity when checking interlayer displacement angle.

(3) The assumption of forced rigid floor should be chosen for checking the displacement ratio, but when the convex and concave are irregular or the floor is discontinuous locally, the calculation model that conforms to the actual stiffness change in the floor plane should be adopted, and the torsional influence should be considered when the plane is asymmetrical.

(4) The maximum story displacement and displacement ratio are the control parameters under the assumption of rigid floor. Component design and displacement information are not the results under the same conditions (that is, component design can be calculated by elastic floor, and displacement calculation must be obtained under the assumption of rigid floor), so the displacement can be calculated by rigid floor first, and then the component analysis can be carried out by elastic floor. (5) Because high-rise buildings are almost always twisted under the action of horizontal force, the maximum displacement of floors generally occurs at the corners of structural units.

2. Cycle ratio:

2. 1 Definition of nouns:

The period ratio is the ratio of the first natural vibration period Tt dominated by torsion to the first natural vibration period T 1 dominated by translation. The period ratio mainly controls the torsional effect of the structure, reduces the adverse effect of torsion on the structure, and makes the torsional stiffness of the structure not too weak. Because when they are close, the torsional effect of the structure will increase obviously due to the influence of vibration coupling.

2.2 Control of relevant specification clauses:

Article 4.3.5 of [High Code] stipulates that the ratio of the first natural vibration period Tt dominated by structural torsion to the first natural vibration period T 1 dominated by translational motion (i.e. the period ratio) of A-level high-rise buildings should not be greater than 0.9; Class B high-rise building, mixed structure high-rise building and complex high-rise building should not be greater than 0.85.

Article 5. 1. 13 of the Code stipulates that the number of calculated vibration modes of high-rise building structures should not be less than 9. The torsional effect of the structure should be considered in the seismic calculation, and the number of vibration modes should not be less than 15. For multi-tower structures, the number of vibration modes should not be less than 9 times of the number of towers, and the participation mass of vibration modes should not be less than 90% of the total mass when calculating the number of vibration modes.

2.3 Key points of judging and adjusting computer results:

(1). See the output file of period, seismic force and mode shape for the calculation results. Because the period ratio is not directly given in the calculation result of SATWE computer, it is necessary to manually check the period ratio for the usual regular single tower structure according to the following steps:

A) According to two translation coefficients and one torsion coefficient of each vibration mode (the sum of them is equal to 1), judge whether each vibration mode is a torsion mode (also called torsion mode) or a translation mode (also called lateral mode). Generally speaking, when the torsional coefficient is greater than 0.5, the vibration mode can be considered as torsional vibration mode, and vice versa. Of course, some extremely complex structures should also be judged by combining the main mode information;

B) The torsional vibration mode with the longest period corresponds to the first torsional vibration period Tt, and the lateral vibration mode with the longest period corresponds to the first lateral vibration period t1;

C) calculate Tt/T 1 to see if it exceeds 0.9(0.85).

The period ratio of multi-tower structure cannot be directly checked by the above method. At this time, the multi-tower structure should be divided into multiple single towers, and the calculation and check should be carried out separately according to multiple structures (note that multiple towers are not defined in the same structure, but divided into multiple structures according to towers).

(2) For the structure with uniform stiffness, generally speaking, the first two or several modes are the main modes when considering the torsional coupling calculation, but for the complex structure with uneven stiffness, the above laws may not necessarily exist. In short, in the design of high-rise structures, the torsional vibration mode should not be ahead to reduce the earthquake damage. The function of calculating the contribution rate of each vibration mode to the base shear force is given in SATWE program. Through the parameter ratio (the percentage of the base shear force of each mode to the total base shear force), we can judge which mode is the main mode in X direction or Y direction, and we can see the contribution of each mode to the base shear force.

(3) When analyzing and calculating the period and seismic force by the mode decomposition response spectrum method, we should also pay attention to two issues, namely, the selection of calculation model and the determination of the number of modes. Generally speaking, when the whole building is assumed to be a rigid floor, the "lateral rigid model" should be selected for calculation. When the structure defines elastic floor, it is more reasonable to choose "total rigid model" for calculation. As for the number of vibration modes, it should be determined according to the above-mentioned [high code] 5. 1. 13. Whether the number of vibration modes is enough should be judged by the only condition that the calculated number of vibration modes makes the participating mass of vibration modes not less than 90% of the total mass.

(4) Like the control of displacement ratio, the control of period ratio focuses on the relative relationship between lateral stiffness and torsional stiffness, rather than their absolute magnitude. Its purpose is to make the plane arrangement of lateral force resisting members more effective and reasonable, so that the structure will not produce excessive torsional effect (relative to lateral displacement). That is to say, the period ratio control does not require the structure to be strong enough, but requires the bearing arrangement of the structure to be reasonable. Considering the limitation of period ratio, from the point of view of new code, the structural plane of previous rules may become "plane irregular structure" Once the period ratio does not meet the requirements, the situation can only be improved by adjusting the plane layout. This change is generally holistic, and small local adjustments often have little effect. The period ratio does not meet the requirements, indicating that the torsional stiffness of the structure is less than the lateral stiffness, and the general adjustment principle is to strengthen the outer ring of the structure or weaken the inner tube.

(5) The torsion period is difficult to control and adjust. Only by finding the key point of the problem and taking corresponding measures can the problem be effectively solved.

A) The torsion period has nothing to do with the eccentricity between the rigid center and the center of mass, but only with the torsional stiffness of the floor;

B) It is easier to satisfy when all shear walls are arranged in two directions orthogonal to the same principal axis; When the outer wall and the core wall are arranged obliquely, attention should be paid to checking whether they meet the requirements;

C) When the period limit is not met, if the control potential of story drift angle is great, the stiffness of vertical members of the structure should be reduced and the translation period should be increased;

D) When the period limit is not met and the control potential of the layer displacement angle is not great, check whether there is a layer with particularly small torsional stiffness, and if so, strengthen the torsional stiffness of this layer;

E) When the limit value of the torsion period is not met, and the control potential of the inter-story displacement angle is not great, and the torsional stiffness of each story is not abrupt, it shows that the proportion of the plane size of the core tube to the total height of the structure is small, so the plane size of the core tube or the thickness of the outer wall of the core tube should be increased to increase the torsional stiffness of the core tube.

F) When the torsion is found to be the first mode in the calculation, shear walls should be arranged around the building as far as possible, instead of adjusting the torsional stiffness of the structure only by increasing the stiffness of the middle shear wall.

3 Stiffness ratio

3. 1 Definition of nouns:

Stiffness ratio refers to the ratio of lateral stiffness of different floors in the vertical direction of the structure (also called interlayer stiffness ratio), which is mainly used to control the vertical regularity of high-rise structures, so as to avoid the sudden change of vertical stiffness and form weak layers. Whether the roof of the basement structure can be used as the embedded end and whether the structural stiffness of the upper and lower floors of the transfer floor can meet the requirements, the judgment of the weak floor is based on the ratio of floor stiffness. There are three methods to calculate story stiffness, namely, shear stiffness (Ki=GiAi/hi), shear-bending stiffness (Ki = Vi/δI) and the ratio of seismic shear force to seismic story displacement (Ki = Qi/δui).

3.2 Control of provisions in relevant codes: Appendix E2. 1 [Code Resistance] stipulates that the lateral stiffness ratio of the upper and lower floors of the transfer floor of the tube structure should not be greater than 2;

Article 4.4.2 of [High Code] stipulates that the lateral stiffness of a high-rise building with seismic design should not be less than 70% of the lateral stiffness of the adjacent upper floor or 80% of the average lateral stiffness of the adjacent three floors;

Article 5.3.7 of 【 High Code 】 stipulates that in the calculation of high-rise building structure, when the basement roof is used as the embedded end of the superstructure, the lateral stiffness of the basement floor should not be less than 2 times of the lateral stiffness of the adjacent superstructure floor;

[High Code] Article 10.2.3 stipulates that the lateral stiffness of the shear wall structure with large space at the bottom and the upper and lower structures of the transfer floor shall comply with the provisions in Appendix E of the High Code:

E.0 1) For the partial frame-supported shear wall structure with one floor at the bottom, the equivalent stiffness ratio γ of the upper and lower floors of the transfer floor can be approximately used to express the stiffness change of the upper and lower floors of the transfer floor, and γ should not be greater than 3 in non-seismic design and γ should not be greater than 2 in seismic design.

E.02) When the story number of the large space at the bottom is more than one story, the ratio of the equivalent lateral stiffness of the frame-shear structure at the upper part of the transfer story to the equivalent lateral stiffness of the frame-shear structure at the lower part of the transfer story should be close to 1, which should not be greater than 2 in non-seismic design and 1.3 in seismic design.

3.3 Key points of judging and adjusting computer results:

The (1) code controls the stiffness ratio and displacement ratio of structural layers, and also requires calculation under the assumption of rigid floor. For an elastic floor or a project with zero floor thickness, it should be calculated twice, and the story stiffness ratio should be calculated under the assumption of rigid floor to find out the weak story, and then other structural calculations should be completed under real conditions.

(2) See general information WMASS. The calculation results of story stiffness ratio of building structure and the seismic shear amplification coefficient of weak story are given. Generally speaking, the lateral stiffness of the structure should be uniform or decrease gradually along the height, but for the middle layer of frame-supported floor or evacuated wall column, it is usually the weak layer. Because the weak layer is vulnerable to severe earthquake damage, the program automatically determines the weak layer according to the calculation result of stiffness ratio or the magnitude of interlayer shear force, and multiplies it by the amplification factor to ensure the safety of the structure. Of course, you can also specify the weak layer manually in the adjustment information.

(3) According to the actual situation, the above three methods should be selected to calculate the story stiffness: "shear stiffness" should be selected for large space at the bottom or multi-storey buildings and brick-concrete structures; "Shear-bending stiffness" should be selected for multi-story or bottom-supported steel structures; For general engineering, you can choose the third method suggested in the specification, which is also the default method of SATWE program.

4. Rigid weight ratio

4. 1 Definition of nouns:

The ratio of the lateral stiffness of the structure to the design value of gravity load is called the rigid-to-weight ratio. It is the main parameter affecting the second-order effect of gravity, and the second-order effect of gravity increases with the decrease of the rigid-to-weight ratio of the structure in a hyperbolic relationship. Under the action of wind load or horizontal earthquake, if the second-order effect of gravity is too large, the structure will collapse, so controlling the rigid-to-weight ratio of the structure can control the structure from instability.

4.2 Control of relevant specifications:

[Gao Gui] Article 5.4.4 stipulates:

1. The stability of shear wall structure, frame-shear wall structure and tube structure must meet the following requirements:

2. The stability of frame structure must meet the following requirements: Di * Hi/Gi & gt；; = 10

4.3 Key points of judging and adjusting computer results:

1. Calculate the equivalent lateral stiffness according to the following formula:

2. For shear frame structure, when the rigid-to-weight ratio is greater than 10, the second-order gravity effect of the structure can be controlled within 20%, and the stability of the structure has a certain safety reserve; When the rigid-to-weight ratio is greater than 20, the second-order effect of gravity has little influence on the structure, so the code stipulates that the second-order effect of gravity can be ignored at this time.

3. For shear wall structure, frame-shear structure and tube structure subjected to bending shear, when the rigid-to-weight ratio is greater than 1.4, the structure can maintain overall stability; When the rigid-to-weight ratio is greater than 2.7, the internal force and displacement increment caused by the second-order effect of gravity are only about 5%, so the code stipulates that the second-order effect of gravity can be ignored at this time.

2. If the structural stiffness-to-weight ratio (EJD/GH2) >: 1.4 meets the overall stability condition, the output result of SATWE refers to WMASS. Get out,

3. When the height-width ratio of a high-rise building meets the limit, the stability checking calculation is not required, otherwise the stability checking calculation should be carried out.

4. When the stability of the high-rise building does not meet the above requirements, the lateral stiffness of the structure should be adjusted and increased.

5. Shear weight ratio:

5. 1 Definition of nouns:

Shear-weight ratio, that is, the minimum seismic shear coefficient λ, is mainly used to control the minimum seismic shear of each story, especially for the structure with the basic period greater than 3.5S and the structure with weak stories. For the sake of structural safety, the code has increased the requirements for shear-weight ratio.

5.2 Control of relevant specifications:

Article 5.2.5 of [anti-code] and Article 3.3 of [high-code] stipulate that the horizontal seismic shear force of any floor of the structure should not be less than the minimum seismic shear force coefficient λ given in the following table during seismic checking. Category 7 degrees 7.5 degrees 8 degrees 8.5 degrees 9 degrees

Obvious torsional effect or fundamental period

Structure is less than 3.5S0.0160.024 0.032 0.048 0.064.

0.0120.0180.024 0.0320.040 for structures with fundamental periods greater than 5.0S

5.3 Key points of judging and adjusting computer results:

(1). For the weak layer of vertical irregular structure, the horizontal seismic shear force should be increased by 1. 15 times, that is, the minimum shear coefficient λ of floors in the above table should be multiplied by 1. 15 times. When the period is between 3.5S and 5.0S, the above table can be evaluated by interpolation.

(2) For ordinary high-rise buildings, the shear-weight ratio of the structure is the smallest at the bottom and the largest at the top. Therefore, in practical engineering, the shear-weight ratio of the structure is controlled by the bottom. From bottom to top, which floor is not enough for design earthquake internal force will be amplified.

(3) Automatically calculate the shear-weight ratio of each floor of the structure and the seismic shear adjustment coefficient of each floor. Please refer to the output file WZQ for the results. Beyond SATWE period, seismic force and vibration mode).

(4) Set a switch on whether the internal force of each layer is automatically amplified in the adjustment information column; If the user considers automatic amplification, SATWE will output the amplification factor used in the program in WZQ.OUT

(5) The shear-weight ratio of the sixth degree zone can be taken from 0.7% to 1%. If the shear-weight ratio is too small, it is all structural reinforcement, which means that the bottom shear force is too small, so it is necessary to check the section size and period reduction of the component; If the shear-weight ratio is too large, it means that the bottom shear force is large. Also check whether the structural model and parameter settings are correct, or whether the structural layout is too rigid.

6. Axial compression ratio

6. 1 Definition of nouns:

Column (wall) axial compression ratio N/(fcA) refers to the ratio between the design value of column (wall) axial compression ratio and the product of the total cross-sectional area of column (wall) and the design value of concrete axial compressive strength. It is one of the main factors affecting the seismic performance of wall columns. In order to make the column wall have good ductility and energy dissipation capacity, one of the measures adopted by the code is to limit the axial compression ratio.

6.2 Control of provisions in relevant codes: [Concrete Code] 1 1. 4. 16[ Anti-Code ]6.3.7 and [High Code ]6.4.2 also stipulate that the axial compression ratio of columns shall not exceed the limit in the following table.

Seismic grade of structure type

One two three

Frame structure 0.7 0.8 0.9

Frame seismic wall, plate column seismic wall tube 0.75 0.85 0.95

0.6-0.7-

Article [Concrete Code] 1 1. 7. 13[ High Code ]7.2. 14 also stipulates that in seismic design, the axial compression ratio of the wall limb under the action of the representative value of gravity load of the steel bar at the bottom of the shear wall with seismic grade I and II shall not exceed the limit in the following table:

6.3 Key points of judging and adjusting computer results:

(1). The higher the seismic grade of a building structure, the higher its ductility requirements, so the stricter the restrictions on the axial compression ratio. For frame columns and I-shaped shear walls, the requirements are more stringent. When the seismic grade is low or non-seismic, it can be appropriately relaxed, but in any case it shall not be less than 1.05.

(2) In order to limit the axial compression ratio of the wall column, the bottom section (maximum axial force) is usually taken for checking calculation. If the section size or concrete strength grade changes, the axial compression ratio of this position should also be checked. SATWE calculation results are detailed. When the calculation result is inconsistent with the specification, the axial compression ratio value will be automatically displayed in red characters.

(3) It should be noted that when calculating the axial compression ratio of the wall limb, the design value of the axial compression ratio generated by the representative value of gravity load (i.e. the partial coefficient of dead load is 1.2, and the partial coefficient of live load is 1.4) is adopted in the code to calculate its nominal axial compression ratio, so as to ensure that the wall limb has sufficient ductility under earthquake action and avoid the situation that the compression area is too large and the eccentric compression is small.

(4) Experiments show that the strength grade of concrete, the form and quantity of stirrups are closely related to the axial compression ratio of columns. Therefore, the limit value of axial compression ratio of columns is appropriately adjusted according to different conditions in the code.

(5) When the axial compression ratio of the wall limb does not exceed the above-mentioned limit value, but the value is large, edge members can be set at the parts with greater stress at the edge of the wall limb to increase the ultimate compressive strain of the concrete at the end of the wall limb and improve the ductility of the shear wall. When the axial compression ratio of the wall limb is greater than 0.3 for the first-level earthquake resistance (9 degrees), 0.2 for the first-level earthquake resistance (8 degrees) and 0. 1 for the second-level earthquake resistance, the restrained edge members should be set, otherwise the structural edge members can be set. The program treats the bottom reinforcement part and all wall limb ends on the upper floor as constrained edge members.