There are three methods in the seismic calculation of structures, and what are the other two besides

1.Bottom shear method.

The bottom shear method can be used for high-rise building structures with a height of no more than 40m, shear deformation and a relatively uniform distribution of mass and stiffness along the height.

2.Response Spectrum Method.

High-level regulations: high-rise building structures should adopt the mode decomposition response spectrum method. For structures with asymmetrical mass and stiffness, inhomogeneous structures, and high-rise building structures with a height of more than 100 m, the mode decomposition response spectrum method considering the influence of torsional coupling vibration should be adopted.

3.Time-course analysis.

Theoretically, time history analysis is the most accurate method for structural response analysis, but due to the complexity of its analysis and the randomness of waves, it is generally only used as a verification method for response spectrum rather than a direct design method. High regulations:

3 7 9 degree seismic fortification of high-rise buildings, the following situations should be used to use the elastic time history analysis method to carry out supplementary calculations under frequent encounters:

1) Class A high-rise building structure;

2) Class B and C high-rise building structures listed in the table;

3) High-rise building structures that do not meet the requirements of Article 1 of these Regulations;

4) Complex high-rise building structures as specified in Chapter 10 of these Regulations;

5) High-rise building structures with particularly uneven mass distribution along the vertical direction.

When carrying out dynamic time history analysis in accordance with the provisions of Article 1 of these regulations, the following requirements shall be met:

1. No less than two sets of actual records and a set of artificial simulation acceleration time history curves should be selected according to the type of building site and design **, and the average ** influence coefficient curve should be consistent with the ** influence coefficient curve used in the mode decomposition response spectrum method, and the bottom shear force calculated by each time history curve should not be less than 65% of the bottom shear force obtained by the mode decomposition response spectrum method. The average value of the bottom shear force calculated by multiple time history curves should not be less than 80% of the bottom shear force obtained by the mode shape decomposition response spectrum method.

2 The duration of the wave should not be less than 3 4 times of the basic natural period of the building structure, nor less than 12s, and the time interval of the wave can be taken or;

4. The effect of structural ** can be taken as the average value of the calculated results of multiple time history curves and the larger value of the calculated results of the mode decomposition response spectrum method.

a, the selection of waves is not only related to the situation of the site, but also related to the dynamic characteristics of the structure, so that the suitable wave can be selected.

b. Different waves should be used in the primary and secondary directions during two-way analysis.

c, the peak of the ** wave can be appropriately adjusted to meet the requirements of the specification, but not too large, which may lead to the ** wave and the seismic fortification level and the site is not suitable.

d, the so-called "statistically consistent" means that the average ** influence coefficient curve is no more than 20 different from the ** influence coefficient curve used in the mode decomposition response spectrum method at each period point.

Bottom shear method, mode decomposition response spectrum method, time history analysis method, refer to the "Code for Seismic Design of Buildings" GB 50011-2010.

The calculation methods in the seismic design of bridges mainly include static analysis method, dynamic analysis method and time history analysis method, and the characteristics are as follows.

1. Static analysis method: It is a calculation method based on the principle of static equilibrium, and the ruler is suitable for the seismic design of simple and rigid structures. The method is simple to calculate, and does not need to consider factors such as vibration frequency and damping, but it cannot reflect factors such as dynamic response and nonlinear effects.

2. Dynamic analysis method: It is a calculation method based on the theory of structural dynamics, which can consider the vibration frequency and damping of the structure, and is suitable for the seismic design of the structure of medium complexity. This method can reflect the dynamic response and nonlinear effects of the structure, but it is computationally intensive and requires a lot of computational resources and expertise.

3. Time history analysis method: It is a calculation method based on the dynamic theory, which can consider the time history characteristics of the wave disturbance and the nonlinear effect of the structure, and is suitable for the seismic design of complex and nonlinear structures. This method can reflect the dynamic response and nonlinear effects of the structure, but it is very computationally intensive and requires a lot of computational resources and expertise.

In short, in the seismic design of bridges, different calculation methods have different characteristics and scope of application, and it is necessary to select the appropriate method of liquid disturbance for calculation and analysis according to the specific situation, so as to improve the seismic ability and safety of the bridge.

The seismic calculation of the structure is as follows:

2. Mode decomposition reaction popularization Scope of application: except for the bottom shear method, the building X0D X0A

3. Scope of application of time history analysis method: particularly irregular buildings, Class A buildings and buildings with a height of more than 100 meters at 7 degrees and 8 degrees; 8 degree class site height greater than 80 meters; Buildings with a height of more than 60 meters at 9 degrees.

It is a kind of random vibration, with complexity and uncertainty that is difficult to grasp, and it is difficult to accurately determine the characteristics and parameters of the building. Today, when the theory of building earthquake resistance has not reached scientific rigor, it is difficult to make a building have good earthquake resistance by calculation alone. Therefore, structural engineers must pay attention to the conceptual design of the overall seismic capacity of the building.

Affected by the disaster, the buildings within the area will be severely damaged. Geological movement caused by ** can lead to direct structural damage to the building, so it can be seen that geological conditions are also an important factor in the damage of housing construction. Therefore, in the design of housing architecture, it is necessary to make a reasonable choice of building site.

On the one hand, geological conditions that are conducive to earthquake resistance, such as hard geology and open terrain, should be preferred, so as to reduce the degree of subsidence of the foundation soil during the first period and prevent the collapse of housing construction. On the other hand, as far as possible, avoid the edge of the hillside, the river bank and other areas where the ground is soft and not conducive to earthquake resistance, so as not to cause the collapse of the building under the joint influence of geological conditions during the first period. If it is really impossible to avoid such a lot, it is necessary to mine oak to conceal the corresponding effective seismic measures.

Dangerous areas such as natural disaster concurrent areas (such as subsidence, landslides and Huiru round debris flows) should not be selected as the construction site of housing construction, so as to avoid the aggravation of the damage caused by other natural disasters. Finally, the soil stiffness and covering thickness of the building site are also an important factor in the damage of the building.

The commonly used analysis methods in China include the bottom shear force method, the mode decomposition response spectrum method and the time history analysis method.

1. Bottom shear method.

Applicable conditions: For structures with uniform weight and stiffness distribution along the height, height not exceeding 40m, and shear deformation (when the height-to-width ratio of the house is less than 4), it has the following characteristics when vibrating; (1) The displacement reaction is dominated by the basic mode shape; (2) The basic mode shape is close to a straight line.

Basic principle: On the basis of the mode decomposition response spectrum method, a method of approximating the horizontal action is obtained by further simplifying the specific conditions of some buildings: simplifying the multi-degree-of-freedom system into a single-degree-of-freedom system, calculating the total action of the structure (that is, the shear force at the bottom of the structure), and then distributing it to each floor according to the inverted triangle principle to calculate the internal force of the structure.

2. Mode decomposition response spectrum method.

Scope of application: building structures other than the above-mentioned bottom shear method.

Basic principle: Using the concept of mode shape decomposition method, the multi-degree-of-freedom system is decomposed into several combinations of vibrations of single-degree-of-freedom systems, and the response spectrum theory of single-degree-of-freedom systems is used to calculate the action of each mode shape vibration, and finally the effects calculated by each mode shape are combined according to certain rules to obtain the total response.

3. Time history analysis.

Scope of application: The "Seismic Code" stipulates that important engineering structures, such as long-span bridges, especially irregular buildings, Class A buildings, and high-rise buildings whose height exceeds the specified range, should be supplemented by the time history analysis method.

Basic principle: The time history analysis method is a dynamic analysis method that directly solves the differential equations of motion of structures step by step. From the time-history analysis, the displacement, velocity and acceleration dynamics of each particle with time can be obtained, and then the time-history variation relationship of the internal forces of the components can be calculated.

Hope it helps.

The so-called regression.

On the basis of mastering a large number of self-observed data, mathematical statistical methods are used to establish the regression relationship function expression (called regression equation) between the dependent variable and the independent variable. In regression analysis, when the causal relationship under study involves only the dependent variable and an independent variable, it is called univariate regression analysis; When the causal relationship under study involves a dependent variable and two or more independent variables, it is called multiple regression analysis. In addition, regression analysis is divided into linear regression analysis and nonlinear regression analysis according to whether the expression of the function describing the causal relationship between the independent variable and the dependent variable is linear or nonlinear.

Linear regression analysis is usually the most basic analysis method, and nonlinear regression problems can be solved by mathematical means.

In the example of univariate linear analysis, in order to establish the relationship between weight y and height x (y=a+bx), we find out what a and b are, assuming that the relevant data of height and weight are as follows.

Height (cm) 175 165 185 178 195

Weight (kg) 73 68 81 75 90

Find ::a=,b=, then y= is the regression equation.

On the basis of a large amount of data, the relationship between the variables can be found through regression analysis. In empirical research, regression analysis requires hypothesis testing.

1. The bottom shear method can be used for structures with a height of no more than 40m, shear deformation as the mainstay, and a relatively uniform distribution of mass and stiffness along the height, as well as structures similar to the single particle system.

2. For building structures other than those included above, it is advisable to use the mode decomposition response spectrum method.

3. For particularly irregular buildings, Class A buildings and high-rise buildings exceeding a certain height, the time history analysis method should be used to carry out supplementary calculations under frequent encounters.

The calculation of the equivalent horizontal action is calculated by the horizontal and vertical methods. The specific calculation methods are divided into two methods: the shear force method at the bottom of the response spectrum and the mode decomposition method of the response spectrum.

Action calculation is the first problem to be solved in the seismic design of structures. Since the 89 seismic norms in China, the role of calculating the number of earthquakes (small earthquakes) has been adopted. The major earthquake-resistant countries in the world and China's 78 seismic codes all adopt the role of calculating according to the fortification intensity (medium earthquake).

With the various problems that have been exposed in the revision, development and use of seismic codes, the academic and engineering circles have repeatedly proposed to restore the role of calculation according to medium earthquakes to solve a series of problems existing in the current seismic codes and other structural design codes. In recent years, with the development of performance-based seismic design methods, this question has been raised again. In 2004, the "General Principles for the Design of Seismic Properties of Construction Projects" was compiled and published, and the first function was calculated according to the medium earthquake.

On the basis of introducing the two first-class action calculation methods, the advantages and disadvantages of the two methods are discussed, and based on the development of performance seismic design, the research direction of the first-class action calculation method in China is proposed.

** When the ground will move horizontally and vertically, it will cause horizontal vibration and vertical vibration of the structure, and when the structure is complex, the center of mass and the center of rigidity do not coincide, it will also cause the torsional vibration of the structure. In general, the horizontal action plays a controlling role in the structure, and the torsional effect caused by the horizontal action should be considered for the obviously inhomogeneous and asymmetrical structure; Vertical and high-rise structures, long-span and long-cantilever structures in the high-intensity zone should be considered.

In seismic design, the role of various building structures should be considered according to the following principles:

1) It is generally believed that the horizontal component of ground motion is larger, and the lateral resistance of the structure is limited, under normal circumstances, the horizontal action plays a controlling role in the structure, and the horizontal action can be calculated in the two main axis directions of the building structure and the seismic calculation is carried out, and the horizontal action in each direction is all borne by the lateral force resistance member in the direction.

2) For structures with oblique lateral force members, when the intersection angle is greater than 15°, the horizontal action in the direction parallel to each lateral force resistance member should be considered.

3) For structures with obvious inhomogeneity and asymmetry in the same plane or along the height direction, the torsional effect caused by the horizontal action should be considered, or the torsional effect should be included by adjusting the action effect.

4) Vertical action should be considered for long-span structures, long cantilever structures, high-rise structures and high-rise structures in 9-degree zones of 8 and 9 degrees.

The principles of seismic calculation of structures are briefly described as follows:

1. Choose a site that is conducive to the earthquake resistance of the building, avoid the parts that are not conducive to the earthquake resistance of the building, and do not build Class A, B and C buildings in dangerous areas.

For unfavorable sections, the sail clearing engineer should put forward avoidance requirements, take effective measures in the case of unavoidable, and consider the indirect causes of structural damage caused by site conditions, such as uneven settlement of foundation soil, surface dislocation and cracks caused by **.

2. The layout of the building façade should meet the requirements of the conceptual design, and no serious irregular scheme should be adopted. For irregular buildings, the horizontal action calculation and internal force adjustment should be carried out in the structural design, and effective seismic structural measures should be taken for the weak parts. Draw on international general practices and foreign norms to make our design more perfect and reasonable.

3. The selection of structural materials and the determination of structural systems should meet the requirements of seismic structures. What kind of structural materials and what kind of silver sedan car-like structural system are determined by the comprehensive technical and economic conditions. At the same time, the front lift minimizes the center of gravity of the building and gives full play to the strength of the material, and the seismic concept of similar dynamic characteristics (period and mode shape) of the two main axes of the structure is proposed.

4. Establish as many seismic lines as possible. **There is a certain duration, which can occur multiple times**. Through the analysis of the collapsed building, it can be seen that the reciprocating effect of the first has caused serious damage to the structure, and the final collapse is that the structure loses the ability to bear gravity loads due to failure.

It is an important measure to correctly handle the relationship between the strength and weakness of the components and make them form multiple lines of defense. For example, in the case of a single frame structure, the frame becomes the only member that resists lateral forces. Then the ductile frame of "strong column and weak beam" type is adopted.

Under the action of horizontal **, the yield of the beam precedes the yield of the column.