How to calculate the axial force of the column

1.

The axial force of AC section is - 20KN, not - 10kN. Because - 10kN acts on point C, the AC is disconnected, the left part is taken as the isolator, and only the left end bears the axial force of - 20KN, so the axial force is - 20KN. Similarly, the axial force of CD segment is - 10kN, and that of de segment is + 10kN

For columns with large slenderness ratio, the initial eccentricity caused by various accidental factors cannot be ignored. With the increase of the load, the lateral deflection also increases. The compression deformation and bending deformation of the member occur at the same time. Finally, the member is destroyed under the combined action of axial pressure and additional bending moment

firstly, the concavity compressive concrete is crushed, the longitudinal reinforcement is bent and bulged out, and the concrete cover is peeled off; At the same time, when the convex surface is under tension, the concrete will proce horizontal cracks, the lateral deflection will increase sharply, and the column will be damaged

Extended data:

for short columns with longitudinal bars and stirrups, the strain of the whole section is basically uniform under axial load. When the load is small, the concrete and steel are in the elastic stage. As the load continues to increase, the lateral deformation of the concrete increases, the fiber stress at the edge of the section first reaches the tensile strength of the concrete, and micro cracks begin to appear in the column

After

because the elastic molus of steel bar is greater than that of concrete, the stress of steel bar increases rapidly, the stress of column longitudinal bar first reaches the tensile strength of steel bar and is crushed, and micro cracks begin to appear in the column

2. According to the building height, the section size of beam and column, the thickness of floor and roof panel, wall material and thickness, decoration method and roof live load of factory building, the axial force of center column, side column and corner column is calculated or roughly calculated in combination with the code for design of building structure and code for seismic design of buildings. In fact, it's very fast to calculate with software
when estimating the area of foundation bottom, the factor of foundation buried depth should also be considered
for reference only. I wish you all the best.

3. The axial force at the bottom of the column is the axial force at the top of the column plus the self weight of the column itself, which is only considered when calculating the vertical dead load. When calculating the live load, the axial force at the top and bottom of the column take the same value.

4. You must give the type of material and strength grade of the column, so that I can help you judge. If it is a concrete column, simply according to the axial compression member calculation, the steps are roughly as follows: the axial force of each column is 2000 × one thousand × 10 / 27 = 740N, l0 / b = 4.75 / 0.5 = 9.5, look up the table stability coefficient φ= 98, according to the formula: n ≤ 0.9 φ( fcA+f' yA' s)=0.9 × zero point nine eight × fcA+f' yA' s) According to what you said, the process can only be written here. You must know the number and size of steel bars and the strength grade of concrete. Of course, if I design it, C30 concrete is used, FC = 19.1n/mm

5. The vertical force acts on the column directly, and its axial force is the vertical pressure. The bearing capacity (i.e. normal pressure) and the pressure stability calculation of the column should be calculated. All must meet the design requirements.

6. If your problem refers to frame column, then:
1. First, calculate the bending moment of the joint, and distribute it to the rod end (including the column end) of each member on the joint to get the bending moment of the column end
2. According to the bending moment at the end of the column, the shear force at the end of the column is assumed to be an unknown number, and the moment balance equation of the member is established to calculate the shear force at the end of the column
3. According to the sum of the beam end shear force from the beams on both sides of the top of the column and the axial force at the bottom of the upper column at the top of the column, the axial force at the upper end of the column is the axial force at the lower end of the column

7. The axial force at the upper end of each column is obtained by adding the shear force at the end of the transverse frame beam, the reaction force at the end of the longitudinal frame beam (calculated according to the simply supported beam) and the axial force from the upper column; The axial force at the lower end of each column is the axial force at the upper end plus the self weight of the column

vertical load is the gravity of various structural members and attachments perpendicular to the ground.

8. If your problem refers to frame column, then:
1. First, calculate the bending moment of the joint, and distribute it to the rod end (including the column end) of each member on the joint to get the bending moment of the column end
2. According to the bending moment at the end of the column, the shear force at the end of the column is assumed to be an unknown number, and the moment balance equation of the member is established to calculate the shear force at the end of the column
3. According to the sum of the shear force at the beam end from the beams on both sides of the column top and the axial force at the bottom of the upper column at the column top, it is the axial force at the upper end of the column. The axial force at the upper end of the column plus the self weight of the column is the axial force at the lower end of the column.

9. This problem involves some in-depth knowledge, not one or two words can explain it to you! Friend, are you right?