# Strength and Stability Checks of Various Components

For different types of components, the program will check the strength and stability of components and select the section according to the relevant provisions of GB 50017-2017. The following will introduce the relevant code terms considered in the inspection of various types of components in the program.

In the following clauses, the numbers in the opening brackets are consistent with the corresponding clauses in the original GB 50017-2017 specification. In the following formula, the meaning of each symbol is the same as that in GB 50017-2017.

## Flexural Members

1. The flexural strength of the solid web member bending in the main plane is as follows:
 $MzrzWnz+MyryWny≤f$ (6.1.1)

In code inspection, the default component is static load or indirect dynamic load. In the calculation and test of the program, the values of parameters and forces are obtained from the data structure of components.

2. The shear strength of the solid web member bending in the main plane is as follows:
 $τ=VSItw≤fv$ (6.1.3)
3. 1. At the edge of the calculation height of the web of composite beam, if there are large normal stress, shear stress and local compressive stress at the same time, or bear large normal stress and shear stress at the same time (such as the support of continuous beam or the change of flange section of beam, etc.), the converted stress is as follows:
 $σ2+σc2−σσc+3τ2≤β1f$ (6.1.5)
4. The global stability of the I-section bending in two main planes is calculated as follows:
 $MzϕbWx+MyryWy≤f$ (6.2.3)
5. Height thickness ratio of Web:

Calculated value = web height / web thickness (I-beam, H-beam, channel steel...)

=Diameter / wall thickness (round pipe)

=Short leg length / short leg thickness (angle steel)

See table 3.5.1 of GB 50017-2017 for calculation limit.

6. Flange width thickness ratio:

Calculated value = flange width / flange thickness (I-beam, H-beam, channel steel...)

=Diameter / wall thickness (round pipe)

=Long leg length / short limb thickness (angle steel)

See table 3.5.1 of GB 50017-2017 for calculation limit.

1. The strength calculation formula of axially loaded members is as follows:
 $σ=NA≤f$ (7.1.1-1)
 $σ=NAn≤0.7fu$ (7.1.1-2)
2. The stability checking formula of axial compression member is as follows:
 $NϕA≤f$ (7.2.1)

For the stability factor ϕ, the program is obtained according to "Appendix D stability coefficient of axial compression members"in the code.

3. Slenderness ratio of compression member

Refer to article 7.2.2 of GB 50017-2017 for calculation value. After calculation of Y-axis and z-axis, take the maximum value.

If the program automatically calculates the limit value, the default value is 150, and then according to the seismic code, the requirements of axial force members are adjusted and modified.

4. Slenderness ratio of tension member

Refer to article 7.2.2 of GB 50017-2017 for calculation value. After calculation of Y-axis and z-axis, take the maximum value.

If the program automatically calculates the limit value, the default value is 300, and then according to the seismic code, the requirements of axial force members are adjusted and modified.

5. Height thickness ratio of Web:

The calculated value is the same as that of flexural member.

For the calculation limit, see article 7.3.1 of GB 50017-2017.

6. Flange width thickness ratio

The calculated value is the same as that of flexural member.

For the calculation limit, see article 7.3.1 of GB 50017-2017.

1. The strength of tension (compression) bending members with bending moment acting on the main plane is as follows:
 $NAn±MzrzWnz±MyryWny≤f$ (8.1.1)
2. Stability:
1. The stability of solid web compression and bending members with bending moment acting in the plane of symmetry axis is considered as follows.
1. When the bending moment acts on the plane, the stability calculation formula is as follows:
 $NψzA+βmzMzrzw1z(1−0.8NN′Ez)≤f$ (8.2.1-1)

When the bending moment acts in the plane of the symmetrical axis and the larger flange is pressed, it should be calculated according to the above formula, and also meet the following requirements:

 $|NA−βmzMzγzw2z(1−1.25NN′Ez)|≤f$ (8.2.1-4)
2. When the bending moment acts outside the plane, the stability calculation formula is as follows:
 $NϕyA+βmzMzϕbw1z≤f$ (8.2.1-3)
2. When the bending moment acts on the imaginary axis direction of the lattice compression bending member, the calculation formula of the overall stability in the bending moment action plane is as follows:
 $NψzA+βmzMzw1z(1−NN′Ez)≤f$ (8.2.2-1)
3. The stability of biaxially symmetric solid web I-shaped and box shaped members with bending moment acting on two main planes is calculated according to the following formula:
 $NϕzA+βmzMzγzw1z(1−0.8NNEz)+βtyMyϕbyW1y≤f$ (8.2.5-1)
 $NϕyA+βmyMyγyw1y(1−0.8NNEy)+βtzMzϕbzW1z≤f$ (8.2.5-2)
4. For the double leg lattice beam columns with bending moment acting on two main planes, the overall stability is calculated by the following formula:
 $NϕzA+βmzMzw1z(1−NN′Ez)+βtyMyW1y≤f$ (8.2.6-1)
3. Shear strength

The calculation method is the same as that of flexural member.

4. Local stability (width thickness ration / height thickness ratio)

The calculated value is the same as that of flexural member.

See table 3.5.1 of GB 50017-2017 for calculation limit.

5. Slenderness ratio

The calculation method is coaxial center stress member