# D. Design Capacity of Columns

Concrete column design through the user-specified component type, seismic parameters such as standardized test grades, the program selected by the user load combinations and design parameters for the design and reinforcement, testing results and design process will be output to the report.

## General Provisions

See "General Provisions" for Beam Design.

## Column Capacity Under Axial Load

### Axial compression component capacity

Axially loaded reinforced concrete structures, when the configuration of the stirrup meet GB50010-2002 the provisions of section 10.3, which is cross-section compression capacity should meet the following requirements:

 N ≤ 0.9ф(fcA + fy ’As ’) (7.2.15)

When the vertical steel reinforcement ratio greater than 3%, the formula (7.2.15) in A Should use (A-A's) in its place.

Axially loaded reinforced concrete structures, when the configuration of the screw or welded steel ring indirectly found GB50010-2002 the provisions of section 10.3, which is cross-section compression capacity should meet the following requirements:

 N ≤ 0.9(fcAcor + fy ’As ’+2αfyAss0) (7.3.2-1)

### Eccentric compression component capacity

Eccentric rectangular cross section compression member compression capacity should meet the following requirements:

 N≤α1 fcbx +   + fy ’As ’ – σsAs (7.3.4-1)

 Ne≤α1 fcbx(h0 – x/2) + fy ’As ’(h0 – as’) (7.3.4-2)

Uniform configuration along the peripheral ring of longitudinal reinforcement section eccentric compression, which is cross-section compression capacity should meet the following requirements:

 $N ≤ α α 1 f c A ( 1 − sin ⁡ 2 π α 2 π α ) + ( α − α 1 ) f y A s$ (7.3.7 - 1)

 $N η e i ≤ 2 3 α 1 f c A r sin ⁡ 3 π α π + f y A s r s sin ⁡ π α + sin ⁡ π α 1 π$ (7.3.7 - 2)

### Axial tension component capacity

Axial tension member tensile capacity of normal section shall meet the following requirements:

 N ≤ fyAs (7.4.1)

### Eccentric tension component capacity

Eccentric rectangular symmetric reinforcement for tension members, both large and small offset tension of the situation, may according to formula (7.4.2-2) calculated:

 Ne' ≤ fyAs(h'0 - as) + fpyAp(h'0-ap) (7.4.2-2)

## Calculation of Oblique Section

### Eccentric compression

Rectangular reinforced concrete eccentric compression, the Shear Capacity meet the following requirements:

 $V ≤ 1.75 λ + 1 f 1 b h o + f y v A s v s h o + 0.07 N$ (7.5.12)

Shear span ratio calculation section the following provisions shall be drawn:

1. Columns on the kinds of structures, should take λ = M / (Vho ); on the frame structure of the frame column, when the inflection point in the story context, the desirability of λ = Hn / (2h0 ); when λ < 1, take λ = 1; when λ> 3, the take λ = 3; here, M for the calculation of the cross section and the shear design value V corresponding moment design value, Hn clear height for the column.
2. On the other eccentric compression, when the bear uniformly distributed load, take λ = 1.5; when the bear meet GB50010-2002 section 7.3.4 provides a concentrated loads, taking λ = a/h0, when λ <1.5, the taking λ = 1.5; when λ> 3, the take λ = 3; here, α for the concentrated load to the bearing or distance from the edge node.

### Eccentric Tension Member

Eccentric rectangular cross-section of reinforced concrete tension members, the Shear Capacity meet the following requirements:

$V ≤ 1.75 λ + 1 f 1 b h o + f y v A s v s h o + 0.07 N$ (7.5.14)

## Seismic design of concrete columns

### Longitudinal reinforcement force

Columns and pillars of steel frame configuration, should meet the following requirements

Box columns and pillars all vertical steel reinforcement percentage of the force should not be less than the values specified table 11.4.12-1 the same time, each side of the reinforcement ratio of not less than 0.2;

Box columns and pillars of strength in all the longitudinal reinforcement ratio should not exceed 5%. Column longitudinal steel should symmetric configuration. Column section size greater than 400mm, vertical spacing of reinforcement should not be greater than 200mm. When the level of design by an earthquake, and the column shear span ratio λ ≤ 2, the columns on each side of longitudinal steel reinforcement ratio should be less than 1.2%.

Table 1. All the reinforced vertical column minimum reinforcement percentage (%), Table 11.4.12-1
Column Type Seismic Level
1 2 3 4

Framework of columns, edge columns

1.0

0.8

0.7

0.6

Framework of the corner column, pillar box

1.2

1.0

0.9

0.8

Note: All of the reinforced column longitudinal reinforcement ratio of the minimum, when using HRB400 grade steel, the values in the table should be reduced by 0.1; when the concrete strength grade of C60 and above, shall be increased by 0.1 values in the table.

### Stirrups

Box columns and pillars of the upper and lower ends of stirrups should be encrypted, encrypted area of the stirrups and the stirrups minimum diameter maximum spacing should be consistent with the provisions of the table 11.4.12-2;

Table 2. Column side stirrup encryption zone construction requirements, Table 11.4.12-2
Seismic Level Maximum Stirrup Spacing (mm) Stirrup minimum diameter (mm)

1

6 times the longitudinal bar diameter and 100 of the smaller value

10

2

8 times the longitudinal bar diameter and 100 of the smaller value

8

3

8 times the diameter of longitudinal reinforcement and 150 (column root of 100) of the small value

8

4

8 times the diameter of longitudinal reinforcement and 150 (column root of 100) of the small value

6 (column root 8)

Note: Column refers to the underlying root of column top of the basement or no basement, a basis for the top; column length should be taken root encrypted area of the layer of column clear height of not less than 1 / 3; when there are rigid surface, in addition to column-side stirrup Encryption should be rigid yet outside the ground, the height of 500mm under the stirrups within the encryption.

Pillar box and the shear span ratio λ ≤ 2 the framework of the column should be encrypted column within the whole stirrup high, and the spacing should not exceed 100mm;

Two level columns earthquake, when the stirrup diameter is not less than 10mm, less than 200mm from the limb, in addition to the root column, the stirrup spacing should be allowed to use 150mm; three seismic level frame column section size not greater than 400mm, the stirrups should be allowed to use the minimum diameter 6mm; 4 seismic rating columns span ratio less than 2, the stirrup diameter is not less than 8mm.

Columns of the stirrup length encryption area, take the long side of column section size (or cross section diameter), column clear height of 1 / 6 and 500mm in maximum. Secondary level prism earthquake along the whole column stirrups high encryption.

Encrypted column stirrup limbs from the region: a seismic level not greater than 200mm; two, three seismic levels should be less than 250mm in diameter and 20 times larger value of hoop; 4 seismic rating not greater than 300mm. In addition, every one vertical bar in both directions should have stirrups or stretching constraints.

One, two, three levels of various types of seismic structure of the frame column and pillar boxes, the axial load ratio N / (fcA) is not greater than the limits specified Table 11.4.16.

Table 3. Framework of the axial compression ratio, Table 11.4.16
Structural System Seismic Level
1 2 3

Frame

0.7

0.8

0.9

Frame - shear wall, tubular structures

0.75

0.85

0.95

Part of the frame-supported shear wall structure

0.6

0.7

-
Notes:
1. An axial load ratio N / (fcA) that consider the combination of earthquake and the box frame column pillar design value of axial pressure on the whole sectional area of N and column A and the design value of concrete compressive strength fc ratio of the product; of the non-seismic the role of the structure calculation, to take no seismic design values combined axial force;
2. When the concrete strength grade of C65-C70, the axial compression ratio should decrease according to values in the table 0.05; concrete strength grade of C75-C80, the axial compression ratio values in the table should decrease by 0.10;
3. shear span ratio λ ≤ 2 columns, the axial compression ratio should be values in the table decreases 0.05;

Column encryption area stirrup reinforcement ratio of the volume of stirrups meet the following requirements:

1. column volume of stirrups stirrup reinforcement encrypted area ratio, shall meet the following requirements:

 ρv ≥ λvfc/fyv (11.4.17)

where
 ρv = column encryption area the size of stirrup reinforcement ratio, according to GB50010-2002 section 7.8.3 of the Ordinance calculated, should be less overlap in the stirrups volume fc = design value of concrete compressive strength; when the intensity level of less than C35, the values according to C35; fyv = stirrups and reinforcement design value of tensile strength; λv = Minimum stirrup values used in Table 11.4.17.
Table 4. Column encryption area stirrup minimum value λv 表 11.4.17 Table 11.4.17
Seismic Level Stirrup Type Axial Compression Ratio
≤0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.05

1

General hoop, composite hoop

0.10

0.11

0.13

0.15

0.17

0.20

0.23

-

-

Spiral hoop, composite or continuous composite rectangular spiral hoop

0.08

0.09

0.11

0.13

0.15

0.18

0.21

-

-

2

General hoop, composite hoop

0.08

0.09

0.11

0.13

0.15

0.17

0.19

0.22

0.24

Spiral hoop, composite or continuous composite rectangular spiral hoop

0.06

0.07

0.09

0.11

0.13

0.15

0.17

0.20

0.22

3

General hoop, composite hoop

0.06

0.07

0.09

0.11

0.13

0.15

0.17

0.20

0.22

Spiral hoop, composite or continuous composite rectangular spiral hoop

0.05

0.06

0.07

0.09

0.11

0.13

0.15

0.18

0.20

Notes:
1. A general refers to a single rectangular hoop or single circular hoop; spiral hoop that a single spiral reinforcement; composite hoop means rectangular, polygonal, circular or reinforcement consisting of stirrups stirrup; compound spiral hoop means spiral hoop and rectangular, polygonal, circular or reinforcement consisting of stirrups stirrup; continuous composite rectangular spiral refers to all the spiral hoop to hoop with a steel processed into the stirrups;
2. in the calculation of the volume of composite spiral hoop reinforcement ratio, one of the spiral reinforcement of the volume of non-conversion factor should be multiplied by 0.8;
3. on 1, 2, 3, 4 seismic rating column, the encrypted area of stirrups stirrup reinforcement ratio of the volume should not be less than 0.8%, respectively, 0.6%, 0.4% and 0.4%;
4. concrete strength higher than C60, the stirrup should the composite hoop, composite or continuous composite rectangular spiral hoop; when the axial compression ratio is not greater than 0.6, the encryption region the value of the minimum stirrup according to values in the table should increase 0.02; when the axial compression ratio greater than 0.6, the appropriate values in the table increased by 0.03.
2. box pillar should adopt the compound spiral hoop or crosswise composite hoop, the minimum transverse reinforcement characteristic values should be the value in Table 11.4.17 0.02 increase access to, and the volume reinforcement ratio of not less than 1.5%;

3. When the shear span ratio λ ≤ 2, the one, two, three seismic level of composite column should spiral hoop or crosswise composite hoop, the hoop reinforcement ratio of volume of not less than 1.2%; 9, when the degree of fortification should not be less than 1.5%.