Column Transverse Reinforcement Detailing and Limits

ICONS

A _c = Gross cross-section area of ​​the column or wall end region
A _ck = Core concrete area within the measure taken outside the outer of the confinement reinforcement
A _sh = s along the height corresponding to the transverse reinforcement range, taking into account the cross-sectional area values ​​of all hoops and crossties in the column or the sum of the projections in the perpendicular direction
b _k = Cross-section dimension of the column or wall end zone core (distance between the outermost transverse reinforcement axes) for each of the perpendicular horizontal directions
b _w =Width of the column in the direction of transverse reinforcement calculation
f _ck = Characteristic cylinder compressive strength of concrete
f _ctd = Design tensile strength of concrete  
f _ywk = Characteristic yield strength of transverse reinforcement
N _d = Axial force calculated under the combined effect of vertical loads and earthquake loads multiplied by load coefficients
s = Transverse reinforcement spacing, spiral / wrapping reinforcement pitch
ρ = reinforcement ratio
ρ _s = volumetric ratio of spiral reinforcement in the column
ϕ = Diameter of reinforcement

Transverse Reinforcement Conditions

Colon coiling zone

Coiling zones are formed at the lower and upper ends of each column . The length of each of the confinement zones is arranged such that the length is not less than 1/6 of the column free height, 1.5 times the largest section size of the column, and 500 mm. In cantilever columns, the confinement zone is formed at the lower end of the column, and the confinement zone is arranged so that its length is at least twice the size of the column.

Transverse reinforcement with a diameter smaller than ϕ8 is not used in confinement areas. In this region, the stirrups and crossties spacing in the longitudinal direction are not selected as 1/3 of the smallest section size, greater than 150 mm, greater than six times the longitudinal reinforcement diameter, and less than 50 mm. The horizontal distance between the stirrup arms and / or crossties, a, is not taken larger than 25 times the stirrup diameter.

The minimum volumetric ratio A _sh calculation changes depending on whether the condition N _d > 0.20 A _c f _ck is met in both directions of the column . In each of the major and minor axes of the column:

N _d > 0.20 A _c f _{ck ise} :

For columns with rectangular reinforcement:

Open

In circular reinforced columns:

Open

If N _d ≤ 0.20 A _c f _ck ;

In case of N _d ≤ 0.20 A _c f _ck , at least 2/3 of the transverse reinforcement calculated with Equation (7.1) and Equation (7.2) will be used as minimum transverse reinforcement in the column confinement regions .

A _sh = 2/3 A _sh or ρ ≥ 2 / 3ρ.

Reinforcement spacing is determined according to the transverse reinforcement diameter selected for confinement zones using A _sh .

s = Number of Transverse Reinforcement * Transverse Reinforcement Area / A _sh

Middle column

The middle region of the column is the region between the confinement regions defined at the lower and upper ends of the column. The central column transverse reinforcement conditions are determined according to 7.3.4.2 .

Transverse reinforcement with a diameter smaller than ϕ8 is not used in the middle of the column. The stirrup, crossover or spiral spacing along the column is not taken larger than half of the smallest cross-section size and 200 mm, and the horizontal distance between the stirrup arms and / or crossties, a , is not made more than 25 times the stirrup diameter.

The column is also checked for the minimum condition given in the TS500.

A_sw/s > 0.3 b_w * f_ctd / f_ywk

Special earthquake hoops and crossties

Special seismic hoops and crossties defined in 7.2.8 are used along the entire column .

The conditions required to be met by special earthquake hoops and crossties are given in Figure 7.1 .

135 degree curved hooks are made at both ends of special earthquake hoops . The internal bend diameter of 135 degree bent hooks, φ to indicate the diameter of the transverse reinforcement, is taken at least 5ϕ. The end straight length of the hooks is not taken less than 6ϕ and 80 mm in ribbed bars, starting from the final tangent point in the fold ( Figure 7.1 ).

Special seismic hoops will grasp the longitudinal reinforcement from the outside and the hooks are closed around the same longitudinal reinforcement. The diameter and spacing of special earthquake crossties are taken the same as the diameter and spacing of stirrups. The crossties are prepared at both ends in an order that will necessarily surround the longitudinal reinforcements and the outer stirrup.

Transverse reinforcement intervals in the column cannot exceed the following conditions. ( Figure 7.3 ).