Info

where:

kjtr is the stiffness coefficient representing component i relative to bolt-row r.

(3) The equivalent lever arm zeq should be determined from:

X Kff.r Ur

(4) In the case of a beam-to-column joint with an end-plate connection, Xeq should be based upon (and replace) the stiffness coefficients X, for:

- the column flange in bending (X4);

(5) In the case of a beam splice with bolted end-plates, Xeq should be based upon (and replace) the stiffness coefficients X, for:

6.3.3.2 Simplified method for extended end-plates with two bolt-rows in tension

(1) For extended end-plate connections with two bolt-rows in tension, (one in the extended part of the end-plate and one between the flanges of the beam, see Figure 6.20), a set of modified values may be used for the stiffness coefficients of the related basic components to allow for the combined contribution of both bolt-rows. Each of these modified values should be taken as twice the corresponding value for a single bolt-row in the extended part of the end-plate.

NOTE: This approximation leads to a slightly lower estimate of the rotational stiffness.

(2) When using this simplified method, the lever arm z should be taken as equal to the distance from the centre of compression to a point midway between the two bolt-rows in tension, see Figure 6.20.

Figure6.20: Lever arm z forsimplified method

6.3.4 Column bases

(1) The rotational stiffness, Sj , of a column base subject to combined axial force and bending moment should be calculated using the method given in Table 6.12. This method uses the following stiffness coefficients:

XTl is the tension stiffness coefficient of the left hand side of the joint and should be taken as equal to the sum of the stiffness coefficients X15 and X16 (given in Table 6.11) acting on the left hand side of the joint.

kT,r is the tension stiffness coefficient of the right hand side of the joint and should be taken as equal to the sum of the stiffness coefficients ki5 and ki6 (given in Table 6.11) acting on the right hand side of the joint.

kCl is the compression stiffness coefficient of the left hand side of the joint and should be taken as equal to the stiffness coefficient k13 (given in Table 6.11) acting on the left hand side of the joint.

kCr is the compression stiffness coefficient of the right hand side of the joint and should be taken as equal to the stiffness coefficient k13 (given in Table 6.11) acting on the right hand side of the joint.

(2) For the calculation of zTl, zCl, zTr, zCr see 6.2.8.1.

Table 6.12: Rotational stiffness Sj of column bases

Loading

Lever arm z

Rotational stiffness 5j,ini

Left side in tension Right side in compression

" = "T,l + "C,r

1Ed > 0 and e > zT,l

1Ed < 0 and e < -zC r

Ez2 e , "c,fK:,r - "-Am

1 (1 / K,,J +1 / Kv ) e + e* X ,1 + K:,r

Left side in tension Right side in tension

" = "T,l + "T,r

1Ed > 0 and 0 < e < zT l

1Ed > 0 and -zT r < e <0

Ez2 e , zr,f X,r - "-Am

1 (1 / x ,1 +1 / Xv ) e + e* X ,1 + K/v

Left side in compression Right side in tension

" = "C,l + "T,r

1Ed > 0 and e < -zT r

1Ed < 0 and e > zC l

Ez2 e zr,f X,r - " :A;,1

1 (1 / K:,1 + 1 / K) e + e* K:,1 + Kv

Left side in compression Right side in compression

" = "C,l + "C,r

1Ed < 0 and 0 < e < zC l

1Ed < 0 and -zC r < e <0

Ez2 e zc,fX;,r - "c.1kc,1

1 (1 / K;,1 + 1 / X> ) e + e X-,1 + K:,r

HEd > 0 is clockwise, NEd > 0 is tension, ¡u see 6.3.1(6). c _ mM

NM nm

Was this article helpful?

0 0

Post a comment