Figure Centre of compression lever arm z and force distributions for deriving the design moment resistance MjRd

Flange Splice Full Diagram
Figure 6.16: Simplified models for bolted joints with extended end-plates

(13) Where the members are not prepared for full contact in bearing, splice material should be provided to transmit the internal forces and moments in the member at the spliced section, including the moments due to applied eccentricity, initial imperfections and second-order deformations. The internal forces and moments should be taken as not less than a moment equal to 25% of the moment capacity of the weaker section about both axes and a shear force equal to 2.5% of the normal force capacity of the weaker section in the directions of both axes.

(14) Where the members are prepared for full contact in bearing, splice material should be provided to transmit 25% of the maximum compressive force in the column.

(15) The alignment of the abutting ends of members subjected to compression should be maintained by cover plates or other means. The splice material and its fastenings should be proportioned to carry forces at the abutting ends, acting in any direction perpendicular to the axis of the member. In the design of splices the second order effects should also be taken into account.

(16) Splices in flexural members should comply with the following:

a) Compression flanges should be treated as compression members;

b) Tension flanges should be treated as tension members;

c) Parts subjected to shear should be designed to transmit the following effects acting together:

- the shear force at the splice;

- the moment resulting from the eccentricity, if any, of the centroids of the groups of fasteners on each side of the splice;

- the proportion of moment, deformation or rotations carried by the web or part, irrespective of any shedding of stresses into adjoining parts assumed in the design of the member or part.

6.2.7.2 Beam-to-column joints with bolted end-plate connections

(1) The design moment resistance Mj,Rd of a beam-to-column joint with a bolted end-plate connection may be determined from:

r where:

Atf,Rd is the effective design tension resistance of bolt-row r ; hr is the distance from bolt-row r to the centre of compression; r is the bolt-row number.

NOTE: In a bolted connection with more than one bolt-row in tension, the bolt-rows are numbered starting from the bolt-row farthest from the centre of compression.

(2) For bolted end-plate connections, the centre of compression should be assumed to be in line with the centre of the compression flange of the connected member.

(3) The effective design tension resistance AtrRd for each bolt-row should be determined in sequence, starting from bolt-row 1, the bolt-row farthest from the centre of compression, then progressing to bolt-row 2, etc.

(4) When determining the value of AtfRd for bolt-row r the effective design tension resistance of all other bolt-rows closer to the centre of compression should be ignored.

(5) The effective design tension resistance AtfRd of bolt-row r should be taken as its design tension resistance AtRd as an individual bolt-row determined from 6.2.7.2(6), reduced if necessary to satisfy the conditions specified in 6.2.7.2(7), (8) and (9).

(6) The effective design tension resistance AtrRd of bolt-row r ,taken as an individual bolt-row, should be taken as the smallest value of the design tension resistance for an individual bolt-row of the following basic components:

- the column web in tension At,wc,Rd - see 6.2.6.3;

- the column flange in bending At,fc,Rd - see 6.2.6.4;

(7) The effective design tension resistance AtfRd of bolt-row r should, if necessary, be reduced below the value of At,Rd given by 6.2.7.2(6) to ensure that, when account is taken of all bolt-rows up to and including bolt-row r the following conditions are satisfied:

the total design resistance < Fwp Rd//? - with fi from 5.3(7) - see 6.2.6.1;

- the total design resistance ^At,Rd does not exceed the smaller of:

- the design resistance of the column web in compression Ac,wcRd - see 6.2.6.2;

- the design resistance of the beam flange and web in compression Ac, fb,Rd - see 6.2.6.7.

(8) The effective design tension resistance AtfRd of bolt-row r should, if necessary, be reduced below the value of AtRd given by 6.2.7.2(6), to ensure that the sum of the design resistances taken for the bolt-rows up to and including bolt-row r that form part of the same group of bolt-rows, does not exceed the design resistance of that group as a whole. This should be checked for the following basic components:

- the column web in tension At,wc,Rd - see 6.2.6.3;

- the column flange in bending A:,fc,Rd - see 6.2.6.4;

(9) Where the effective design tension resistance AtxRd of one of the previous bolt-rows x is greater than 1,9 AtRd , then the effective design tension resistance AtfRd for bolt-row r should be reduced, if necessary, in order to ensure that:

where:

Ux is the distance from bolt-row x to the centre of compression;

x is the bolt-row farthest from the centre of compression that has a design tension resistance greater than 1,9 At, Rd .

NOTE: The National Annex may give other situations where equation (6.26) is relevant.

(10) The method described in 6.2.7.2(1) to 6.2.7.2(9) may be applied to a bolted beam splice with welded end-plates, see Figure 6.17, by omitting the items relating to the column.

Section End Plate Column Splice
Figure 6.17: Bolted beam splices with welded end-plates

6.2.8 Design Resistance of column bases with base plates 6.2.8.1 General

(1) Column bases should be of sufficient size, stiffness and strength to transmit the axial forces, bending moments and shear forces in columns to their foundations or other supports without exceeding the load carrying capacity of these supports.

(2) The design bearing strength between the base plate and its support may be determined on the basis of a uniform distribution of compressive force over the bearing area. For concrete foundations the bearing strength should not exceed the design bearing strength, fd , given in 6.2.5(7).

(3) For a column base subject to combined axial force and bending the forces between the base plate and its support can take one of the following distribution depending on the relative magnitude of the applied axial force and bending moment:

- In the case of a dominant compressive axial force, full compression may develop under both column flanges as shown in Figure 6.18(a).

- In the case of a dominant tensile force, full tension may develop under both flanges as shown in Figure 6.18(b).

- In the case of a dominant bending moment compression may develop under one column flange and tension under the other as shown in Figure 6.18(c) and Figure 6.18(d).

(4) Base plates should be designed using the appropriate methods given in 6.2.8.2 and 6.2.8.3.

(5) One of the following methods should be used to resist the shear force between the base plate and its support:

- Frictional design resistance at the joint between the base plate and its support.

- The design shear resistance of the anchor bolts.

- The design shear resistance of the surrounding part of the foundation.

If anchor bolts are used to resist the shear forces between the base plate and its support, rupture of the concrete in bearing should also be checked, according to EN 1992.

Where the above methods are inadequate special elements such as blocks or bar shear connectors should be used to transfer the shear forces between the base plate and its support.

Flange Splice Full Diagram

ZC,l zC,r a) Column base connection in case of a dominant compressive normal force

Flange Splice Full Diagram
+1 -1

Responses

  • Gloria
    How to calculate lever arm in column splice?
    1 year ago
  • BRIGITTE
    How to derived the design lever arm?
    6 months ago

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