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The column splice connection is intended for the design of open I and H-section members subjected to axial forces, major and minor bending and transverse shears arising from forces acting in the major and minor axes. The column splice requires flange plates but can be designed with either web cover plates, web end plates or web end plates with angle cleats. Column splices can also be designed as direct bearing, or the gap between sections can be specified such that the axial force is transferred through the bolts and flange plates. In the EC design, the forces are split between the flanges and the web in proportion to their relative section modulus.
A typical column splice screen layout is shown below.
The General area, shown below, allows a title for the connection to be input by the user.
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The forces input area provides inputs for the major and minor bending moments, transverse shear forces and the input for the axial force in the connection. In a linked connection, these forces are taken from the analytic model. The Forces area also provides an input to specify the minimum flange forces, input as a percentage of the flange capacity. For a standalone connection, the default forces are as shown in the image below. Since the design is based on the ultimate limit state, the input forces should be factored.
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Axial Force Fc - the maximum factored axial force in the connection. Compression is entered as a positive value
Moment M - the maximum factored major axis bending moment.
Shear Fv - the factored shear force (due to force acting to produce major axis bending)
Axial Fcd - the minimum factored axial force (or maximum factored tensile force)
Tie Force - the tying force require to meet robustness design criteria
The Column Properties area provides inputs to define the column section(s) to be spliced. It is also possible to input the gap between the column sections, with a gap of zero giving direct bearing in the compression. Where a non-zero gap is specified, the transfer of forces from flange-to-flange is by way of the bolts and the flange plates.
The layout of the Column Properties area is shown below. Since a column splice may involved different sections, the column properties input contains separate inputs for the upper and lower column section sizes.
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Upper Column - indicates the currently selected column section and steel grade.
Lower Column - indicates the currently selected column section and steel grade
Gap - the gap between the upper and lower column sections. A gap of zero indicates direct bearing between the sections. The default value is zero.
Concentric Columns - indicates the alignment of the upper and lower sections where different sections are used. The alignment is selected by clicking in the line and using the drop down options.
Linked splice type - for a splice design linked to a Masterframe model, indicates the splice type.
In a standalone connection, the default connection sizes are 203UC46 sections. A design linked to a Masterframe model will use the section sizes defined in the Masterframe model. To define the column section, the Upper or Lower Column area is expanded by clicking on the arrow to the left of the required row. The expanded Upper Column area is shown below.
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Steel Grade - the grade of the section
Section Type - section type selection. Only open I- or H-sections can be used
Section - the currently selected section
Cell depth - for cell beams, the overall section depth at the splice point
To select the steel grade, section type and section size, each of these inputs can be clicked on the choose the appropriate option can be choose for the dropdown. The Lower Column area is the similar to the Upper Column and functions in the same manner.
The Bolt Details area provides inputs to define the parameters of the bolts to be used in the column splice connection. The default bolts are Grade 8.8 bolts of 20mm diameter. The default layout of the bolt area is shown below.
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To input the required bolt parameters, the Bolt Details row can be expanded by clicking on the arrow to the left of the Bolt Details row. The expanded area is as shown below.
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Bolt Grade - indicates the grade and diameter of the currently selected bolts
Bolt Diameter - indicates the selected bolt diameter. To select a bolt diameter, click to select the row and use the drop down options
Hole Dia - click to select and use the drop down options to select the required bolt diameter as a function of the selected bolt diameter
Slip factor - the slip resistance factor ks for preloaded bolts
Long shank - select whether the bolt has a long or standard shank length
The Flange Cover Plates area provides inputs to define and set up the plates to the flanges of the splice. This area provides options to control the thickness, width and size of the flange plates, along with options to define the number of bolts and the bolting pattern in the flange plates. This area also allows the user to determine whether the splice uses only outer flange plates (plates on the outside of the section) or both inner and outer plates. Where differing column sections are to be spliced, this area also provides inputs to define the weld size used on the required packer plates. The steel grade of the flange plates can also be controlled in this area.
The default layout of the Flange Cover Plate area is shown below.
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To define the flange plates, the Plates row can be expanded by clicking on the arrow to the left of this row. The layout of the expanded Plates input area is shown below. The default settings are for a 10mm thick outer flange plate with 3 bolts rows at 80mm centres and a 40mm end distance.
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Exterior - indicates the currently selected exterior plate size
Number of bolts rows - indicates the current number of bolt rows. The number of bolt rows is modified by selecting and over-typing the required number
Bolt Long c/c - the longitudinal bolt centres.
Bolt Outer Horz c/c - the horizontal centres of the outer line of bolts.
Bolt Inner Horz c/c - the horizontal centres of the inner line of bolts. A value of zero means no inner line of bolts will be provided
End Distance - the distance from the end of the flange plate from the centre of the last bolt row.
Bolt Centre Gap - the centre to centre distance of the bolt rows either side of the splice location.
Countersunk - bolts can be be either standard or countersunk. To select the required option, click on the countersunk row and use the drop down
Stagger Pattern - the stagger pattern of the bolts can be selected by clicking on the row and selecting the required option
The input area for the inner flange plates are shown below.
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Thickness - the current inner flange plate thickness. A value of zero indicates there are no inner plates. To input a thickness, select the row and type in the required thickness
Width - the width of the inner flange plates. The default width is 75mm
The Web Cover Plates area provides a range of inputs to define type and dimensional setting of the web plates, including the selection of cover or end plates. The default set up is for Web Cover plates of 8mm thick, with a web cover plate on each side of the web.
The default layout of the Web Cover Plates area is shown below.
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Plate type? - displays the currently selected web plate type. The type of plates can be chosen by selecting the row and then using the drop down
Thickness - displays the selected plate thickness. The default value is 8mm. The thickness can be input by selecting the row and inputting the required value
Width - the current selected plate width
Bolt Cross c/c - the number of bolt cross centre gaps and the current centre to centre spacing
Bolt Long c/c - the current number of bolt centre to centre gaps. And input of 0 means there is a single set of bolts
End Distance - the bolt edge distance from the end of the plate to the centre of the last bolts
Half length - the length of half of the plate. Web cover plates are symmetrical about the splice location
Stagger Pattern - select the pattern for the bolts in the web cover plate. To select, click on the row and use the drop down
When the Plate Type is set as Web End plates, the area amends to reflect the required inputs for a web end plate connection. The default layout is shown below.
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Plate type? - displays the currently selected web plate type. The type of plates can be chosen by selecting the row and then using the drop down
Thickness - displays the selected plate thickness. The default value is 8mm. The thickness can be input by selecting the row and inputting the required value
Bolt Cross c/c - the number of bolt cross centre gaps and the current centre to centre spacing
Bolt Long c/c - the current number of bolt centre to centre gaps. And input of 0 means there is a single set of bolts
Weld Size - indicates the current selected flange and web weld sizes. The default value are welds of zero size, that is, no welds.
With no welds selected, the column splice is assumed to be in direct bearing and the shear force in the column is determined by the frictional resistance of the connection. The frictional resistance is based on the minimum axial force in the column. If the column is defined to going into tension then the frictional resistance is zero. With no welds, the web end plates will not be provided with bolts, so if the weld size is set to none, any bolts input will be ignored. Once weld sizes have input, the defined bolt arrangement will then be used and displayed in the graphics area.
When the end plate and angle cleats option has been selected, the area amends to reflect the inputs for the end plate and angle cleats connection. This area is shown below.
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Plate type? - displays the currently selected web plate type. The type of plates can be chosen by selecting the row and then using the drop down
Thickness - displays the selected plate thickness. The default value is 8mm. The thickness can be input by selecting the row and inputting the required value
Bolt Cross c/c - the number of bolt cross centre gaps and the current centre to centre spacing
Bolt Long c/c - the current number of bolt centre to centre gaps. And input of 0 means there is a single set of bolts
Weld Size - indicates the current selected flange and web weld sizes. The default value are welds of zero size, that is, no welds.
The shear force in the splice is resisted by a combination of friction, the bolts in the angle plates and the cap plate. For the cap plate to resist shear, it must be welded to the column sections.
When the Web end plate & angle cleat option is selected, an additional input area will appear in the property grid area. This is the Angle Cleats input area, where the properties of the angle cleats are defined. The default layout of the angle cleats area is shown below.
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Dimensions - displays the current thickness, width and height of the angle cleats. To input dimensions, the row can be expanded by clicking on the arrow to the left of the row
Horz Length - the horizontal length of the angle cleat. The length can be amended by clicking on the row and over-typing the value
Bolt Log c/c - the longitudinal centres of the bolts. To input values, expand the row by clicking on the arrow to the left of the row
Back Marks - the back mark to locate the bolt position within each leg of the angle cleat. To input a value, click on the row and over-type the required value
Ideally any splices in a member in compression would be located at or near a point of lateral restraint or a point of inflexion. Where this is not possible, account needs to be taken of the second order effects which will be additional to the forces and moments in the member at the splice location. The second order effects as additional moments due to strut actions, moments due to lateral torsional buckling and amplification of the moments due to the eccentricity of the axial force in the member due to the deformed shape under the applied moments.
The SCI Advisory Desk have produced the advice note AD 243 which provides a methodology for determining the additional second order effects. Background to the method covering the need for such additional moments is given in SCI AD 314, with an explanation of the second order effects given in SCI AD 244.
The default Internal Moments area is shown below. The default values are all zero.
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Moment(yy) (kNm) - the minor axis moment at the splice location.
Moment(xx), max (kNm) - the maximum major axis moment between lateral restraints
Lex, Ley - the effective lengths in the major and minor axes.
Lzx, Lzy - the distance from the splice location to the nearest point of inflexion in the major and minor axes
mx, my - the moment modification factor for flexural buckling about the major and minor axes
mLTB and Pb - the equivalent uniform moment factor for lateral torsional buckling and the bending resistance strength for lateral torsional buckling