Simple Connections
Simple connections can be one of three types - end plate, fin plate or (double) angle cleat. These are termed 'connecting elements'. In the case of fin plates and the leg of the angle cleat to the supported beam, a double line of bolts can be specified. Any of these can be provided for beam to beam, beam to column flange and beam to column web connections provided that both the supported beam and the supporting column or beam is an I- or H-section. In the current release only fin plates can be used to connect to hollow section columns.
Supporting and supported members and their connecting elements are limited to S275 and S355 grade steels - there are a number of semi-empirical rules in the design models that preclude the use of S460 grade steels.
For beam to beam connections a notch length can be defined that suits the width of the supporting beam flange - this must be the same on both sides of the supporting beam. For each side a notch depth at the top and bottom of the supported beam can be defined - these can be different top and bottom and, different on each side. For convenience 'standard' notch lengths and depths are defaulted and via the 'Set Standard Notches' button you can recover these if you have changed something but wish to get back to the standard values. Notch details also appear on beam to column connections but changing the default values from zero has no effect.
To avoid notching in beam to beam connections a fin plate can be selected to ensure that the supported beam and the fin plate are joined outside of the flanges of the supporting beam. This will usually create a 'long fin plate' and certain additional checks are required and are carried out by Fastrak.
Connecting elements can be of different types on each face of the supporting beam or column although those either side of a beam or column web have some design restrictions - see
“Ultimate Limit State” on page 110. Beams can frame in at different levels or can be aligned (in beam to beam connections) with the top flange, bottom flange or centre line of the co-joined members.
A wide range of bolt grades and sizes can be defined and, by default, their layout (end and edge distance, pitch and gauge) meet the 'Recommended detailing practice' given in the Green Book on simple connections (Check 1). The number of bolts is defaulted to meet the 'standard connections' contained therein. Similarly, weld sizes for use with fin plates and end plates are the standard values. For angle cleats the default bolt layout is the same in both legs but you can select different layouts in each leg if required. You are able to adjust all these defaults but you are advised to do so with care.
The design forces for simple connections are shear in the plane of the web1 of the supported beam and where appropriate tie forces. A set of these can exist for each design combination and these are established from the analysis of the building model as a whole (or entered independently in the stand alone application). You can edit the design forces, delete and add
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load combinations and these changes will be reflected in the design of the connection
immediately following the changes. However, all these changes will be lost if subsequently you use the 'Update Connections' function in Fastrak Building Designer.
The necessity for tying is a matter of regulation and requirements are included in BS 5950-1: 2000.
The April 2007 amendment to BS 5950 includes an adjustment to the tie force that is
dependent on the number of storeys in the structure. Since the number of storeys in a building can vary and some ‘levels’ in a building are not ‘floors’ e.g. mezzanine. Fastrak will establish the number of storeys from the number of levels set to be ‘Included’ on the Levels dialogue of the Building menu. Note that the uppermost level will be included irrespective of the setting of the Included check box.
Currently only simple connections are checked for tie forces if applicable. In the building model you are able to set simple connection attributes to allow for tying in one of three ways,
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no tie force -this member does not form part of the tying system,•
minimum tie force - regulations permit only nominal tying of the building (75kN)•
vertical reaction - full tying requirements are necessary and the tie force is taken to be,MAX(n x reaction, 75kN) where n is the reduction factor for number of storeys. For 5 storeys and above n = 1.0, for 4 storeys, n = 0.75, 3 storeys, n = 0.5, 2 storeys, n = 0.25 and 1 storey, n = 0.0
In the latter case if a member does not support a floor but simply acts as column tie or masonry restraint for example under 'normal' stage loading (i.e. at the Ultimate Limit State), there may be no reaction and hence the tie force will be set to the minimum.
When establishing your connections, Fastrak will use these settings to determine the tie force (which may be zero if the no tie force option is selected).
Results of your connection design can be viewed on the screen. The input, diagrams, and design results can be incorporated into a report by sending the connection or selection of connections out to Fastrak Connections. From there you can control exactly what you wish to see in the report.
Connection components e.g. bolts, welds, stiffeners are not listed in the Material Listing report.
Moment Connections
Moment connections can be one of three types - single-sided beam to column flange, double-sided beam to column flange and beam to beam. They are formed using bolted end plates that can be flush or extended top and/or bottom. Haunches can be defined below the supported beam and can be either,
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a section cutting - cut from the same size as the beam, same size as the column or from any (valid) section that you select or,Integrated connection design : Chapter 22 : Scope Advisory Note for Fastrak Building Designer page 101
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built up from plates - a plate size (width and thickness) is required for the web and flange plates.Where a section cutting is defined, you are provided with a button to calculate 'Max Depth' of the haunch based on the length of the haunch, slope of the beam and section size selected for the haunch.
In beam to column moment connections the column and the individual beams can be assigned a 'level' within the connection application. This is not reflected in the building model. Columns, beams and end plates that make up you connection can be S275, S355 and S460 grade steels. Care should be exercised when selecting S460 grade steel since the original 'Green Book' on moment connection design was written with S275 and S355 steel in mind and there may be limited availability of plate in this grade.
A range of standard width and thickness of plates is provided from which the end plate can be selected. Flush end plates are given a 'projection' above and below the connection whilst for extended end plates it is necessary to define the extension (above and/or below).
A wide range of bolt grades and sizes can be defined and, by default, only one pair of 'tension' bolts and one pair of 'shear' bolts are provided. You can add bolts individually or use the Generate Regular Bolt Layout button. In either case you need to go to the Combinations page and click on the appropriate Bolts column to set which of your additional bolts should be used in tension and which in shear. You need to do this for each design combination.
Welds to the beam flanges, beam web and to the haunch if appropriate are all defaulted to 8 mm fillet welds. You should adjust these both in terms of size and type (a butt weld might be more appropriate) to suit the particular application.
Stiffeners in moment connections are often required and a wide range is provided,
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rib - usually relatively short stiffeners that are used principally to improve column flange bending capacity,•
full depth - often required to resist compression particularly where the column is a UB section,•
shear - these can be diagonal, K or 'Morris' types and may be required to assist the web panel shear capacity,•
web plate - help both compression and shear capacity of the web panel and have the advantage that they do not interfere with any beams framing into the web,•
cap plate - can be provided for other purposes e.g. to connect parapet posts but if present will usually assist flange bending, and compression in 'reverse' bending combinations,•
flange plate - these are 'loose' flange plates i.e. they are not fully welded to the flange - theyare usually tack-welded to keep them in place during transport and erection. They assist flange bending,
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extension plate - for an extended end plate connection the extension can be relatively weak in bending and this vertical stiffener will improve the capacity. It is essential when there are two rows of bolts in the extension.Note that incorporating stiffeners is expensive in fabrication terms and most can interfere with other members framing into the same area. It is often economic to avoid stiffeners by
increasing the section size (of the column and possibly the beam) or deepening the haunch. This may also avoid detailing issues and improve erection efficiency.
The design forces for moment connections are shear in the plane of the web of the beam, moment in the same plane and where appropriate axial force in the beam. Tie forces are not included. For haunched connections, the moment at the 'sharp end' of the haunch can be entered - due to the length of a typical haunch this can be significantly less than that at the connection interface. This moment is used to check the capacity of the beam web at that position - (see page 112) A set of these design forces can exist for each design combination and these are established from the analysis of the building model as a whole (or entered
independently in the stand alone application). You can edit the design forces, delete and add load combinations and these changes will be reflected in the design of the connection
immediately following the changes. However, all these changes will be lost if subsequently you use the 'Update Connections' function in Fastrak Building Designer.
Results of your connection design can be viewed on the screen. The input, diagrams, and design results can be incorporated into a report by sending the connection or selection of connections out to Fastrak Connections. From there you can control exactly what you wish to see in the report.
Connection components e.g. bolts, welds, stiffeners are not listed in the Material Listing report.
Column Base Connections
Integrated connection design : Chapter 23 : Limitations and Assumptions Advisory Note for Fastrak Building Designer page