Warning in RAM: Bolt slip class does not match slip resistance recommendations

Question

I am designing column splice joint of bearing type according to EN 1993-1-8 
 There exists net tension in the flange, hence I will have to use preloaded bolts & hence apply slip resistance check. 
 1) Now when i enable check slip resistance, i dont find any option to enter slip factor for it. Then how does RAM checks the slip resistance of the joint? 
 2) Even after applying slip resistance, warning appears in the result: 
 "Bolt slip class does not match slip resistance recommendations." 
 What is the meaning of this warning, as far as i know only 8.8 & 10.9 grades are allowed to be used for preloaded application. 
 And i have selected the 8.8 grade bolt, so what is the meaning of this warning? 
 3) Why web & flange coverplates are checked in separate connections? 
 4) What is the purpose of providing additional plate from inside of column, as far as i know SCI allows use of cover plate either from inside or outside. 
 I am using RAM connection integrated with STAAD Pro V8i 20.07.11.90 
 Please give reply as early as possible. 
 -Vishal

rtully14 · Answer

Hi Vishal 
 Please see response from development team. Your queries are shown in bold and the response in italics. 
 I am designing a column splice of bearing type according to EN 1993-1-8. There exists net tension in the flange hence I will have to use preloaded bolts and hence apply slip resistance checks.

Now when I enable check slip resistance, I don&rsquo;t find any option to enter slip factor for it. Then how does RAM cjhevck the slip resistance of the joint?

EN connection design in order to check slip resistance needs that user choose the corresponding bolt diameter. For slip resistance checks the application have bolts with different slip factor values. For example:

If user choose normal bolt diameter with &ldquo;Check slip resistance&rdquo; flag turned on; the application will show the design warning &ldquo;Bolt slip class does not match slip resistance recommendations&rdquo;. 
 This methodology has recently change for Indian connections, now users when turn on the &ldquo;check slip resistance&rdquo; flag the user is capable to set also the slip factor; but currently only available for Indian connection design. 
 2. Even after applying slip resistance the following warning appears in the result: 
 &lsquo;Bolt slip class does not match slip resistance recommendations&rsquo; 
 What is the meaning of this warning, as far as I know only 8.8 and 10.8 grades are allowed to be used for preloaded application and IO have selected the 8.8 grade bolt, so what is the meaning of this warning? 
 
 As explained in the last questions; the warning is displayed due the user choose normal bolt diameter using the &ldquo;Check slip resistance&rdquo; flag turned on. Just need to choose one of the bolts using slip factor and the warning will disappear. 
 
 3. Why web and flange coverplates are checked in separate connections? 
 Because they are two separate connections, the web cover plate is one and the flange cover plate is the other. In other codes not only a plate could be user to join the webs but also double angles, etc. That is the reason of why we separate shear and moment connections so we can combine them if required. 
 4. What is the purpose of providing additional plate from inside of column, as far as I know SCI allows use of cover plate either from inside or outside. 
 I am using RAM Connection integrated with STAAD.Pro V8i 20.07.11.90. 
 Green book describes the use for internal cover plates. The EN connection design follow the procedures described in: 
 
 The consideration or not of the internal cover plates affect directly to bending capacities in major and minor axis; also affecting in plate shear capacity. 
 If user turn on the flag the interior plate will be considered in the capacities. 
 
 Also, in the results:

In above it refers to SCI P358 p 185 however, that page refers to non-bearing splices and NOT bearing splices: 
 
 The references in the report results are correct. The user is reporting the flange cover plate from a Non-bearing connection design. 
 The only template that user can assign to have a bearing type connection is the &ldquo;Smart WAC CS&rdquo;; which use a division plate between columns. Also is noticed that the model is using standard bolts with the check slip resistance flag turned on. Once the user change to the correct one the warning will disappear. 
 
 Should the refereance be to SCI P358 p 176? 
 
 The only template exclusively for Bearing Type is WAC CS (Web angle cleats &ndash; Column splice) which uses the division plate between the columns. If user model use the correct template (bearing type) the reference should be the one described above.