Seismic/Ductile Design of steel connections

[theodosokon]

Hello,

I need to design a steel structure to EC3, and the load cases include seismic events.

I am aware of the capability of ROBOT to design steel connections to several codes, including EC3.

I would please like to know if there is the option of including the earthquake design requirements for connections (ie ductility) within the steel connections design function of ROBOT?

Any help is appreciated.

[StefanoPasquini6790]

Hi @theodosokon , What do you mean exactly?

The connection design module give you the opportunity to check the connection according to "Eurocode 3: Design of steel structures - Part 1-8:Design of joints". You apply in the connection the values of the actions with automatic combinations (including seismic ones), manual combinations, single load cases or specified load defined by user.

If you mean to check the capacity design according the "EN 1998: Design of structures for earthquake resistance", you can try to use the plugin included in Robot called "Italy NTC2008 steel" where you can find all the options for capacity design of steel structures, including the ductility checks for beams, column and bracings.

Keep in mind that everything it depend by your behaviour factor, if it's equal to 1.5 you don't have to check the ductility for your members and your connection because of you are in elastic field of the structure.

Let me know if I solved your issue

[theodosokon]

Hi @StefanoPasquini6790 

Thanks a lot for the reply.

What I had in mind is whether there is a way to design steel connection accounting for the requirements/provisions within Eurocode 8-1, section 6.

As you say, for low behaviour factors the design is elastic so I can just follow Eurocode 3.

I was interested, though, in case I have a structural system with high dissipation, where I would need to follow additional rules such as section 6.5.5 of Eurocode 8-1.

Do you know if there is a design option for this on ROBOT?

In addition, I couldn't find the option for the Italian code plugin. Is it not somewhere under Job Preferences?

Many thanks for your help once again.

[Stephane.kapetanovic]

[StefanoPasquini6790]

Hi @Stephane.kapetanovic ,

Probably it depends by the Country Settings in installation, this is the tool for capacity design for steel structures:

Cheers

[StefanoPasquini6790]

Hi @theodosokon ,

According to my knowledge, you have no chance to design a connection according to 6.5.5 of Eurocode 8-1. Anyway, the code tell:

6.5.5 Design rules for connections in dissipative zones
(1)P The adequacy of design should limit localization of plastic strains, high residual stresses and prevent fabrication defects.
(2) Non dissipative connections of dissipative members made by means of full penetration butt welds are deemed to satisfy the overstrength criterion.
(3) For fillet weld or bolted non dissipative connections, the following requirement should be met:
Rd  1,1 ov Rfy (6.1)
Rd resistance of the connection according to clause 6 of EN 1993-1-1,
Rfy plastic resistance of the connected dissipative member based on the design yield stress of material as defined in EN 1993-1-1.
(4) Categories B and C of bolted joints in shear and category E of bolted joints in tension should be used. Shear joints with fitted bolts are also allowed. Friction surfaces should belong to class A or B as defined in ENV 1090-1.
(5) For bolted shear connections, the design shear resistance of the bolts should be higher than 1,2 times the design bearing resistance.
(6) The adequacy of design should be supported by experimental evidence whereby strength and ductility of members and their connections under cyclic loading should should be supported by experimental evidence, in order to comply with specific requirements defined in 6.6 to 6.9 for each structural type and structural ductility classes. This applies to partial and full strength connections in or adjacent to dissipative zones.
(7) Experimental evidence may be based on existing data. Otherwise, tests should be performed.

The real check that you have to do is the point 3 and the overstenght, that you can check manually. If you want to format the report as in the usual Robot report, you can export the connection report in excel and manage it adding the Ec8 checks.....

Let us know your progress.....postin here the results

Hope I help you, cheers

[theodosokon]

Hi @StefanoPasquini6790 ,

Thank you for the reply.

It would be really nice if ROBOT could automatically do the capacity design to ensure that the connections have the 10% overstrength required by EC8 (10% stronger than the plastic capacity of the connected members).

Seems like it is something we have to do manually in post processing.

Maybe something that ROBOT developers could consider!

Thanks again