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CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

(OP)
Hello

I have a truss with a Square hollow section webs and chords. I need to connect the web to the chord using gusset plates. That is, the web has a plate welded to each side face.
The chord has 2 gussets, the web then gets inserted in between gussets and the bolts are tightened. This is called the " modified shear splice" in the "Cidect" books. Refer to Design Guide number 3, section 8.2.

Question: The Cidect publication make reference to having the shear lag applied to "each individual area elements". I do not understand how to apply equation (3)to each of the four elements to account for shear lag (whilst incorporating the shear lag reduction factors based on weld length).

Can any one do a quick example calc with some numbers to understand this concept. Please refer to figure 8.9b in the cidect book as this is the exact case I have.

many thanks

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

Sorry I have no idea what the cidect book is, any chance of a sketch?

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

I have found the books your looking at I will try and get back shortly

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

(OP)
Hi desertfox. Sorry..i was driving when ur message came thru. Yes those design guides are freely availble from cidect website. Number 3 has the connection i refer to. Cheers

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

hi geopat69

Well from what I am reading I would say you need to calculate the net area which is (the width of plate X the plate thickness - area of bolt holes), then if applicable you multiply that area by the factor given on page 90 which give options of 0.9,0.85,0.75.
To understand the mechanics behind it you might like to visit this site:-

http://www.roymech.co.uk/Useful_Tables/Rivets.html

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

(OP)
Hi desertfox

Thanks for your quick reply...actually i was alluding to the "4 element areas" that the guide refers to. In particular, its reference to the weld and weld length.

I just dont know what/how the 4 element areas have to do with it or how it can be done. I thought shear lag had to do with the "entire" cross section ( not individual elements).

REGARDS
GEOPAT69

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

hi geopat69

Reading further in to the book it appears that hi and bi refer to the depth and width of the RHS see page 51 for example.
Now looking on page 91 where the factors are for welded joints, to me I read it that the factors are applied depending on the weld lengths being greater than or less then the depth and width of the RHS.
So if your weld lengths are less than 2*bi but greater than bi then you use:- (0.5 + 0.25Lw/bi) in the formula of 8.13 as the shear factor.

hope this helps

desertfox

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

(OP)
Cheers for all your help desertfox.

RE: CIDECT section 8.2: Square Hollow Section connected to Square Hollow Section chord, using Gussets

your welcome!

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