Lateral brace at glulam over column

[braves25]

Hello all,
I have a roof structure consisting of glulam beams supporting roof purlins (bottom of purlin is connected to the top of the glulam beam). Glulam is 6.75"x21". Left end of glulam is cantilevered over a beam a distance of 3'-4". Right end of the glulam is cantilevered over a beam a distance of 6'-0". There is one column supporting the bottom of the glulam resulting in a two span condition between beam supports at the cantilever. I have a 11' span and a 19' span each side of the middle support column. ----^--------^-----------^----- Where the ^ is the supports. Originally, I was providing kickers at the interior column location to brace the bottom of the glulam; however, the arch is wanting a "clean" look and does not want these kickers. What are my options in order to eliminate any "kickers" at interior columns?

Thank you and have a great day.

 

[BAretired]

Just take them out. You don't need them. Make the column continuous through the beam with an appropriate connection.

 

[jerseyshore]

Agreed. Also, make sure you are referencing the manufacturer's specs if you can. Many have good info. Glulams are rare in NJ, but last time I used them I downloaded the istruct software which was very helpful.

 

[braves25]

BAretired, are you saying to discontinue the glulam beam and frame this into the column (extending the column up to the bottom of purlin)? Or, providing some type of "saddle" connection in order to keep the beam continuous? Thank you.

 

[BAretired]

braves25,
Either of those options could be used, but you stated that the glulam beam was continuous, so I was thinking of a saddle.

 

[XR250]

Design a saddle on top of the beam with tall side plates that will keep the glulam from rotating.

 

[BAretired]

And for consistency, do the same for all three columns.

 

[bobbyboucher]

if you didn't have sufficiently large or strong saddles, then you would absolutely need a brace, right? at every point of bearing and especially at points with negative flexure adding bracing is a good idea and often required, or could change the effective unbraced length that you can use

 

[BAretired]

if you didn't have sufficiently large or strong saddles, then you would absolutely need a brace, right?

Well, I suppose so, but why use saddles which are not sufficient? And what criteria would you use to determine how strong they need to be? And if you decide to use braces, how strong do they need to be?

One point to consider if using a saddle...make sure the connection to the beam is not too low.

 

[bobbyboucher]

agreed. i was mainly wanted to make sure that it's conveyed that bracing is required... it's just that the saddle can be that brace. as far as the force and strength.. i don't know. steel (AISC) has some equations to use for brace forces. i would think somewhere in the 1% to 2% of the design moment in the beam at the column. or perhaps 1% or 2% of the shear reaction multipled by the distance between the shear center of the beam. essentially need to have a fixed connection between column, saddle, and beam.

if the connection is too low, then you are essentially relying on cross grain bending in the beam for the stabilizing moment, which is not ideal.. so i agree that the connection should not be too low (the saddle would have tall side plates like XR250 suggested)

 

[StrucPatholgst]

Rothoblaas North America has a bunch of cool hidden connector products. They even have design software, but I haven't used it yet.