Discussion: View Thread

Hello,

im a new grad and im looking for some direction on designing girts for a building. 
I've looked into the components and cladding chapter of ASCE but im not sure how next to proceed. Is there a step by step process I should be following?

thanks for any advif

Kylie

I assume this is a steel industrial building with steel deck or similar siding.  The most common girt design uses steel channel "C" members with the major axis turned horizontal to resist wind pressures from the siding.  The girts are designed for the same "component and cladding" pressures as the siding itself, although depending on the span and spacing of the girts, some reduction on pressures due to tributary area may be appropriate.  The girts must be designed for biaxial bending, with the wind pressure (positive and negative) causing major axis bending and the weight of the girts and siding, minor axis bending.  The siding weight also causes some torsion of the girt.  Some engineers account for this by only using the outer half of the channel to resist the siding weight.  It is common to use sag rods at the mid- or third points of the girts, to cut down the span for minor axis bending.  The sag rods are typically 3/8 or 1/2 inch diameter rods that extend through the channel web and attach to an eve strut at the top of the wall that resists the weight in major axis bending.

For purposes of computing available strength of the girt, it is common to assume that the outer flange is laterally supported by its attachment to the siding.  The inner flange is laterally unsupported.

Start by selecting a siding and determining the permissible span under wind loading.  Then select a channel spacing that accommodates this span. Select a channel section, and evalute it for adequacy using AISC 360.  

There are several text books on industrilal building design you may find helpful.

------------------------------
Ronald Hamburger, SE
Consulting Principal
Simpson Gumpertz & Heger

Original Message:
Sent: 09-09-2024 03:24 PM
From: Kylie Canova
Subject: Girt Design

Hello,

im a new grad and im looking for some direction on designing girts for a building. 
I've looked into the components and cladding chapter of ASCE but im not sure how next to proceed. Is there a step by step process I should be following?

thanks for any advif

Hello,

im a new grad and im looking for some direction on designing girts for a building. 
I've looked into the components and cladding chapter of ASCE but im not sure how next to proceed. Is there a step by step process I should be following?

thanks for any advif

Designing the structure that supports components and cladding will be influenced by the type of cladding being attached to it.

Each type of cladding has its own requirements.  Deflection is likely to be the determining factor in some elements.

I suggest finding a mentor that is in your firm to help you understand how the cladding needs to be supported, which support will take gravity and lateral loads, which should only be lateral loads and how to determine the forces and detailing of the connections to the girts and how to determine the load the girt will be transferring into the base structure.

There are going to be a multiple different checks required depending on the base structure and the members chosen as the girts.  And even the detailing of how you are attaching each element to the next.  At a minimum, strength, stability and deflections all need to be considered.  Additionally, constructability is a big factor because the detailing can create construction issues that increase expense and jeopardize the quality of the final result.

All this to say that this is not a boilerplate design because there are too many variables.

My best advice is to separate out the problems you need to solve as much as possible.  If a single connection starts to get to complicated figure out if there is a different way to detail it so that each connection is easier to design and construct.

Also, remember that a person is going to have to build your design.  What you can put on paper is not always constructible.

------------------------------
Sarah Halsey P.E., M.ASCE
New York NY

Original Message:
Sent: 09-09-2024 03:24 PM
From: Kylie Canova
Subject: Girt Design

Hello,

im a new grad and im looking for some direction on designing girts for a building. 
I've looked into the components and cladding chapter of ASCE but im not sure how next to proceed. Is there a step by step process I should be following?

thanks for any advif