Exposed steel rigid frames, purlins, and bracing inside an Ontario clear-span building

Anatomy of a steel building

Primary frames, secondary steel, bracing, foundation, and sheeting. Click a part on the drawing to see what it does.

80'-0" clear span · 100'-0" length · 4 bays @ 25'-0".

How load reaches the ground

Snow and wind do not stop at the panels. Force moves from the sheeting through secondary steel into the frames, then into the concrete.

1Sheeting takes the weatherSnow, rain, and wind hit the roof and wall sheets first. Ribs stiffen the thin steel so it spans between secondary members.

2Purlins and girts bridge the bayPurlins and girts collect panel load across the bay and put it into the main frames.

3Frames and bracing carry the spanRafters and columns take vertical load across the open floor. X-bracing resists lengthwise wind racking.

4Anchors lock into concreteGravity, uplift, and thrust land on the base plates and pass through cast-in bolts into the piers.

Parts by system

Same drawing as above. Use Locate to jump to that member.

Primary framing

Welded I-beam frames that span the floor and carry snow and dead load down to the piers.

: Vertical welded I-beam at the sidewall. Carries roof and wind load down to the pier. Deeper at the top where bending is highest. Locate
: Sloped primary beam spanning the width with no interior columns. Sized for snow, dead weight, and uplift at that address. Locate
: Bolted joint where the column meets the rafter. End plates and web stiffeners take the peak moment in the frame. Locate
: Field splice at the roof high point. Joins the left and right rafters into one continuous frame across the bay. Locate
: Corner columns, wind posts, and a lighter endwall rafter. Can be a full rigid frame if you plan to add bays later. Locate

Secondary steel

Purlins, girts, eave struts, and door framing that bridge the bays and back the panels.

: Cold-formed Z-sections running frame to frame across the roof. Carry the roof sheets and put snow load into the rafters. Locate
: Horizontal Z or C members bolted to the columns. Back the wall sheets and move wind load into the main columns. Locate
: Formed C-section at the top of the sidewall where roof meets wall. Carries the top of the wall sheet, the first roof run, and bracing forces. Locate
: Jambs and header framed into the wall where girts stop for overhead doors, docks, or hangar openings. Locate

Bracing

Diagonal rods and flange braces that keep the frame square under wind and racking.

: Crossed rods, cables, or angles in braced bays. Keeps the building from racking lengthwise under wind or crane braking. Locate
: Angle struts from purlins and girts to the inside flange of the primary frame. Stop the deep beam from twisting under load. Locate

Foundation

Anchor bolts, base plates, and concrete piers that lock the steel to the ground.

: Shop-welded plate at the foot of each column over threaded rods cast into the concrete. Passes uplift, shear, and compression into the foundation. Locate
: Reinforced pier and frost wall below Ontario frost depth. Takes column loads and gives the wall sheet a curb to sit against. Locate

Sheeting

Roof and wall panels plus trim that close the building to weather.

: 24- or 26-gauge galvalume and painted steel sheets on purlins and girts, with ridge, eave, and corner trim. Insulation and liner sit under the sheets when the building is conditioned. Locate

Crane setting a steel rafter on an Ontario job site

Plan your steel package

Send span, eave height, doors, and site address. We size the frames, secondary steel, and bolt layout for your lot.