Some steel packages look “simple” until you realize they sit directly behind glass — and every inch becomes visible.
This project focused on detailing the exterior atrium framing that supports a two-sided structurally glazed curtain wall, including a cable support system for a ladder truss, plus the associated bracing and connection work needed to make it buildable.
Our goal was straightforward: deliver a constructible, fabrication-ready package that wouldn’t trigger field fixes once the curtain wall and architectural systems started going up.
The Challenge
1) Elevation control + curtain wall interface
The atrium elevations carried multiple critical control points (mullion elevations, curb lines, slab elevations), and the steel had to land correctly relative to the glass and mullion system. Even a small mismatch could have cascaded into shim stacks, rework, or misaligned façade components.
2) Cable-supported truss coordination
The drawings referenced a cable support system for the ladder truss, which adds another layer of coordination: steel framing, attachment points, and surrounding façade geometry all have to work together in the same “real world” space.
3) “Missing reactions” and connection design assumptions
A major risk was incomplete reaction information at multiple locations. The reaction plan clarified that the boxed locations (where reactions were not provided) should be designed for up to 15 kips vertical gravity reaction plus any brace forces.
Separately, fabrication questions surfaced around connection capacity and what was realistically achievable with member sizes (including clarification that certain W10x12 connections only needed 15 kips, not 24).
4) Slip-critical bolt requirements (where they actually apply)
Approver notes triggered questions about SC bolts. The returned clarification was specific: SC at shear tabs; double-angle connections do not require SC bolts. That kind of detail matters because it impacts cost, lead time, and shop workflow.
5) Constructability and erection access
Some bracing and moment conditions required smarter connection solutions for erection clearance (bracing to column webs, stiffeners for web crippling, and moment details that avoid bottom flange cuts). These approaches were confirmed as acceptable when capacity is properly developed through the plates/column.
6) Exterior finish requirements (galvanize + high-performance coating)
Exterior exposed steel required galvanizing and a high-performance coating system. For the welded ledge angle assembly, the clarification was explicit: galvanize the entire assembly, and paint exposed surfaces with the specified high-performance coating.
Our Expertise
Here’s how we turned a “high-visibility” exterior atrium package into something the shop and field could trust:
- Elevation-first detailing: We treated elevation control as a primary deliverable, aligning steel interface points with the curtain wall geometry and key architectural datums before drawings moved forward.
- Connection logic that respects erection reality: Where standard details would create field friction, we developed practical connection approaches (clearance-friendly bracing, stiffeners where needed, moment plate strategies) and verified acceptance through the RFI flow. RFI #2 Reaction Plan
- Clear assumptions for incomplete design info: When reactions weren’t fully shown, we anchored connection design to the documented requirement (15 kips + brace forces), preventing guesswork and last-minute redesign.
- Specification-driven finishes: We detailed with coating requirements in mind so galvanized + painted surfaces were correctly called out—especially in exposed architectural areas.
The Result
- A fabrication-ready steel package that coordinated cleanly with curtain wall and cable-supported truss requirements.
- Fewer downstream surprises by locking reactions and connection expectations early (including the 15-kip design basis where reactions were missing).
- Reduced risk of expensive “late fixes” by clarifying SC bolt usage, realistic connection capacities, and erection-friendly connection geometry.
- Finish intent preserved: galvanized assemblies where required, with exposed surfaces painted per the high-performance coating requirement.
Ready to Elevate Your Steel Packages?
At ESD Solutions, we don’t just create drawings — we deliver constructible fabrication packages that streamline your schedule and minimize installation risks.
Let’s build it right the first time. Reach out to ESD Solutions and get detailing that delivers.
