5-Storey Steel Frame – SAP2000 Analysis & Connection Design
Full design workflow for a 5-storey steel frame in Sydney CBD: SAP2000 modelling, member optimisation to AS4100, and four connection types designed from first principles.
Project Objective
Model, analyse, and fully design a 5-storey steel frame — from load calculation and SAP2000 analysis through to connection-level detailing — demonstrating the complete structural engineering design chain to AS4100.
Structural System
5-storey steel frame — UC columns, UB beams, PFC X-bracings (Y-direction), moment frames (X-direction) — Sydney CBD, designed to AS4100 / AS/NZS 1170
Tools Used
Project Visualization
Image 1 — SAP2000 model of the 5-storey steel frame used for structural analysis and connection design to AS4100.
The Real Challenge
The key challenge was maintaining consistency across two separate submissions: the SAP2000 member forces had to feed directly into the hand-calculated connection designs. Simple connections carry shear only; rigid connections must transfer both moment and shear simultaneously, requiring bolt group analysis and end plate flexural checks. Base plate design required checking both concrete bearing and steel plate bending capacity. Drift had to be verified against the AS3600 limit of h/500 for each storey.
My Approach
I built the SAP2000 model from architectural drawings, defined all load patterns (dead, superimposed dead, live, wind to AS/NZS 1170.2 Region A2, 45 m/s), and ran the analysis. Member sections were optimised iteratively — columns as UC sections, beams as UB sections, bracings as PFC channels, joists as 180UB18.1 throughout. Drift was checked and confirmed within limits for all five storeys. For connections, I extracted design actions directly from SAP2000 and designed each connection type to AS4100: web side plate simple connections (M20 8.8/S bolts, 6mm E48XX fillet welds), extended end plate rigid connections (6 M20 8.8/TB bolts, full penetration butt welds on flanges), pinned base plates (350×350×25mm plate, 4 M36 4.6/S anchors), and pinned bracing connections (200mm gusset plate, 2 M20 4.6/S bolts).
My Process
Load Calculation to AS/NZS 1170
Calculated dead loads (brick masonry walls, RC slabs), live loads, and wind loads for Sydney CBD (Region A2, 45 m/s, Terrain Category 4) before touching the model.
SAP2000 Model Build
Built the 5-storey steel frame from architectural drawings — UC columns, UB beams, PFC X-bracings, UB joists — with correct end releases for simple vs rigid connections.
Analysis & Validity Check
Ran analysis for all load patterns, checked deformed shapes in both X and Y directions, and verified drift against the h/500 limit per AS3600 Clause 2.3.2.
Member Optimisation to AS4100
Iteratively optimised all sections using SAP2000's steel design module with AS4100-1998, targeting demand/capacity ratio ≤ 1 while minimising section sizes floor by floor.
Connection Design from First Principles
Extracted member end forces from SAP2000 and hand-calculated all four connection types — bolt shear, bearing, plate tearing, and weld checks — to AS4100.
Key Results
5-storey SAP2000 model built with dead, live, and wind loads to AS/NZS 1170.1 & 1170.2
All members optimised: UC columns (100UC–200UC), UB beams (150UB–360UB), PFC bracings, 180UB18.1 joists
Inter-storey drift verified ≤ h/500 for all five floors (max 5.12 mm at Level 1 vs 6 mm limit)
Simple beam connection: Grade 250 web side plate, 2× M20 8.8/S bolts — shear capacity 92.6 kN > 45 kN demand
Rigid beam connection: extended end plate, 6× M20 8.8/TB bolts — moment capacity 159.1 kNm > 45.9 kNm demand
Pinned base plate: 350×350×25mm plate, 4× M36 anchors — bearing capacity 2419 kN > 910 kN demand
Pinned bracing connection: 200mm gusset plate, 2× M20 bolts — tension capacity 606.6 kN > 90 kN demand
All four connection types satisfy AS4100 strength requirements across bolt shear, bearing, plate tearing, and weld checks
Interested in How I Work?
This is just one example of the challenges I've solved. I love tackling new structural problems and collaborating with teams to deliver great results. Let's chat about your project!