Day 2 of 11 — Class 2

Beam Modelling
& Analysis

Model a simply-supported RC beam, apply dead and live loads, run a linear static analysis, and extract moment, shear, and deflection diagrams.

ETABS Dead Load Live Load BMD / SFD
01 — Why

Why beams before buildings?

Every multi-story frame is just a collection of beams and columns. Understanding beam analysis in isolation — with verified results against hand calculation — gives you the confidence to trust the software on complex models.

Content Coming Soon Intuition: beam as the simplest structural element. Where beams appear in real buildings (floor framing, transfer beams, girders).
02 — Concept

Loads, reactions, and internal forces

A beam in equilibrium: external loads are balanced by support reactions; internal forces (moment, shear) are what the cross-section must resist.

Content Coming Soon BMD and SFD derivation for UDL and point loads. Load combination intro: 1.2D + 1.6L (ACI). Interactive diagram.
03 — Walkthrough

Step-by-step: Beam model in ETABS

Build a 6 m simply-supported beam (300×500 mm, f'c = 25 MPa) with UDL dead = 10 kN/m, live = 8 kN/m.

01

Create a 1-bay, 1-story grid

New model → set 1 bay (6 m) in X, 1 story (0 to 0 — just a flat grid). No Y bays needed for a 2D beam.

02

Define beam section (300×500)

Define → Section Properties → Frame Sections → Add New → Concrete Rectangular. Set b=300 mm, h=500 mm.

03

Assign support conditions

Select left node → Assign → Joint → Restraints → Pin (fix UX, UY, UZ). Right node → Roller (fix UY only).

04

Apply distributed loads

Define → Load Patterns → add DEAD, LIVE. Select beam → Assign → Frame Loads → Distributed. Enter 10 kN/m for DEAD, 8 kN/m for LIVE.

05

Define load combination and run

Define → Load Combinations → Add: 1.2×DEAD + 1.6×LIVE. Analyze → Run Analysis. View → Show Forces/Stresses → Frames.

06

Read and verify output

Midspan moment should be ≈ wL²/8. Check against hand calc: M = (12+12.8)×6²/8. If they match, your model is correct.

04 — Check Yourself

Verify before you continue

Answer these without looking at ETABS.

Interactive Quiz Coming Soon Questions: What does a pin restraint fix? What load combo does ACI use for gravity? What is the formula for max moment under UDL? How do you read shear at a support from ETABS?