Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
A multi-storey reinforced-concrete frame under construction — the column-and-beam skeleton before any infill walls.
Unit I25ART202 · Concept of Building Structures

Introduction to Structures

The great structural systems — and how a building carries itself to the ground.

≈ 30 min + study task

Before a building is beautiful it must stand up. A structure has three jobs: to carry its loads safely (strength), without sagging or swaying too much (stiffness), and without tipping or sliding (stability). This unit introduces the great systems that do this work — and the one rule they all obey: a continuous load path to the ground.

Learning objectives

By the end of this lesson, you will be able to — mapped to the course outcomes for Concept of Building Structures:

1
CO1 · Understand

Explain what a structure must do — carry load safely, stiffly and stably to the ground.

2
CO1 · Understand

Distinguish load-bearing, framed (RCC), and steel-framed structures.

3
CO1 · Analyse

Trace the load path through each system and see why it must stay continuous.

4
CO6 · Understand

Match a structural system to a building's height, span and context.

Four ways to stand

The structural systems

An architect should know four families: load-bearing masonry (walls carry the load), the framed RCC structure (a column-and-beam skeleton does, with infill walls), the steel frame (light, fast, tall), and long-span systems (trusses, space frames, shells) for column-free halls. Pick one.

Three ways a building stands up load-bearing thick walls carry load framed (RCC) columns & beams carry load steel frame braced steel skeleton
DiagramThree structural systems: a load-bearing building with thick walls, an RCC framed building of columns and beams, and a braced steel frame

Load-bearing / masonry

Walls themselves carry the load down to the foundation. Simple and economical to about three storeys; walls grow thicker with height and openings are limited. The oldest system — brick, stone and, today, reinforced masonry.[1, 4]

A multi-storey reinforced-concrete frame under construction — the column-and-beam skeleton before any infill walls.
PhotoA multi-storey reinforced-concrete frame under construction — the column-and-beam skeleton before any infill walls.ChillerCity · CC BY-SA 3.0 · via Wikimedia Commons
A steel-framed building under erection — rolled sections bolted into a skeleton.
PhotoA steel-framed building under erection — rolled sections bolted into a skeleton.PortlandAppraisalBlog · CC BY-SA 4.0 · via Wikimedia Commons
The one rule

The load path

Whatever the system, load must travel an unbroken path: from where it lands, through the structure, into the foundation, and finally the soil — load → slab → beam → column → footing → soil. Break the path anywhere and the building fails.[6]

The load path — slab to soil slab + beam load on slab down columns footings spread the load the path must stay unbroken — load → slab → beam → column → footing → soil.
DiagramThe load path through a framed building — load on the slab passes to beams, down columns, into footings and is spread into the soil
Read across

Load-bearing vs framed

AspectLoad-bearingFramed (RCC / steel)
What carries loadthe wallscolumns & beams (frame)
Wallsstructural, thickinfill, thin & constant
Economical heightup to ~3 storeysmulti-storey / high-rise
Planning freedomlow — walls fixedhigh — open, flexible plans
Governing IS codeIS 1905 (masonry)IS 456 (RCC) / IS 800 (steel)
Apply it

Study task

Pick a building you know. Sketch it and label its structural system, then draw arrows tracing the load path from roof to soil. In two lines, say why that system suits the building's height and use.

Check your understanding

Self-assessment

1. In a framed (RCC) structure, what carries the building's load to the foundation?

2. The load path in any system must be —

3. Which system is most appropriate for a column-free 100 m exhibition hall?

In a nutshell

Recap

A structure carries load safely (strength), without excessive movement (stiffness), and without overturning (stability).
Load-bearing: the walls carry load. Framed: a column-and-beam skeleton does, in RCC or steel.
Steel is strong in tension and compression and spans far; RCC is the Indian workhorse; masonry suits low-rise.
Every system obeys one rule — a continuous load path from load to soil.
The evidence

References & further reading

  1. [1]B.C. Punmia, Ashok K. Jain & Arun K. Jain, Comprehensive RCC Designs. New Delhi: Laxmi Publications.
  2. [2]IS 456:2000 — Plain and Reinforced Concrete — Code of Practice. Bureau of Indian Standards. https://law.resource.org/pub/in/bis/S03/is.456.2000.pdf
  3. [3]IS 800:2007 — General Construction in Steel — Code of Practice. Bureau of Indian Standards. https://archive.org/details/gov.in.is.800.2007
  4. [4]IS 1905:1987 — Code of Practice for Structural Use of Unreinforced Masonry. BIS.
  5. [5]S. Ramamrutham, Theory of Structures. New Delhi: Dhanpat Rai & Sons.
  6. [6]Mario Salvadori, Why Buildings Stand Up: The Strength of Architecture. New York: W.W. Norton.

Further reading

  • Mario Salvadori, Why Buildings Stand Up — the classic introduction for architects.
  • B.C. Punmia, Strength of Materials and Theory of Structures (Vol. I).
  • Angus J. Macdonald, Structure and Architecture. Routledge.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.