Seven worked examples covering the design of a small reinforced concrete building, in the order you would actually do them, with more examples, reference tables, what happens to the design on site, and practical guides after them. They are written for students and for engineers coming back to something they last did at university.

It is one building all the way through. The loads worked out on the first page become the slab on the second, the slab loads the beam on the third, the beam's reaction becomes the column on the fourth, that column's load sizes the footing on the fifth, and the last two design the stair and turn the whole lot into a bar bending schedule. Numbers carry across, so you can see where each one came from — and every one of them can be checked with a calculator.

1. Load takedown

Dead and imposed loads, the 1.4G_k + 1.6Q_k combination, tributary areas, and carrying the load down a column to the foundation. Ends with 589 kN at the base of a three-storey interior column.

2. Slab design

One-way or two-way, and how to tell. A 150 mm slab that fails deflection by a hair, and the 160 mm slab that fixes it — which is the lesson: slabs are governed by stiffness, not strength.

3. Beam design

Moment, K and K', lever arm, steel area, shear stress and links, deflection. Includes the case students most often miss — where the code's minimum link provision beats the shear the beam actually has.

4. Column design

Effective height, the short/slender test, equations 38 and 39, steel limits and link spacing. Plus what changes when a column is slender, and the corner-column trap.

5. Pad footing design

Sizing on the service load and reinforcing on the ultimate one — the distinction that makes half of all footings the wrong size. Bending at the column face, vertical shear, punching shear, and the 1.8 m square that carries page one's 589 kN.

6. Staircase design

Risers and goings, the slope factor that turns a waist into a load on plan, and the 15% span/depth allowance a flight gets. Stairs are governed by deflection, and shear misses by a factor of three.

7. Bar bending schedules

Every column of a BS 8666 schedule explained, cutting lengths and shape codes, the d²/162 mass rule, and the beam from page three scheduled in full — 35.8 kg of steel.

More worked examples

Members and effects the seven above do not cover. Each stands on its own, and each says what it leaves out.

Strip foundation design — the footing under a load-bearing wall, per metre run, and the 45° dispersion rule that explains why a bungalow's strip is sized by what you can dig rather than by the soil
Raft foundation design — when a raft beats pads, the net upward pressure that actually bends it, punching shear at the heaviest column, and why the span steel goes in the top face
Lintel design — the 45° arching triangle and when it does not apply, worked over a 2.1 m opening. The loading is the whole design; the bending is three lines
Wind loads and stability — pressure from wind speed, storey shears, braced against moment frame, plan torsion, sway and P-delta, on a four-storey frame
Ground beam design — the beam that carries the ground floor walls between the pads, with no imposed load at all, and the reaction it puts back into the footing that nobody counted

Reference tables

The lookups you need beside you while doing any of the above.

Rebar weight chart — kg per metre and area for every bar size, steel area per metre width at each spacing, bars per tonne in 12 m lengths, and why what you order is never the total length over twelve
Cover, grades and mixes — nominal cover and what governs it, cover for durability and for fire, and what a 1:2:4 site mix really gives you
Span/depth ratios — the basic ratios and both modification factors tabulated, and the slab that fails at 150 mm and passes at 160. The check that decides more member sizes than strength does
Concrete, block and steel quantities — bags of cement per cubic metre for each nominal mix, blocks and mortar per square metre, render coverage, and reinforcement rates that are a sanity check and not an order
Lap and anchorage lengths — where 40 diameters comes from, every lap in millimetres, and the two multipliers that make a top bar lap twice as long as the one everybody quotes

On site

What happens to the design after it leaves the desk. These decide whether the concrete standing there is the concrete the calculation assumed.

Decking a floor — concrete, cement, steel, formwork and props per square metre of deck, a worked 100 m² floor, and the checks that have to happen before the mixer starts
Cube tests — crushing load to N/mm², what a 7-day result is worth, why a set averaging exactly 25 fails a grade 25 specification, and the order to do things in when one comes back low
Striking formwork — the minimum periods, why the props outlast the forms, back-propping, and the week after striking when a slab carries more than it ever will again

Guides

Not worked examples — the practical decisions around them.

BS 8110 vs Eurocode 2 — load factors, cube against cylinder, 460 against 500 steel, and why two changes that each look large very nearly cancel
Soil bearing capacity — presumed values, what Nigerian ground is like from Lagos to Jos, when a test stops being optional, and how the number decides between a pad, a raft and piles
Which foundation? — strip, pad, raft or piles: the line that sizes any of them, pad sizes against load and bearing pressure, the coverage test that calls for a raft, and how deep to found
Bungalow or duplex — why a bungalow's footing is sized by buildability and a duplex's column by detailing, and what it really takes to add a floor later
What size should a beam be? — trial depths tabulated by span and load, where the span/12 rule of thumb actually comes from, how many bars fit across a width, and what a 225 × 450 really reaches
How thick should a slab be? — the span 125, 150, 175, 200 and 250 mm each reach one-way and continuous, why deflection decides it, and why a ground floor slab is not designed this way at all
What size should a column be? — the capacity of every common section tabulated, a load estimate in one line, and the four things other than load that decide the answer: moment, slenderness, fire and whether a poker fits
Approval drawings — what a structural submission contains, sheet by sheet, and what gets one sent back
The plan underlay — a how-to for the app: importing an architect's plan, calibrating its scale from a written dimension, marking the columns where the building actually has them, typing irregular bay dimensions and drawing a building that steps in. Includes why calibrating off a short line costs you 9% of your bending moment
Scanning a plan — the paid shortcut through that reading: what it extracts, why it refuses to guess a scale, what you must check before designing from it, and what leaves your device

Then run it yourself

Structura is the same calculation, done for you and shown the same way: formula, substituted values, and a PASS or FAIL on every check. Single members — slab, beam, column, footing, stair, lintel — are free to run, as many as you like, which is more than enough for coursework and for checking your own hand calculations.

It runs in the browser, so there is nothing to install.

Open Structura in your browser

On Android, get it on Google Play; on iPhone and iPad, get it on the App Store — same account as the browser.

A word of warning worth taking seriously: a tool that agrees with you is not the same as being right. Work the example by hand first, then run it — the disagreements are where the learning is.

About the engine behind it

What Structura designs — every member and the checks it runs
How it works — inputs, calc sheets, schedules, drawings
What it will not do — no seismic, no piles, no settlement, and why