#ec2

4 posts

Choosing a Slab System: Flat, Beam-and-Slab or Waffle

The slab is usually the largest single element of a building by volume, and the system chosen for it decides the floor-to-floor height, the services strategy and the construction programme long before any reinforcement is calculated. This guide sets out what each system is actually good at, where each one fails, and why on a tall building 200 mm of structural depth can be worth an entire extra floor.

CivilAxis · 8 Sept

Guide

Deflection: Why the Cracked Section Changes Everything

Run a deflection check on the gross concrete section with the short-term modulus and a beam will pass comfortably. Run the same beam cracked and creeping, as it will actually behave, and the answer is roughly twelve times larger. This article works one 7 m beam through both routes and shows exactly where the factor of twelve comes from.

CivilAxis · 2 Sept

Structures

The 0.3 mm Crack Limit: What It Actually Protects

Almost every reinforced concrete element gets checked against a 0.3 mm crack width, and almost nobody asks what that number is for. It is not about leaks and it is not about looks. Working the calculation by hand reveals a genuine paradox: increasing the cover to protect the steel makes the surface crack wider.

CivilAxis · 31 Aug

Structures

One-Way vs Two-Way Slabs: the Difference That Matters

Supports decide how a slab spans - the famous "ratio of 2" rule is only a shortcut for panels supported on all four edges. Where the rule comes from (a one-line stiffness derivation), what EN 1992-1-1 actually says, and how the reinforcement layout changes between the two.

Tran Nguyen Vuong · 12 July