Development Length

When you hear the term used in structural called development length two words should always come to mind, "straight and hook".

Straight pertains to the length needed for your rebars to be embedded in your walls/sructure to maximize its strength at the same time prevent from being easily pulled out.

Hook is the length which is bended if the wall or structure for your rebar is limited and cannot accommodate your "straight" development length being required.

Moreover, you would mostly see often in construction sites the "hook" type of development of length mainly in beam connection to columns, suspended slabs to its beam supports and your column rebars to your footing.

A typical development length (hook) as sample shown.

source: link

Here's a simple Excel file you may wish to try and get a rough idea on needed development length for different steel bar diameter. How to download read here.

You may check with your structural plans and notes and compare if approved Ld submitted for your project is within the minimum required as per your local structural standards or codes.
This calculator in conjunction with your steel rebar estimates will be handy if you will be preparing your actual cutting lists to get the right length to minimize wastage on site.
You may read other sample computations like suspended slabs, mix ratio of concrete etc, by exploring the home section that you may find interest with.
related computations: video 1 & video 2
Just a quick overview of sample calculator

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