Rebar detailing can look incredibly complicated on construction drawings. Interpreting them can be difficult and requires an understanding of how things work in three dimensions.
A great way to appreciate what’s going on in a drawing is to compare it with existing premade steel cages, or other structures, to understand the relationships between the elements.
What is Rebar Detailing?
Rebar detailing is the interpretation of a structural engineer’s specifications to deliver the reinforcement required in a concrete construction. A rebar detailer will produce assembly drawings for workshop, or site fixing by steelworkers.
The structural engineer usually reviews these drawings as part of the design process to ensure compliance with expectations. Rebar detailing should provide all the comprehensive information required regarding quantity, size, and any bespoke, or standard shape, for the concrete reinforcement.
Detailing the rebar required in a drawing can require a good understanding of how elements in a two-dimensional diagram interact in three dimensions.
Standard Details for Rebar
Some rebar details are quite standard and can often be supplied premade directly from the steel reinforcement supplier. These premade items, cages, pile columns, etc, have already been detailed to deliver the structural reinforcement required for a number of standard construction site conditions.
Where things do vary, sometimes quite considerably, is the way these standard items are linked together, and their configuration on a construction site. This is where the rebar detailing on the drawing will need to be followed carefully, to ensure all the potential forces are catered to.
The Basics of Rebar Detailing
There is a lot of information compiled in a number of ways when it comes to rebar reinforcement, so let’s break it down:
Specifications and Spacing
The space between the steel rebar is as important as the specification of size, shape, bend, hook, lap, splicing, etc.
Bending Schedules
The dimensions of every piece of rebar required should be on a bar bending schedule, detailing the specific shape and any bespoke form.
Anchoring Details
Drawings should show how every element is connected, how columns are anchored to foundations, slabs, or pile caps, whether there are any requirements for seismic or other movement conditions.
Splicing Details
Continuity of tensile strength is detailed in lapping, or splicing requirements, how forces are shared between sections or other elements.
Concrete Cover
The depth of concrete cover can differ according to environmental and other considerations. The critical base number is 50mm, but this can rise in certain situations and is a standard part of a rebar detail drawing.
Why is Rebar Detailing Important?
Rebar detailing isn’t just about tying foundations, columns, and beams together. Most steel fixers know how to do common connections. Detailing confirms the needs of a particular structure.
Concrete Structural Integrity
The structural integrity of a project depends upon the detailing being correct. It is essential that all the beams, columns, foundations, and floor slabs have the correct reinforcement to manage the forces, loads, and stresses to which they will be exposed.
Carbon Cost Effective
Decarbonisation is a key performance marker for the construction industry and carefully detailed rebar drawings help to keep waste to a minimum. Steel rebar is highly recyclable, with up to 96% of steel used in construction circling back into the economy.
Clashes and Coordination
Services and utilities are where 90% of the clashes occur in construction drawings. Understanding where existing drains need to be bridged, or how electrical services are expected to enter a building needs effective design team coordination to avoid changes and delays on site.
Compliance and Quality Standards
Getting rebar detailing standards right goes a long way to ensuring a structure is compliant with all relevant building regulations and quality recommendations. The safety of a structure depends upon the drawings accurately reflecting construction standards set out in industry codes of practice.
Using Rebar Detailing Software
For complex structures, using rebar detailing software is sometimes an essential option. Software such as Tekla is commonly used to help minimise congestion. A problem with rebar detailing is that it is easy to over-engineer a solution, leading to the inclusion of an unnecessarily large ratio of steel to concrete.
Steel reinforcement is essentially an elegant way to deliver resistance to the dynamic stresses experienced by concrete structures. In a large, or complex project, it can be tempting to detail more rebar than is actually required.
Rebar detailing software makes sharing design issues with teams easier too, where changes due to clashes with services or existing structures can be highlighted.
The Purpose of Rebar Detailing
The purpose of rebar detailing is to ensure that the design intent of the structural engineer and architect is translated into a buildable solution that can be understood by those required to deliver the final structure.
All elements of a reinforced concrete detail drawing should contribute to the structural integrity, overall performance, and durability, safety, and building regulation compliance of a construction project.
Talk to our professional team today if you need any help with interpreting rebar detail requirements on your project.
