REINFORCEMENT CONCRETE DETAILING
Detailing can only relay being in earnest one the final design is available. The design requirements are normally given to the detailer in the form of design calculation, marked up GA drawings, beam schedules or completed pro forma or similar.
It is important that detailing is carried out with responsibilities and adequate timescales clearly defined. Issues such as site constraints, relevant standards, laps, covers, concrete grades holes, detailing preferences, etc must all be covered. These requirements should be formalized into detailing specification weather is carried out in-house or outsourced. Ideally, the contractor’s preferred methods and sequences of construction should be made known and accommodated.
Advantages/ disadvantages of Designer and Contractor detailing
Advantages of Designer Detailing/ disadvantages of Contractor Detailing
Advantages of Contractor Detailing/ disadvantages of Designer Detailing
Details from Designer Detailing are produced as an integral part of the design and can be more easily tailored to the demands of the Designer
Contractor Detailing can more readily take into account the Contractor’s preferred method of working
Production of reinforcement details by designer Detailing can take place while the designer is still being finalised, thus saving elapsed time. A typical example where it might be more efficient for the designer to produce details is for foundations.
Reinforcement details by Contractor Detailing can be prepared taking account of the Contractor’s preferred methods of construction and final material section.
Preparing clear design information for Contractor Detailing takes longer and is likely to be later than for the Designer Detailing with less time for checking or changes.
Preparing reinforcement details by Contractor Detailing benefits from following the actual construction program.
The approval process for Contractor Detailing can take longer because of the researching required.
Designer detailed work may require re-working to take account of the contractor’s method of working.
Considering the above advantages and disadvantages we are the opinion that the Detailing in-house by the Designer is the best solution considering the following items:
Reinforcement drawings describe and locate the reinforcement in relation to the outline of the concrete work and the relevant holes and fixings.
Generally circular or rectangular holes up to 150mm diameter in slabs or walls need not be indicated on the reinforcement drawings. All other holes should be indicated on the reinforcement drawings and should be trimmed, where necessary, by suitable bars.
Separate drawings or plans for top and bottom layers of reinforcement should be used for fabric and occasionally for complex constructions.
Reinforcement drawings are primarily for the use of the steel fixer. It is preferable that general arrangement and reinforcement drawings be kept separate, but for simple structures a combined drawing may be appropriate.
Reinforcement drawings contain also standard details. These details on a repetitive basis. Details used in this way must be carefully worked out, fully detailed and totally applicable to each location where they are to be specified. They should be drawn to a large scale.
Reinforcement detailing should be kept as simple as possible consistent with showing its shape and the exact location. The information given on a drawing should be in accordance with BS 8666. The standard description is as follows:
Number, type and grade, size, mark, bar centers, location and comment
Egg. 20H16-63-150B1 (20Nos. high yield deformed bars of 16mm nominal size at a pitch of 15mm in the bottom outer layer. Bar mark is 63).
Reinforcement bar schedules
Scheduling is an operation of listing the location, mark, type and size, number of, length and bending details of each bar or sheet of fabric.
CAD detailing provides automatic the bar schedules by different criteria decided by the user.