Element installation is regarded as hazardous work for which the developer must create a Health and Safety Plan (PSS) if there is more than one employer working on the building site at the same time.
In the case of particularly hazardous work, the employer must also carry out a written assessment with arrangements (work plan) so that the work can be carried out properly from the point of view of health and safety, and it should be included in the basic information for the startup meeting and instructions for employees.
A lot of parties are involved in an element project. The developer’s coordinator over the project phase should check that the temporary statics of the building are taken into account while it is being constructed. This includes creating a plan for temporary reinforcement and when it has to be removed.
It is important to coordinate the work prior to installation and at the same time to review every detail of the project. This should take place at a meeting at which the Health and Safety Plan may be adjusted.
The agreement basis will be established according to the models in BIPS 113A.
The installation gang must have instructions on installation at a startup meeting. Here, the project documentation, Health and Safety Plan, supplier information, special elements, control points, crane placements, etc. must be reviewed here.
Roads, storage locations and work areas for cranes must be described in the developer’s Health and Safety Plan.
The installation guide must describe correct installation and reinforcement.
Transport and unloading of elements
There must be a flat, horizontal surface with sufficient bearing capacity where pallets/flats or similar can be placed.
Elements must be unloaded according to the supplier’s instructions.
If a pallet is defecting on delivery to the site, e.g. if the elements do not engage in mandrels, the supplier MUST specify an alternative way of unloading the elements. Otherwise the elements must be returned to the supplier.
Temporary storage on site must be avoided as far as possible. If transshipment or temporary storage is necessary, this must always take place according to the instructions of the supplier. Storage will normally take place on shelves/pallets or flats designed for the purpose.
If other storage methods are selected, this is actionable. Therefore, it is necessary to ensure that transshipment and storage have at least the same safety level as the method described in the supplier’s instructions.
When using a crane, its lifting capacity must be great enough to allow the elements to be positioned correctly and safely. The weight of the element is specified on the label for the element. Be aware that the tolerance for elements is +/–10% of the weight of the element.
There is a “standard” for mandrel sizes:
- 40 mm, max. 4.5 tonnes, 100–800 mm element width
- 60 mm, max. 10.5 tonnes, 200–800 mm element width
- 90 mm, max. 25.5 tonnes, 200-1200 mm element width
A mandrel of 34CrNiMo6 quality is required.
Webbing or a chain must be placed as close as possible to the element to lift is so that the mandrel does not bend. Use spacer tubes.
To plan safe, correct installation, you need to use all the information that may influence the temporary reinforcement of the concrete elements. It is the responsibility of the installation manager to acquire this information. This information must include a calculation and decision on the overall temporary statics and hence for the temporary reinforcement as well.
The supplier must provide the necessary instructions for installation of individual elements.
The sequence of the elements and the temporary reinforcement is determined on the basis of this information.
While installing concrete elements, other work must not take place nearby at the same time. The employer’s written assessment of the work must define were and when other work may be carried out, including tamping.
Temporary reinforcement of the concrete elements must take place in compliance with the reinforcement plan, which will be formulated on the basis of the structure’s temporary statics and the instructions of the individual concrete element suppliers.
It is good practice in the industry to ensure that there are at least two reinforcements during the installation of wall and column elements; either two struts or a strut and a connecting fitting for linking with an adjacent element. This stops them falling over.
Columns must also be secured at the base.
When securing box girders or concrete which is not cured fully (including elements), it may be necessary to check whether the necessary extraction value can be achieved.
Concrete screws should only be used once – a defective thread will impair the extraction value.
Torques for bolts are dependent on the inserts used and must be implemented in compliance with the supplier’s usage instructions.
Ask the supplier if you are in any doubt about the torque.
You have to use torque wrenches for tightening.
The end surfaces on the element supports must abut fully against the element and the floor.
If the design of the project makes specially shaped fittings necessary, the planner must provide information on this.
Removal of reinforcements
Do not remove reinforcement until the building is stable. This will only be the case when foundations, etc. have set sufficiently. This must be specified in the project documentation.
Façade and wall elements
When installing outer walls, the railings must be in position prior to installation.
Remove the railings again either as installation progresses or at a later date. The structure has to be secured to prevent falling when the railings are removed, e.g. by using fall protection equipment.
Installation of floor/roof elements
When installing floors, the load-bearing structures must be tamped beforehand or the load-bearing capability must be assured in some other way.
There must be railings along the façade which can easily be laid to the front of the installation.
There must always be railings behind and along the outer side of the front of the installation.
Floor elements must be laid in parallel as this minimises the risk of falling and tilting.
Beneath the installation work must be secured to prevent falling,with fall protection equipment as a minimum.