Superstructure Logistics

28 Nov

Constructing the superstructure requires the use of a lot of machinery, equipment and vehicles.

It is under the main contractors remit to assess site and produce a logistics plan for where the required plant and equipment will be situated. This is often done with input from the specialist Frame Subcontractors.

I recommend finding the latest logistics plan drawing for your project and understanding it. This can usually be found within the Construction Phase Plan (CPP), which is a requirement in the Construction Design and Management Regulations (CDM).

The plant, equipment and vehicles needed for Superstructure works depends on the type of superstructure to be built.

Broadly, they can be split into categories as follows:

Concrete Equipment:

All of the following are required if the superstructure designed is reinforced concrete. Some may not be required if the structure is steel, timber or masonry.

In these cases there may be smaller sizes of the plant and equipment listed below dependant on the estimated use of concrete.

1. Concrete wagons/mixers - vehicle in which concrete is delivered onto site to be poured into the superstructure elements. They are equipped with rotating drums or agitators that continuously mix the concrete during transit to maintain its consistency and quality.

2. Concrete pumps - concrete is deposited from the concrete wagon into the hopper incorporated in the concrete pump. This then pumps concrete through a large concrete line - think of this as a large diameter garden hose which pumps concrete instead of water.

What's the longest the concrete line can be? Will it need to be relocated?

Is there a clear route to the pump or skip where concrete is required?

The use of a static concrete pump is common if they can be situated in one area and won't constantly require moving.

An alternative is the below - a mobile concrete pump which can be driven to site when it's needed. It serves the same purpose but is usually driven away once concrete pour is complete.

Is the ground under where the mobile pump is planned to be situated suitable?

Sometimes there may not be enough space for a static or a mobile pump. Or perhaps the structure is so high that the pumps can't reach. In these cases, a boat skip is used.

This is filled straight from the concrete wagon and lifted into where it's required by mobile crane. Concrete finishing operatives control the release and positioning of the skip in co-ordination with the crane team

Is there a lay down area where the concrete wagon can fill the skip?

Where will the lined waste skip be situated so the boat skip can be washed out after use?

3. Concrete vibrators - commonly referred to as a 'poker'. Placed into wet concrete whilst it's freshly poured to compact it and reduce any air voids.

The only type of structural concrete which doesn't require vibrating is self-compacting concrete.

4. Curing tank - a water storage tank with a maintained temperature. Used to store concrete cubes (shown below) which are to be taken away to be tested for their compressive strength.

Is there a power supply in close proximity?

Reinforcement Material/Equipment:

1. Reinforcement bars (rebar) - the inclusion of materials like steel bars (rebar) or mesh within concrete structures.

These materials provide additional tensile strength to the concrete, helping it withstand tension forces that it might otherwise crack or fail under.

Is there a suitably sized lay down area for reinforcement steel to be dropped into?

2. Rebar cutters and benders - used to cut or bend reinforcement bars or mesh to size required. Sometimes an angle grinder isn't sufficient as the bars are too strong.

Note: in theory there should be no cutting of reinforcement required as what is shown on the Structural Engineers bending schedules is ordered. However, this often isn't the case and modifications are required to solve issues which arise in practice.

Temporary Works Equipment:

1. Formwork systems - also known as shuttering, refers to the temporary structure or mould used to shape and support freshly poured concrete until it sets and gains sufficient strength to support itself.

What formwork system will we use?

Is there enough working area around where formwork is to be installed for operatives?

2. Tower Crane - a tall, fixed piece of equipment used to lift heavy loads around a construction site.

Scattered across the skyline of many cities around the world, tower cranes lift up all elements required to construct the superstructure up to where they are needed.

Dependant on the size of the job, multiple tower cranes may be required.

Surveying and Measurement Equipment:

1. Total stations - Surveying instruments and tools are necessary for accurate setting out positioning of superstructure elements to the construction plans.

Initially, if no site control has been established a GPS version may be used.

Is the ground suitable for someone to operate surveying equipment on?

Have site control points been set out? Are they visible?

Misc.

1. Temporary Water Supply - usually in the form of a bib tap. This provides water to site for cleaning and other activities.

Note: temporary services are usually down for the main contractor to provide

2. Temporary Electric Supply - ideally before the Groundworks/frame subcontractor starts on site there is an established temporary building electric supply in the form of a substation of some description.

If there isn't all plant and equipment will need to be powered with fuel or portable generators.

Has a temporary electrical supply been established?

If so, where is it in relation to the substructure works?

3. Personal protective equipment (PPE) - besides the standard hard hat, hi-visibility vest, gloves, glasses and safety boots required on sites there may be a requirement for hearing protection or specialist goggles for higher risk activities.

For example, when using an angle grinder to cut steel reinforcement, higher impact safety goggles will be required to reduce chances of damage to operatives eyes.

Is there a safe space to store PPE?

4. Fall Arrest system - a safety mechanism designed to protect workers from falling while working at heights, typically using harnesses and anchorage points.

As construction of the superstructure has risk of working on leading edges where there is a potential of falling from height these are essential.

Definitions

Construction Phase Plan (CPP) - according to the Health and Safety Executive (HSE): A CPP must be prepared by the principal contractor before the construction phase of a project begins. It must outline the health and safety arrangements, site rules and specific measures concerning any work involving the risks listed in the CDM Regulations

CDM Regulations - Construction Design and Management Regulations which aim to ensure health, safety, and risk management in UK construction projects, involving all stakeholders

Health and Safety Executive (HSE) - Britain's national regulator for workplace health and safety

Plant - Construction plant refers to machinery and equipment used in projects for tasks like excavation, lifting, and material handling

Self-compacting concrete - has the ability to flow and compact itself under its own weight without the need for external vibration. This unique property makes it highly advantageous in situations where traditional concrete placement methods might be difficult or impractical.

Compressive Strength - the ability of a material to withstand compressive or crushing forces without collapsing or undergoing significant deformation. Measured in kN/m squared

Tensile strength - the ability of a material to withstand stretching or pulling forces without breaking or undergoing permanent deformation. Measured in kN/m squared

Setting out - process of establishing position and level of an element of a project physically on site, references usually taken from drawings.

Site Control - is established by setting control points. These are points on the ground or any permanent structure whose horizontal and vertical position is known.

Posts to Follow

We plan to go into more details on Superstructure and add sections on:

Temporary Works
Build Sequence
Health, Safety & Environment
Quality
Programme
Commercial

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Basit Haq

Superstructure Logistics

Types of Superstructure

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