A roof structure is suitable for a suspended KBK crane system if the load-bearing capacity of the structure is sufficient to absorb the static and dynamic loads of the system. This does not automatically apply to every roof structure: steel structures generally offer more possibilities than lighter roof structures made of wood or concrete. The questions below help you assess step by step what is needed.
What load does a suspended KBK system place on the roof structure?
A suspended KBK crane system places both static and dynamic loads on the roof structure. The static load consists of the dead weight of the crane system itself, including rails, trolley, and any drive unit. The dynamic load arises during use: lifting a load, moving the trolley, and braking movements significantly increase the forces on the suspension points.
In addition to the vertical forces from the weight of the load, horizontal forces also play a role. When a load is lifted or the trolley brakes abruptly, oscillations occur that exert lateral forces on the suspension points. When dimensioning a suspended crane system, these dynamic factors are taken into account through calculated amplification factors, so that the actual load on the structure is never underestimated.
The lifting capacity of the KBK system is a determining factor: a system with a capacity of 500 kg requires a substantially different roof load than a system with a capacity of 2,000 kg. In addition, the weight of the runway structure itself must be taken into account, which can be considerable depending on the span and the profile.
Which roof structures are suitable for a suspended crane system?
Steel roof structures with sufficient profile weight are the most suitable for a suspended crane system. Steel allows targeted suspension points on beams and trusses, and the load-bearing capacity can be calculated accurately. Concrete roof structures can in principle also be suitable, provided the reinforcement and the quality of the concrete allow this and suspension points are professionally installed.
Light roof structures made of wood or sandwich panels are in most cases unsuitable as a direct suspension structure for a KBK system. These structures are designed for roof and wind loads, not for the concentrated point loads that a suspended crane system causes. In such situations, a freestanding steel structure that is independent of the roof structure is often the appropriate solution.
Decisive is not only the material, but also the age and condition of the structure. An ageing steel structure with corrosion or previous modifications always requires a current assessment by a structural engineer, even if the structure appears robust enough at first glance.
How is the load-bearing capacity of a roof structure determined?
The load-bearing capacity of a roof structure is determined by a structural calculation, carried out by a certified structural engineer. This involves analysing the existing construction drawings, the steel type used, the profile dimensions, and the current load situation. Based on this, it is calculated how much additional load the structure can absorb at specific suspension points.
If construction drawings are no longer available, an on-site visual inspection is necessary. A structural engineer then measures the profiles, assesses the connections, and establishes which steel type was used. In some cases, material samples are taken to verify the strength.
In addition to the load-bearing capacity of the structure itself, deflection is also assessed. A roof structure that is strong enough to carry the load may still be unsuitable if the deflection under load is too great. Excessive deflection affects the travel performance of the trolley and can over time cause damage to both the crane system and the roof structure.
What if the roof structure cannot handle the load?
If the roof structure cannot handle the load of a suspended KBK crane system, several solutions are possible. The most commonly applied solution is placing a freestanding steel structure that carries the crane runway without loading the roof structure. These columns stand on the floor and carry the crane rails entirely independently.
Another option is to reinforce the existing roof structure. This can be done by adding extra beams, strengthening existing profiles, or distributing the suspension points over a larger area so that the point load decreases. Whether reinforcement is feasible and cost-effective depends on the specific situation and always requires a structural assessment.
In some cases, a modification to the crane system itself leads to a solution. By choosing a lighter KBK profile, a smaller span, or a lower lifting capacity, the total load on the roof structure decreases. This does require that the adjusted specifications still meet the operational requirements of the company.
What information does a crane builder need to assess suitability?
A crane builder needs concrete technical information to assess whether a roof structure is suitable for a suspended KBK crane system. The more complete this information, the more accurate the assessment and the faster the process from design to realisation.
- Construction drawings of the roof structure: including profile dimensions, steel type, and spans
- Structural calculations: if available, they provide direct insight into the remaining load-bearing capacity
- Required lifting capacity: the maximum load the KBK system must be able to lift
- Work area and span: the desired travel length and width of the crane system
- Usage frequency: how intensively the system is used determines the duty class and thus the dynamic load factors
- Clear height below the roof structure: relevant for the installation height of the system and the available hook height
- Current condition of the structure: any previous modifications, corrosion, or damage
With this data, a crane builder can make an initial technical assessment and determine whether additional structural engineering advice is needed. When in doubt about the load-bearing capacity, an on-site inspection is always the most reliable step.
How we help with the assessment of your roof structure
At BKRS we guide the entire process, from the initial technical assessment to the final installation and commissioning of your KBK crane system. We work with a single dedicated point of contact who handles coordination, planning, and communication for you, so you lose no time on alignment between different parties.
- Technical pre-assessment: based on your construction drawings and specifications, we assess the feasibility of a suspended crane system
- Custom design: our design office designs a KBK system that precisely matches your roof structure and operational requirements
- Structural engineering advice: where necessary, we engage certified structural engineers for a full load-bearing capacity calculation
- Alternative solutions: if your roof structure cannot handle the load, we actively think along about freestanding structures or system modifications
- Installation, inspection, and maintenance: we handle the complete realisation including annual inspection and maintenance
Would you like to know whether your roof structure is suitable for a suspended KBK crane system? View our services or contact us directly contact us for a no-obligation consultation.
Frequently Asked Questions
How long does the process from assessment to installation of a suspended KBK system take?
The lead time depends on the availability of construction drawings and the complexity of the roof structure. If all technical information is immediately available, an initial assessment can take place quickly. With additional structural engineering research or a custom design, the process takes longer.
Do I need to engage a structural engineer myself before contacting a crane builder?
That is not necessary. A specialised crane builder such as BKRS can carry out an initial technical pre-assessment based on your construction drawings and specifications. Only if there is reason to do so will a certified structural engineer be engaged for a full load-bearing capacity calculation.
What are the most common mistakes when installing a suspended crane system?
A common mistake is underestimating the dynamic loads, causing the roof structure to appear sufficient on paper but becoming overloaded in practice. Another common mistake is suspending the system from roof elements that are not designed for this, such as sandwich panels or purlins, without additional reinforcements.
Can a suspended KBK system be expanded or modified later?
Yes, KBK systems are modularly constructed and can in many cases be expanded. However, every modification requires a renewed assessment of the roof structure, because a higher capacity or larger span also changes the load on the suspension points.