Eurocodes are a method for detecting static systems. The effects calculated according to Eurocode 0 and Eurocode 1 are compared with the resistances determined according to the material-dependent Eurocodes 2 to 9.
The DGUV Regulation 115-002 ("Staging and production facilities for the entertainment industry", formerly BGV C1) refers in §4 to DIN 56950-1 Event technology - Mechanical equipment - Safety requirements and tests for the design of superstructures (such as ceiling elements and truss constructions).
Likewise, the DGUV information 215-313 ("Overhead Loads - Safety for events and productions", formerly BGI 810-3) refers to DIN 56950.
DIN 56950-1 refers to Eurocodes 3, 4 and 9. The trusses to be classified as lifting accessories and the suspension points to be classified as load handling devices belong to the mechanical equipment and thus to the content of DIN 56950.
Due to the references and classification of trusses and suspension points, the Eurocodes are considered to be state of the art for the design of these systems.
Eurocodes are a unified European system for the calculation of static systems.
The special feature of these Eurocodes is the new partial safety concept compared to previous standards. In contrast to nominal voltage concepts, the Eurocode basically distinguishes between load effects and resistances. There are safety factors both on the load side and on the resistance side.
Load effects comprise all effects acting on the structure. An example of an load effect is e.g., a force or an imperfection. Resistances counteract load effects and result from the cross-sectional and material properties.
Partial safety coefficients on both sides are used, for example, to absorb dispersions of material properties, imperfections or load sizes.
The advantage of the Eurocodes is, among other things, that the load effects are determined independently of the material. For both steel construction (EC3) and aluminum construction (EC9) load effects are determined in the same way. Only on the resistance side does the procedure differ: For steel structures, the load effects against resistance of the cross-sections are determined in accordance with EC3, for aluminum buildings in accordance with EC9.
All loads are regarded as being at rest. This means that dynamic actions (acceleration, braking, swinging) are neglected as long as they are negligible.
If non-negligible dynamic load effects occur, they must be taken into account via additional partial safety factors (for example, by "factor all loads" or load combinations) or additional loads.
Dynamic load effects occur in particular when truss systems are moved using motors (hoists) at high speeds and accelerations.
Each load is classified according to its nature either as a permanent or as a variable effect.
| Constant effects | Variable effects | |
|---|---|---|
| Classification | The loads are constantly present during the service life of the structure | The loads are not constantly present during the service life of the structure |
| Formula characters | Gk | Qk |
| Examples | Dead weight, soil loads, ground movements | Payload, snow loads, ice loads, wind loads, temperature fluctuations |
| Partial safety coefficient | unfavorable - 1,35 favorable - 1 | unfavorable - 1,5 favorable - 0 |
The partial safety coefficient designated "unfavourable" in each case is to be be applied if a load negatively stresses (loads) a supporting structure. The partial safety coefficients designated 'favourable' shall be used if a load supports or stabilises a structure.
Accordingly, a favourable effect must not be included in the calculation (factor 0) if it is not permanent and is not to be included in the calculation with an additional factor (factor 1) if the effect is constantly present over time. This ensures that supporting or stabilizing loads do not cause a low load on the structure.
In the case of unfavorable effects, the load-increasing factors are provided, for example, to take into account uncertainties of the load variables.
Eurocode 0 distinguishes between two different protection objectives. These are:
| Load-bearing Capacity | Serviceability | |
|---|---|---|
| Standard | DIN EN 1990 3.3 | DIN EN 1990 3.4 |
| Protection objective | Safety of functions Safety of the structure | Function of the supporting structure User well-being Appearance of the structure |
| Investigation | Loss of positional safety Failure due to excessive deformation Transition of the structure into a kinematic state Break Unstable condition | Deformation Vibration Damage |
| Description | The determination of load-bearing capacity should exclude any failure of the structure. It is therefore a "hard" criterion and protects not only the supporting structure but especially also persons underneath. | Serviceability serves the well-being of the user and to ensure functionality. It is therefore more of a "soft" criterion. Care should be taken to ensure that the user feels safe under strongly curved or oscillating structures (even if they may not fail). In addition, a deformed structure can impair functions, e.g., of rail systems. |
| Calculation and reference values | The reference values for determination of load-bearing capacity are the resistances of the cross-sections and materials used. - cables are determined with respect to maximum normal force - pipes are determined with respect to yield strength - trusses are determined with respect to the characteristic maximum forces according to the manufacturer's specifications (maximum bending moments, as well as belt and bracing forces) - for further information on determination see =>cross-section utilization | As a rule, serviceability exists if the deflection of truss sections does not exceed l/200 or l/300. This means that greater deflection is permitted for longer truss sections than for shorter ones, reflecting the resulting appearance and curvature. Serviceability must be considered and assessed by the user. |