The CTE establishes as a method for checking the resistance of railing systems the verification of the Ultimate Limit State (ULS). Limit states are those states beyond which the structure no longer meets the project requirements. We distinguish two major groups:
- Serviceability limit states (SLS): These are the conditions that, if exceeded, affect the comfort and well-being of users or third parties, the proper functioning of the building or the appearance of the construction.
- Ultimate limit states (ULS): These are the conditions that, if exceeded, pose a risk to people, either because they result in the building being put out of service or its total or partial collapse.
For the Serviceability Limit State (SLS) verification, it is considered that there is appropriate behaviour, in relation to deformations, if it is met, for the relevant sizing situations, that the effect of the actions does not reach the admissible limit value established for said effect. For railings, the CTE does not establish any deformation limit value, so an SLS verification cannot be carried out. Therefore, the resistance verification established in the CTE is for the Ultimate Limit State (ULS) and through the partial safety factor.
Application of the Technical Building Code
As specified by the Technical Building Code (CTE) in its Basic Document on Structural Safety DB SE-AE regarding Actions in Building, railing systems must withstand a horizontal force with an established characteristic value. In Table 3.3 Actions on railings and other divisional elements, the characteristic value of this horizontal force is defined in kN/m according to the usage category of the railing:
The testing of actions on railings is established in the CTE, specifically in section 3.2 of the DB-SE-AE, where the verification of an ultimate limit state (ULS) is required, and not a serviceability limit state (SLS). Therefore, the verification of ultimate limit states (ULS), through the partial safety factor (1.5) for variable loads as the main load, is the method of resistance verification included in the current regulations.
It is often accepted that the serviceability limit state (SLS) is a valid check, but this would be incorrect. Resistance verifications by SLS are carried out through displacements, and currently, the CTE does not provide data to perform this verification. Thus, under the serviceability limit state, only the corresponding characteristic load would be applied with no method of resistance verification for the railing, and without this final step, compliance with regulations cannot be ensured.
To carry out a resistance verification of the railing, the CTE provides the partial safety factor for variable loads acting as the main load, which is the value of 1.5, and this would be a valid method of verification through the ultimate limit state (ULS).
To confirm the obligation of performing an ultimate limit state verification, one can consult both the blog of the Public Administrations Architects of Spain, an entity linked to the Superior Council of Architects of Spain, and the website of the General Council of Official Associations of Industrial Engineers, which addresses the inquiry made on this matter.
In which documents can it be verified that the railing has been tested according to these requirements?
In the tests provided by the manufacturer, all tests carried out by Comenza verify the ultimate limit state (ULS) using the load amplification factor of 1.5, and this can be verified in their tests available in the technical documentation section of each system.
The absence of a handrail strength check constitutes a breach of the CTE requirements.
Compliance and Safety of Comenza Railing Systems
At Comenza, we have made a fundamental commitment to the users of our railing systems. For this reason, our R&D department specialises in the development of industrialised and innovative railing systems that comply with building regulations and thus guarantee the required level of safety. Our railing systems are rigorously tested according to CTE requirements, using the only verification method with a variable action by applying a partial safety factor of 1.5. This is an essential requirement to ensure maximum safety and regulatory compliance of a railing system.
We have our own climate-controlled testing laboratory for carrying out both static and dynamic load tests, which allows us to launch products on the market that have been tested under the most demanding conditions. In addition, we work closely with the most prestigious international certification companies to ensure that our railing systems adapt to and comply with the specifications of the standards. Our technical office offers tailor-made services for each project, providing professionals with:
- FEM simulations adapted to the project.
- Study of the anchoring of the railing.
- Review of the wind static pressure.
- BIM objects or material certificates, among others.
If you need advice on your project or want to know more information about our systems, contact us via [email protected] or through our contact form. Let's get started!