In Spain, the Technical Building Code (CTE) is the regulatory framework that encompasses the basic quality requirements that building projects and their installations must meet to ensure regulatory compliance. Information related to railing systems, as they are a protection system against falls, can be found in the basic documents: DB-SUA, DB-SE-AE and DB-SE.
Constructive features
A fundamental aspect that influences the safety of railing systems is the construction characteristics, as stated in the DB-SUA, specifically in safety against the risk of falls. A railing will be considered a protective barrier whenever it protects a difference in height of 55 cm. It is established that protective barriers must have a minimum height of 900 mm when protecting a drop from 55 cm to 6 metres. From 6 metres onwards, the minimum height must be 1100 mm.
They must comply for residential use, homes, nursery schools, commercial, or public gatherings where children may be present, with the following conditions:
At a height between 30 and 50 cm, there should be no protrusions over 5 cm, and at a height between 50 and 80 cm, there should be no protrusions over 15 cm.
There should be no openings that a sphere of 10 cm in diameter can pass through, and the slope of the stair should not exceed 5 cm.
For uses other than those mentioned, it is only essential to comply with condition b) considering a sphere of 15 cm.
Actions on Railings: Limit States
The verification methods based on Limit States are established in the CTE:
Serviceability Limit States (SLS): These are the states that, if exceeded, affect the comfort and well-being of users or third parties, the correct functioning of the building, or the appearance of the construction.
Ultimate Limit States (ULS): These are the states that, if exceeded, pose a risk to people either because they result in the building being put out of service or in its total or partial collapse.
For the verification of the Serviceability Limit State (SLS), it is considered that there is appropriate behaviour concerning 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 that effect.
For railings, the CTE does not establish any limit value for deformation, so an SLS verification cannot be carried out. Therefore, the strength verification established in the CTE is for the ULS and by means of the partial safety coefficient.
Resistance checks
The Basic Document of Actions in Building DB-SE-AE defines the action on railings as a variable action, and these must withstand a uniformly distributed horizontal force, applied at 1.2 m in height or on the top edge of the element if it is at a lower height. In Table 3.3 Actions on railings and other dividing elements, the characteristic value of this horizontal force is defined in kN/m according to the usage category of the railing, which are defined in Table 3.1. Characteristic values of usage overloads.
To perform resistance verification with a variable action according to the CTE, it will be done using partial safety factors; this corresponds to a verification of ultimate limit states (ULS), as mentioned in the previous point.
These coefficients are defined in Table 4.1 Partial safety coefficients (γ) for the actions of the Basic Document on Structural Safety DB-SE.
For the railing case, the partial safety coefficient has a value of 1.5, which will be used to multiply the characteristic value of the previous table. Thus, if a railing is used in a concert hall, for example, it must withstand a horizontal force of 3 kN/m multiplied by 1.5, which means the railing must resist 4.5 kN/m. The same applies to the rest of the usage categories.
COMENZA railing systems are tested, according to the requirements of the CTE, to define the characteristics of their composition, such as the base or support, the glass, the anchoring, and the handrail, thus ensuring the safety of the end users, verifying that they pass static and dynamic load tests, using the resistance verification method with a variable action established by the CTE, through the application of the partial safety coefficient of 1.5. This is an indispensable requirement to ensure the maximum safety and regulatory compliance of a railing system.
Action of the wind
Another action to consider with railings when they are outdoors is the action of the wind. For local analysis of façade elements, Annex D. Wind action of the DB-SE-AE is used; this annex allows us to obtain the forces we would have at each point of the building. This action must always be considered outdoors, and indoors of buildings which have large gaps or openings.
This is important because we will have to consider the combination of actions where two hypotheses are proposed:
COMENZA's technical office provides bespoke services for each project, offering professionals support in the calculation of wind pressure review, in addition to the following services: project-adapted FEA simulations, railing anchorage study, BIM objects, or material certificates, among others.
Additional Guarantees: Tests of the UNE 85238-91 Standard
This is not a mandatory requirement; however, COMENZA railings are also tested according to this standard to provide extra assurance of the quality and safety of our systems.
The team of designers and engineers in the R&D department of COMENZA develops solutions that enable all our glass and stainless steel railing systems to be installed quickly and easily, while ensuring the safety of their users.
Our Technical Office collaborates daily with architectural studies and installers worldwide, accompanying them and providing technical support during all stages of their building projects. Thanks to this, we have specific and unique knowledge that allows us to swiftly find solutions that facilitate both the specification and installation of our systems. Do you need support in the development of your project? Contact our team here.