Documento Básico SE-AE Seguridad Estructural: Acciones en la edificación – Spanish Building Code for Structural Actions
The Documento Básico SE-AE (Seguridad Estructural: Acciones en la edificación) is a statutory regulatory document issued by the Ministerio de Fomento of Spain. It forms a primary component of the Código Técnico de la Edificación (CTE), the national framework governing building standards and construction quality. Published in April 2009, this document establishes the technical requirements for determining the various actions (loads and forces) that must be considered during the structural design and calculation of buildings to satisfy the requirements of load-bearing capacity, stability, and serviceability.
The scope of this basic document encompasses the determination of actions affecting buildings within Spanish territory. It classifies actions into three primary categories: permanent actions, variable actions, and accidental actions. Regulatory domains include dead weight of structural and non-structural elements, ground pressure, use-related overloads, and climatic forces such as wind and snow. The text details specific procedures for residential, administrative, and commercial structures, while explicitly excluding elevators, cranes, silos, and storage tanks from its regulatory scope. It defines critical terminology such as Carga (gravity-based force), Esbeltez (slenderness ratio), and Periodo de retorno (return period).
Structured through multiple chapters and detailed annexes, the document provides characteristic values and calculation methods. These include Anejo C (compendium of weights for building materials), Anejo D (wind action parameters), and Anejo E (climatic data across Spanish provinces). Professionals utilize these standardized values to verify compliance with the overarching DB-SE structural safety requirements.
Permanent Actions and Dead Loads
Permanent actions consist of forces that remain constant throughout the life of the building. These primarily involve the self-weight of structural elements and fixed non-structural components.
- Peso propio (Self-weight): Calculations must account for structural members, enclosures, partitions, finishes, and fixed equipment such as boilers or cooling towers.
- Tabiquería (Partitions): For standard dwellings with partitions weighing less than 1.2 kN/m², a uniform equivalent load of 1.0 kN per square meter of constructed area is generally accepted.
- Pretensado (Prestressing): Actions derived from prestressing are evaluated according to the Instrucción EHE standards.
- Acciones del terreno (Ground actions): Forces exerted by soil pressure or displacements are treated under the specific DB-SE-C regulations.
Sobrecarga de Uso (Live Loads)
Variable actions related to usage represent the weight of mobile elements, including people, furniture, and vehicles. These are simulated as uniform distributed loads or concentrated loads acting locally.
- Category A (Residential): Requires a uniform load of 2 kN/m² and a concentrated load of 2 kN.
- Category C3 (Public Access Areas): Zones such as lobbies in public buildings require a higher uniform load of 5 kN/m².
- Balconies: Cantilevered balconies must be calculated based on their use category plus a linear horizontal load of 2 kN/m at the edges.
- Reduction Coefficients: Loads on vertical elements like columns or horizontal elements with large tributary areas can be reduced using coefficients provided in Tabla 3.2.
Acción del Viento (Wind Actions)
The wind action is calculated as a static pressure perpendicular to the exposed surfaces. This regulation applies to buildings at altitudes below 2,000 meters and with a slenderness ratio of 6 or less.
- Presión dinámica (Dynamic pressure): A simplified value of 0.5 kN/m² can be used across the Spanish territory, though Anejo D provides specific values for zones A, B, and C.
- Coeficiente de exposición (Exposure coefficient): This factor varies based on the height of the point and the roughness of the environment (Grades I to V).
- Coeficiente eólico (Pressure coefficient): Depends on building shape, orientation, and surface permeability. Negative values indicate suction forces.
Climatic Loads and Accidental Actions
Snow loads and accidental forces such as impacts or fires are regulated to prevent catastrophic failure or loss of stability during exceptional events.
- Nieve (Snow): On flat roofs of buildings under 1,000 meters altitude, a minimum load of 1.0 kN/m² is required. Specific provincial values are listed in Tabla 3.8 (e.g., Madrid: 0.6 kN/m², Burgos: 0.6 kN/m²).
- Impacto (Impact): Vehicle impacts in garages or transit areas must consider static equivalent forces of 50 kN parallel to the path and 25 kN perpendicular.
- Incendio (Fire): Thermal actions from fire are defined by DB-SI, but structural actions for firefighting vehicle zones must support 20 kN/m² over a specific surface area.
Frequently Asked Questions
What is the standard snow load for a building in Madrid?
According to Table 3.8 in the DB SE-AE, the characteristic snow load for the capital of Madrid is 0.6 kN/m².
What horizontal force must railings and terraces resist?
For residential use (Category A), the required horizontal force is 0.8 kN/m, whereas for public assembly zones (Category C5), it increases to 3.0 kN/m.
Is there a minimum load for flat roofs at low altitudes?
Yes, for flat roofs at altitudes below 1,000 meters, the document prescribes a minimum snow load of 1.0 kN/m².
How is the dead weight of typical partition walls calculated in dwellings?
A uniform equivalent load of 1.0 kN per square meter of constructed surface is generally sufficient for standard partitions in residential units.
Does this document apply to buildings above 2,000 meters altitude?
The provisions for wind actions in this document are not applicable to buildings located at altitudes exceeding 2,000 meters; such cases require empirical data.
What are the weight values for reinforced concrete and steel?
Anejo C specifies a specific weight of 24.0 kN/m³ for normal concrete (increasing by 1 kN/m³ if reinforced) and 77.0 to 78.5 kN/m³ for steel.
