Timber structure has been present in hundred of historic building in urban centers in Spain. It was common to use timber structural floors, timber framework with clay or other filler, and structural roofs. But, in the last century the use of structural timber was declining, for different reason, e.g.: the lack of regular supply of wood specially the last 50 years; fast development of other materials like steel or reinforced concrete; shortage an official building norm to regulate calculation of timber structure.
In the last decade this situation has changed with the introduction of the key Eurocode for the design of timber structures, [EN 1995-1-1](called Eurocode 5) and since three years ago with the introduction of a new Spanish Building Regulation (Código Técnico de la Edificación – CTE) with a specific part for design timber structures (Documento básico de Seguridad Estructural – Madera).
CTE is subdivided into a series of documents including timber structure design. Calculation of timber structure is included in document Structural Safety-Timber (Documento básico Seguridad Estructural,Madera[DB-SE-M]). According to Eurocode 5, this document determined mechanical properties (e.g. strength properties, modulus of elasticity and density), design material parameters (e.g. kmod), assigned three service classes (Service class 1, 2, and 3, to take into account the moisture content in the timber and wood-based materials) and to take into account the influence of load duration on strength, load shall be assigned to one of the five load-duration classes. Structural timber design with regulation described before is guaranteed with different modern solid timber products and wood-based products in Spanish market. Serviceability limit states is another part in DB-SE-M, mean stiffness values are used directly to obtain the best estimates of expected deformation. The most notorious structural serviceability problems in timber buildings are excessive vibration motions caused by activities of people and operation of equipment. Modal stiffness to modal mass is insufficiently high, or deformation constraints inadequate. Modern multi-storey building should be effective solutions involve combinations of selection of construction details and use of other adequate materials.
Mixed Residential and day centre for elderly
Urbanism Public Company (Empresa Municipal d’Urbanisme de Lleida, SL) is developer of a mix-use building with sustainable parameters in the historic centre of Lleida (Catalonia). The project building is a 3086.59 m2, divided 2 underground, ground floor and 4 floors of flats. The ground floor will have a day centre for seniors, 22 apartments and 32 parking spaces. Apartments will have 1, 2 and 3 bedroom, from 40 m2 to 48 m2. The ground floor project has 500 m2 and it will have different areas, a dining room, laundry services, rehabilitation rooms and living room.
Floor plan Cross-section plan
Reinforced concrete will be used in foundations, parking walls and the first floor slab. The others structural walls, floors and roof will build with cross-laminated timber. Box elevator will have independent cross-laminated panel separated 2 cm from structural building walls. The construction system helps to reduce the execution time of the work and reduce environmental impact. All vertical panels for walls are similar with a thickness of 94 cm. The union of the girders with vertical panels will do with screws. All of timber member will have biocide treatment. The connection between reinforced concrete plate with panel will do with lag screw and adds a neoprene membrane of 20 mm thick. Façade will have ventilated. Fire resistance is REI 60 minutes for all structure and REI 120 minutes for slab parking. Lateral wall will have 4 cm of rockwool. The ideal relative humidity for the product remains well is 40% to 60% (ideal comfort).
Location: Lleida (Catalonia), Spain; Architect: Puigdemasa Arquitectes SLP; Architect and Structural designer: Miguel Nevado; Maximum high façade: 15.72 m; High ground floor: 3.93m; High minimum floors: 2.50 m; Project: 2009 Completion: No date
Apartments building in Barcelona
This project is a multi-storey apartment building with timber structure. The front of plot is 5.90 m wide and 20 m lengthwise, between two buildings. The architectural project has a total of 579.96 m2. The ground floor will have a commercial premise and four floors of flats. The first two floors have two bedrooms with 78.6 m2 and the third and fourth floor are duplex with four bedrooms.
Floor plan Cross-section plan Wind load and stiffness analysis
Panels of cross-laminated timber will use to structural walls, slab floors and roof from second level to the top level.
Location: Barcelona (Catalonia), Spain; Architect: Carlos Narváez; Architect and Structural designer: Miguel Nevado; Maximum high façade: 18.03 m; Project: 2009; Completion: No date
Abstract of paper “Analysis of Structural Timber System for Multi-Storey Building in Spain” presented by Rodriguez V., INCAFUST’s researcher at World Conference on Timber Engineering. Riva del Garda, Italia. 2010