sentd.01 - Timber design

The Timber design module offers an interactive, semi-automated tool for the design of timber structures according to EN 1995-1-1. Ultimate and serviceability verifications are available for solid and glue laminated timber.

Benefits

• Timber elements are designed within a graphical 3D modelling and design environment; their structural response and possible interaction with structure parts from other materials are captured accurately.
• Both linear and second-order analysis with initial imperfections may be used for the design; corrections to the material properties are taken into account depending on the chosen analysis type, as specified in the code.
• The design is in full compliance with Eurocode 5 and supported National Annexes. Additional NCCIs (non-contradictory local publications) have been implemented to widen the scope of the performed verifications.
• The computational performance of the Timber design benefits from multi-threading and efficiently written routines.
• Stress and stability verifications are performed in the ULS; section dimensions may be optimised to fulfil ULS criteria via a built-in optimisation routine.
• Buckling lengths may be determined automatically:
  • from the deformation response of the whole structure in the case of flexural buckling (compression),
  • according to Eurocode 5 for lateral-torsional buckling (bending), also considering your choices of point of load application (stabilising or destabilising load),
  • buckling factors for flexural buckling may be determined from stability analysis as well.
• Instantaneous and final deflections are controlled on the level of SLS, correctly taking creep into account.

Scope

• Verifications are supported for beam elements from solid timber and glulam timber; the elements (beams, columns, etc.) can be prismatic, curved or tapered.
• Timber classes are provided in the Material library: according to EN 338 for solid timber, and according to EN 14080 for glulam timber; users may extend materials with other timber classes.
• The Cross-section library contains standard shapes that can be used or adapted.
• When second-order analysis is performed, the stiffness of timber elements (E- and G-modulus) is automatically reduced according to chapter 2.2.2. of EN 1995-1-1;
• The following National Annexes are supported: Austria, Belgium, Czechia, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Romania, Slovakia, Slovenia, Sweden, United Kingdom.
• Along with the rules of EC5, the following NCCIs have been followed in order to extend the scope of the checks:
  • Structural timber design to Eurocode 5, Blackwell Publishing Ltd, 2007;
  • Handbook on structural timber design to Eurocode 5 rules including strength capacity tables for structural elements, Coford, 2006;
  • Design and perpendicular to grain tensile stress in double-tapered glulam beams, Wallin & Dalholm Digital AB, 2010.

Checks

Timber is a material whose strength and deformation are influenced by environmental conditions; this is something explicitly addressed in Eurocode 5. Modifications factors specified in the code are taken into account:

• kmod: modifies strength properties for moisture content depending on Service class and load duration;
• kh: depth factor, modifies strength to account for section size;
• ksys: strength correction factor that takes into account the combined action of equally spaced members, components or assembly that are connected by a continuous load distribution system (e.g., a floor).
• kdef: corrects stiffness and deflections for moisture content depending on the service class.

In the ultimate limit state, the following verifications are performed:

• Section checks: stress verifications for the present internal forces: tension, compression, bending, shear, torsion. Interaction checks are also performed, as specified in the code (for bending and compression) or in other publications (NCCIs) for double bending, shear and torsion, etc.
• Also, an extensive verification of compression perpendicular to the grain of the beams, with consideration of contact length and width.
• Stability checks: buckling failures are checked, such as flexural, torsional, torsional-flexural and lateral torsional buckling and combined compression and bending. Some of these checks can be skipped when 2nd order analysis with initial imperfections is performed.
• Buckling spans are managed independently from how the individual beams are split: a beam element may span multiple spans and a span may consist of multiple beams.
• SCIA Engineer is able to derive the buckling factors (buckling length vs span length) automatically from the deformation response of the structure and the stiffness of the member and members that connect to it.
• Special rules are supported for tapered beams according to 6.4.2.
• Special rules are supported for curved beams according to 6.4.3.

In the serviceability limit state, the following verifications are performed:

• instant deflections are controlled;
• final deflections are controlled: these are calculated using the deformation factor kdef to account for creep.

Report

The Timber design module benefits from an interactive reporting interface, where the results of the design are easily accessible in various forms:

• colour-coding utilisation diagrams in the 3D scene helps to quickly identify problems anywhere in the structure;
• the design outcome for all members is easily printable in table form via the Brief report or via Table Results.

Required modules:

• sen.00