Eurocode 5 Masterclass: Dive Deep into Timber Design with RFEM 6!

The presenter welcomes learners to the course on timber structures per EC5 in RFEM 6, outlining modules from basic calculations to stress verification, stability, and SLS deformation. He notes free downloads of the training materials and models, a course certificate on completion, and a free 90 day RFEM 6 trial.

The presenter outlines the course PDF and 5 modules, then EC5 parts 1-1 and 1-2, ULS, SLS with a vibration analysis using the dynamic add-on, and fire resistance. He compares the timber design add-on (RFEM and RSTAB) with the multi-layer surfaces add-on (RFEM only), ending on a customer projects slide with trusses.

Explains timber's orthotropic behaviour, shrinkage and swelling, and rolling shear, where GYZ is only about 10% of the shear modulus, with a gamma M of 1.3. Hooke's law with E-modulus 11,000 and G modulus 690 gives around 7, far above 0.5, so beams keep E and G while surfaces take Poisson's ratio 2.52.

Creates a new model named example one in 3D with solids and the load wizards off, showing the timber design standard groups and national annexes before deactivating them again. Opens new rectangular surface with a 20 centimetre thickness and a user defined S235 material, E-modulus 11,000 and Poisson's ratio 0.1.

Models a 4 by 2 metre surface with line supports on three sides, fixed in Z with small spring constants in X and Y to avoid kinematic issues. Applies a uniform 20 kilonewton per square metre surface load in Z, then deactivates self-weight since the steel surface's self-weight is high.

Copies the surface model twice with a 3 metre Y direction displacement including loading, then edits both copies to an orthotropic C24 material with Poisson's ratio 2.52. Rotates the third surface's specific axes by 90 degrees so its stiffness direction differs from the second, shown in the display navigator.

Calculates the one load case and divides lines with N intermediate nodes to read nodal displacements at the same spot. These give 4.3 millimetres isotropic, around double orthotropic and almost 50 millimetres with the wrong stiffness direction, while moments around the X axis are biggest in the middle surface.

Covers Eurocode 5's creeping factor K-Def: 0.6 for moisture class one, 0.8 for class two, 2.0 for class three, raising the load by 1.6 in class one to approximate creep. Notes pre-camber suits time dependent analysis but not rare situations, then opens RFEM to model a continuous beam.

Builds a two field GL 28C beam, 180 by 260 millimetres, spanning 4 and 5 metres, in a model named example two with the timber design and modal analysis add-ons under the German annex and K-Def 0.6. Assigns nodal supports at both ends and the middle node, applying a uniform 2 kilonewton per metre load to both members.

Adds two imposed load cases with a member load of five per field, then creates a member set from both members with design properties ticked. Sets effective lengths with buckling off and Mcr by the analytical method, and reviews the ULS, SLS and fire resistance configurations, exposing only the bottom side.

Creates a design support, 240 millimetres, Z axis only, KC 90 factor 1 for glued laminated softwood, assigned to the start, end and middle node, with deflection checked over the 4, 5 and 9 metre lengths. Adds an accidental design situation on first order theory with no imperfections, then reviews the load combinations.

Runs the calculation for five design situations: the stability design is fulfilled and the design support effective length is 270 millimetres at the member start, 300 at the inner support. A 2 kilonewton nodal load in Y and fire design then give 101% utilization, and fire design is fulfilled with a reduced section.

Switches Mcr for the member set to the eigenvalue method with an intermediate node and eccentricity at the upper flange, keeping the design ratio. Combination 21 copies combination 9 but reduces stiffness with a factor of 0.625 instead of raising the load, giving the same 30.5 millimetres in Y, 12 and 4.8 in Z.

Creates a vibration design situation with 100% self-weight plus 30% of load case three, then clears a Y overload via deflection settings, leaving about 14% overload. The Hamm-Richter diagram checks frequency against a limit, 6 hertz for single-family homes, then a 2 kilonewton force against the 1 millimetre limit.

Divides the longer member with an intermediate node, then runs load case four for modal analysis, masses from combination 22, giving a 6.8 hertz frequency against the 6 hertz limit. Load case five applies the 2 kilonewton force, landing just over the one millimetre limit, with results showing buckling out of the plane.

Models a 15 metre curved arc member in RFEM 6, 2.4 metres high, with a 14 by 60 centimetre GL28 section, a fixed X rotation support, and a 2 kilonewton per metre wind load for kmod one. Deleting the SLS situations and setting first order theory, the low moment shows lateral torsional buckling is not needed.

Sets effective lengths on the curved beam in RFEM 6: 1.25 buckling factor from the German annex, 1.0 for lateral torsional buckling, destabilizing load position. Timber design shows almost 90 percent overloading, the 16 metre length raised by 1.25 as equivalent member length; formulas can go into the printout report.

The curved member's 16 metre length in RFEM 6 gives a 20 metre equivalent length under the destabilizing effect, and the stabilizing edge with a 0.5 reduction reaches only 15.7 metres. An intermediate support via the eigenvalue method with factor 1.25 fulfills the design, shown as warping in the results navigator.

Models an 18 metre GL28 roof truss in RFEM 6 on the XZ workplane, with a saddle section distribution from 180 by 360 millimetres to 180 millimetres by 2 metres at 50 percent. Adds a support fixed except Y rotation plus a movable one and a 5 kilonewton per metre load, then sets the load case to wind for kmod one.

Calculates self-weight in RFEM 6: 24.2 millimetre deformation, bending moment almost 250. A support in Y direction clears the 26 percent lateral torsional buckling overload, shear then almost 96 percent. Stress point one has a 10 degree cut to grain angle, strength reduced by factor 0.69, then the eigenvalue method.

Activates timber design and structure stability in the add-ons, then sets the German annex. A 5 metre C24 column of 140 by 200 millimetres gets a support clamped around the X direction. Self weight and wind add a 10 kilonewton nodal load in Z and a 1 kilonewton per metre member load in X.

In the member's Design Types tab, disables lateral torsional buckling and sets a beta factor of 2, then keeps only ULS design situations by 1st order theory. The Timber Design table, filtered to utilizations past 20 percent, confirms an equivalent member length of 10 metres against the 5 metre member.

Activates Calculate critical load, left linear with four lowest eigenvalues. A copy of load combination 2 goes to a new design situation, ULS without equivalent, calculated by 2nd order theory with a buckling mode imperfection. Its magnitude, analytical length over 200, updates when the node moves to minus 7 metres.

The structure table gives combination 5 a critical load factor of 4.86 and 50 kilonewtons critical load in Y, so the structure is stable. Bending is near the 4.69 of combination 2, but its zero out of plane moment is not zero here. Deactivating effective lengths skips buckling verification and slightly raises stress.

Opens Example 6 in RFEM 6, using the Display navigator to show dimensions and grid on a 20 by 14 by 5.8 metre hall with 5 axes on 5 metre spacing. A load transfer surface is then edited to show its kilonewtons per square metre wind load passed to the main beams as a member load via the Load transfer tab.

The Settings and options tab activates member representatives, shown in the Display navigator as coloured squares grouping identical members. Edit member representative holds effective length type 2 with lateral torsional buckling for the top girder, serviceability and fire resistance for the bottom one.

With all design situations active, show results runs on the timber design table and selected objects only filters it to one member representative. Fire resistance on the 14 by 14 centimetre columns is not fulfilled with the reduced section, and deactivating the ULS and fire resistance filters leaves the deflection.

The existing printout report is edited in the Printout report manager with model location, effective lengths, service class and design situations, plus 0.5 in the design ratios filter to drop results under 50% utilization. Multiprint then inserts several images and Insert PDF appends a course materials page.