Timber EN 1995 Benchmark 6

Project file: Benchmark_Timber_EN_6.esa

SCIA Engineer Version 19.1

Introduction

This benchmark concerns Example 6.7.1 of Structural Timber Design to Eurocode 5, J. Porteous, A. Kermani, Blackwell Publishing Ltd, 2007.

A series of glulam beams 115 mm wide by 560 mm deep with an effective span of 10.5 m is to be used in the construction of the roof of an exhibition hall.

The roof comprises exterior tongued and grooved solid softwood decking exposed on the underside and covered on the top with insulation and a weather protective roof covering.

The decking will provide full lateral support to the beam but load sharing between the beams is assumed not to apply.

The beams are glulam strength class GL 24h to BS 1194:1999 and will function in service class 1 conditions. The bearing length at the end of each beam is 155 mm.

Assume that the limiting value for vertical deflection at the instantaneous condition is span/300 and at the net final condition is span/250, for the loading condition given below:

(a) determine the required pre-camber in each beam;

(b) confirm that the beams will comply with the design rules in EC5.

Beam loading:

Characteristic permanent vertical load on each beam 1.4 kN/m

Characteristic short-term variable vertical load on each beam 2.5 kN/m

Reference results

The reference gives the following results:

Bending Strength (middle)

Md = 88.25 kNm

sm,y,d = 14.68 N/mm²

kh = 1.1 (Incorrect !)

fm,y,d = 19.01 N/mm²

fm,y,d = 17.40 N/mm² (Corrected using correct kh of 1.007)

Shear Strength (end)

Vd = 33.62 kN

tv,d = 0.78 N/mm²

fv,d = 1.94 N/mm²

Beam deflection (middle)

uinst = 37.56 mm

winst = 35 mm (allowable)

unet,fin = 46.13 mm

wnet,fin = 42 mm (allowable)

SCIA Engineer results

Bending Strength (middle)

Shear Strength (end)

Beam deflection (middle)

Comments

The results correspond to the benchmark results.

Notes:

- The reference specifies a variable load of 2.5 kN/m but calculates with 2.75 kN/m. Therefore in Scia Engineer also 2.75 kN/m is used.

- The reference incorrectly calculates the depth factor kh as 1.1 however it should be 1.007

- The reference is based on the original version of the EN 1995-1-1. It thus does not yet include the crack factor kcr in the shear stress calculation.

- The reference is based on the original version of the EN 1995-1-1 while Scia Engineer uses the Amendment A1. In this Amendment the Check for Compression perpendicular to the grain was completely revised. Therefore the reference results regarding this item are not given.