Technical information EL RANCHO

Technical information EL RANCHO

Wooden frame:
All wooden EL RANCHO tent frames come with an 100 millimetre round wooden frame.
Earlier this year, we decided to have a new construction calculation drawn up by the engineering consultancy firm TenTech. This showed that for a construction with 100 millimetre-thick round wood, each tent is guaranteed to withstand at least wind force 8 and a 10-centimetre snow load.
That makes us unique, because we are the first to decide to change the construction to 100 millimetre-thick round wood without any added charges.
Furthermore, we will now be including a certificate with each tent.
The new construction calculation will be implemented in 2016.

1.

Introduction

In this memo the maximum wind and snow load are calculated at which the strenght and stability are sufficient for the construction of an EL RANCHO.

2.

Assumptions

2.1.

Description

The EL RANCHO consists of an inner and outer tent which is tensioned in a frame of circular wooden beams and steel connection elements.

2.2.

Geometry

2.3.

Materials and cross sections

2.3.1

Innertent:

• Material
  Tencate solair
• Type
  VA-46
• Weight
  420 g/m2
• Tensile strenght [N/5cm]
  1600/1200 (ketting/inslag)

2.3.2

Outertent:

• Material
  Heytex
• Type
  5671
• Weight
  650 g/m2
• Tensile strenght [N/5cm]
  2500/2500 (ketting/inslag)

2.3.3

Beams:

• Material
  rondhout
• Class
  C24
• Diameter
  ⌀100mm

2.4.

Applied codes and standards

The following Eurocodes are applied:

• • NEN-EN 133782
  • NEN-EN 1990
  • NEN-EN 1991-1-4
  • NEN-EN 1991-1-3
  • NEN-EN 1991-1-1
• Temporary contructions – Tents – Safety.
  Basic of structural design.
  General actions on structures – Wind.
  General actions on structures – Snow.
  Design and calculation of steel structures.

2.4.1

Load combinations

2.4.1.1

Fundamental – Ultimate limit state
For the verification on strenght/connection of the elements.

	One variabel load	Multiple variabel load
Unfavorable permanent load	1.35 x G + 1.5 x Q	1.35 x G + ∑ 1.35 x Q1
Favorable permanent load	1.0 x G + 1.5 x Q	1.0 x G + ∑ 1.0 x Q1

This means the following load combinations are calculated and checked
1. 1.0 x EG + 1.5 x Wind load
2. 1.35 x EG + 1.5 x Snow load

3.

Results

Wooden beams:
No wood strenght class is known, therefore the assumption of strenght class C24 is to be verified.

Maximum wind load:
The structure can be loaded with a maximum wind load of 0.25 kN/m2, which is in the reach of Beaufort scale 8. Therefore the strenght and stability ca be secured to Beaufort 7.

Maximum snow load:
A maximum snow load of S=0.22kN/m2 can be applied on the structure, which corrsponds to 22kg/m2 or about 10cm of fresh snow.

Normative section:
The wooden beams are normative for strenght of the construction. A reletively slender section on a large span combined with point loads from the innertent.

Anchorage / Verification of ground structure:
In this stage no checks have been done for the anchorage and connections of the ground structure, as well as the connections between the wooden beams. Also the satbility of the structure against sliding, lifting and overturning should be checked.

End coupling:
Our years of experience in building various tents have shown that the ratchets in
the end couplings installed in the wooden frame can come loose after a certain
period of time. The result is that the ends of the pinewood trusses can tear after
some time due to weather conditions. This can cause the ratchet to come loose and
go through the roof in the event of a strong gust of wind. After this information
came to light, we came up with a new end coupling to prevent this from happening
in the future. Our solution: a steel galvanised pipe joint which is slid over the
wooden frame. This clever new construction, specially designed to better secure
the ratchet, will prevent the ratchet from coming loose over the years. This provides better securing for the roof against strong winds and storms.
this special new end coupling comes as standard with each EL RANCHO.

Roof tensioning:

The roof of the traditional EL RANCHO tent is tensioned at the front with a tied rope. In our experience, this is not a sustainable solution for the long term. We have come up with a solution for this without a point load per tied grommet: we can tension any roof with a pole sleeve. The image shows how it works.
ofcourse we can explain this in further detail in a personal meeting.