THE NATIONAL RIBAT UNIVERSITY

Eng. Mazin Elsayed A. Mustafa

Teaching Assistant

Faculty of Architecture

“THE TENTS STRUCTURE SYSTEM”

CONTENTS :

1. Introduction.

2. Definition of the Tent Structure System.

3. Why tensile (Tent) are the shape they are ?

4. Types of Tents Fabric Structures.5. Components & Materials.

6. Advantages & Disadvantages.

• Tensile fabric structures have been with us since the Mongolians swept

down from the plains, with their yurts as their transportable overnight

accommodation.

• There’s evidence that the Romans even covered the Colosseum with

massive canopies, hoisted by an intricate system of pulleys, to protect the

audience from the elements.

• They really came into their own in the last half of the 20th century, when

designs like this by Germany’s Frei Otto.

Introduction :

Definition of the Tent Structure System:

• A Membrane is a thin, flexible surface that carries loads primarily through the

development of tension forces.

• Holding a stress tension force.

• Provide strong lighting features.

• Desert architecture identity, inspired from ten design and geometry.

((Net structures are conceptually similar; expect that their surfaces are made from cable net meshes.))

Jeddah Sports Hall, Jeddah,

Saudi Arabia, Frei Otto

* There are several ways of stabilizing a membrane or net surface:

1.An inner rigid supporting framework.

2.Restressing the surface by:

a. External force (Tents)b. Internal pressurization (Pneumatic structure).

DENVER INTERNATIONAL AIRPORTCHICAGO’S NAVY PIER

• Fabric structures cannot take heavy weather conditions is an incorrect statement.

• Fabric is elastic and stretches. Fabric has a strong tensile strength and will creep (stretch very

slightly) only a few percent over 20 years of use.

Common Misconceptions:

Why tensile (Tent) are the shape they are ?

•Large flat pieces of fabric are very poor at resisting loads.

•Imagine four of you each pulling on the strings laced through a tennis ball.

Fig 1. A fifth person pushing down on the ball can deflect it easily.

•Imagine a flappy marquee roof. Try lifting two opposite strings and lowering the other two.

Fig 2. The ball is now locked in space. Apply this principle to fabric and you have created

‘anticlastic’ double curvature

Fig. 1 Fig. 2

1. Saddle roof

2. Mast supported

3. Arch supported

4. Combinations

Types of Tents Fabric Structures:

1. `

• Four or more point system when the fabric is stretched

between a set of alternating high and low points

1. Saddle Roof

• The roof plan, taken

directly from the

structural engineering

working drawings,

illustrates the roof

configuration and its

components.

• The saddle-shaped roof of the stage cover nestles under the auditorium

roof of the project. The leaning A-frames and the stay cables which

hold them back are clearly visible, along with the radial cables which

shape the tent units. The corner tripods, each consisting of a vertical

mast and two sloping cables, are connected to concrete anchors rising

from the water.

Section through the project showing the

stage roof tucked under the auditorium

roof.

• Tent-like in appearance, mast supported structures typically

have one or sometimes several peaks that are supported by

either interior or perimeter masts.

• The fabric is attached to the interior mast by special connections, usually a bale

ring or cable loop.

• Mast-supported structures can also be supported by adjacent buildings. The

peaks of a mast supported structure are determined by the design and how the

fabric is attached.

• Openings are typically ovoid or elliptical. The fabric that

extends from the top of the opening is seamed and can

necessitate patterning.

• Mast supported systems are suitable

for long span roofs.

2. Mast Supported:

`

• Curved compression members are used as the main supporting elements and

cross arches are used for lateral stability.

• In a plane arch, large differences between the thrust lines and the main

geometry will produce large bending moments that in turn produce large

changes in shape and high stresses in the arch chord section. One method to

significantly reduce these effects is to tie or restrain points along the arch

chord to reduce the initial large deformations of the chord

• The buckling length of the arch chord can also be reduced by discretely or

continuously supporting the chord with tension elements or systems comprised

of cables or membranes.

• Typical arch shapes defined by physical

and ergonomic constraints.

3. Arch Supported Roof:

4. Combinations

• Combination of several support types.

Components & Materials:

Base plate:

• Connection to concrete foundation pillar

Membranes:

• Forms the enclosure of the structure. Connections can be glued or

heat welded

• PVC coated polyester (polyvinylchloride)

• Silicon coated glass

• Teflon coated glass P.T.F.E (poly tetra fluro ethylene)

Bale ring/ membrane plate:

Provide a link between the membrane and structural elements..

• Bale rings are used at the top of conical shapes.

• Membrane plates accept centenary cables and pin connection

hardware.

Types of fabric membrane:• PVC : Less expensive (15 to 20 year life span and easy to erect)• Silicon glass: Higher tensile Brittle (subject to damage from flexing 30+

year life span)

• Specialized Hardware:

Tripod head with centenary cables

Centenary cables at a side connection

Extruded section with membrane

plate and centenary cablesTensioner

• Cable clamps

Edge c able with c lamps. Used mainly for PTFE-coatedfiber glass fabric , but also for PVC coated poly ester fabricwhen edge spans are longer than 20 m.

• Bale rings are a good way to control stresses in fabric roofat high or low points. Used at high points they must becovered to make the structure watertight. If used at lowpoints, they can be used to gather rainwater and snowfor redistribution on site.

• Channel (with grommets) and lacing. Used with PVC-coated polyester fabric where the edge has grommets spaced at frequent intervals.

• Rope is laced through the grommets and to a tie rodwithin the channel.

Distribution of Pillars or Columns and Gridlines

Advantages Disadvantages

• Longer life cycles of materials.

• Materials can be re-used in form.

• Most materials are completely recyclable.

• Less impact on site.

• Less construction debris after demolition.

• Unique designs.

• Lightweight and flexible.

• Environmentally sensitive.

• High strength weight ratio.

• Little to no rigidity.

• Loss of tension is dangerous for stability.

• Thermal values limit use

• Load Transfer on Fabric Structures

• Attachment Weaknesses in Mono cover

Fabric Structures

Tents system design – shaped by Aluminum sections

Al-Masjid Al-Nabawy – Madina Monwra

THANK YOU …