ldb convergenze parallele_13

C o n v e r g e n z e p a r a l l e l e l a b o r a t o r i d a l b a s s o

Lecce / Brindisi - Mesagne, 10 -11 luglio 2013

Progettazione e realizzazione di una passerella in compositi (CF) Ricerca, sviluppo e progettazione interdisciplinare

Filippo Broggini arch.EPFL BlueOffice Architecture, Bellinzona (Suisse)

C. TSCB, twin shape composed beam

TSCB - TWIN SHAPE COMPOSED BEAM

Filippo Broggini BlueOffice Architecture (Bellinzona, Switzerland)

Architecture structural design Luca Diviani

University of Applied Sciences of Southern Switzerland (Manno, Switzerland) Study, design and material characterization

Study, develop and build a modular pedestrian bridge 18 m wide, characterized by a fast assembly-disassembly system

mc2012 : Matérialités Contemporaines; Lyon 30.11.2012

1.1 – THE IDEA Context

When using composite materials, smaller is the unit, lower are the costs involved in the production of the basic mold. Therefore, global production costs can be reduced by reducing the dimension of the unit and optimizing the assembly costs.

The basic idea is to produce a monocoque shell starting from the combination of identical spatial elements. The project aims at pushing the product beyond its usual shape by seeking new creative hints in the morphogenetic shapes found in diatoms, radiolars spatial elements.

1.2 - DESIGN Introduction

By observing micro-organisms like diatoms, the architect decomposes complex shapes into spatial iterations and complex symmetries laying out simple elements (modules) in space and generating more complex and expressive units.

1.2 - DESIGN Preliminary Concept

Initially the beam was thought just as a load-bearing element onto which some plates made of pultrused products (walking zone), the fixed systems, the parapet and the handrail were fixed.

1.2 - DESIGN Preliminary Concept

The construction of the first model not only stimulated our plastic research, but also increased our confidence in the solidity of the adopted shape.

Initially the beam was thought just as a load-bearing element onto which some plates made of pultrused products (walking zone), the fixed systems, the parapet and the handrail were fixed.

1.2 - DESIGN Final Concept

By actually handling the object, we gradually discover it, approaching more and more closely the reality to build. So the idea of crossing the bridge going inside the beam instead of on it gained footing.

By transforming the beam inside into a transit zone and crossing in a real spatial experience, we develop a number of openings which aesthetically lighten the beam, but which also play the role of windows on the surrounding territory

1.2 - DESIGN Scaled model of the foot-bridge

Also the internal aspects is strongly relevant. Space is decomposed in shadow and light zones, yielding a sort of kaleidoscopic geometrization which modifies its own aspect during daytime.

We have further improved body geometry by setting up a new model which is then produced exactly as in reality, i.e. by means of a mold.

2.1 – MATERIAL CHARACTERIZATION Mechanical and Physical properties

The adhesion properties, with and without ageing treatment, in order to obtain the characteristics of the glue best suited to composite-composite and to composite-foam combinations.

•  Laminates physical properties: traction (ISO 527-1/4/5), compression (ISO-14126), and bending (ISO-14125).

Essentially, the fallowing test are carried on:

•  Sandwich Flexural and Shear Stiffness properties (ASTM D 7250M, C 393M)

2.1 – MATERIAL CHARACTERIZATION Physical and durability properties

The specimens have been subjected to artificial accelerated ageing by a climatic chamber able to simulate the weathering. The ageing was based on the repeated exposure of the specimens to the main weathering agents, such as rain, temperature, freeze/thaw cycles, humidity and sunlight.

Durability properties, for the verification of resistance to atmospheric, environmental and UV ageing.

2.2 - DIMENSIONING Finite Elements Model

Dimensioning, verification and structural optimization was carried out by means of the Finite Element (FEM) software Ansys 13.0

( TETTO:

Top layout core = 30 mm

Lateral layout core = 20 mm Bottom layout core = 40 mm

Joint layout

L7 CC283 ; s = 0.3 mm; 0° L6 CC283 ; s = 0.3 mm; 45° L5 CC283 ; s = 0.3 mm; 90° L4 CORE : AIREX ; s = 30 mm L3 CC283 ; s = 0.3 mm; 90° L2 CC283 ; s = 0.3 mm; -‐45° L1 CC283 ; s = 0.3 mm; 0° L7 CC283 ; s = 0.3 mm; 0° L6 CC283 ; s = 0.3 mm; 45° L5 CC283 ; s = 0.3 mm; 90° L4 CORE : AIREX ; s = 20 mm L3 CC283 ; s = 0.3 mm; 90° L2 CC283 ; s = 0.3 mm; -‐45° L1 CC283 ; s = 0.3 mm; 0°

L7 CC283 ; s = 0.3 mm; 0° L6 CC283 ; s = 0.3 mm; 45° L5 CC283 ; s = 0.3 mm; 90° L4 CORE : AIREX ; s = 40 mm L3 CC283 ; s = 0.3 mm; 90° L2 CC283 ; s = 0.3 mm; -‐45° L1 CC283 ; s = 0.3 mm; 0°

L12 CC283 ; s = 0.3 mm; 0° L11 CC283 ; s = 0.3 mm; 45° L10 CC283 ; s = 0.3 mm; 90° L9 CC283 ; s = 0.3 mm; 90° L8 CC283 ; s = 0.3 mm; -‐45° L7 CC283 ; s = 0.3 mm; 0° L6 CC283 ; s = 0.3 mm; 0° L5 CC283 ; s = 0.3 mm; 45° L4 CC283 ; s = 0.3 mm; 90° L3 CC283 ; s = 0.3 mm; 90° L2 CC283 ; s = 0.3 mm;-‐ 45° L1 CC283 ; s = 0.3 mm; 0°

2.2 - DIMENSIONING Finite Elements Analysis – Static behavior

[mm]

The computed foot-bridge dimensions are: length 18.0 m; width 4.2 m and height 2.4 m;

Boundary conditions were defined in a way to simulate the action of a pedestrian 4.0 kN/m2 on the walkable surface; wind loads of 1.2 kN/m and Snow load of 0.8 kN/m.

Analysis use loads combination, based on SIA (Swiss Society of Engineers and Architects) codes, which try to excite the instability of the critical elements.

2.2 - DIMENSIONING Modal and dynamic Simulations

The vertical vibration frequency is 8.6 Hz and lateral vibration frequency is 6.2 Hz. it is satisfied with the SIA design requirements of 4.5 Hz as minimal frequency.

Tsai-Wu failure criteria was used to verify the delamination of materials.

2.4 - MANUFACTURING 1:1 scale model

The first step for the mold construction is to create a perfectly designed reverse mold of the final piece. To do that, a 1:1 scale model has been realized in polyurethane material

2.4 - MANUFACTURING 1:1 scale model

The first step for the mold construction is to create a perfectly designed reverse mold of the final piece. To do that, a 1:1 scale model has been realized in polyurethane material

After the milling phase, the model has been accurately painted and polished

2.4 - MANUFACTURING Mold realization

The 1:1 polyurethane scale model has been use to obtain the reverse mold in glass fiber material reinforced with a steel reticular structure.


All the semi-modules are been laminated using vacuum bag laminating technique that uses atmospheric pressure as a clamp to hold laminate plies together.


After the lamination of the external skins and the assembly phase with internal core material, the semi-modules was post-cured and finished.


Two semi-models are glued together using an extremely high strength structural adhesive. The complete module will be post-cured for 24 h.

2.4 - MANUFACTURING Assembly

Internally, Steel beams are used to align modules and to support axial loads.

Externally, modules are joined together by two bonding carbon fiber layered belts, for inside and outside bonding area of the modules.

2.4 - TESTING Mapping tensional state

The foot-bridge will be put to real service equipped with sensors aimed at mapping the tensional state in function of loads induced by different load conditions, and allowing us to verify the static calculations and check the manufacturing production quality. This will be accomplished using electrical and optical fiber strain gages and will allow, at the same time, to evaluate the peculiar features of these different devices by comparing the results they deliver.

Fiber-optic sensors embedded within composite materials represent a new branch of engineering with the potential to greatly enhance the confidence and use of these materials.

3.1 - CONCLUSIONS “Ready to listen the material’s soul”

In the history of technologies and materials, the first reaction of man is to apply the typical shapes of old, known materials to the usage of new ones.

3.1 - CONCLUSIONS “Ready to listen the material’s soul”

In the history of technologies and materials, the first reaction of man is to apply the typical shapes of old, known materials to the usage of new ones.

Now the times are mature to face composite materials through the logics pertaining to the material itself. It has to be left to future designers in next years (but something is already happening now) to interpret this challenge, which will have to aim at creating not only new structural and formal approaches, but also at conceiving spaces resulting from the meeting of matter, forces and fantasy.

ldb convergenze parallele_13

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