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The composite tower of Valencia
The composite tower of Valencia A tall structure made entirely from reinforced plastics? We’ve built one, say Spanish engineers. Liz Nickels takes a look at the Torre Rovira project.
A
Spanish university and a pultrusion company say they have built the highest tower ever made entirely of plastic composite materials, in Valencia, Spain. Make that almost entirely: according to the manufacturers, the only parts of the tower that are not made of composites are the bolts and supports of the foundation attachments, which are made of steel. The Torre Rovira is named after the professor who led the project to design and build the tower, Professor Juan
The bottom part of the tower is lowered into place.
34
REINFORCEDplastics
June 2004
Antonio Rovira. He is head of the Department of Mechanics of Continuous Media and Structures Theory (Departamento de Mecánica de los Medios Continuos y Teoría de Estructuras) at the Polytechnic University of Valencia. The tower was designed, developed and tested in the university, while pultrusion specialist Tadipol, based in Barcelona, manufactured most of the parts and helped build the tower. Tadipol says that the tower was conceived to be an eye-catching landmark which could display the entrance to the
university from far away. The manufacturers also wanted to test the boundaries of what can now be achieved using reinforced plastics in building projects – and show off the results. While the use of fibre reinforced plastics (FRP) as building materials is increasing, many people still think that using only composites to build a large, rigid structure is practically impossible.
The tower The tower is 44 m high and 8.5 m in diameter at the base, tapering to 1 m in diameter at the crown. It is topped with a decorative glass sphere and a sign displaying the name of the university (‘Universidad Politécnica’) and a 2 m high lightning conductor. The tower’s structure incorporates parts and joints made of a variety of FRP and moulded using a variety of processes. The base of the tower is made up of 12 struts made of glass fibre reinforced isophthalic vinyl ester, made by a pultrusion process. The struts are placed geometrically equidistant to each other, forming a dodecagon (12-sided) shape. The dodecagon shape of the struts at the base of the tower tapers from an average diameter of 8.5 m at the base, to a diameter of 2.4 m up to a height of 10.9 m through what the manufacturers call a ‘determined curvature’. At this point the 12 struts are reduced to six, forming a hexagon shape. The struts provide vertical support for the rest of the tower, which is made up of circular rings made of glass fibre reinforced vinyl ester and placed every 2 m 0034-3617/04 ©2004 Elsevier Ltd. All rights reserved.
The composite tower of Valencia
up to a height of 10.9 m. Above this, two rings (exterior and interior) are joined to each section, while in the parts of the tower above 12 m, rings are only fixed to the exterior, except at the highest point where the sphere and university sign are fixed to the main structure. Between the heights of 23.4 m and 35.8 m, each side of the structure is supported by parts made of glass reinforced vinyl ester. The university sign at the top of the tower is at the 31.2 m point of the tower and is attached to the main structure by means of six trusses made from pultruded glass reinforced vinyl ester. The supporting structure for the sign is made from a glass fibre reinforced polyester laminate which is 6 mm thick. The sphere placed above the sign is 2 m in diameter and made of glass reinforced polyester laminate coloured black. It is fixed to the main structure of the tower by means of glass fibre reinforced vinyl ester.
Material strength compared to metals Tensile strength
FRP
Steel
Aluminium
Maximum load (MPa)
>600
500
400
Elastic modulus (Gpa)
>40
210
70
Maximum load (MPa)
>100
500
400
Elastic modulus (GPa)
>10
210
70
In the axis direction
In the transverse direction
Flexural strength In the axis direction Maximum load (MPa)
>600
500
400
Elastic modulus (GPa)
>40
210
70
In the transverse direction Maximum load (MPa)
>200
500
400
Elastic modulus (GPa)
>12
210
70
Compression strength In the axis direction Maximum load (MPa)
>300
In the transverse direction Maximum load (MPa)
>30
Table taken from ‘Construction of a tower with pultruded FRP composites’, Journal of the International Association for Shell and Spacial Structures, vol 41.
Joints and bolts All the joints used in the structure are fixed with nuts, bolts and washers made of glass reinforced vinyl ester, except for the ring of the attachment plate and the fixing-pin, which are made of steel. The internal and external rings are stiffened by bolted joints to ensure they can withstand compression and torsion forces, say the manufacturers, while articulated joints are used to attach the 12 pultruded struts to the base. They say that some of the joints were specially designed for the structure.
Processing According to the manufacturers, the processing method used to produce the composite components varied according to the part being produced. It says that the rings, articulation joints, sphere and seals were manufactured by traditional hand lay-up, (hand laminates, in the case of the rings) while the bolts, base struts, trusses, washers, sockets caps, nuts and cables were manufactured via the pultrusion process.
The top half of the tower is made ready to be fitted onto the bottom half.
June 2004
REINFORCEDplastics
35
The composite tower of Valencia
Once moulded, the components were transported by road to the final building site. The manufacturers says that they were made in different stages in order to be easily transportable in this way. This meant that they had to create special components to connect the tower parts on site. All of these components are made from hand laid-up FRP.
The end result
Finally, the topmost part of the tower is prepared to complete the structure.
Tadipol; website: www.tadipol.com. Departamento de Mecánica de los Medios Continuos y Teoría de Estructuras, Universidad Politécnica de Valencia; website: www.mes.upv.es.
The finished tower is 44 m high.
36
REINFORCEDplastics
After testing the strength of the material (see table, page 35) the manufacturers say that they went on to test various structural prototypes made of pultruded parts with adhesive bonded joints to check the combined response to testing. They also carried out static model testing, lineal elastic testing, model analysis and dynamic analysis. The manufacturers say that the testing allowed them to make materials that were fatigue resistant enough to give the tower structural integrity and withstand winds of up to 160 km/hr. They made the lower third of the structure more rigid than the upper part, so that it could act as an embedded base for the rest of the tower. They also say that the project incorporated innovative elements, such as the use of a handling process to make the construction of curved elements possible and using pinned, rather than bolted joints. They claim that the tower requires no maintenance and has an excellent surface finish. Tadipol maintains that the success of the tower project is due particularly to using the pultrusion process to manufacture parts. Because this process is not limited only to high technology and specialised crafts, but can also be used to produce industrial parts, the company thinks that it will be increasingly used for this kind of large-scale project. ■
June 2004
A
Spanish university and a pultrusion company say they have built the highest tower ever made entirely of plastic composite materials, in Valencia, Spain. Make that almost entirely: according to the manufacturers, the only parts of the tower that are not made of composites are the bolts and supports of the foundation attachments, which are made of steel. The Torre Rovira is named after the professor who led the project to design and build the tower, Professor Juan
The bottom part of the tower is lowered into place.
34
REINFORCEDplastics
June 2004
Antonio Rovira. He is head of the Department of Mechanics of Continuous Media and Structures Theory (Departamento de Mecánica de los Medios Continuos y Teoría de Estructuras) at the Polytechnic University of Valencia. The tower was designed, developed and tested in the university, while pultrusion specialist Tadipol, based in Barcelona, manufactured most of the parts and helped build the tower. Tadipol says that the tower was conceived to be an eye-catching landmark which could display the entrance to the
university from far away. The manufacturers also wanted to test the boundaries of what can now be achieved using reinforced plastics in building projects – and show off the results. While the use of fibre reinforced plastics (FRP) as building materials is increasing, many people still think that using only composites to build a large, rigid structure is practically impossible.
The tower The tower is 44 m high and 8.5 m in diameter at the base, tapering to 1 m in diameter at the crown. It is topped with a decorative glass sphere and a sign displaying the name of the university (‘Universidad Politécnica’) and a 2 m high lightning conductor. The tower’s structure incorporates parts and joints made of a variety of FRP and moulded using a variety of processes. The base of the tower is made up of 12 struts made of glass fibre reinforced isophthalic vinyl ester, made by a pultrusion process. The struts are placed geometrically equidistant to each other, forming a dodecagon (12-sided) shape. The dodecagon shape of the struts at the base of the tower tapers from an average diameter of 8.5 m at the base, to a diameter of 2.4 m up to a height of 10.9 m through what the manufacturers call a ‘determined curvature’. At this point the 12 struts are reduced to six, forming a hexagon shape. The struts provide vertical support for the rest of the tower, which is made up of circular rings made of glass fibre reinforced vinyl ester and placed every 2 m 0034-3617/04 ©2004 Elsevier Ltd. All rights reserved.
The composite tower of Valencia
up to a height of 10.9 m. Above this, two rings (exterior and interior) are joined to each section, while in the parts of the tower above 12 m, rings are only fixed to the exterior, except at the highest point where the sphere and university sign are fixed to the main structure. Between the heights of 23.4 m and 35.8 m, each side of the structure is supported by parts made of glass reinforced vinyl ester. The university sign at the top of the tower is at the 31.2 m point of the tower and is attached to the main structure by means of six trusses made from pultruded glass reinforced vinyl ester. The supporting structure for the sign is made from a glass fibre reinforced polyester laminate which is 6 mm thick. The sphere placed above the sign is 2 m in diameter and made of glass reinforced polyester laminate coloured black. It is fixed to the main structure of the tower by means of glass fibre reinforced vinyl ester.
Material strength compared to metals Tensile strength
FRP
Steel
Aluminium
Maximum load (MPa)
>600
500
400
Elastic modulus (Gpa)
>40
210
70
Maximum load (MPa)
>100
500
400
Elastic modulus (GPa)
>10
210
70
In the axis direction
In the transverse direction
Flexural strength In the axis direction Maximum load (MPa)
>600
500
400
Elastic modulus (GPa)
>40
210
70
In the transverse direction Maximum load (MPa)
>200
500
400
Elastic modulus (GPa)
>12
210
70
Compression strength In the axis direction Maximum load (MPa)
>300
In the transverse direction Maximum load (MPa)
>30
Table taken from ‘Construction of a tower with pultruded FRP composites’, Journal of the International Association for Shell and Spacial Structures, vol 41.
Joints and bolts All the joints used in the structure are fixed with nuts, bolts and washers made of glass reinforced vinyl ester, except for the ring of the attachment plate and the fixing-pin, which are made of steel. The internal and external rings are stiffened by bolted joints to ensure they can withstand compression and torsion forces, say the manufacturers, while articulated joints are used to attach the 12 pultruded struts to the base. They say that some of the joints were specially designed for the structure.
Processing According to the manufacturers, the processing method used to produce the composite components varied according to the part being produced. It says that the rings, articulation joints, sphere and seals were manufactured by traditional hand lay-up, (hand laminates, in the case of the rings) while the bolts, base struts, trusses, washers, sockets caps, nuts and cables were manufactured via the pultrusion process.
The top half of the tower is made ready to be fitted onto the bottom half.
June 2004
REINFORCEDplastics
35
The composite tower of Valencia
Once moulded, the components were transported by road to the final building site. The manufacturers says that they were made in different stages in order to be easily transportable in this way. This meant that they had to create special components to connect the tower parts on site. All of these components are made from hand laid-up FRP.
The end result
Finally, the topmost part of the tower is prepared to complete the structure.
Tadipol; website: www.tadipol.com. Departamento de Mecánica de los Medios Continuos y Teoría de Estructuras, Universidad Politécnica de Valencia; website: www.mes.upv.es.
The finished tower is 44 m high.
36
REINFORCEDplastics
After testing the strength of the material (see table, page 35) the manufacturers say that they went on to test various structural prototypes made of pultruded parts with adhesive bonded joints to check the combined response to testing. They also carried out static model testing, lineal elastic testing, model analysis and dynamic analysis. The manufacturers say that the testing allowed them to make materials that were fatigue resistant enough to give the tower structural integrity and withstand winds of up to 160 km/hr. They made the lower third of the structure more rigid than the upper part, so that it could act as an embedded base for the rest of the tower. They also say that the project incorporated innovative elements, such as the use of a handling process to make the construction of curved elements possible and using pinned, rather than bolted joints. They claim that the tower requires no maintenance and has an excellent surface finish. Tadipol maintains that the success of the tower project is due particularly to using the pultrusion process to manufacture parts. Because this process is not limited only to high technology and specialised crafts, but can also be used to produce industrial parts, the company thinks that it will be increasingly used for this kind of large-scale project. ■
June 2004