The Development and the Future of Advanced Polymer Composites In the Civil Infrastructure.

Transcription

1 International Conference on Advanced Polymer Composites in Construction (ACIC) April University of Southampton The Development and the Future of Advanced Polymer Composites In the Civil Infrastructure. Professor Len Hollaway University of Surrey UK.

2 Advanced Polymer Composites in Construction 2002 Historical Dates st commercial synthetic polymer introduced - Bakelite Chemical structure of polymers established Glass fibre research commenced in the USA 1932 Synthetic resins glues produced in Germany Rapid development of polymers 1940s - 1 st all reinforced polymer introduced as - radomes late 1940s polymer composites continued to be used but they were expensive The attraction of the material was the ease with which it could be moulded into complex shapes. School of Engineering (Civil Engineering) University of Surrey

3 Advanced Polymer Composites in Construction 2002 Between 1950s and 1960s the material went through a bad phase in the construction industry because of *** poor manufacturing procedures by inexperienced operators. *** The main growth, interest and technology in GFRP composites in buildings and construction commenced in the latter part of the 1960s The main reason was the development of resins, catalysts and accelerators which cure at room temperature. Most important for the civil engineering industry Two principal structures which played a major role in the development of polymer composite material for construction were manufactured in the UK and shipped to their final locations in the middle-east. These were the Benzaghi Dome and the Dubai airport roof.

4 Advanced Polymer Composites in Construction 2002 The Benzaghi Dome Lybia 1970

5 Advanced Polymer Composites in Construction 2002 The Dubai Airport Roof in Dubai School Of Engineering, Civil Engineering, University of Surrey

6 Advanced Polymer Composites in Construction 2002 During the 1970s FRP building systems were constructed as part load bearing infill panel structures. Examples of these in the UK. include: (a) Mondial House, London, UK (b) Covent Garden Flower Market, London, UK (c) American Express building, Brighton, UK These structures build at this time were one-off prestigious buildings

7 Advanced Polymer Composites in Construction 2002 Covent Garden Flower Market London

8 Advanced Polymer Composites in Construction 2002 In 1974 the first all polymer composite structure using the building block technique was built. This was a classroom structure conceived and erected by Lancashire County council UK. The building block technique consists of manufacturing a unit Building block and forming the complete structure with such units

9 Advanced Polymer Composites in Construction 2002 GFRP Composite Class Room System conceived by Lancashire County Council UK.

10 Advanced Polymer Composites in Construction 2002 Double layer skeletal structure manufactured from pultruded tubes

11 Advanced Polymer Composites in Construction 2001 In the mid-1980s, it was realised that, if all FRP Composite structures were to be developed, the complete system should be developed and manufactured from an automated unit building block. School Of Engineering, Civil Engineering, University of Surrey

12 Advanced Polymer Composites in Construction 2002 The first FRP composite automated building block was designed by Maunsell Structural Plastics, London, UK. (known as the Maunsell Plank). School Of Engineering, Civil Engineering, University of Surrey

13 Advanced Polymer Composites in Construction 2002 Maunsell Plank and a box beam section

14 Advanced Polymer Composites in Construction 2002 Using this system the following well known All Polymer Composite Structures were manufactured: (1) The Aberfeldy Bridge. (Using single Maunsell Planks). (2) Bonds Mill Bridge. (Using the box beam system formed from 10 number Maunsell Planks). (3) The 2 nd Severn Crossing Contract Office. (Using single Maunsell Planks to form the enclosure units).

15 Advanced Polymer Composites in Construction 2002 Opening ceremony of the Bonds Mill Lift-bridge Gloucestershire UK. - May 1994 ( Span 8.2 m, Width 4.27m)

16 Advanced Polymer Composites in Construction 2002 Further all polymer composite systems used, as a building block, were introduced into construction in the late 1990: Composite Bridge Decks To replace conventional degraded deck systems in minimum time. Durable lightweight easy installation systems have been produced in advanced composites.

17 Advanced Polymer Composites in Construction 2002 An all composite bridge deck being developed by a European consortium (ASSET) - Section of ASSET deck unit. (Courtesy of Mouchel Consultants, West Byfleet, UK.)

18 Advanced Polymer Composites in Construction 2002 Future challenge for FRP decks There is a growing interest in these structures particularly in the USA but there are technical needs and questions to be addressed. (1) Development of design standards and guidelines (2) Efficient design and characterization of panel-topanel joints and attachment of decks to stringers. (3) Fatigue behaviour of panels and connections. (4) Durability characteristics under combined mechanical and environmental loads. (5)Failure mechanisms and ultimate strength, including local and global buckling modes

19 Advanced Polymer Composites in Construction 2001 There will always be a place in construction for all polymer composite structures & composite bridge decks are an important growth area but The current trends for Advanced Polymer Composites is in the form of a combination of APCs and the more conventional materials Polymer composites and concrete, acting compositely in conjunction with each other, were introduced in the early 1990s. The various forms of combinations under broad headings are: (a) Upgrading and retrofitting to structural beams and columns (b) Non-metallic rebars (c) Combination of advanced polymer composite/concrete structural units; the two materials act compositely with each other.

20 Advanced Polymer Composites in Construction 2002 (a) Upgrading and retrofitting of structures and structural units. Structures may require to be strengthened for a number of reasons: Design deficiencies Inferior materials Poor construction, workmanship/management

21 Advanced Polymer Composites in Construction 2002 There is a choice between strengthening [or demolition] (i) Flexural strengthening Bonding a rigid plate, (CFRP), on to the soffit of the beam. This plate can be applied either as an unstressed or prestressed plate. Or Wrapping with a carbon fibre prepreg wrap. Flexural strengthening is generally though of in terms of RC beams but it can also be undertaken on metallic structures. The design approach for plated RC and metallic beams is completely different.

22 Advanced Polymer Composites in Construction 2002 (ii) Shear strengthening Bonding a plate on to the vertical sides of beams Wrapping prepreg composites around the sides and soffit

23 Advanced Polymer Composites in Construction 2002 Flexural strengthening Un-stressed plate R W W R Beam CFRP Plate Adhesive layers CFRP Plate R W W R Beam CFRP Plate CFRP Plate Lateral support during Polymerisation

24 Advanced Polymer Composites in Construction 2002 Flexural strengthening Process of Prestressing FRP plate W Part- Beams W External load Prestress Force P Adhesive CFRP plate R Prestress Force P R Plate prestress applied and adhesive applied to plate and beam Plate bonded to beam plate still under external prestress

25 Advanced Polymer Composites in Construction 2002 W R.C. Beams W R P R Plate end anchorage fitted (bonded bolt shown) Prestress release

26 Advanced Polymer Composites in Construction Shear Strengthening Pins (a) (b) Various methods of wrapping FRP composites on to the sides of a Tee RC beam (a) FRP wrapped entirely around the beam (b) FRP wrap in the form of a U (either with or without pin fixings) (c) FRP wrap bonded to the two sides of the beam (c)

27 Advanced Polymer Composites in Construction 2002 There are now design guidance for the strengthening concrete structures using FRP materials, in various countries these are:- The UK - The technical Report No 55. (Concrete Society) (2000) Europe-fibTG9.3, FRP Reinforcement for Concrete Structures(2001) Canada - The ISIS-MO5-00 (ISIS Report) (2001) USA - American Concrete Institute (ACI) Committee 440 Guide Japan - JSCE Concrete Committee, Recommendations for upgrading of Concrete Structures with Use of CFRP sheets (2000) A Scandinavian design guide approach (2001)

28 Advanced Polymer Composites in Construction 2001 The design codes for the CFRP plate bonding of metallic structures is different from that for RC structures. The design guide currently in existence is:- The Institution of Civil Engineers London UK. :- ICE design and practice FRP Composites - Life extension and strengthening of metallic structures (2001). A design guide currently being developed for the CIRIA (UK.) is:- RP 645: Strengthening existing metallic structures using externally bonded FRP (2002). School Of Engineering, Civil Engineering, University of Surrey

29 Advanced Polymer Composites in Construction FRP jacket fibre wrapped in the hoop direction Reinforced concrete column Maximum FRP jacket stress Main direction of fibres (in the hoop direction) Axial compressive stress FRP wrap Unreinforced concrete Axial strain Wrapping of prepreg composite around concrete column

30 Advanced Polymer Composites in Construction External FRP reinforcement for impact resistance at Sycamore footbridge Warrington Eleven layers of vertically aligned and two layers of horizontally wound carbon fibre composite sheets for car and lorry impact resistance

31 Advanced Polymer Composites in Construction (b) Composite rebars Used for specialised work in construction such as: (i) Flexural and shear reinforcement (ii) Prestressing tendons in concrete structures If correctly formulated they should prove more desirable than conventional steel in aggressive environments

32 School of Engineering (Civil Engineering) University of Surrey Advanced Polymer Composites in Construction 2002 (c) Combination of advanced polymer composites with conventional materials, in particular concrete, (although any material could be used) to produce a duplex unit in which the two materials are used to their best advantage: (a) Manufacture of beams (b) Manufacture of columns (c) Manufacture of structural units of say composite skeletal members and a continuum plate as the top member. Consider a beam system consisting of two materials concrete in compression and advanced polymer composite in tension.

33 Advanced Polymer Composites in Construction N (a)... Shear reinforcement not shown (b)... Shear reinforcement not shown (c) A N Steel rebars (d) A + shear links N FRP rebars (e) A Concrete CFRP plate Strain Diag. GFRP webs to take shear force CFRP flange CFRP flange Hybrid CFRP/GFRP/concrete beam

34 Advanced Polymer Composites in Construction Permanent shuttering mm plywood plate CONCRETE Two plies of +/- 45 o GFRP manufactured from XLTM65U prepreg Eight plies of 0/90 o CFRP from XLTM65U prepreg 80 Cross-section of Tee beam of composite/concrete construction.

35 Advanced Polymer Composites in Construction metre beam placed in a vacuum bag and prepared for the oven at 65 C for 18 hours - the shear web stiffeners, encapsulated into prepreg, are clearly visible. [BRITE/EURAM Contract COMPCON] (Courtesy of Dragados Spain)

36 Advanced Polymer Composites in Construction 2002 The 17 metres long composite/concrete beam test set-up at Taylor Woodrow s Laboratories (Kind permission of Taylor Woodrow Southall UK)

37 Advanced Polymer Composites in Construction metre span beam under continuous loading at Dragados factory area [Brite/Euram Contract COMPCON] (Courtesy of Dragados Spain)

38 Advanced Polymer Composites in Construction metre innovative polymer composite/concrete bridge under test load in Australia (By kind permission of Prof. G Van Erp)

39 Advanced Polymer Composites in Construction (b) Concrete filled filament wound composite tubes The advantages of these systems are: Concrete core prevents buckling of the hollow FRP tubes FRP tube confines the concrete and increases strength and ductility The best characteristics of the individual materials are utilised The systems are used for two reasons 1. To produce non-corrosive columns and piles 2. To enhance the ductility of the system

40 Advanced Polymer Composites in Construction Helical rib on the inside of a carbon filament wound pipe.(courtesy of V. Karbhari and F. Seible)

41 Advanced Polymer Composites in Construction Challenges of and the way forward for FRP materials in the civil infrastructure FRP has been successfully implemented into the infrastructure over a number of years. However, there are many problems still to be solved, some of these are: (a) Long term durability (50+ years) is required to be determined The CERF (ASCE) undertook a Gap Analysis and has identified seven areas where long term durability and performance data are required : (1) environment (2) Alkaline environment (3) Thermal effects (4) Creep and relaxation effects (5) U.V. effects (6) Fatigue performance (7) Fire performance

42 Advanced Polymer Composites in Construction Educate the civil engineering/construction industry and the composites communities in the method and development in composites for construction. (responsibility of Universities and design centres). Recent advances in materials, manufacturing techniques and design of composites have all indicated the continued development of innovative materials and structural systems that will enable: 1. Synthetic forms and functions to be undertaken. 2. Greater emphasis to be given to the aesthetic and the integration of the structure into the environment. 3. Use of intelligent, self monitoring of structural systems.

43 Advanced Polymer Composites in Construction Observations (a) Advanced polymer composites (APCs) are exciting and valuable materials to be use in the civil infrastructure, but they must be designed and installed according to existing design guides and best practice rules if a rejection of composites and a re-occurrence of the disasters of the 1960s are to be avoided (b) Currently and into the foreseeable future the APC will be combined with the more conventional materials to be formed into structural units (c) Only very specialised structures will be manufactured wholly from APCs (d) APCs possess excellent mechanical and in-service properties which are generally superior to the more conventional materials in corrosive environments. (e) Advanced polymer composites are now important materials, along-side concrete and steel, all these materials must be considered and the most appropriate one used by engineers when designing for civil construction. (f) In civil engineering the most suitable material must be used when designing.