Carbon fibre reinforced polymer (CFRP) post-tensioned masonry diaphragm walls: prestressing, behaviour, and design recommendations

1999 ◽  
Vol 26 (3) ◽  
pp. 324-344 ◽  
Author(s):  
Ezzeldin Y Sayed-Ahmed ◽  
Shelley L Lissel ◽  
Gamil Tadros ◽  
Nigel G Shrive
Keyword(s):  
Carbon Fibre ◽  
Masonry Wall ◽  
Prestress Losses ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymers ◽  
Fibre Reinforced Polymer ◽  
Diaphragm Walls ◽  
Post Tensioning ◽  
Post Tensioned

The use of post-tensioned masonry can lead to economic and elegant structures. A major problem associated with post-tensioning is the corrosion of the steel tendons, especially for unbonded tendons. If carbon fibre reinforced polymer (CFRP) tendons could be used to replace the traditional steel tendons, the corrosion problem would be overcome. However, a number of issues need to be resolved before CFRP tendons can be used comfortably in post-tensioning applications. The first part of this paper deals with a diaphragm wall post-tensioned using CFRP tendons. The post-tensioning procedures are described and the prestress losses occurring in the past 12 months are presented. Results from thermal, flexure, and racking shear tests performed on the wall are reported. The second part of the paper deals with the development of design procedures and equations based on both the test results and the database currently available. The equations presented are specifically for CFRP unbonded post-tensioned masonry diaphragm walls but with appropriate modification could be applied to the design of any CFRP post-tensioned masonry wall. A design example is included.Key words: anchorage system, carbon fibre reinforced polymers, diaphragm walls, flexural strength, masonry walls, prestress losses, prestressed masonry, post-tensioning, shear strength, thermal loads.

scholarly journals Shear in plain, bed joint reinforced, and post-tensioned masonry

2000 ◽  
Vol 27 (5) ◽  
pp. 1021-1030 ◽  
Author(s):  
Shelley L Lissel ◽  
Nigel G Shrive ◽  
Adrian W Page
Keyword(s):  
Shear Strength ◽  
Substantial Effect ◽  
Cycle Basis ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Diaphragm Walls ◽  
Post Tensioning ◽  
The Web ◽  
Post Tensioned

Masonry is cost competitive on a life cycle basis with other forms of construction, and should therefore be considered as a structural material more frequently by both architects and engineers. Post-tensioned geometric sections of masonry are structurally efficient wall systems. Post-tensioning with carbon fibre reinforced polymer (CFRP) is an attractive solution to potential corrosion problems with unbonded tendons. Tests on CFRP post-tensioned diaphragm walls have revealed that shear strength in prestressed masonry is an area deserving more study and improvement. The tests also showed that the bonding pattern of the masonry at the web-flange junction can have a substantial effect on the resulting strength of that connection. A test series to evaluate the effects of prestress force and bed reinforcement on shear strength has been carried out and a summary of the results is presented here. Tests to determine the effect of bonding pattern on the strength of the web-flange connection have also been conducted.Key words: post-tensioning, masonry, shear, FRP tendons, corrosion-free.

Design of carbon fibre reinforced polymer post-tensioned masonry diaphragm retaining walls

2005 ◽  
Vol 32 (3) ◽  
pp. 579-594 ◽  
Author(s):  
S L Lissel ◽  
N G Shrive ◽  
J Gilliland
Keyword(s):  
Carbon Fibre ◽  
Monitoring Program ◽  
Retaining Walls ◽  
Prestressing Force ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Post Tensioning ◽  
The University ◽  
Post Tensioned

Two masonry diaphragm retaining walls were constructed on the University of Calgary campus and post-tensioned with carbon fibre reinforced polymer (CFRP) tendons. As these are the first masonry diaphragm walls post-tensioned with CFRP tendons outside of a laboratory, one objective in the design was to provide a wide margin of safety, especially concerning the effective, or sustained, prestressing force and losses. The tendons are unbonded, so guidance chairs were placed during construction to meet the requirements of the clauses expected in the next edition of the Canadian masonry design code. Research has shown that the strength of masonry to resist shear in the webs is enhanced by the normal stress induced by post-tensioning, so this was used in the design. The webs of the walls interlock with the flanges, imposing restrictions on the spacing of the webs. A centre-to-centre spacing of 500  mm was selected, with one tendon per cavity. The design of the walls and capping beams is detailed, and the construction sequence and monitoring program are described briefly. Key words: post-tensioning, masonry, retaining walls, design, FRP tendons, corrosion free

Flexural behaviour of concrete beams strengthened with prestressed carbon fibre reinforced polymer sheets subjected to sustained loading and low temperature

2004 ◽  
Vol 31 (2) ◽  
pp. 239-252 ◽  
Author(s):  
Raafat El-Hacha ◽  
Mark F Green ◽  
R Gordon Wight
Keyword(s):  
Low Temperature ◽  
Carbon Fibre ◽  
Flexural Behaviour ◽  
Prestress Losses ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Prestressed Cfrp Sheets

This paper presents results of an experimental investigation that examined concrete beams post-tensioned with bonded carbon fibre reinforced polymer (CFRP) sheets and then exposed to either room (+22 °C) or low (-28 °C) temperatures. The primary objective of this investigation was to assess the flexural behaviour of the strengthened beams after sustained loadings at both room and low temperatures. The strengthened beams showed significant increases in flexural stiffness and ultimate capacity as compared with the control-unstrengthened beams. Failure of the strengthened beams was by tensile rupture of the prestressed CFRP sheets. Test results showed that the long-term and low temperature effects did not adversely affect the strength of the beams. Long-term loading and low temperature exposure caused prestress losses in the CFRP sheets. The load–deflection behaviour of the long-term beams was predicted accurately by an analytical model. These results suggest that bonded prestressed CFRP sheets could be used to increase the strength of damaged prestressed concrete girders under extreme environmental conditions.Key words: strengthening, anchorage, low temperature, long-term, prestress losses, sustained load, carbon fibre reinforced polymer sheet.

Fatigue behaviour of concrete beams post-tensioned with unbonded carbon fibre reinforced polymer tendons

2006 ◽  
Vol 33 (9) ◽  
pp. 1140-1155 ◽  
Author(s):  
Abass Braimah ◽  
Mark F Green ◽  
T Ivan Campbell
Keyword(s):  
Carbon Fibre ◽  
Concrete Beams ◽  
Fatigue Behaviour ◽  
Reinforced Concrete Beams ◽  
Premature Failure ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Prestressing Strands ◽  
Post Tensioned

Much research has been conducted in the past decade to evaluate the suitability of fibre reinforced polymer (FRP) reinforcement in concrete structures. Most of the research has concentrated on the short-term performance of FRP prestressed and reinforced concrete beams. Only a limited amount of research has considered the fatigue behaviour of FRP prestressed beams. This paper presents an experimental research program designed to examine the fatigue behaviour of unbonded carbon fibre reinforced polymer (CFRP) post-tensioned concrete beams. The fatigue test program consisted of five large-scale (4.0 m span) concrete T-beams. Three of the beams were post-tensioned with CFRP tendons, and the remaining two beams were post-tensioned with steel prestressing strands. The fatigue load limits were chosen to produce an additional stress range of about 100 MPa in the lower prestressing reinforcement. During fatigue testing, some of the prestressing strands fractured at the anchor location. In the steel post-tensioned beams, fracture of wires in the seven-wire prestressing strands did not result in total failure of the steel post-tensioned beams, as the unbroken wires continued to carry prestress force. In the CFRP post-tensioned beams, however, fracture led to splintering of the tendon between the anchors and total loss of prestress force. In general, the CFRP post-tensioned beams performed satisfactorily in fatigue, in comparison with the steel post-tensioned beams, as long as premature failure of the tendons near the anchor location was prevented.Key words: fibre reinforced polymer (FRP), anchorage, tendon, fatigue, post-tension, concrete, beam, dynamic, testing.

Effect of overloading on fatigue performance of reinforced concrete beams strengthened with externally post-tensioned carbon-fibre-reinforced polymer tendons

2008 ◽  
Vol 35 (11) ◽  
pp. 1294-1307 ◽  
Author(s):  
Ahmed Elrefai ◽  
Jeffrey S. West ◽  
Khaled A. Soudki
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Carbon Fibre ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fatigue Performance ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Post Tensioned

This paper presents the results of an experimental and analytical study of the fatigue performance of reinforced concrete beams strengthened with externally post-tensioned carbon-fibre-reinforced polymer (CFRP) tendons. Two loading conditions prior to strengthening the beams were investigated: in-service loading and overloading. A total of 18 beams were tested to failure: three under monotonic loading and fifteen under fatigue loads. The CFRP tendons were post-tensioned to 40% of their ultimate capacity. The results demonstrated that overloading the beams had no discernable effect on the fatigue life of the strengthened beams. The strain-reduction approach for unbonded steel tendons was modified to account for using CFRP tendons and for the permanent deformations resulting from the overloading process. The loading history of the beams prior to and after post-tensioning was incorporated into a strain-life fatigue model to predict the fatigue life of the strengthened beams.

Influence of Ply Stacking Sequences on the Impact Response of Carbon Fibre Reinforced Polymer Composite Laminates

2019 ◽  
Author(s):  
Kristian Gjerrestad Andersen ◽  
Gbanaibolou Jombo ◽  
Sikiru Oluwarotimi Ismail ◽  
Segun Adeyemi ◽  
Rajini N ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Polymer Composite ◽  
Composite Laminates ◽  
Impact Response ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
The Impact
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